John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

GEOLOGY AND PALEOENVIRONMENTS OF THE CLARNO UNIT John Day Fossil Beds National Monument, Oregon

By Erick A. Bestland, PhD Erick Bestland and Associates, 1010 Monroe St., Eugene, OR 97402

Gregory J. Retallack, PhD Department of Geological Sciences University of Oregon Eugene, OR 7403-1272

June 28, 1994

Final Report NPS Contract CX-9000-1-10009

TABLE OF CONTENTS

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

TABLE OF CONTENTS

COVER

ABSTRACT

ACKNOWLEDGEMENTS

CHAPTER I: INTRODUCTION AND REGIONAL GEOLOGY

INTRODUCTION

PREVIOUS WORK AND REGIONAL GEOLOGY Basement rocks Clarno Formation John Day Formation

CHAPTER II: GEOLOGIC FRAMEWORK

INTRODUCTION Stratigraphic nomenclature Radiometric age determinations

CLARNO FORMATION LITHOSTRATIGRAPHIC UNITS Lower Clarno Formation units Main section

JOHN DAY FORMATION LITHOSTRATIGRAPHIC UNITS Lower Big Basin Member Middle and upper Big Basin Member Turtle Cove Member

GEOCHEMISTRY OF LAVA FLOW AND TUFF UNITS Basaltic lava flows Geochemistry of andesitic units Geochemistry of tuffs

STRUCTURE OF CLARNO UNIT AREA Structural analysis of folded strata

SEDIMENTATION AND VOLCANISM Clarno Formation depositional setting John Day Formation depositional setting

LATE EOCENE PALEOCLIMATE AND TECTONICS

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Step-wise change in paleosol weathering trends

CHAPTER III: PALEOSOLS AND PALEOENVIRONMENTS

INTRODUCTION

FEATURES OF THE PALEOSOLS Traces of land life Soil horizons Soil structure

BURIAL ALTERATION OF PALEOSOLS

DESCRIPTION AND INTERPRETATION OF PEDOTYPES Acas paleosols Cmuk paleosols Lakayx paleosols Lakim paleosols Luca paleosols Luquem paleosols Micay paleosols Pasct paleosols Patat paleosols Pswa paleosols Sayayk paleosols Scat paleosols Sitaxs paleosols

CHAPTER IV: PALEOENVIRONMENTAL SUMMARY

Deposition of Clarno volcaniclastic deposits Deposition of "Red Hill" claystones Deposition of "Mammal Quarry" siltstones Summary

REFERENCES

APPENDICES

Appendix 1. Individual named paleosols in the Clarno area Appendix 2. Textures of paleosols Appendix 3. Mineral composition of the paleosols Appendix 4. Chemical analysis of the paleosols Appendix 5. Trace element analysis of the paleosols Appendix 6. Molecular weathering ratios of the paleosols Appendix 7. Radiometric age data Appendix 8. Chemical analysis of igneous rocks Appendix 9. New fossil collections Appendix 10. Checklist of middle Clarno fossils Appendix 11. Checklist of upper Clarno fossils Appendix 12. Checklist of late Eocene John Day fossils Appendix 13. Checklist of early Oligocene John Day fossils Appendix 14. Checklist of late Oligocene fossils

GLOSSARY

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

ABSTRACT

The Clarno Unit of the John Day Fossil Beds National Monument includes a complex sequence of Eocene volcaniclastic sediments, volcanic flows and intrusions. Through section description and mapping in this type area of the Clarno Formation we have generated a geologic framework for numerous fossil sites, including several newly discovered sites.

Two widespread conglomeratic units of andesitic composition in the middle Eocene (Bridgerian-Uintan) part of the Clarno Formation are separated by red claystones including several paleosols. The lower unit, conglomerates of the Palisades, consists of channel and floodplain debris-flow conglomerates and hyperconcentrated flood flow or lahar runout deposits. The overlying conglomerates of Hancock Canyon also contain channel and floodplain debris-flow conglomerates, but have in addition, fluvially reworked conglomerates and pebbly sandstones, reworked tuff beds, a distinctive amygdaloidal basalt flow and the "Nut Beds" fossil site. The Palisades unit is interpreted as a debris flow apron on which there was little fluvial reworking. The Hancock Canyon unit is interpreted as a debris flow apron to a braidplain in an area of complex topography, including hills of a pre-existing dacite intrusion. Both accumulated on footslopes of a large andesitic stratovolcano.

Above the conglomerates are thick but discontinuous red claystones, which record a long period of local volcanic quiescence, slow floodplain aggradation and soil formation. An abrupt climatic change is inferred during accumulation of the red beds because the lower sequence of paleosols is mainly Ultisols, whereas the upper sequence is mainly Alfisols. The fossil Ultisols, like paleosols and fossil plants from the "Nut Beds" can be taken as evidence of a climate that was subtropical (mean annual temperature or MAT 23-25°C) and humid (mean annual precipitation of MAP of 1500-2000 mm). Both fossil plants and soils are more like those of modern southern Mexico, than northern Mexico or Central America. Most fossil plants were transported, but aguacatilla (Meliosma) dominated paleosols of both swamps and lowland colonizing forest, and fresh ash was colonized by ferns (Saccoloma) and fresh alluvium by horsetails (Equisetum). Permineralized forests with sycamore (Macginitea) and katsura (Joffrea) of temperate climatic affinities in the lahars are similar to montane forests of southern Mexico. Thus they reflect an ecotone boundary rather than paleoclimatic change. The abrupt transition to Alfisols in the upper Clarno red beds may represent a decline in both temperature (to MAT 19-23°C) and rainfall (MAP 1000-1500 mm), with dry seasons.

Disconformably overlying the red beds are gray-brown siltstones and conglomerates of the "Mammal Quarry" which has yielded a titanothere-dominated fossil fauna. This is the most ancient known fauna of the late Eocene Duchesnean NALMA and of the White River Chronofauna. Paleosols in the beds of the "Mammal Quarry" show better preservation of primary volcanic grains, and may represent a climatic drying (MAP 550-1000 mm) or increased sedimentation due to volcanic influences.

The Clarno Formation is overlain abruptly by an ash-flow tuff of the basal John Day Formation, here newly dated by single-crystal 40Ar/39Ar techniques at 39.22±0.03 Ma. Additional new radiometric dates include 38.4±0.07 Ma for a tuff and 33.62±0.19 Ma for the http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/abstract.htm[4/18/2014 12:20:28 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Abstract)

"Slanting Leaf Beds", both in the lower John Day Formation. The fossil leaf beds are thus very earliest Oligocene in age because the Eocene-Oligocene boundary is currently recognized at 34 Ma. Thus the Clarno Formation is entirely Eocene and the John Day Formation ranges from late Eocene to early Miocene in age.

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

ACKNOWLEDGMENTS

This three year project was funded by contract No. CX-9000-1-0009 from the National Park Service. The contract was administered by Beth Faudree with Theodore Fremd as the technical contract advisor. Dr. G.J. Retallack and Dr. E.A. Bestland were the principal investigators and Dr. C. Swisher was consultant in geochronology and provided age determinations. Consultations with Allan Kays, Dave Blackwell, John Stimac, John Dilles, Andrea Mindzenty, Judit German, Edward Taylor, Mike Woodburne, Joseph Jones, and Theodore Fremd have added to our understanding of the geology of central Oregon and the Clarno Unit area. XRF analyses were done in Peter Hooper's laboratory at Washington State University under the direction of Diane Johnson. Christine McBirney analyzed samples for loss on ignition and ferric iron. Petrographic thin sections were made by Tim Tate and specimens were currated by Wendy Abel.

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http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/ack.htm[4/18/2014 12:20:29 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 1)

JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

CHAPTER I: INTRODUCTION AND REGIONAL GEOLOGY

INTRODUCTION

The scenic high desert of north-central Oregon contains a colorful volcanic and alluvial sequence of Tertiary age. The combination of low precipitation (320 mm annually in Antelope) and seasonal temperature extremes (January mean of -1 °C and August mean of 19 °C; Ruffner, 1978) favors xerophytic, sparse vegetation and good exposures. In contrast, fossil floras of Eocene age from sites in the Clarno Unit indicate paratropical climate analogous to that of modern southeast Asia (Manchester, 1981, 1994). The transition from steamy jungles of the past to the open ranges of today is recorded in a copious fossil record of a diverse flora, invertebrates, freshwater fish, reptiles, and mammals in this region (Merriam, 1901a, b, Merriam and Sinclair, 1907; Hanna, 1920, 1922; Merriam and others, 1925; Chaney, 1924; Stirton, 1944; Scott, 1954; Downs, 1956; Cavender, 1968; Mellett, 1969; Naylor, 1979; Manchester, 1981; Wolfe, 1981a and 1981b; Ashwill, 1983; Martin, 1983; Rensberger, 1983; McFadden, 1986; Manchester and Meyer, 1987; Hanson, 1989; Fremd, 1988, 1993). These profound paleoenvironmental changes are also reflected in sequences of paleosols ranging in age from middle Eocene to the present (Fisher, 1964; Retallack, 1981, 1991a, 1991b; Pratt, 1988; G.S. Smith, 1988; Bestland and others, 1994a, b). Three units of the John Day Fossil Beds National Monument (Sheep Rock, Clarno, and Painted Hills) were established for the protection and appreciation of these geologic and paleontologic resources.

The purpose of this project is to provide an updated geologic and paleoenvironmental evaluation of the Clarno and John Day Formations in the Clarno Unit area of the John Day Fossil Beds National Monument. Special emphasis was put on stratigraphic and chronostratigraphic ordering of fossil sites in the area (Fig. 1.1). Detailed stratigraphic work focused on the upper part of the Clarno Formation in the interval containing the "Nut Beds" and "Mammal Quarry" fossil sites. New age determinations combined with local lithostratigraphic mapping aimed to correlate fossils sites in the Clarno Formation with the North American and world wide paleontologic and paleoclimatologic data base. The study of the paleosols in the area was also a major focus. Most of the paleoenvironmental conclusions presented in this report were generated from our detailed study of the numerous and varied paleosols in the Clarno area.

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Figure 1.1. Geological section and fossil assemblages of the upper Clarno Formation in the Clarno Unit area (illustrations adapted from Knowlton, 1930; Scott, 1954; Mellett, 1969; Manchester, 1981, 1986; Crane and Stockey, 1985; and Savage and Long, 1986). (click on image for an enlargement in a new window)

The geologic framework of the area was addressed by mapping and stratigraphic documentation of lithostratigraphic units (debris flow deposits, lava flows, alluvial claystones, and pyroclastic deposits). This basic mapping was done in order to put the local stratigraphy into a regional context of the Clarno and John Day formations. Significant geologic work has been done in recent years by B. Hanson (Hanson, 1973; pers. communication, 1985, 1994), University of Oregon Geology Field Camp staff (A. Kays, D. Blackwell, E. Bestland, J. Stimac), Portland State Geology Field Methods staff (P. Hammond). However, little of this work has been published and much of this work is not currently accessible. Paleosols in the Clarno and John Day formations have been studied in some detail (Retallack, 1981; Pratt, 1988; Smith, 1988; Getahun and Retallack, 1991) and this project aimed to connect and extend this work. Until this project, the paleosols and

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geology of the Clarno Unit area were not comprehensively evaluated. PREVIOUS WORK AND REGIONAL GEOLOGY

The Clarno Formation is a thick section (up to 6,000 ft, 1800 m) of largely andesitic volcanic and volcaniclastic rocks of Eocene age which crops out over a large area of north-central Oregon (Fig. 1.2). The formation was named by Merriam (1901) for exposures of volcanic rocks at Clarno's ferry, now a bridge over the John Day River just west of the National Monument boundary. A variety of older rock units underlie the formation and range from a melange of Permian-Triassic metamorphic rocks to Paleocene(?) arkosic sedimentary deposits. The Clarno Formation is overlain for the most part by the John Day Formation. Where the formation formed ancient volcanic highlands, younger rock units such as the Miocene Columbia River Basalt Group, Miocene Mascall Formation, Miocene-Pliocene Rattlesnake Formation and the Miocene-Pliocene Deschutes Formation, disconformable overlie the Clarno Formation.

Figure 1.2. Location map of north-central Oregon modified from Walker (1977) and Walker and Robinson (1990), showing the distribution of the Clarno and John Day formations and Mesozoic and Paleozoic rocks. (click on image for an enlargement in a new window)

Basement rocks

Basement rocks in north central Oregon consist of highly deformed metasediments of Permian to Triassic age (Hotz and others, 1977). In some areas, these are overlain by a thick sequence of Cretaceous marine rocks as in the Mitchell area of central Oregon. In the Clarno area, argillites of uncertain affinity are exposed in the Muddy Ranch dome. These folded

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argillites have been mapped as Cretaceous sedimentary rocks of uncertain age by Swanson (1969), interpreted as Paleocene sedimentary equivalents of the Herren Formation by Fisk and Fritts (1987), and interpreted as equivalents of the late Cretaceous Gable Creek and Hudspeth formations on the basis of lithologic similarities and non-Clarno Formation metamorphic character of these argillites (A. Kays pers. communication, 1993). Similar argillites occur in the Hay Creek Anticline and have been determined to be early to middle Eocene in age on the basis of coccoliths (Wareham, 1986). These basement rocks are intruded and overlain by andesitic volcanic and alluvial rocks of the Clarno Formation.

Clarno Formation

The Clarno Formation consists of non-marine volcanic and volcaniclastic units that range in age from middle to late Eocene, some 54 to 39 m.y. old (Evernden and others, 1964; Evernden and James, 1964; McKee, 1970; Enlows and Parker, 1972; Rogers and Novitsky- Evan, 1977; Manchester, 1981; Fiebelkorn, and others, 1982; Vance, 1988; Walker and Robinson, 1990; Bestland and others, 1993; Manchester, 1990, 1994). Volcanic plugs, lava flows, and lahars with convergent-margin andesitic compositions and textures indicate accumulation in and around andesitic volcanic cones (Taylor, 1960; Noblett, 1981; Suayah and Rogers, 1991; White and Robinson, 1992; Bestland and others, 1994b). The calc-alkaline volcanic rocks represent subduction related andesitic volcanism, probably on thin continental crust (Noblett, 1981; Rogers and Novitsky Evans, 1977; Rogers and Ragland, 1980; Suayah and Rogers, 1991). White and Robinson (1992) evaluated the sedimentology of the volcaniclastic deposits on a regional scale and interpreted the strata as non-marine volcanogenic deposits that were deposited in alluvial apron and braidplains that flanked active volcanoes. Some conglomerates and sandstones in the Clarno Formation record fluvial reworking of syn-eruptive deposits.

A variety of paleosols are present in the Clarno Formation; clayey alluvial paleosols of stable floodplains, weakly developed paleosols between debris flow deposits and andesite lava flows, and strongly developed residual paleosols with thick saprolite zones between major lithostratigraphic units. Thick, residual paleosols have been previously recognized in several areas of the Clarno Formation and referred to variously as "soil zones," "saprolite" or "weathering zones" (Waters and others, 1951; Peck, 1964; Hay, 1963; Fisher, 1964; Fisher, 1968). Some relatively continuous paleosol horizons have been used locally as marker horizons (Waters and others, 1951; Oles and Enlows, 1971), however, no regional stratigraphic framework utilizing volcanic marker beds or paleosol horizons has been attempted for the Clarno Formation (Oles and Enlows, 1971; Walker and Robinson, 1990). Red, clayey paleosols and thick saprolites are present throughout the Clarno Formation, but, thick and laterally continuous exposures of these weathering profiles are most common in the upper part of the formation. Their abundance toward the top of the Clarno Formation supports the extension of the Telluride erosion surface and its corresponding tectonic hiatus to the Pacific Northwest (Gresens, 1981).

John Day Formation

The John Day Formation consists of rhyolitic ashflow tuff and dacitic to rhyodacitic tuffs and alluvial deposits of latest Eocene, Oligocene, and early Miocene (22-to 39-my) age (Peck, 1964; Woodburne and Robinson, 1977; Robinson and others, 1990; Bestland and others, 1993, 1994a, b). These primary pyroclastic, alluvial and lacustrine deposits were supplied with volcanic ash from vents to the west in the Western Cascades (Robinson and others, 1984) and from vents now buried or partially buried by the High Cascade volcanic cover. Thus, the Clarno and John Day formations of central Oregon record a late Eocene westward jump of the subduction zone in the Pacific Northwest and a corresponding change from Clarno andesitic volcanism to Cascade volcanism and John Day back-arc basin deposition.

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap1.htm[4/18/2014 12:20:31 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 1)

The John Day Formation is divided into an eastern, western, and southern facies (Fig. 1.3) on the basis of geography and lithology (Woodburne and Robinson, 1977; Robinson and others, 1984). The Blue Mountains uplift separates the western and eastern facies and restricted deposition of much of the coarser-grained pyroclastic material to the western facies. The western facies is informally divided into members A through I based largely on the presence at the base of members of ash-flow tuffs (Peck, 1964; Swanson and Robinson, 1968; Swanson, 1969). The western facies contains coarse-grained volcaniclastic deposits, welded ash-flow tuff sheets, and a variety of lava flow units including trachyandesite flows of member B, rhyolite flows of member C, and alkaline basalts in member F (Fig. 1.4). The Clarno Unit area is in the western facies where the John Day Formation has been mapped reconnaissance style by Robinson (1975) using the A through I stratigraphic divisions. The eastern facies is divided into four formal members (Fisher and Rensberger, 1972). From bottom to top they are, Big Basin Member (red claystones), Turtle Cove Member (green and buff tuffaceous claystones), Kimberly Member (massive tuff beds) and Haystack Valley Member (tuffaceous conglomerates). We report stratigraphic subdivisions of the John Day Formation in the Clarno Unit area based on both the A through I system of Peck (1964) and the formal members of the eastern facies of Fisher and Rensberger (1972) as modified by Bestland and others (1993) and Retallack and others (1994). The southern facies occurs south of the Ochoco Mountains and has a similar tuffaceous and zeolitized character as the Turtle Cove Member of the eastern facies but lacks the "Picture Gorge ignimbrite." New age determinations of tuffs from Logan Butte in the southern facies indicates that these deposits are coeval with the Turtle Cove Member (C. Swisher, pers. communication, 1993).

Figure 1.3. Estimated distribution of the three facies of the John Day Formation in central Oregon (from Robinson and others, 1984). (click on image for an enlargement in a new window)

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Figure 1.4. Stratigraphy of the John Day Formation in the eastern and western facies (from Woodburne and Robinson, 1977; modified by Robinson and others, 1990). (click on image for an enlargement in a new window)

Paleosols have been described from the John Day Formation by Fisher (1964, 1968) in the Turtle Cove-Big Basin area of central Oregon and by Retallack (1991b, c) throughout the John Day Basin and by Getahun and Retallack (1991) from the Clarno Unit area. According to Fisher (1964), laterization and the formation of an iron, kaolinite-rich hardpan occurred during the hiatus between Clarno and John Day volcanism. The iron-rich hardpan described by Fisher (1964) was developed on Cretaceous conglomerates and defines an erosional surface that has relief of up to 90 m. Fisher (1968) also compares less well-developed red and drab colored paleosols from the John Day Formation and noted their landscape association (well-drained with red colors and poorly-drained with drab colors) and their incipient lateritic character. Hay (1963) similarly recognized in these tuffaceous claystones evidence for "pre- burial weathering at the land surface," however his work focused on burial alteration, especially zeolitization, of the tuffs. Both Hay (1962a) and Fisher (1968) recognized distinct sedimentary facies in the John Day Formation, and inferred from these that hilly initial relief on the underlying Clarno Formation was mantled and subdued as deposition continued. Getahun and Retallack (1991) identified an Ultisol-like paleosol in the red basal claystones of the formation. Retallack (1991b,c) interpreted the change in paleosol types in whole of the John Day Formation from red clayey paleosols in the basal part to vitric calcareous paleosols in the upper part as indications of pronounced drying and cooling climatic conditions during Oligocene time.

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

CHAPTER II: GEOLOGIC FRAMEWORK OF THE CLARNO AREA

INTRODUCTION

The alluvial strata, paleosols. tuffs and lava flow units studied in the Clarno Unit area are in the Clarno and lower John Day Formations, and span middle Eocene to middle Oligocene time. This chapter outlines geologic and paleoenvironmental findings of a three year study of the Clarno Unit and describes new informal lithostratigraphic subdivisions of the Clarno and John Day formations (Fig. 2.1). Data presented in this report were largely gathered from measuring and describing stratigraphic sections of outcrops, with extensive trenching to exposed fresh rock beneath badlands mantled with soil, and mapping of units using low elevation color aerial photographs (Fig. 2.2 and maps of Plates I and II).

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap2.htm[4/18/2014 12:20:37 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 2)

Figure 2.1. Composite stratigraphic section of the upper Clarno and lower John Day formations in the Clarno area. Age determinations obtained from C. Swisher as part of this project.

Figure 2.2. Generalized geologic map and cross-section of the Clarno Unit area showing the distribution of lithostratigraphic units and the fold axis of the monoclinal flexure that passes through the project area. (click on image for an enlargement in a new window)

The informal stratigraphic subdivisions of the Clarno Formation are based on rock type and stratigraphic position. The John Day Formation is also divided into informal units following both western facies stratigraphic nomenclature of Peck (1964) and Robinson (1975) and eastern facies nomenclature of Fisher and Rensberger (1972). This chapter investigates the geologic framework of these stratigraphic subdivisions and examines the tectonic and paleoclimatic implications of these paleosols and associated volcanic units during the waning stages of Clarno volcanism and initial stages of John Day volcanism.

A major discoveries in the Clarno Unit area is the approximately 4 million year time span between the "Nut Beds" fossil site and the "Mammal Quarry" fossil site. This span of time is occupied in large part by the red beds of "Red Hill" which record a long period of humid subtropical soil formation. The "Mammal Quarry" beds are associated with a widespread andesite flow unit (andesite of Horse Mountain) which is stratigraphically at the top of the Clarno Formation in this area. Another discovery includes the stratigraphic position of the "Nut Beds" in the upper part of the Clarno Formation in the same package of lahars as the "Hancock Tree." These conglomerates and tuffs onlap the Hancock dacite dome.

A second important discovery in the Clarno Unit is the placement of the Eocene-Oligocene boundary high up in the John Day Formation, stratigraphically just below the Bridge Creek flora site at the "Slanting Leaf Beds." An Eocene-Oligocene boundary age of approximately

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap2.htm[4/18/2014 12:20:37 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 2)

34 Ma is accepted here based on single-crystal, laser fusion 40Ar/Ar39 dates and magnetostratigraphy of North American non-marine rocks (Swisher and Prothero, 1990; Prothero and Swisher, 1992) and the paleomagnetic record from the ocean ridges (Cande and Kent, 1992). New age determinations from tuffs in the lower John Day Formation include a date of 39.2 Ma from the basal welded tuff of member A and clearly indicates a late Eocene age (age determinations by C. Swisher; reported in Bestland and others, 1993).

Table 2.1. Informal locality names for the Clarno area

TOWNSHIP & NAME DESCRIPTION RANGE

"Black Spur" SE1/4 sec. 27, T7S, Basalt capped ridge below "Mammal Quarry" R19E "Equisetum Steep, small canyon cut into conglomerates of NW1/4 sec. 35, T7S, Canyon" Palisades R19E "Dumbbell Large, hoodoo-forming butte capped by andesite and center sec. 32, T7S, Butte" shaped like a dumbbell R20E "Hancock sec. 26, T7S, R19E Main drainage in the Camp Hancock area Canyon" "Indian Lower part of north-south drainage that joins Pine E half sec. 26, T7S, Canyon" Creek at the Palisades R19E "Indian Small plateau capped by conical knolls between NW1/4 sec. 35, T7S, Mesa" Indian and Hancock canyons R19E "Italian Hill" Red, yellow, and green banded hill of lower John NW1/4 sec. 24, T7S, Day Formation (hill 2802) R19E "Mammal Abandoned paleontology excavation in yellowish- E half sec. 27, T7S, Quarry" brown siltstones R19E "Nut Beds" Resistant buff cliff containing abundant silicified S half sec. 27, T7S, plant fossils R19E "Palisades" Hoodoo-forming cliff at the junction of Pine Creek center sec. 25, T7S, and Indian Canyon R19E "Red Hill" Red and white banded ridge northwest of Hancock S half sec. 27, T7S, Field Station R19E "Sienna Small badland area near the divide between Indian NE1/4 NW1/4 sec. 26, Ridge" and Hancock Canyons T7S, R19E "Slanting SE1/4 sec. 22, T7S, White fossil leaf bearing outcrop Leaf Beds" R19E "West Face Large cliffs on the east side of the John Day River Secs. 10 & 3, T8S, Cliffs" south of Clarno R19E "Whitecap White capped knoll above red badlands in lower NW1/4 sec. 26, T7S, Knoll" John Day Formation R19E

Stratigraphic nomenclature

In this report, new stratigraphic units identified are all informal in accordance with rules about such units in the North American Commission on Stratigraphic Nomenclature (1983). http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap2.htm[4/18/2014 12:20:37 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 2)

The new subdivisions of the John Day and Clarno formations will be denoted by lower case such as "lower Big Basin Member." Other options for naming these new units included, for example, "lower Big Basin beds" or "lower Big Basin sequence." All three of these names are informal units, are not capitalized, and therefore do not need to conform to the formal requirements of the code. Some of the new divisions conform to the concept of "beds," however, formal members would be needed in order to refer to these units as beds. Beds as explained by Article 26a of the Stratigraphic Code, "should be limited to certain distinctive beds ...". Examples of lithostratigraphic units in the Clarno Unit area that follow the concept of beds would be the "Nut Beds" or "Mammal Quarry" beds. Formal declaration of units such as the conglomerates of Hancock Canyon as a member of the Clarno Formation is beyond the scope of this project. Many of the stratigraphic sections and localities in this report are referred to with informal place names (Table 2.1).

Radiometric age determinations

Three new radiometric age determinations were made by C. Swisher of the Institute of Human Origins using single crystal, Ar40/Ar39, laser fusion methods (Table 2.2). This method involves the age determination of multiple grains of feldspar from tuff samples (Appendix 7). In samples with fresh feldspar crystals that were produced during the same volcanic event, the ratio of Ar40 to Ar39 will be much the same in each crystal and yield similar age estimates. If the crystals were weathered or altered during or since burial, Ar gas may have escaped from the crystal causing the determined age to be anomalously young. Feldspar grains incorporated from older deposits but still fresh will yield older ages compared to the majority of grains from the primary volcanic source. With this single crystal method, altered grains and older detrital grains can be identified and separated from a population of fresh grains of uniform age and so can be discarded from the age estimate. Previous "whole rock" or "feldspar separate" age determination techniques did not have this kind of single- crystal control. Thus, the new age determinations presented here and elsewhere using this method are generally significantly older and more precise than previous age determinations of the same units probably because of the incorporation of altered grains in the previous age determinations.

Table 2.2. New Ar40/Ar39 age determinations from the Clarno Unit

number of standard unit mineral type crystals Age deviation rounded age

Member A Sanidine 7 39.22 0.027 39.2 ± 0.03 White Knoll tuff Plagioclase 5 38.19 0.06 38.2 ± 0.06 Slanting Leaf beds Plagioclase 6 33.62 0.19 33.6 ± 0.2

Note: Age determination data for individual crystals is in Appendix 7.

CLARNO FORMATION LITHOSTRATIGRAPHIC UNITS

Lower Clarno Formation units

Conglomeratic debris flow deposits of uncertain affinity and of local extent were first recognized by Hanson (1973) in a structural dome just west of Hancock Field Station (Fig.

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2.2). The partial dome in this area was interpreted by Hanson (1973) to be a structural window into lower Clarno Formation strata that had been deformed and onlapped by later Clarno Formation deposits. Mapping of the deposits during the coarse of this work indicates that a partial dome is present, however, the stratigraphic position and relationship of the deposits with the dacite body is not clear. The structural dome plunges away from the dacite dome (Plate II) but, a careful search of the deposits on the south side of the dacite dome failed to reveal a clear intrusive relationship. Our current interpretation is that there is a lower sequence of strata that was deformed by the emplacement of the dacite dome and that these deposits were onlapped by the main section of Clarno Formation units (Fig. 2.3).

Figure 2.3. Diagrammatic summary of the geologic history of the Clarno Formation in the Clarno area.

Lower Clarno conglomerates. A sequence of boulder-sized, matrix-supported conglomerates exposed just to the west of Hancock Canyon is the oldest and most deformed unit in the map area and is referred to as lower Clarno conglomerates. This unit was recognized first by Hanson (1973). Clasts of boulders and cobbles of altered plagioclase porphyritic andesite are common in the debris flows. The unit lacks tuff beds or paleosols which could aid in stratigraphic correlation. The southwestern half of a structural dome is defined by the strike and dip of a resistant debris flow bed that is extensively exposed in this unit (Plate II). The andesite of Pine Creek apparently overlies these folded debris flows, however, a small and poorly exposed outcrop just west of the access road to Hancock Field Station (NE1/4 sec 34; P. Hammond pers. communication, 1992) is the only exposure of this contact. Another less likely stratigraphic interpretation is that this unit is part of the conglomerates of the Palisades which have been locally faulted and folded.

Hancock dacite dome. A plagioclase hornblende dacite porphyry is exposed in the hills and gullies to the northeast of Hancock Field Station (Figs. 2.2 and 2.3). Excellent exposures of this unit in tributary gullies of Hancock Canyon indicate that it is a homogenous igneous body and not boulders of dacite weathering out of a debris flow as has been interpreted

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previously (unpublished mapping by E.A. Bestland, D.L.S. Blackwell, and M.A. Kays). This igneous body was first recognized by Hanson (1973) and referred to as an andesitic intrusion. Geochemical analysis of this unit during the course of this project and with the help of P. Hammond, indicates that this unit is of dacitic composition (see geochemical section of this chapter). Stratigraphic sections of strata directly overlying this igneous body do not show intrusive features such as baking, veining, hydrothermal alteration and mineralization (Fig. 2.4a-d). The overlying claystones contain boulders exclusively of weathered, altered hornblende dacite (Fig. 2.4). The claystones are interpreted as well-developed paleosols of the Pswa pedotypes that developed on an igneous body and which incorporated colluvial debris (dacite clasts) from the underlying dacite. Thus the dacite body was an erosional feature that was mantled by colluvium and soils. The lack of intrusive igneous features in onlapping conglomerates of the Palisades and Hancock Canyon and the presence of cobbles and boulders of the dacite in colluvium suggests that the dacite was a topographic feature, probably a stubby lava flow or a lava dome. The Hancock dacite dome is pervasively altered, probably by deep weathering during the Eocene.

Figure 2.4. Photographs of the Hancock dacite dome and overlying stratigraphic units. Figure. 2.4A. View of "Black Spur" and the dacit-basalt section. Figure 2.4B. View of "Black Spur" capped by basalt and underlain by dacite. Figure. 2.4C. Lignitic siltstones interbedded with green claystones (Cmuk pedotype). Figure. 2.4D. Boulder of weathered hornblende dacite surrounded by claystone (Pswa pedotyp).

A dike of dacite can be observed to intrude lower Clarno conglomerates along the track to the "Nut Beds" from the field station. This observation constrains the age of the dome to between deposition of the lower conglomerates and conglomerates of the Palisades. Vance (1988) has dated a comparable dacite clast in lahars overlying the "Fern Quarry" by fission track at 44.3 Ma, older than dates of 43.6-43.0 on fossil localities of the conglomerates of Hancock Canyon.

Main section

In the Clarno Unit area, the Clarno Formation contains laterally extensive and mappable lithostratigraphic units (Fig. 2.5, Plates I and II). These units are of three types: 1) andesitic http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap2.htm[4/18/2014 12:20:37 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 2)

debris flow packages, 2) andesite lava flows, and 3) claystones. Smaller-scale lithostratigraphic units, such as basalt flows or thin andesite flows, tuff beds and minor red beds were used to characterize and help identify larger stratigraphic packages (Plate II). Of the three lithostratigraphic types, the debris and andesite flow units constitute the majority of the cliffs along the John Day River in the area south of Clarno bridge and along the western part of Pine Creek.

Figure 2.5. Fence diagram of the Clarno Formation in the Clarno Unit area.(click on image for an enlargement in a new window)

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Figure 2.6. Generalized north-south cross-section of the Clarno Formation from the "Red Hill"-Hancock Canyon area to the cliffs above the John Day River south of Clarno.(click on image for an enlargement in a new window)

Andesite of Pine Creek. The base of the stratigraphically coherent section in the Clarno Unit area is a thick andesite referred to as the andesite of Pine Creek. This consists of thick lava flows of dark-colored pyroxene-plagioclase andesite that are altered by varying degrees. The andesite flows have a very irregular upper surface which is mantled by a well developed red saprolite breccia. To the east of Cove Creek, this basal andesite unit is extensively exposed and contains a number of different subunits. The lowest flows in this area are thick, autobrecciated andesite flows that contain abundant plagioclase phenocrysts and are present in the lower third of hill 2932 ("Dumbbell Butte"). Several dark-gray, basaltic andesite flows onlap the thick autobrecciated andesite on the west side of hill 2932. The stratigraphic relationship between the andesite in the lower part of Pine Creek with the andesite to the east of Cove Creek in not known.

Paleorelief of this unit is best exposed in cliffs along Pine Creek between the "Palisades Cliffs" and the entrance to Hancock Field Station where more than 40 vertical meters of andesite is onlapped by debris flows over a lateral distance of 200 m. Pockets of red and white claystones are preserved between the andesite and overlying debris flows and were mapped separately (Plate II). The claystones are best exposed in roadcuts just east of the Palisades wayside on Highway 218. The clayey saprolite and claystones erode to form an erosional bench which is occupied in part by the modern Pine Creek floodplain. Basal sapping of these cliffs is in part due to the erodability of these claystones.

Conglomerates of the Palisades. Onlapping the irregular surface of the andesite of Pine Creek is a thick sequence of debris flows dominated by clasts of andesitic composition. The conglomerates of the Palisades weather to form the spectacular hoodoos along Pine Creek and in the lower part of the "West Face Cliffs" along the John Day River (Fig. 2.7a-d, Fig. 2.8). Most of the conglomerates are matrix-supported, moderately clast-rich, laterally continuous and interpreted as floodplain debris-flows (in the sense of Scott, 1988). The "Palisade Cliffs" contain numerous clast-rich, channelized debris flows. Some are clast supported at their base. Hyperconcentrated flood flow deposits (in the sense of G.A. Smith 1986; and Nemec and Muszynski, 1982) are common at the base of debris flows where they grade into debris-flow deposits. Well exposed at approximately the middle of this unit are several thin, green, clayey paleosols with wood fragments and leaf impressions. These thin, green paleosols, of the Scat and Sitaxs pedotypes, are present in the Palisades section and are well exposed in the lower part of the cliffs along the John Day River. Above the green clayey horizons is a tuffaceous breccia layer which grades up into a massive debris flow. This debris flow weathers brown-orange and crops out prominently along the "West Face Cliffs."

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Figure 2.7. Photographs of the "West Face Cliffs" along the John Day River showing the conglomerates of the "Palisades" (Tccp), conglomerates of Hancock Canyon (Tcch), middle andesite unit (Tcam), and andesite of Horse Mountain (Tcah). Figure 2.7A. The "West Face Cliffs" viewed from the south. Figure 2.7B. The "West Face Cliffs" viewed from the north. Figure 2.7C. Lahars and paleosols in the conglomerates of the "Palisades." Figure 2.7D. Close-up of Sitaxs paleosols with well developed green and purple mottles (from exposure shown in Figure 2.7C).

Figure 2.8. Photographs of the conglomerates of the "Palisades" and the conglomerats of Hancock Canyon. Figure 2.8A. The "Palisade Cliffs" in Indian Canyon. The bench above the cliffs is caused by poorly resistant red claystones between the two conglomerate units. Figure 2.8B. The "Palisade Cliffs" and "Indian Mesa" viewed from the top of Horse Mountain. Figure 2.8C. The southwestern flank of Horse Mountain.

To the east of Cove Creek, conglomerates of the Palisades onlap, thin and pinch-out against

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andesite of Pine Creek (Figures 2.2). From the "Palisades Cliffs" to exposures in canyons on the north side of Horse Mountain this lahar package has a dip of approximately 2° toward the northwest and away from former volcanic highlands to the southeast. This dip is interpreted as an original debris flow apron gradient and indicates a source area to the southeast.

Saprolite mantles the conglomerate of the "Palisades" and is commonly overlain by brown and red claystones (paleosols). These claystones erode to form a bench on the mesa between Hancock Canyon and Indian Canyon (Indian Mesa on Fig. 2.2). This bench is also present on the north and west sides of Horse Mountain and along the canyon walls of Cove Creek. These fine-grained deposits and claystones weather to form low angle slopes and reddish soil and were mapped separately (unit Tcrp on Plate II). They are well exposed in the south spurs of the first upstream westward branching gully of both Indian Canyon and Cove Creek. A continuous stratigraphic section is exposed in the southern part of Cove Creek and contains in stratigraphic order conglomerates of the "Palisades," several red claystone horizons, conglomerates of Hancock Canyon, several red claystone horizons of the claystones of "Red Hill," and welded tuff of basal John Day Formation member A. These claystone interbeds can be traced to the east and documents the pinch-out of the conglomerates of the "Palisades" against the andesite of Pine Creek.

Middle Clarno andesite. This thick andesite is locally present in the southern part of the project area south of Clarno along the John Day River. Along the John Day River the unit makes-up the lower half of the monolithic buttes on the west side of the river (hills 2441 and 2373, sec 9). Here it is a blocky, dark colored, pyroxene-plagioclase andesite. In the very most southern part of the project area (center of sec 9), the andesite fills a paleovalley cut into the conglomerates of the "Palisades." This andesite, or its stratigraphic equivalent, crops out extensively in the upper reaches of Hay Bottom Canyon and canyons to the north. Thick accumulations of flow breccia, autobrecciated flows and associated andesite flows are interbedded with debris flows of the conglomerates of "Hancock Canyon." A stratigraphic interpretation possible from these relationships is that the lava flow capping "Dumbbell Butte" may be part of this lava flow sequence and not part of the andesite of Horse Mountain. Along the John Day River, the unit is clearly onlapped by conglomerates of Hancock Canyon.

Conglomerates of Hancock Canyon. Overlying the red claystone interbed at the top of the conglomerates of the "Palisades" is the conglomerates of Hancock Canyon (Fig. 2.8). Like the conglomerates of the Palisades, clasts are principally of andesitic composition. A nearby volcanic source is also indicated by heavy minerals of the "Nut Beds" which are mainly of volcanic affinities (77% magnetite/ilmenite, 12% altered volcanic, 2% zircon, 4% pyroxene and 2% rutile) with less than 2% possible metamorphic minerals (garnet, epidote, amphibole; M. Sorenson, pers. comm., 1983). This unit includes tuffaceous beds and a distinctive basalt flow, but is dominated by matrix-supported boulder debris flows (Figures 2.9 and 2.10). Deposits of this unit onlap the Hancock dacite dome and the middle andesite unit. The prominent bench and red soil produced by an interbed of red claystone separates conglomerates of the "Palisades" from conglomerates of Hancock Canyon. In the Clarno Unit area, the conglomerates of Hancock Canyon can be distinguished by their more prominent bedding, less coarse-grained and massive texture, and common thin tuff interbeds when compared with the conglomerates of the "Palisades." Toward the east from the Clarno Unit area, conglomerates of Hancock Canyon are dominated by thick, coarse debris flows and contains few fine-grained tuffs or medium-grained lahar-runout type deposits so common in Hancock Canyon (Fig. 2.10b). A distinctive and widespread amygdaloidal basalt flow occurs stratigraphically in the upper half of the unit (Fig. 2.11). The basalt is holocrystalline, contains common plagioclase and pyroxene grains and displays pahoehoe flow structures and local columnar jointing. The basalt can be mapped from the Hancock Field Station area to the Gables, is thickest in the "West Face Cliffs," but is not present east of Indian Canyon (Plate I

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and II). This basalt flow can be traced along the cliffs of the John Day River south to Melendy Ridge.

Figure 2.9. Fence diagram of the conglomerates of Hancock Canyon and claystones of "Red Hill" in the "Red Hill"-Hancock Canyon area. (click on image for an enlargement in a new window)

Figure 2.10. Photographs of conglomerates of Hancock Canyon. Figure 2.10A. The amygdaloidal basalt pinches-out between debris flows in the canyon of the "Hancock

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Tree". Figure 2.10B. The upper part of the "Dumbbell Butte" section with red claystone horizons underlying conglomerates of Hancock Canyon. Figure 2.10C. View looking east of the debris flow that contains the "Hancock Tree" with the upper andesite of Horse Mountain (Tcau) and claystones of "Red Hill," in the background. Figure 2.10D. "Red Hill," underlying "Nut Beds" unit of the conglomerate of Hancock Canyon, and overlying siltstones of "Mammal Quarry" exposed in trench at the top of the hill.

Figure 2.11. The upper Hancock Canyon section includes units above the "Hancock Tree" lahar, a truncated interval of claystones of "Red Hill" (Lakayx paleosols), and an upper conglomerate unit interpreted as part of the claystones of "Red Hill." (click on image for an enlargement in a new window)

The conglomerates of Hancock Canyon contain the "Nut Beds" fossil site (Fig. 2.10a) and the Muddy Ranch tuff, both dated at approximately 44 Ma; Carl Swisher obtained a date of 44 Ma from a plagioclase separate from a reworked crystal tuff in the "Nut Beds" using the 40Ar/39Ar method (pers. comm., 1992), and Brent Turin (for Manchester 1990, 1994) used the same method on plagioclase of the "Nut Beds" for an age of 43.766±0.29 Ma, and Joe Vance (1988) obtained a date of 43.6 and 43.7 Ma from fission track of zircon crystals in the 'Nut Beds" and 44 Ma in the Muddy Ranch Tuff (also known as the Rajneesh Tuff) near the Gables. The Muddy Ranch tuff is stratigraphically below the "Nut Beds." Many large, well- preserved Cercidiphyllum (katsura) and Macginitea (sycamore) permineralized tree trunks and limbs are in this unit, similar to the "fossil forests" found in comparably-aged Lamar River Formation on the Yellowstone plateau (Dorf, 1964; Retallack, 1981b).

Another prominent, although local unit is a tuff breccia debris flow deposit that contains abundant purplish-gray hornblende andesite clasts. This unit was mapped separately in the Indian Mesa area, and referred to as the lavender lahar. The unit grades into an autobrecciated andesite flow which is exposed at the base of the debris flow unit on the west spur of hill 2066 (SW 1/4 sec 26 on "Indian Mesa," Plate I). The boulders and cobbles of hornblende andesite have a light gray-purple weathering rind and forms fields of light colored boulders where they weather out from the debris flow matrix.

Claystones of "Red Hill." In the Clarno Unit area, a thick sequence of reddish (Lakayx pedotype) and grayish-purple (Acas pedotype) claystones overlie the conglomerates of Hancock Canyon (Fig. 2.10d and Fig. 2.12). The unit is 59 meters thick in the "Red Hill" area (Fig. 2.1) but thins dramatically to the east (Fig. 2.2 and Fig. 2.13). In the cliffs on the west and north side of Horse Mountain, only a reddish saprolite with thin clay layer is present at this stratigraphic level. The unit at "Red Hill" contains a lower reddish paleosol sequence of

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very deeply weathered Ultisol-like paleosols (Lakayx pedotype) and an upper less well developed, Alfisol-like paleosol sequence (Luca pedotype; G.S. Smith, 1988; Retallack, 1991a). A stony tuff bed above the lowest Luca paleosol approximately divides the two paleosol sequences. Detailed descriptions of these paleosols are given in Chapter III.

Figure 2.12. Stratigraphic section of "Red Hill" West. (click on image for an enlargement in a new window)

Figure 2.13. Stratigraphic section of "Sienna Ridge" (also called "Red Hill" east). (click on image for an enlargement in a new window)

Conglomeratic beds are locally present in the claystones. At the southern tip of the Gables (Plate I), a thick, coarse-grained conglomerate body is interbedded with red claystones. The conglomerates are clast-supported, contain rounded clasts andesite and amygdaloidal basalt.

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The conglomerates cut into underlying units of the conglomerates of Hancock Canyon (Fig. 2.14c).

Figure 2.14. Photographs of "Red Hill" east and west localities. Figure 2.14A. "Red Hill" west showing contact between the conglomerates of Hancock Canyon (Tcch) and claystones of "Red Hill" (Tcrh). Figure 2.14B. "Red Hill" east section with saprolitic conglomerate at the top of conglomerates of Hancock Canyon (Tcch), a truncated section of claystones of "Red Hill," a saprolitic andesite breccia (Tcau), siltstones of the "Mammal Quarry" (Tcq), and member A of the basal John Day Formation. Figure 2.14C. Fluvial conglomerate unit of the claystones of "Red Hill" exposed at the Gables cutting into welded tuff unit of the conglomerates of Hancock Canyon. Figure 2.14D. Plant remains and accretionary lapilli from the base of the member A tuff.

The claystones of "Red Hill" are prone to landslides. Most landslides mapped on Plate I and II occur where thick exposures of these claystones are overlain by the welded tuff of member A of the basal John Day Formation. Good examples of these landslides occur on the eastern side of "Indian Canyon." The landslides do not appear deep seated; the coherent blocks of member A form shallow, rocky slides, which in some cases are similar in appearance to rock glaciers.

Andesite of Horse Mountain. This thick andesite unit is extensively exposed in the project area where it caps much of Horse Mountain. The unit consists of platy to blocky andesite which varies from pyroxene-plagioclase andesite to very porphyritic plagioclase dacite with traces of hornblende. Along the west and north side of Horse Mountain, the unit overlies a thick red saprolite developed on the amygdaloidal basalt flow in the Hancock Canyon unit. Ramp-like flow structures are common in lava flows exposed in the "West Face Cliffs." The base of the unit dips gently to the west, probably following a paleoslope.

An upper andesite unit is recognized based on stratigraphic position and lithology. On the rolling top of the west part of Horse Mountain, a plagioclase phyric, basaltic andesite flow is exposed above thin red claystones (paleosols) and below member A of the basal John Day Formation. This unit (Tcau) was mapped separately on Plate I and identified by bulk rock geochemistry (see geochemistry section). Lithologically and geochemically similar andesite crops out in the upper part of Hancock Canyon where it forms the base of the siltstones of the

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"Mammal Quarry" in the "Red Hill" east section (Figures. 2.13 and 2.14b). A saprolite andesite breccia can be traced into coherent exposure of the upper andesite unit.

Siltstones of the "Mammal Quarry." The tan, clayey siltstones and cobble conglomerates of the "Mammal Quarry" beds are only locally present in the "Red Hill"-Indian Canyon area. Vertebrate remains in this unit make it paleontologically important. A diverse vertebrate fauna has been excavated from the "Mammal Quarry," located stratigraphically in the uppermost Clarno Formation and below member A of the John Day Formation (Hanson, 1973 and pers. comm., 1993). Several taxa in this assemblage have close affinities with Asiatic faunas and the early Duchesnean North American Land Mammal Age. Pratt (1988) described Inceptisol-like paleosols from the "Mammal Quarry." By her interpretation, the fossil remains accumulated as carcasses and were disarticulated in a fluvial point bar. Stratigraphic work during this project has shown that the "Mammal Quarry" unit was deposited in response to the eruption of the upper andesite flows (unit Tcau) of the andesite of Horse Mountain. At several exposures east of the "Mammal Quarry," red claystones of the "Red Hill" claystone unit are overlain by andesite breccia which can be traced to outcrops of andesite of Horse Mountain (Fig. 2.14b). This breccia is capped by Acas paleosols which are overlain by the tan clayey siltstones of the "Mammal Quarry" unit.

JOHN DAY FORMATION LITHOSTRATIGRAPHIC UNITS

In the Clarno Unit area, the John Day Formation has been mapped and stratigraphically subdivided by Robinson (1975) following Peck's (1961, 1964) informal subdivision of the John Day Formation on the basis of distinctive pyroclastic and lava flow units. In this report, these pyroclastic and lava flow units are recognized and given the names defined by Peck (1964) and mapped by Robinson (1975), however, only distinct lithologic units were mapped in the Clarno Unit area. These volcanic units along with the interbedded claystones, lacustrine shales and tuffs are assigned to eastern facies members of the John Day Formation (Fisher and Rensberger, 1972).

Lower Big Basin Member

The lower Big Basin member in the Clarno Unit area includes all lithostratigraphic units from and including the welded tuff of member A of the basal John Day Formation up to a truncation surface marked in places by conglomerates and sandstones of probable Oligocene age (Fig. 2.15). These sandstones and conglomerates are exposed in gullies to the west of the "Slanting Leaf Beds" which they are stratigraphically below.

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Figure 2.15. Stratigraphy of the John Day Formation in the Clarno Unit area.

Welded tuff of member A. Rhyolitic pyroclastic volcanism of the John Day Formation is first recorded in north central Oregon by an ash-flow tuff now re-dated in the Clarno area at 39.2 Ma by Carl Swisher as part of this project. This basal ash-flow tuff sheet is extensively exposed in the western facies (Peck, 1964; Robinson, 1975). The distinctive and widespread ash flow tuff of member A is useful in delineating the Clarno surface at the onset of John Day volcanism.

A lower, densely welded tuff forms prominent outcrops in the Clarno Unit area and is approximately 30 m thick. Locally near the base of the unit is a perlitic vitrophyre which is best exposed in a roadcut at the Gables. At the very base of the ash-flow tuff are unwelded tuff deposits some containing accretionary lapilli and plant remains (Fig. 2.14d). Lithic fragments are common in the lower tuff as are bi-pyramidal (beta) quartz crystals. The tuff, where densely welded, has a red-purple color.

An upper, weakly welded to unwelded ash flow tuff, approximately 25 m thick, crops out extensively in the Clarno Unit area where it commonly forms the dip slope on the member A cuesta. This unit also contains abundant bi-pyramidal quartz crystals but less lithic fragments than the lower densely welded part. Fluvially reworked beds occur in places such as in upper http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap2.htm[4/18/2014 12:20:37 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 2)

Indian Canyon area where concentrations of bi-pyramidal quartz and feldspar crystals derived from the underlying tuff occur.

The two part division of member A in the Clarno Unit area is consistent with member A stratigraphy in more complete sections to the west (Robinson and others, 1990). Near Ashwood, the tuff consists of a basal and upper ash-flow tuff sheet, both welded and approximately of similar crystal content (Robinson and others, 1990). Between the two ash- flow sheets lies a complicated stratigraphic package of reworked tuffs, tuffs of airfall origin and tuffs containing plant remains (Robinson and others, 1990).

Member B basaltic andesite. In the Clarno Unit area, distinctive aphanitic basaltic andesite flows overlie member A. Red claystones are locally present between the two units, although exposure of this thin interbed is poor. The flows consist of aphanitic to sub-glassy basaltic andesite that weather into cobble-sized blocks. These basalts correlate with the member B trachyandesites of Peck (1964) which form a thick unit in the Ashwood area (Swanson, 1969), but has also been mapped in the Clarno Unit area (Robinson, 1975). Peck (1964) identified 1,500 ft of very dark gray aphanitic flows of trachyandesite in the Ashwood area. These basaltic andesite flows of member B of the John Day Formation are widespread in the western facies (Peck, 1964; Robinson, 1975) and occur as flows and dikes in the Clarno Unit area. In the Clarno Unit area a 21 m thick columnar jointed basaltic andesite lava flow crops out at the head of Indian Canyon and is the thickest occurrence of member B in the area. Other small exposures are scattered throughout the area and are recognizable by their aphanitic texture and small cobble-sized weathering character, similar to Peck's (1964) description of member B. A set of basaltic andesite intrusions of this lithology forms a small hill between Hancock Canyon and Indian Canyon (NE 1/4 of sec. 26). The rock contains pebble-sized cognate xenoliths of gabbro. The geochemistry of lava flows and dikes of this unit are discussed and compared to other basaltic units in the area later in this chapter.

Member C rhyolite. In the Clarno area, there are very limited exposures at the head of Indian Canyon of rhyolite flows stratigraphically above the member B basalt flow. Here the rhyolite caps the eastern part of the cuesta and forms a weathered, cobbly outcrop. Rhyolite of member C forms 1,000 ft thick rhyolite dome and flow complexes north of Ashwood (Peck, 1964).

White tuff of member F. A massive white vitric tuff approximately 1-3 m thick is widespread but poorly exposed in the lower John Day Formation in the Clarno area. Robinson and Brem (1981) identified a massive white vitric tuff located in a roadcut just west of Clarno Grange on Highway 218 as the base of member F in this area. This white vitric tuff is low in the John Day Formation and interbedded with clayey red beds and has been mapped in the Clarno Unit area and is referred to as member F tuff (Plate I, II). However, according to Peck (1964), the weakly welded ash flow tuff that defines the base of member F is not a widespread unit making the correlation of this tuff in the Clarno area with the type area of the western facies questionable. The member F tuff further west toward Ashwood is crystal poor as is the tuff in the Clarno area. Robinson (1975) mapped member F units in the Clarno area and Robinson and others (1990) define member F as a group of heterogenous tuffaceous sedimentary rocks that lie between the ash-flow sheets of E and G and commonly contain olivine basalts toward the top of the unit. The vitric tuff referred to here as member F tuff was dated at the "Whitecap Knoll" locality by Carl Swisher at 38.2 Ma, considerably older than previously thought (Getahun and Retallack, 1991). Getahun and Retallack (1991) identified an Alfisol-like paleosol (Luca pedotype) directly below this tuff at "Whitecap Knoll" and referred to this part of the section as Oligocene in age.

Lower Big Basin Member claystones. Widespread, thick clayey red beds in the lower part of the John Day Formation in the Clarno Unit area are mapped as Big Basin Member based

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on lithologic and stratigraphic similarities with the type section of this member in the Big Basin area of Picture Gorge. Recently recognized subdivisions of this member in a reference section from the Painted Hills area (Bestland and others, 1993; Bestland and others 1994; Bestland and Retallack, 1994) are also recognized in the Clarno Unit area (Fig. 2.16).

Figure 2.16. Photographs of lower and middle Big Basin members of the John Day Formation. Figure 2.16A. Contact between strongly developed red paleosols of the lower Big Basin Member (Tjlb) and lapilli tuffs and moderatley developed paleosols of the middle Big Basin Member (Tjmb) at "Italian Hill." Figure 2.16B. Moderately developed red-brown paleosols of the middle Big Basin Member in the foreground and cliff-forming tuffaceous channel complex. This locality is 300 m north of the "Slanting Leaf Beds."

The John Day Formation in the Clarno Unit area contains a thick section of late Eocene strata, as indicated by our new 38.2 Ma and 33.6 Ma age determinations from this area. These late Eocene paleosols are not dominated by colluvial reworked and lateritic paleosols as are the paleosols of this age in the Painted Hills and Big Basin areas. This part of the John

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Day basin was probably a floodplain depocenter during the late Eocene, rather than a colluvial slope on the south side of the Blue Mountains uplift.

Middle and upper Big Basin Members

The middle and upper Big Basin Members were not delineated in the Clarno area as they were in the Painted Hills (see the Painted Hills report). In the Clarno area, red-brown silty claystones, tuffs, and lacustrine shales with leaf impressions, similar to strata in the Painted Hills area identified as middle Big Basin member, occur above clayey red beds identified as the lower Big Basin Member and below green tuffaceous strata of member G containing the sanidine tuff (Fig. 2.15). This tuff occurs in the lower part of the Turtle Cove Member in the Painted Hills where it was dated at 29.8 Ma. Additionally, the 33.6 Ma age determination from the "Slanting Leaf Beds" and the well documented Bridge Creek flora (Meyer and Manchester, 1994) from these strata allows correlation with the middle Big Basin Member. In the Painted Hills area age determinations on tuff beds of 33.0 Ma and 32.7 Ma are associated with the type locality of the Bridge Creek flora and are contained within the middle Big Basin Member. Red silty claystones stratigraphically above the "Slanting Leaf Beds" and below a prominent tuffaceous channel complex (Fig. 2.16B) are similar to Ticam and Skwiskwi pedotypes identified in the middle and upper Big Basin members from the Painted Hills.

Conglomerates containing weathered clasts of tuff and igneous flow rocks are locally present in the Clarno area at the base of the middle Big Basin Member (Fig. 2.1). In gullies to the west of the "Slanting Leaf Beds", brown calcareous paleosols overlie these conglomerates and underlie the lacustrine and carbonaceous shales of the "Slanting Leaf Beds".

A large exposure of red, brown and green claystones and tuffaceous claystones at "Italian Hill", is the longest and most continuous section of the lower and middle Big Basin Members in the Clarno area (Fig. 2.16a, Plate I and II). The section contains four fairly resistant and fresh pumice lapilli tuffs that contain feldspar crystals. The section may contain the Eocene-Oligocene boundary based on comparison with lithologies of paleosols associated with the "Slanting Leaf Beds" section dated at 33.6 Ma and the "Whitecap Knoll" section dated at 38.2 Ma. Lateral tracing of the package of red, clayey paleosols and vitric tuffs of the "Whitecap Knoll" section indicates that the lower part of "Italian Hill" is probably lower Big Basin Member. Lateral tracing of the "Slanting Leaf Beds" is more difficult, but preliminary inspection indicates that the upper half of "Italian Hill" with its pumice lapilli tuffs and paleosol types correlates with the middle Big Basin Member.

Turtle Cove Member

Tuffs and tuffaceous siltstones and claystones of the Turtle Cove Member are recognized in the Clarno Unit area based on correlation of tuffs in the western facies with this member in the eastern facies. Ash-flow tuffs of member G, H, and I occur in the Clarno Unit area. Member H has been correlated with the "Picture Gorge ignimbrite" based on lithology and stratigraphic position (Robinson and others, 1990). The Turtle Cove Member as well as the ash-flow tuffs of member G, H, I do not occur in the project area, however, they are exposed just to the north of the project area in The Cove and have been mapped previously by Robinson (1975) and by Bestland, Blackwell and Kays (unpublished mapping 1986 and 1988). These units are significant in the context of correlating the Turtle Cove Member of the John Day Formation.

Member G tuff. This ash-flow tuff sheet is extensively exposed in the western facies (Robinson, 1975) and along the Iron Mountain escarpment in the Clarno area. This sanidine rich tuff has been correlated with a sanidine tuff in the Painted Hills area (Hay, 1963;

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Woodburne and Robinson, 1977) which has been recently dated at 29.8 Ma by Carl Swisher. In the Clarno area the tuff is 1-6 m thick, gray, yellow-gray and green-gray, non-welded to weakly welded, and contains abundant sanidine and quartz crystals in a vitric groundmass. A distinctive set of green and greenish-blue tuffaceous claystones and siliceous claystones occurs above the sanidine bearing tuff. Locally in The Cove, this section contains beds rich with snails (locality L1354 of Appendix 9).

Member H tuff. Above the greenish tuffaceous deposits is a thick (10-20 m), light brown, fine-grained welded ash-flow tuff sheet that is widespread in the western facies (Peck, 1964; Robinson, 1975) as well as in the eastern facies (Fisher, 1966) where it is referred to as the "Picture Gorge ignimbrite." Two recent age determinations of this unit in the Painted Hills are both 28.7 Ma (dates by Carl Swisher, reported in Bestland and others, 1993). This tuff is crystal poor and contains variable amounts of lithic fragments of rhyolite and tuff. Two cooling units are present in the Clarno area as has been recognized in the eastern facies by Fisher (1966). To the west of Clarno, closer to the source, only one cooling unit is recognized (Robinson and others, 1990). In cliffs below the Columbia River Basalt Group on Iron Mountain, member H tuff is commonly overlain directly by the member I ash-flow tuff sheet with no intervening sedimentary deposits. Elsewhere in the western facies, tuffaceous sedimentary deposits occur between the tuffs of member H and I.

Member I tuff. In the Clarno area, this distinctive coarse-grained ash-flow sheet occurs in scattered exposures high on the slopes of Iron Mountain. It was eroded in most places prior to the accumulation of the Columbia River Basalt Group. The tuff is up to 15-20 m thick and contains coarse pumice fragments, coarse vitric shards, and obsidian fragments. Where the base of the unit is exposed, these pebble-sized obsidian fragments are vaguely cross-bedded and may represent the basal surge of the ash-flow. GEOCHEMISTRY OF LAVA FLOW AND TUFF UNITS

Sixty Clarno Unit igneous and tuff samples were analyzed for whole rock geochemistry in order to characterize these units and aid with stratigraphic correlations (Appendix 8). Selection of rock samples and analytical XRF work was done with the help of Paul Hammond.

Basaltic lava flows

Basaltic units in the upper Clarno and lower John Day formations are distinguishable on the basis of both their lithology and bulk rock geochemistry (Fig. 2.17). Three lithostratigraphic basalt units are recognized: 1) amygdaloidal basalt in the conglomerates of Hancock Canyon, 2) member B trachy-andesite or basaltic-andesite in the lower John Day Formation, and 3) alkalic basalts also in the lower John Day Formation although stratigraphically higher than member B (Fig. 2.1). Analyses of basaltic rocks from the lower John Day Formation by Robinson (1969), Robinson and others (1990), Hay (1962a), Taylor (1981) are compared to whole rock data from Clarno Unit basaltic rocks (Fig. 2.17).

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Figure 2.17. Scatter plots of XRF whole rock data of basalt flow from the upper Clarno and lower John Day Formation in the Clarno Unit area.(click on image for an enlargement in a new window)

The amygdaloidal basalt is stratigraphically in the upper part of the conglomerates of Hancock Canyon and is the stratigraphically lowest of the basaltic units discussed here. The basalt is an important local marker unit which ties the conglomerates of Hancock Canyon in the Clarno area with Clarno Formation units south along the John Day River. The unit has been identified further to the south along the John Day River on the north side of Melendy Ridge (sec. 26, R19E, T8S) across from Bowerman's ranch. The lithology and distribution of this unit is covered in the stratigraphy section. The unit is a high-silica basalt to basaltic andesite in major element composition. The most mafic of the six samples analyzed is from the "West Face Cliffs" where the flow is thickest (26 m). All other samples are from the north side of Pine Creek. The sample labelled basalt clast, collected by Paul Hammond, is from a conglomerate bed to the west of Hancock Field Station in the upper part of the conglomerates of Hancock Canyon. The correlation of this basalt flow in the Clarno Unit area with the laterally extensive exposures of the amygdaloidal basalt to the south in the "West Face Cliffs" is well established by this lithologic and geochemical data.

The second group of basaltic rocks occurs in the lower John Day Formation as discontinuous lava flows stratigraphically just above member A welded tuff. Small intrusive bodies at hill

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2148 (NE 1/4 sec 26) intrude Clarno Formation units and have very similar lithology and geochemistry as the lava flows. These basaltic andesites or trachyandesites compare well with member B lavas extensively exposed near Ashwood in the lower John Day Formation (Peck, 1964; Robinson 1975). The prominent lava flow above the welded tuff of member A at the head of Indian Canyon, mapped as member B basalt, is somewhat richer in SiO2 than both the intrusive rocks and an average trachyandesite composition from Robinson and others (1990).

The third group of basaltic rocks also occurs in the lower John Day Formation, although at a significantly higher stratigraphic level than member B basalts. These lava flows are alkalic basalts and are known from the lower John Day Formation in both the western and eastern facies (Hay, 1962; Robinson, 1969). In the Clarno Unit area, one sample of the stratigraphically lowest occurrence of these basalts was analyzed (Fig. 2.17). This basalt caps the ridge above the "Slanting Leaf Beds" fossil site. These member F basalts, using the terminology of Robinson (1975), are extensively exposed stratigraphically higher on the flanks of Iron Mountain and in The Cove.

Geochemistry of andesitic units

The geochemical compositions of the two major andesite units (andesite of Pine Creek and the andesite of Horse Mountain) in the Clarno Unit area are largely indistinguishable (Figures 2.18 and 2.19). Both units are typical of Clarno Formation convergent margin andesites and show chemical characteristics, such as K2O content, indicative of thin continental margin settings (Rogers and Novitsky-Evans, 1977). Several geochemical features of the andesites allow smaller groupings to be made (Fig. 2.18). The andesite of Pine Creek is more compositionally homogeneous and more strictly andesite than the andesite of Horse Mountain. The samples of andesite of Pine Creek from the center of the project area are very similar in composition and slightly more mafic than the andesites of Horse Mountain. These basaltic-andesites contain 4 to 5 times the Cr and Ni of other analyzed andesite samples.

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Figure 2.18. Scatter plots of selected major elements from XRF whole rock data of andesitic igneous rocks in the Clarno Formation. (click on image for an enlargement in a new window)

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Figure 2.19. Scatter plots of Zr and Sr vs Ti in andesitic igneous rocks from the Clarno Formation. (click on image for an enlargement in a new window)

The andesite of Horse Mountain ranges from andesite to dacite (Fig. 2.18). Four samples of the andesite of Horse Mountain are compositionally very similar and include two samples of platy andesite from hill 2066, a sample from the nearby hill to the north in the center of sec. 26, and a sample from an andesite flow in the upper part of the lava flow package of Horse Mountain, above the massive cliff-forming flows and identified as upper andesite unit discussed below. These are probably the same flow unit. On top of Horse Mountain (NE 1/4 of sec 10), a couple of meters of red beds (strongly developed paleosols) lie between the andesite of Horse Mountain proper and this upper andesite unit (see Plate I). Thus, the massive cliff-forming flow of Horse Mountain is not the small flow as the andesite capping hill 2066.

Six of the least altered samples of the Hancock Dome were analyzed. Five of the samples are in the dacite range and one, containing 75% SiO2, is clearly rhyolitic (Fig. 2.18). The range in silica values may be due to non-homogenous parent material, hydrothermal alteration, or deep tropical weathering. The TiO2 content does not vary with SiO2 contrary to the expected trend of decreasing TiO2 with increasing SiO2 which would be expected from normal

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igneous processes of crystal differentiation. Low temperature hydrothermal alteration or deep weathering would produce leaching of mobile bases (Na2O, K2O and CaO), while keeping TiO2 values constant. However, Na2O and K2O do not change significantly whereas CaO does. The great change in CaO values in the sample with the highest SiO2 probably reflects lack of abundant Ca-feldspar and so the variation in the Hancock Dome is probably due to original heterogeneities in the plagioclase content of the igneous body.

Geochemistry of tuffs

Thin and laterally discontinuous tuff beds are common in the volcaniclastic strata of the Clarno Unit area. Most tuff beds occur in the conglomerates of Hancock Canyon and include stony reworked tuff beds and thin white vitric tuff beds. There is also a welded tuff (Muddy Ranch Tuff or Rajneesh Tuff of Vance, 1988) in the upper part of the conglomerates of Hancock Canyon thought to correlate with an extensive tuff sheet in the Muddy Ranch area and dated at 44 Ma by Vance (1988). Additionally, the upper, poorly welded, white part of the John Day member A tuff was analyzed in order to differentiate it from similar-appearing white tuffs in the upper Clarno Formation. Many of the tuffs have been reworked and contain admixtures of volcanic rock fragments which has changed their original composition. However, several correlations are possible from the analyses of these 21 tuff samples (Fig. 2.20; Appendix 8).

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Figure 2.20. Scatter plots of XRF whole rock data of rhyolitic tuffs from the Clarno Formation in the Clarno Unit area. (click on image for an enlargement in a new window)

Two samples of the Muddy Ranch tuff were analyzed; one from the welded portion of the thick tuff sequence in the eastern part of the Muddy Ranch valley along Current Creek (south-central portion of sec. 34, T8S, R18E) and one sample of a welded tuff in the upper part of conglomerates of Hancock Canyon at the Gables. These two tuffs are rhyolitic, compositionally consistent, and have significant Ba and Sr contents that are much higher than most Clarno tuffs. The "Fern Quarry Tuff" also contains significantly lesser amounts of Sr and Ba. Tuff sample C1-5 which crops out in the upper part of the conglomerates of Hancock Canyon, is possibly correlative to the Muddy Ranch Tuff. Two samples of the upper John Day member A were also analyzed (Fig. 2.20) and have similar compositions to the Muddy Ranch Tuff. Another possible correlation is the tuff bed at the base of the "Nut Beds" section (lithic tuff at 27 m lever of Fig. 11) with the tuff at the base of the "Red Hill West" section (Fig. 2.12). These tuffs are referred to as the lower Tcch tuff in Figure 2.20. Other tuffs in the conglomerates of Hancock Canyon have similar but variable compositions that restrict correlations between the sections in the upper part of the Clarno Formation. Vivid green tuffs occur at scattered localities in the Clarno Unit area, however, geochemical analyses of a few http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap2.htm[4/18/2014 12:20:37 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 2)

of these tuffs has so far not revealed any correlations.

STRUCTURE OF CLARNO UNIT AREA

The Clarno Unit-Hancock Field Station area can be divided into two areas based on structure: 1) relatively flat-lying strata of Horse Mountain, and 2) these same strata folded along a NE- SW fold limb. Other smaller folds are present in the area, however, the NE-SW fold dominates the local structure. This fold has the same orientation as the Muddy Ranch dome (Robinson, 1975), to the southwest of the project area. The fold dies out in the northeastern part of the project area (Fig. 2.2). In the Clarno Unit area, the geologic sequence is complicated by this NE-SW fold limb, intrusion of a dacitic dome, another small structural dome, and laterally variable volcanic facies.

Supporting evidence that this structural dome exposes older Clarno units is the identification by Hammond (pers. communication, 1993) of strata underlying the andesite of Pine Creek flow unit, thus documenting that "lower Clarno lahars" underlie this andesite. Mapping of individual lahar units in this lower unit by Hammond as well as strike and dip measurements define a partial domal structure (Plate II). Because the "lower Clarno lahars" have a much different structural signature than the overlying strata (see following section), and are intruded by hornblende dacite, the intrusion of the hornblende dacite, either as a subsurface intrusion or as a viscous surface dome, probably domed the surrounding country rock. Later erosion, deposition and folding has masked much of this relationship. This older sequence is only found around the dacite dome and has not been correlated to other units in the area.

The Clarno Formation above the level of the hornblende dacite dome consists of a series of debris flow aprons variously interrupted by lava flows and minor ash falls and flows. Separating the laharic debris flows from the Mammal Quarry conglomerates and siltstones and andesite of Horse Mountain is the thick sequence of floodplain paleosols in "Red Hill" which represent a profound break in volcanism and hiatus of voluminous coarse-grained volcanogenic sedimentation. Volcanogenic sedimentation again resumed with the eruption of the large and extensive andesite of Horse Mountain and the corresponding deposition of the "Mammal Quarry" beds.

Structural analysis of folded strata

Structural analysis of the folded strata of the Clarno Unit has revealed an episode of relatively inconsistent folding of the area. Strike and dip measurements from the Clarno Unit were grouped into subareas (Table 2.3). These subareas were defined according to their stratigraphic position and structural homogeneity. Wulff net or bottom hemisphere plots is a common technique used to analyze folded strata from strike and dip measurements.

TABLE 2.3. Strike and dip measurements of the Clarno Formation

"Bat Barn Area" "Indian Mesa Area" "Core of Dome" lower section upper section

N35W 12W N10W 12SW S30W 18E N58W 8S N33W 11W N15W 11SW S5E 15E N45E 32N N40W 12W N25E 23SW S35E 19N N37E 34N N20W 10W N15E 22SW S25E 20N N15E 17W http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap2.htm[4/18/2014 12:20:37 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 2)

N10W 30S N15W 33SW N65E 21N N22E 18W N50W 26S S10E 10E N15W 30SW S30E 10NE N3OW 16SW N60W 4N N28W 13SW S80W 7N S45W 13N

Based on field observations, the folded strata in the Clarno Unit are non-homogenous; that is, their orientation has not just been caused by a parallel, single folding event. Their orientations may result from superposed folds, or by fault-block tilting of folded strata. The oldest strata in the area (Lower Clarno lahars of Figure 10) have scattered plots which do not define a fold axis or axial fold plane (Fig. 2.21a). In map view, however, these strata and their strike and dips, define half of a dome. Up-section in the "Bat Barn" area, two subareas have been defined according to their stratigraphic position and homogenous strike. The lower section strike and dips (Figure 2.21b) define a fold axis that trends approximately 52°E and plunges 8° to the S (Figure 2.21b). The upper section has a less well defined axis which trends S39°W and plunges 5° SW (Figure 2.21b).

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Figure 2.21. Stereographic plots of structural data from the Clarno Unit area. Figure 2.21A. Strike and dips from the lower Clarno conglomerates. The non-linear scatter http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap2.htm[4/18/2014 12:20:37 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 2)

of points is consistent with a shallow angle dome structure. Figure 2.21B. Strike and dip measurements from conglomerates of the "Palisades" and conglomerates of Hancock Canyon from the west side of the structural dome (Plate II). Figure 2.21C. Strike and dip measurements from "Indian Mesa" and including both conglomerates of the Palisades and conglomerates of Hancock Canyon. Data defines a fold axis trending N31°E and plunging 9° NE.

The preferred conclusion is that there is a diffuse northeast-southwest trend to these folded rocks, except for the "Lower Clarno lahars" which, at this level of analysis, do not have a clear fold axis orientation. A northeast-southwest axial plane defined in Fig 2.21 is consistent with the northeast-southwest trend of member A in this area.

SEDIMENTATION AND VOLCANISM

Clarno Formation depositional setting

The Clarno Formation sedimentary units in the project area can be broadly grouped into coarse grained debris flow dominated deposits and fine grained, alluvial paleosol or overbank deposits. Lacustrine shales and lacustrine delta deposits are significant locally, however, sedimentary deposits in the Clarno Formation are dominated by conglomeratic debris flow and coarse-grained fluvial deposits (White and Robinson, 1992; Bestland and others, 1994a, b). Fine-grained overbank deposits and paleosols are common in the formation, however due to the poor exposure of these claystone units, the distribution and sedimentology of these units has been largely ignored (Robinson, 1975; Swanson, 1969) except in a few places such as "Red Hill" (Retallack, 1981; 1991a) and in the Cherry Creek area where White and Robinson (1992) briefly describe a thick section of clayey red beds.

The coarser-grained deposits in this area, notable the lahars of the Clarno Formation and the pyroclastic deposits of the John Day Formation, have received some attention. White and Robinson (1992) interpret the coarse-grained Clarno Formation deposits as proximal, non- marine lahar aprons and reworked fluvial deposits that flanked stratovolcanoes, possibly in fault-bounded mini-basins in a tensional arc setting, similar to the Quaternary High Cascade graben of the central Oregon Cascades (Taylor 1990, Smith and others, 1987).

Coarse-grained, non-marine volcaniclastic deposits display a continuum between debris flow and stream flow depositional features (Nemec and Muszynski, 1982; Smith, 1986; Scott, 1988). The continuum exists largely because of rapid transformations that occur between the various flow types. Scott (1988) documents flow transformations from pyroclastic flows to debris flow, debris flows to hyperconcentrated flood flows, and flood surge to lahar based on the deposits and sedimentation records of the 1980 Mt St Helens eruption. These modern examples are important for the understanding of Clarno Formation debris flow deposits. For example, a common deposit combination in the formation consists of a thin layer of vaguely bedded pebbly conglomerates at the base of massive debris flows such as occurs at the base of the lahar containing the "Hancock Tree." The vaguely bedded, granular or pebbly sandstones common in the Clarno Formation have grain to grain contact and stringers of coarser clasts indicating deposition by traction current (Fig. 2.22a). However, cross-bedding or climbing bedforms are missing, indicating that these are not normal fluvial deposits. Deposits such as these have been recognized as an intermediate between fluvial and debris flow processes and referred to as hyperconcentrated flood flow deposits (Smith 1986; Nemec and Muszynski, 1982). In the Mt St Helens case, Scott (1988) documents "bulking" of traction flood surges into debris flows by the incorporation of debris from the fluvial channel by hyperconcentrated floods. The flood surge then precedes the debris flow and produces the depositional package of hyperconcentrated flood deposit with overlying debris flow deposit.

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In the case of Mt St Helens, the flood surge was caused by the rapid melting of the snow pack and glacial ice by hot pyroclastic debris. In the case of a volcano in a humid tropical setting, the stripping of vegetation followed by a large rainfall event (possibly eruption induced) can trigger such flood surges. Bulking of flood surges and the corresponding erosion is more likely to occur in the high gradient landscape positions (high on the alluvial apron) and deposition of the debris flow and associated deposits occurs on lower gradient apron positions.

Figure 2.22. Photographs of volcaniclastic deposits in the Clarno and John Day Formations. Figure 2.22A. Hyperconcentrated flood flow deposits onlapping eroded paleosol (Sayayk pedotype) in the conglomerates of the "Palisades" in the "Palisades Cliffs." Figure 2.22B. Clast-supported debris flow deposit in the conglomerates of Hancock Canyon. Figure 2.22C. Example of a sandy channel deposit in the John Day Formation, Turtle Cove Member, Logan Butte. Backpack on the right side of channel gives scale.

Another common feature in the coarse-grained deposits of the Clarno Formation are clast- rich channelized debris flows. In the south facing part of the "Palisades Cliffs," clast-rich and clast-supported debris flows fill channels cut deeply into underlying lahars. The lahar layers and superposition or nesting of channels in this locality is complex. The resulting stratigraphy

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consists of laterally discontinuous layers on a scale of 10's of meters that contain protruding sticks and logs. Scott (1988) documents channel facies debris flows from the deposits of the 1980 Mt St Helens eruption. These channel facies debris flows are commonly clast supported, sit on an eroded pavement, are localized to the channel area, have protruding logs and sticks and have large-scale longitudinal bar features referred to by Scott (1988) as whale back bars. These channel facies debris flows contrast with floodplain debris flow facies. Floodplain facies debris flows are clast-poor, relative to channel facies, have non-erosive bases commonly with hyperconcentrated flood flow deposits, forest litter, standing trees as well as protruding sticks and logs and lateral continuity of single debris flows. This debris flow facies has a high preservation potential due to lateral continuity and lower chance of fluvial reworking compared to channel facies. Scott (1988) also documents debris flow recession, whereby a "high water mark" is achieved that is significantly higher than the resulting deposit. This process encourages deposition in relatively elevated floodplain or low terrace settings and also causes the pre-debris flow topography to be mantled. Thus, subsequent fluvial channels tend to be located preferentially where the channel facies debris flows were deposited causing superimposed channel complexes (nested channels).

There is a distal-proximal component to channel and floodplain facies debris flows. Proximal to the volcano on the debris flow apron, nearer the apex, channel facies debris flows and fluvial incision and reworking of debris flow deposits are more common. Distal from the volcano and on lower gradient apron settings, floodplain debris flow facies are widespread. Here, fluvial incision and reworking of debris flow deposits also occurs, however, these fluvial conglomerates have a greater preservation potential than on higher gradient areas where syn-debris flow erosion (bulking) is a common process.

These concepts can be applied to the two mapped debris flow packages in the Clarno area to make the following interpretations. The conglomerates of the Palisades are generally coarse grained through-out the mapped area and contain very coarse-grained channel facies debris flow deposits in the "Palisade Cliffs". Such a large debris flow apron with little proximal- distal clast size distribution and largely lacking fluvial conglomerates probably represents a large alluvial apron which flanked a large volcano. If this were a braidplain, then fluvial conglomerate beds would be interbedded with debris flows. This interpretation supports the conclusion of White and Robinson (1992) that the Clarno Formation volcaniclastic deposits accumulated in volcanic flank and apron settings, but is an exception to the conclusion of White and Robinson (1992) who concluded that the volcanoes responsible for Clarno Formation deposition were small. Conglomerates of Hancock Canyon have a mix of debris flow deposits, fluvial conglomerates and tuff beds. The abundance of flood surge or hyperconcentrated deposits and fluvial reworking indicate a lower gradient or more distal depositional setting than the conglomerates of the "Palisades." Additionally, the mixed nature of the deposits with their numerous thin tuff beds indicates a braidplain setting. Lateral variation of this conglomerate unit from a mixed debris flow and fluvial package with tuff beds to a package of coarser grained debris flows from west to east indicates an apron to braidplain transition in this direction.

Coarse-grained volcaniclastic deposits commonly contain sedimentary features indicative of formation during and immediately after volcanic eruptions and also can be interpreted as a record of the volcanic events or even eruptive history of individual volcanoes (Williams and McBirney, 1979; Fisher and Schmincke, 1984; and Cas and Wright, 1987). Proximity and direction to source volcanoes has been worked out in a number of ancient examples (Palmer and Walton, 1990; and Waresback and Turbeville, 1990, to name just a few) using sedimentologic data from modern analogues such as Volcan Fuego, Guatemala (Vessel and Davies, 1981) and Ruapehu, New Zealand (Hackett and Houghton, 1989). The Clarno Formation debris flow packages are similar to previously described proximal apron packages (Palmer and Walton, 1990; Waresback and Turbeville, 1990) interpreted as syn-eruptive

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deposits associated with explosive eruptions. In these cases explosive eruptions produced abundant sand and gravel-sized debris that was initially transported as small block and ash pyroclastic flows and as more widespread fallout layers as at Mt. St Helens in 1980. These types of eruptions are common on andesitic to dacitic volcanoes where they blanket the landscape with ash, kill the plant cover and add moderate volumes of fragmental debris to the headwaters of streams. This material is rapidly redistributed to form alluvial plains that surround the erupting volcano. Build-up of these encircling alluvial plains gives rise to apron facies (alluvial fan equivalent) and arena or ring plain facies (braidplain equivalent) volcaniclastic successions (Pickford, 1987). In practice, the apron and arena facies commonly overlap due to far-traveled coarse grained, eruption-induced aggradational events (Scott, 1988).

The coarse-grained debris-flow-dominated sedimentary units in the Clarno Formation are interpreted as the product of syn-eruptive sedimentation (White and Robinson, 1992; Bestland and others, in press). The debris flow units are laterally continuous and mappable for 5-15 km in the Clarno area and onlap hilly topography to form an upper planar surface. The geometry and rapidly deposited sets of debris flows with little reworking is evidence for debris flow aprons. Sets of debris flows with no paleosol interbeds are common in these debris flow packages. These sets of debris flows are separated by weak to moderately developed paleosols whereas the mappable debris flow packages such as the conglomerates of the Palisades and the conglomerates of Hancock Canyon are separated by well-developed paleosols. The debris flow sets are interpreted as syn-eruptive sedimentation from one eruptive episode and the whole mappable debris flow package probably represents the main eruptive period of a medium-sized volcano.

In the Clarno area tracing of the debris flow apron deposits into proximal and vent facies has been done thus far only at Keyes Mountain (Oles and Enlows, 1971). The lack of a regional stratigraphic framework and marker units in the Clarno Formation has hampered efforts to identify more eruptive centers. High weathering rates in a humid climate may have destroyed much of the constructional central vents of these Eocene volcanoes.

White and Robinson (1992) report from their summary of the sedimentological characteristics of the Clarno Formation that much of the deposits have features consistent with deposition in lowlands flanking large central vent volcanoes at distances of 10-50 km. Therefore, White and Robinson (1992) conclude, as do previous workers (Oles and Enlows, 1971 and others), that the Clarno Formation represents the deposits of an active volcanic arc. The lack of systematic variation in the sedimentary deposits of the Clarno Formation is interpreted by White and Robinson (1992) to represent deposition in braidplains around small volcanoes. Large volcanoes should have produced distal-proximal facies relationships in the coarse-grained sequences. This conclusion of White and Robinson (1992) is premature. Lateral stratigraphic and sedimentologic work on a coarse grained unit in the Clarno Formation was not done by White and Robinson (1992). The complexity and juxtaposition of volcanic units and facies is probably the reason that this type of lateral work was not attempted by White and Robinson (1992). During the course of the present study, the two conglomerate units identified in the Clarno Unit area were mapped over a lateral distance of 10-15 km (Fig. 2.23). The conglomerates of Hancock Canyon change from a mixed fluvial- debris flow package in the western part of the project area to a package of debris flows in the eastern part of the area. The distribution of tuffs and other beds is interpreted as apron to braidplain depositional setting. The conglomerates of the Palisades is a homogenous coarse- grained debris flow package which has some variations from channel to overbank facies but no obvious lateral grain-size change. In this debris flow package, a thick resistant lahar bed (8 m thick) can be traced for 5 km. This type of large volume debris flow probably originated from a large volcano. Other evidence of large volcanoes in the Clarno Unit area are the large volume, laterally continuous andesite units such as the andesite of Horse Mountain (Fig.

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2.23). This unit was probably part of an andesite shield volcano.

Figure 2.23. Photographs of lava flow features in the Clarno Formation. Figure 2.23A. Intracanyon andesite flow of the middle andesite unit (Tcam) exposed along the John Day River south of Clarno. Figure 2.23B. Pipe vesicles in the base of amygdaloidal basalt flow in the "West Face Cliffs" (flow direction is from right to left or towards the northwest). Figure 2.23C. Ramp structures in the cliff-forming flow of the andesite of Horse Mountain, at "West Face Cliffs." Figure 2.23D. Vent facies in the Clarno Formation consisting of steeply dipping coarse pyroclastic strata. Locality is on the east side of the John Day River from Melendy Ridge.

Depositional setting of fossil sites in conglomerates of Hancock Canyon. Within the Clarno area are numerous fossil plant localities (including several new sites, Appendix 9) that indicate apparently dissimilar climates. The classic "Nut Beds" site yields plant fossils strongly indicative of a tropical to paratropical climate (Manchester, 1981, 1994). In contrast, at the same stratigraphic level and in a similar debris-flow depositional environment, fossil plants found in Hancock Canyon suggest temperate conditions. These contrasting floral types are probably not different stages in ecological succession, because early successional fossil soils and plants are also found in this unit, and are dominated by horsetails and ferns. It is more likely that the "Nut Beds" flora represents a lowland rainforest, like the selva of tropical Mexico, whereas the "Hancock Tree" flora represents a higher altitude forest of cooler climatic affinities like the Liquidambar-oak forests of Mexico (Gomez-Pompa, 1973). This does not mean that the "Hancock Tree" fossil locality was at a greatly different elevation than the "Nut Beds." The conglomerates of Hancock Canyon probably contain the ecotone between these two distinct forest types: an upland deciduous woodland (bosque caducifolia) and a lowland tropical forest (selva of Lauraceae of Mata and others, 1971).

Deciduous forests of volcanic and other Eocene uplands were an important source of new plant communities as paleoclimate became cooler and drier from middle to late Eocene and then more dramatically in the early Oligocene (Wolfe, 1987). The vertebrate faunas also reflect these climatic shifts. Fossil mammals of the Clarno "Nut Beds" are comparable to the middle Eocene forest-dwelling faunas of much of North America. The "Mammal Quarry" fauna however, represents an immigration of new mammals from Asia, adapted to cooler and

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drier conditions. The Clarno volcanic arc provides some of the earliest evidence of these later faunas and may represent a staging area for the widespread North American faunas of the Chadronian NALMA (Retallack, 1991a).

Paleosols and overbank deposits. An overbank to piedmont alluvial setting is interpreted for the "Red Hill" claystones based on laterally continuous paleosol horizons present in "Red Hill" and channel conglomerates interbedded with the claystones. An erosional terraced alluvial bottomland was also probably a component of the depositional setting, considering gleyed paleosols (Scat and Sitaxs) at a few levels in "Red Hill." The upper "Red Hill" section contains a thick stack of red Luca paleosols with few gleyed intervals. A large channel-fill conglomerate is interbedded with the claystones of "Red Hill" (Fig. 2.14C) indicating that large channels did exist on the alluvial plain.

Thick accumulations of alluvial paleosols only occurs in scattered pockets elsewhere in the Clarno Formation. Their distribution is not widespread probably due to rapid aggradation of coarse-grained units which was followed by incision during volcanic quiescence. Only occasionally did alluvial plains exist for any length of time during which finer-grained alluvium accumulated. "Red Hill" sits stratigraphically near the top of the Clarno Formation and probably marks the end of explosive andesitic volcanism in this part of the Clarno arc.

John Day Formation depositional setting

Introduction. In regional geologic plate tectonic terminology, the John Day Formation is a non-marine backarc basin. The John Day Formation becomes finer-grained from west to east following the dispersal pattern of pyroclastic material from Cascade vents to the west (Robinson and others, 1984). Geochemical analysis of tuff beds (Hay, 1962, 1963; Fisher, 1966) and C horizons of paleosols (Fisher, 1967; Getahun and Retallack, 1991; this report) indicate a rhyolitic to rhyodacitic composition for the tuffs and tuffaceous alluvial deposits. Previous workers (Robinson and others, 1984; Robinson and others, 1990) have inferred an andesitic composition for the alluvial deposits of the John Day Formation based on the abundance of sanidine, scarcity of biotite and quartz and correlation with the andesitic Western Cascades, the John Day Formation's most obvious source. The ash flow tuffs of the John Day Formation contain sanidine and quartz and are rhyolitic (Robinson and others, 1990) and thus resemble the alluvial deposits analyzed during this project in their geochemical characteristics. The John Day ash-flow tuffs of the western facies are relatively homogenous in composition and differ from the biotite and quartz-rich rhyolitic tuffs of the Western Cascades such as the 35 Ma Bond Creek Tuff (Smith and others, 1980). The western facies ash flow tuff sheets thicken toward the Warm Springs and Mutton Mountain areas. Taken together, these factors support an interpretation of a restricted source area for the John Day Formation that was separate from the Western Cascades.

Alluvial plain depositional setting. The thick, colorful claystone and tuff sequences so well known from the John Day and Clarno formations have been historically problematic in terms of interpretations of depositional environment. The scarcity of classic fluvial depositional features, such as cross-bedded sandstones and other channel type deposits is probably the reason little sedimentologic work has been done on these fine-grained units. Ash-flow tuff sheets have been identified in the John Day Formation and used to informally divide the western facies into members (Peck, 1964; Robinson and others, 1984). The "Picture Gorge ignimbrite" flowed from west to east across the John Day Basin as determined by Fisher (1966) on the basis of changes in lithic and pumice size. These ash-flow tuffs are evidence for low-relief topography. The sedimentology of the fine-grained rocks has been largely ignored except for scattered comments. Hay, (1962 and 1963), interpreted the John Day tuffaceous claystones as massive airfall tuffs variously affected by pre-burial weathering. Other interpretations of the fine-grained sequences include lacustrine silts and claystones

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(Oles and Enlows, 1972), and loess (Fisher, 1967). In this report, and previously (Retallack, 1981, 1991a, b; Bestland and others, 1993, 1994a, b), we interpret most of the claystones and tuffaceous claystone beds of the John Day and Clarno formations as paleosol horizons. Furthermore, most of the paleosols and their associated, although pedogenically modified, substrate, are interpreted as alluvial, and in a few cases colluvial, deposits. Many different paleosol horizons have been identified and interpreted (see Chapter III), however these paleosols can be broadly grouped into floodplain setting (alluvial) and hillslope setting (colluvial) soil forming environments. Landscape aggradation in the form of floods, pyroclastic airfall, wind blown dust and ash, and colluvial movement from up-slope locations caused vertical accretion of soil horizons. Larger-scale additions of alluvium and colluvium periodically buried the landscape and caused new soils to form on these deposits. Aggradational periods were interspersed with episodes of downcutting during which the alluvial and colluvial basin fill would be partially removed (Bestland and others, 1993).

Floodplain depositional environments are well known from both the study of modern fluvial environments (Wolman and Leopold, 1957; Edelman and Van der Voorde, 1963; Allan, 1965; Kesel and others, 1974; Ruhe, 1975) and from the geologic record (Miall, 1985; Bown and Kraus, 1987; Smith, 1990; Willis and Behrensmeyer, 1994). Traditionally, sandstone and conglomerate bodies have been studied and the fine-grained overbank or paleosol facies have been ignored (Retallack, 1990a; Willis and Behrensmeyer, 1994). Models of alluvial architecture have concentrated on channel body geometries of sandstones and conglomerates (Miall, 1977; Nemec and Steele, 1984; Willis and Behrensmeyer, 1994) and channel bedforms with only a few attempts to integrate overbank deposits and paleosols with alluvial models (Bown and Kraus, 1987; Kraus and Bown, 1986).

The fine-grained sequences of the John Day and Clarno formations are interpreted here as floodplain paleosols based on the following general considerations. They are relatively laterally continuous and show evidence of both well and poorly drained conditions. They largely lack coarse-grained channel bodies. During the course of this work only a few coarse- grained channel bodies were described and interpreted (Fig. 2.22c). Channel bodies in the Turtle Cove Member are only slightly coarser-grained than the surrounding deposits and probably represent rapid deposition of fresh pyroclastic material in channels and near channel levees. Overlying and underlying deposits were pedogenically altered to clays so that these tuffaceous channel beds are resistant. In the middle and upper Big Basin Members in the Painted Hills, a few sandy and tuffaceous beds occur some with small scale cross-bedding and graded bedding indicating deposition in fluvial bedforms. The Haystack Valley Member contains gravel conglomerates and channel bodies.

The lack of coarse-grained material in much of the alluvial deposits of the John Day Formation probably has a variety of causes. Humid paratropical conditions during the late Eocene and humid temperate conditions during the early Oligocene would have allowed a thick vegetative and soil cover to blanket the hills where they served to stabilize the landscape, cause low sediment yields and weather gravel-sized detritus into clay. Soil erosion when it did occur would have produced predominantly fine-grained detritus. Pyroclastic alluvium so abundant in the John Day Formation was largely fine-grained in the eastern facies and thus lacked a gravel component. When climate changed during the middle Oligocene to drier and cooler conditions, during deposition of the Turtle Cove Member, the soils on the surrounding hills became thinner, but by this time the topography of the Clarno volcanoes would have been subdued by both millions of years of erosion in humid climates and by the basin-filling of the lower portions of the John Day Formation. Additionally, pumiceous and vitric material in the John Day strata may have been originally coarser- grained than it appears now; the fragile and angular ash shards and pumice fragments lose their integrity during compaction and zeolitization.

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We interpret the lack of gravel conglomerates in both the Clarno and John Day formation fine-grained sequences to reflect the above considerations of paleoclimate, primary alluvial material and the lack of a through-going river system in this depositional area. During Clarno time, the thick fine-grained paleosol sequences formed during pronounced volcanic hiatus. Additionally, the lack of coarse-grained deposits in the eastern facies of the John Day Formation, with the exception of the Haystack Valley Member, indicates a lack of nearby fault-related tectonism and nearby volcanism. The depositional setting for these fine grained floodplain sequences is interpreted to be small, restricted basins that were close to the headwaters of small streams. In most of the John Day Formation, the few channel or fluvial beds that are present consist of fine sand and coarse silt beds, reflecting the lack of gravel in the pyroclastically derived alluvium. Therefore, coarse-grained bedforms with good potential for recognition and preservation are largely absent.

LATE EOCENE PALEOCLIMATE AND TECTONICS

Introduction

The transition from the Eocene to the Oligocene was a period of profound change in the Earth's climate and biota. The earth changed from the warm, mostly subtropical world of the Mesozoic and Paleocene, to the glaciated world of today, or from the "hot house" to the "cold house" (Prothero, 1994). These climatic and biotic changes are centered around the Eocene Oligocene boundary with the changes appearing to be stepwise over several million years on either side of this boundary.

Recent work on the timing and global correlation of the Eocene-Oligocene boundary (Swisher and Prothero, 1990; Prothero and Swisher, 1992; Cande and Kent, 1992) allows for a comparison of the stratigraphy and age determinations established in this project with the global data base of climate change (Fig. 2.24). Much of the existing global climate change data come from deep sea sediments and their oxygen and carbon isotopic record. Paleosols have also been used as evidence of global climate change over this age span (Retallack, 1983; 1992). It has been long known that major shifts exists in the oxygen and carbon isotopic ratios in mircofossils from deep see cores of Eocene and Oligocene age (Keigwin, 1980). These isotopic shifts represent changes in ocean temperature and thus, climatic changes of warming and cooling of the earth. As more and more of these deep sea records have been collected and examined, it has became evident that this long term Eocene- Oligocene climatic transition was punctuated by a series of steps (Zachos et al., 1993). In the Painted Hills these climatic steps correlate approximately with member boundaries in the John Day Formation and with boundaries between the North American Land Mammal Ages (Fig. 2.24). Most notable from this stratigraphic study of paleosols is the abruptness of the Eocene-Oligocene climatic transition. The short time span of this change is not apparent from paleontological evidence of vertebrates and plant fossils in the Pacific Northwest because of the incompleteness of the fossil record. The paleoclimatic record from paleosols in the Clarno and John Day formations, in contrast, is much more complete.

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Figure 2.24. Correlation of the upper Clarno and lower John Day formations with global climatic and tectonic events. The Clarno section is from the Clarno area and the John Day section is from the Painted Hills area. Oceanic events include hiatuses (gaps in sedimentation or erosional events) and γO18 "spikes" which are caused by temperature excusrsions or cooling events. Major cooling events are indicated from both γO18 data and from paleontological evidence. The R19 plate tectonic reorganization is dated from the bend in the emperor Hawaiian seamount chain and has been correlated with climatic cooling. Paleomagnetic time scale is from Cande and Kent (1992) and Eocene-Oligocene follows Swisher and Prothero (1990). (click on image for an enlargement in a new window)

Step-wise change in paleosol weathering trends

Five different paleosol facies are contained in the upper Clarno and lower John Day Formation in the Clarno area and follow major stratigraphic subdivisions. The paleosol types (pedotypes of Retallack, 1994b) that make up these paleosol facies are covered in Chapter III. In each paleosol facies, one pedotype is representative of the optimum degree of weathering that occurred under a particular depositional setting and paleoclimate (Fig. 2.25). These paleosol types are the most developed paleosols in the section, but are not residual paleosols (as is the Pswa pedotype). They are also from well-drained soil forming environments. In stratigraphic order the pedofacies are: 1) conglomeratic debris flow dominated deposits contain Patat pedofacies, 2) lower "Red Hill" claystones contain Lakayx pedofacies, 3) upper "Red Hill" claystones and lower Big Basin member contain Luca pedofacies, 4) siltstones of the "Mammal Quarry" contain Micay pedofacies, 5) middle Big Basin Member contains Ticam pedofacies (see Painted Hills volume for this pedotype).

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Figure 2.25. Weathering trends from paleosols in "Red Hill." Parent material compositions of igneous rocks and tuffs from the Clarno area are also plotted. Scat and Lakayx pedotypes are from the lower, very strongly weathered part of Red Hill. Sitaxs and Luca pedotypes are from the upper, strongly weathered part of "Red Hill."

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Correlations of the stratigraphic subdivisions, and thus the stratigraphically controlled pedofacies, are based on Ar/Ar dates, estimates of the time of soil formation of paleosols, and stratigraphic thickness (Fig. 2.24). The duration of stratigraphic units is estimated by graphing stratigraphic thickness with time using these age determinations (Fig. 2.26). The timing of stratigraphic boundaries are estimated by linear extrapolation from two or more age determinations in the same unit. These linear extrapolations also approximate sedimentation rates since they represent thickness over time. The utility of graphic correlations such as Figure 2.26 depends on the stratigraphic completeness, the quantity and quality of the age determinations, and uniformity of sedimentation rates within units.

Figure 2.26. Graphic correlation of the upper Clarno Formation units from the Clarno area and lower John Day Formation from the Painted Hills area. (click on image for an enlargement in a new window)

In the conglomeratic deposits (conglomerates of the Palisades and conglomerates of Hancock Canyon), only weakly developed paleosols are present between some debris flow deposits. Sedimentation rates were high and time intervals between episodes of eruption and sedimentation where short, consequently, the paleosols are Entisol and Inceptisol-like paleosols. The Inceptisols-like paleosols, referred to as Patat and Sayayk pedotypes, represent 10's to 100 yrs of soil formation and their geochemical compositions are not much different from the andesitic to dacitic parent alluvium (Fig. 2.25).

In the lower part of "Red Hill," strongly developed, Ultisol-like paleosols of the Lakayx pedotype are present and represent a dramatic change in depositional setting from an active volcaniclastic apron of the conglomerates of Hancock Canyon to a quite floodplain. This change represents the cessation for a long period of time of proximal volcanic activity in at least this part of the Clarno Formation. Each Lakayx type paleosol represent approximately 50,000 years of soil formation in a humid paratropical climate. These paleosols and their associated poorly drained Scat pedotypes are the most weathered paleosols in the upper Clarno and lower John Day formations in the Clarno Unit area (Fig. 2.25).

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In the upper part of "Red Hill," strongly developed Alfisol-like paleosols of the Luca pedotype dominate the section. Each Luca paleosol represents 20,000-50,000 years of soil formation in a humid paratropical climate. The change from Ultisol-like Lakayx to Alfisol- like Luca paleosols is interpreted as a result of climatic cooling and drying during the late Eocene. This break between the lower and upper "Red Hill" claystones may correlate to a period of oceanic cooling centered around paleomagnetic time interval chron R19 (reversed) which is thought to be caused by a major plate tectonic reorganization, best expressed by the bend in the Hawaiian-Emperor seamount chain but also recorded in new spreading in the Indian Ocean (Williams, 1986). The age of chron R19 has recently been adjusted to approximately 42 Ma by Cande and Kent (1992) which fits well with our 42.5 Ma estimated age of the boundary between the lower and upper "Red Hill" claystones (Fig. 2.26). Changing patterns of oceanic circulation and volcanism are the hypothesized causes for this climatic change (McGowan, 1989). The R19 plate tectonic reorganization may have caused the change from Clarno arc subduction to Cascade arc subduction. By this reasoning, "Red Hill" marks the end of voluminous Clarno volcanism. The change in paleosol type from lower to upper "Red Hill" marks the climatic change set in motion by the plate tectonic reorganization. The hiatus in volcanism recorded in the "Red Hill" section from 44 Ma to about 40 Ma, when John Day or Cascade volcanism began, is correlated to Gresens (1981) Telluride erosion surface and in central Oregon was a period of sporadic volcanism transitional from the Clarno to the Cascade arc.

Following this volcanic hiatus of approximately 2-4 million years, renewed volcanism, represented by the andesite of Horse Mountain, rejuvenated the alluvial system with fresh andesitic material and caused the deposition of the "Mammal Quarry" beds. More rapid alluvial aggradation and fresh andesitic material changed the soil type from red and clayey "Red Hill" type paleosols to the brown Inceptisol-like paleosols in the "Mammal Quarry" siltstones. These paleosols are too weakly developed to interpret much in the way of paleoclimate, except that it was humid and relatively warm.

With the onset of John Day volcanism, the dominent alluvial material changed from andesitic detritus to fine-grained rhyodacitic ash. In the late Eocene, lower Big Basin Member in the Clarno Unit area, strongly developed Alfisol-like paleosols of the Luca pedotype are the most weathered of the paleosols in this thick and varied section (Fig. 2.25). The geochemical composition of these John Day Luca paleosols are much the same as Clarno Luca paleosols and indicate little if any climatic change from late Clarno time to early John Day time. The higher amount of bases in the John Day paleosols is due to rhyodacitic parent material and pyroclastic rejuvenation. Not until approximately 34 my at the Eocene-Oligocene boundary did the climate change dramatically. In the Clarno area this boundary is marked by the change from the lower Big Basin Member to the middle Big Basin Member, or from Luca pedofacies to Ticam pedofacies. The change from subtropical to temperate conditions across this boundary is contrasted dramatically by comparing the Eocene "Nut Beds" flora and "Red Hill" Lakayx paleosols with the Oligocene Bridge Creek flora ("Slanting Leaf Beds") and middle Big Basin Member Ticam paleosols.

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

CHAPTER III: PALEOSOLS AND PALEOENVIRONMENT OF THE CLARNO AREA

INTRODUCTION

The Clarno Formation is largely andesitic volcanic and volcaniclastic rocks but fossil soils are locally conspicuous. Thick red clayey fossil soils have long been used to subdivide the formation (Waters and others 1951; Noblett, 1981). In recent years, paleosols also have been used to try to reconstruct the fossil record of Eocene ecosystems (Retallack, 1981a, 1991a,b, Smith, 1988; Pratt, 1988). Both approaches are part of the work presented in this chapter, which is a comprehensive account of the variety of paleosols found in the Clarno Formation in its type area around Hancock Field Station. Each distinctive paleosol type or pedotype (of Retallack, 1994b) has been given a name in the Sahaptin Indian language, which will be defined and described in due course, but are summarized in Table 3.1. Before proceeding with characterization of the paleosols, we consider various features by which they have been identified and likely alteration of the profiles after burial. For this preliminary discussion the paleosol names merely provide convenient labels.

TABLE 3.1 - Diagnoses and identifications of pedotypes from the Clarno area

PEDO- INDIAN ORTHO- TYPE DIAGNOSIS U.S. F.A.O. AUSTR- NORTH- TYPE MEANING GRAPHY PROFILE MAP ALIAN COTE

Acas eye acas Hancock Purple, Plinthic Ferric Lateritic Gn3.21 Canyon slickensided, Haplohumult Acrisol Podzolic subsurface clayey (Bt) horizon Cmuk black cmúk below Black lignite Hemist Eutric Acid Peat O "Black on gray Histosol Spur" claystone with local iron- manganese nodules Lakayx shine la.kày X "Red Red (2.5YR- Hapludult Ferric Krasnozem Gn3.11 Hill" 10R), clayey, Acrisol thick, abundant slickensided cutans, http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap3.htm[4/18/2014 12:20:46 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 3)

deeply weathered Lakim soot la.ki'm Painted Brown to Aquandic Eutric Humic Uf6.61 Hills olive, with Placaquept Gleysol Gley large black iron- manganese nodules Luca red lucá Maurer's Red (2.5YR- Hapludalf Chromic Red Gn4.41 Ranch 10R), thick, Luvisol Podzolic clayey to silty, with remnant weatherable minerals Luquem decayed luq'em "Fern White Typic Vitric Alluvial Um1.21 fire Quarry" bedded Udivitrand Andosol volcanic ash with root traces Micay root míeay "Mammal Brown to Hapludand Ochric Grey Clay Uf1.41 Quarry" olive bedded Andosol claystone with root traces Pasct cloud pásct "Red Olive gray to Sombrihumult Humic Grey Gn3.94 Hill" orange, Acrisol Brown slickensided, Podzolic subsurface clayey (Bt) horizon Patat tree pátat Hancock Bedded Psammentic Eutric Brown Um5.51 Canyon sandstone Eutrochrept Cambisol Earth with root traces, mildly leached and ferruginized Pswa stone, clay pswá below Purple clayey Lithic Orthic Brown Gn2.01 "Black subsurface Hapludalf Luvisol Podzolic Spur" (Bt) with core-stones and gradational contact down to andesite Sayayk sand sayáykw "Nut Bedded Tropofluevent Eutric Alluvial Um1.21 Beds" siltstone with Fluvisol root traces Scat dark sc'at "Red Thin gray to Haplumbrept Humic Alpine Uf1.41 Hill" green Cambisol Humus claystone on andesitic http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap3.htm[4/18/2014 12:20:46 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 3)

conglomerate Sitaxs liver siráXs "Red Olive-purple Placaquand Eutric Humic Uf6.41 Hill" silty Gleysol Gley claystone, with relict bedding, and iron manganese skins and nodules

Note: Sahaptin Indian names are from Rigsby (1965) and DeLancey and others, 1988).

Detailed petrographic and geochemical studies of the paleosols have focused on a reference measured section through the upper Clarno Formation near the well known fossil "Nut Beds" and a few other measured sections on Hancock Field Station (Figs 3.1 - 3.10, Tables 3.2-3.3), but the paleosol types can be recognized more widely in the region.

Figure 3.1. Location of measured sections of paleosols in the Clarno Unit of the John Day Fossil Beds National Monument. (click on image for an enlargement in a new window)

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Figure 3.2. Trenches used for detailed study of paleosols in the upper Clarno and lower John Day Formation near Hancock Field Station, Clarno: A, lower conglomerate trenches of reference section viewed from south; B, upper conglomerate trench of reference section is visible in central bluff and both "Nut Beds" trenches were in that southernmost outcrop of these silicified conglomerates and sandstones, viewed from east along trail to "Red Hill" on skyline: C, lower "Red Hill" trench of reference section from south; D, upper "Red Hill" trench of reference section from south; E, "Mammal Beds" trench in foreground viewed from north toward "Red Hill" and John Day Valley in distance; E, "Whitecap Knoll" section viewed from south with Iron Mountain in the distance.

Figure 3.3. Lithological symbols for columnar sections of paleosols. (click on image for an enlargement in a new window)

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Figure 3.4. Composite reference section of paleosols in the upper Clarno Formation near Hancock Field Station. Lithological symbols after Fig. 3.3. Degree of http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap3.htm[4/18/2014 12:20:46 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 3)

development, calcareousness after Retallack (1988) and hue from Munsell color (1975) chart. (click on image for an enlargement in a new window)

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Figure 3.5. Lower conglomerates or subsection 1 of the reference section through upper Clarno Formation near Hancock Field Station. Lithological symbols after Fig. 3.3. Degree of development, calcareousness after Retallack (1988) and hue from Munsell color (1975) chart.

Figure 3.6. Upper conglomerates or subsection 2 of the reference section through the upper Clarno Formation near Hancock Field Station. Lithological symbols afer Fig. 3.3. Degree of development, calcareousness after Retallack (1988) and hue from Munsell color (1975) chart. (click on image for an enlargement in a new window)

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Figure 3.7. Lower "Nut Beds" or subsection 3 of the reference section through the upper Clarno Formation near Hancock Field Station. Lithological symbols after Fig. 3.3. Degree of development, calcareousness after Retallack (1988) and hue from Munsell color (1975) chart.

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Figure 3.8. Upper "Nut Beds" or subsection 4 of the reference section through the upper Clarno Formation near Hancock Field Station. Lithological symbols after Fig. 3.3. Degree of development, calcareousness after Retallack (1988) and hue from Munsell color (1975) chart.

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Figure 3.9. Lower red beds or subsection 5 of the reference section through the upper Clarno Formation near Hancock Field Station. Lithological symbols after Fig. 3.3. Degree of development, calcareousness after Retallack (1988) and hue from Munsell color (1975) chart. (click on image for an enlargement in a new window)

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Figure 3.10. Upper red beds or subsection 6 of the reference section through the upper Clarno Formation near Hancock Field Station. Lithological symbols after Fig. 3.3. Degree of development, calcareousness after Retallack (1988) and hue from Munsell (1975) color chart. (click on image for an enlargement in a new window)

TABLE 3.2. Component measured sections of the reference section (1-6) and other measured sections (A-G) of paleosols in the Clarno and John Day Formations, near Clarno.

Level No. Name Location Formation (m)

lower 1 SW1/4 SW1/4 SW1/4 SE1/4 sec.27 702782E 4977306N Clarno 0-14 conglomerates upper 2 SE1/4 SW1/4 SW1/4 SE1/4 sec.27 702894E 4977348N Clarno 12-53 conglomerates 3 lower "Nut Beds" SW1/4 SW1/4 SW1/4 SE1/4 sec.27 702748E 4977295N Clarno 52-62 4 upper "Nut Beds" SE1/4 SE1/4 SE1/4 SW1/4 sec.27 702744E 4977294N Clarno 61-67 5 lower "Red Hill" NE1/4 SE1/4 SE1/4 SW1/4 sec.27 702695E 4977388N Clarno 67-97 SW1/4 NW1/4 NW1/4 SE1/4 sec.27 702783E 6 upper "Red Hill" Clarno 94-150 4977537N NE1/4 SW1/4 NW1/4 SW1/4 sec.26 704022E A Hancock Canyon Clarno 28-30 http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap3.htm[4/18/2014 12:20:46 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 3)

4978153N B "Fern Quarry" SE1/4 NW1/4 SE1/4 SW1/4 sec.26 703986E 4977651N Clarno 17-18 middle "Black SW1/4 NW1/4 SW1/4 SE1/4 sec.27 703112E C Clarno 39-40 Spur" 4977736N SW1/4 NW1/4 SW1/4 SE1/4 sec.27 703112E D lower "Black Spur" Clarno 36-39 4977736N E "Sienna Ridge" SW1/4 SE1/4 NE1/4 NW1/4 sec.26 704106E 4978605N Clarno 120-122 F "Mammal Quarry" NE1/4 NW1/4 NE1/4 SE1/4 sec.27 703283N 4978117N Clarno 122-124 SW1/4 NE1/4 NW1/4 NW1/4 sec.26 703741E G "Whitecap knoll" John Day - 4978852N

FEATURES OF THE PALEOSOLS

Recognition of paleosols in sedimentary rocks is an interpretation similar to recognizing paleochannels or tuffs. In our studies of Eocene and Oligocene paleosols in the Clarno area, we used three main kinds of evidence to recognize paleosols: traces of land life, soil horizons and soil structures.

Traces of land life

To many soil scientists (Buol and others, 1980), it is life that distinguishes soils from sediments and rocks. Traces of land life, such as root traces and burrows, are the best possible evidence for the existence of paleosols. This is not to say that paleosols or soils must show traces of life. Because of chemical and other conditions prevailing during burial of a soil, very little of their original life is preserved (Retallack, 1984a). Few Precambrian paleosols or Antarctic soils show much trace of life, because little life was present (Retallack, 1990a). In the case of Eocene and Oligocene paleosols from Oregon, research has been directed toward their rich fossil record of plants and mammals (Retallack, 1991a,b). These paleosols also contain a variety of fossil root traces, burrows, and other useful paleontological features indicating that they were soils.

Root traces. Both burrows and root traces are abundant and diverse in paleosols of the Clarno area. In some cases they are difficult to distinguish, as in drab colored backfilled burrows seen in some Lakayx paleosols (Smith, 1988). In other cases root traces are obscured by nodular overgrowths, as in the iron- manganese nodules and septaria of Lakim paleosols (Pratt, 1988). In general, root traces are irregularly shaped, branching and tapering downward (Fig. 3.11). Burrows on the other hand are parallel sided, branching systematically, if at all, and nodules are rounded to ellipsoidal masses. In some cases fossil root tissues are preserved by cellular permineralization (Fig. 3.12).

Figure 3.11. Fossil root trace (black) in a vertically-oriented petrographic thin section of a cobble similar to a Sayayk paleosol within colluvial breccia above the type Pswa paleosol in the late Eocene upper Clarno Formation below "Black Spur" (rock specimen JODA5055). Scale is 1 mm.

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Figure 3.12. Downward branching fossil root with remnants of central conducting strand and marginal epidermis in A horizon of type Luquem paleosol in the middle Eocene Clarno Formation in the "Fern Quarry" (rock specimen JODA5095). Scale is 1 mm.

Many of the root traces in these paleosols show drab haloes: diffuse zones of green-gray to blue-gray carbonate or clay extending outward from the sharp inner boundary of the root hole (Fig. 3.13). Such drab-haloed root traces are common in red paleosols of the Clarno area (Lakayx, Luca, Acas paleosols). Drab haloed root traces are sparse and simple in most Lakayx paleosols, but the last paleosol of this type below a major erosional disconformity in "Red Hill" shows associated haloes of iron-manganese, or mangans in the terminology of Brewer (1976). Chemical study of these indicates significant iron depletion within the drab haloes, which is most extreme in examples with complex double haloes (Fig. 3.14). These data indicate open system alteration typical of gleization in the original profile. Considering the highly oxidized matrix this was more likely local slow drainage than pervasive waterlogging. Observations of the drab haloes as diffuse areas of discoloration around deeply penetrating root traces in a red matrix is evidence against their origin as holes filled with drab-colored material from overlying layers (krotovinas in soil terminology) or as areas unaffected by burial reddening of the paleosols. The way in which the haloes extend out from stout parts of the root traces, as well as from fine rootlets, is incompatible with the idea that the drab haloes represent an ancient rhizosphere depleted of iron and other nutrients. The active rhizosphere is at the tips of the rootlets where there are abundant root hairs, not on the old main roots (Russell, 1977). Thus, the most likely of the various possible origins for these drab haloes around root traces (discussed by Retallack, 1990a, 1991d) is as products of anaerobic decay during early burial of organic matter of the root in Luca and Acas paleosols, perhaps with some chemical reduction and transport of iron and manganese due to local or seasonal waterlogging in Lakayx paleosols. Pervasive waterlogging of Lakayx paleosols is ruled out by their strong development, deeply penetrating root traces and burrows and highly oxidized chemical composition. Because dead roots in these well-drained lowland soils would already have decayed aerobically before burial, the drab-haloed root traces represent the last crop of vegetation and humus before burial. Thus, drab-haloed root traces can be a guide to the nature of former vegetation.

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Figure 3.13. Drab-haloed root traces from the tpe Luca clay paleosol in the lower John Day Formation at "Whitecap Knoll". The root trace is a central streak of pale yellow (5Y7/4), flanked by drab halo of light gray (5Y7/2) which grades out into the dark red (2.5YR3/6) matrix. Scale in centimeters and millimeters (Retallack specimen R417). (click on image for an enlargement in a new window)

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Figure 3.14. Microprobe traverses through drab-haloed traces, from root (or), to halo (dh) and red matrix (rm), in the Lakayx clay manganiferous variant paleosol at 85 m in references section. Specimens analyzed are from left to right JODA4185, 4186, 4187. Data from Smith (1988).

Several different patterns of root traces were observed during excavation of these paleosols. Patterning and ecology of modern roots now is increasingly well documented (a summary is given by Jackson, 1986). Most of the fossil root traces seen were deeply penetrating, and most of them were near vertical. In contrast, tabular root systems were found with root traces deflected by boulders of volcanic lava in Pswa paleosols and in underclay below lignites of Cmuk paleosols. Tabular root systems are found in permanently waterlogged soils (Jenik, 1978) and low-nutrient soils of tropical rain forest (Sanford, 1987).

Plant remains. Paleosols of the Clarno area contain diverse plant fossils in addition to the root traces already discussed. Both the nature and style of preservation of these remains are compatible with interpretation of these rocks as sequences of fossil soils.

Fossil pollen, leaf impressions and silicified wood are known from the Clarno and John Day Formations near Clarno mainly from drab-colored weakly-developed paleosols (Retallack, 1981a: Cmuk, Luquem, Micay, Patat, Sayayk paleosols). The plant fossils show a bias toward wet and mesophytic vegetation

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types, whereas red paleosols represent vegetation of seasonally wet and well-drained sites in which plant remains were seldom preserved, as is usual for paleosol sequences (Retallack, 1984a, 1990a). Preservation of the leaves is primarily as impressions, as would be expected on moderately aerated weakly developed soils. In Cmuk paleosols, which include coaly surface horizons, some of the fossil leaves have cuticle, presumably preserved under the anaerobic conditions of a local swamp.

Many of the fossil plant beds in the Clarno lahars have the character of fossil leaf litters, especially in Sayayk and Patat paleosols (localities L750, L1359, L1730, L1732, L1753, L1754, L1755, L1756, L1759, L1760, L1761, L1854, L1855, L1856, L1857, L1858, L1859, L1860, L1861, L1873 of Appendix 9). The leaves are crowded into a thin bedding plane between sparsely fossiliferous overlying sediments and sediment with large root traces below. The leaves are commonly fragmented, skeletonized, and covered with scribbling marks like those of fungal hyphae and insect feeding trails. In some cases leaves are preserved in high relief, as if dried and curled in a leaf litter. In the Patat paleosol preserved below a 11 m lahar underlying a distinctive amygdaloidal basalt in Hancock Canyon (L1750, L1733), the leaf litter layer also has rooted within it large permineralized stumps, including the "Hancock Tree" (Retallack, 1981a, 1991a). Other paleosols preserve plants in growth position arching up into overlying strata: for example, horsetails (Equisetum clarnoi) in a Luquem paleosol and ferns (Saccoloma gardneri) in a Luquem paleosol in the Clarno "Nut Beds" (Fig. 3.15) and in a Sayayk paleosol in Hancock Canyon (L1650), and ferns (Saccoloma gardneri) in a Luquem paleosol in the "Fern Quarry" (L1099). Rapid burial within lahars and hyperconcentrated flows, followed by permineralization in warm muddy volcaniclastic sediments may explain this remarkable record of early successional and herbaceous Eocene vegetation. Comparable burial and preservation of forests and fossil leaf litters in volcanic airfall ash was observed following the 1980 eruption of Mt St Helens in Washington (Karowe and Jefferson, 1987) and the 1982 eruption of El Chichon volcano in Mexico (Burnham and Spicer, 1986).

Figure 3.15. Fossil horsetails (Equisetum clarnoi) in growth position in a Luquem paleosol in the central outcrop of the "Nut Beds" of the middle Eocene Clarno Formation. The example indicated by finger is branching upwards.

Plant remains also have been found in a fluvial conglomerate, perhaps partly hydrothermally sintered, at the well known "Nut Beds" locality of the Clarno Formation (L685, L977; Manchester, 1981, 1994), and in lacustrine varved shales at the "Slanting Leaf Beds" (L743) and correlative strata of the John Day Formation on Knox Ranch (L1352, L1352: Manchester and Meyer, 1987; Meyer and Manchester, 1994) as well as from a new locality of lacustrine shales in the lower John Day Formation (L1568).

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Few of these abundant and diverse fossil remains are of fully aquatic plants: with the possible exception only of monocot leaves similar to reeds.

Invertebrate fossils. The rarity of invertebrate fossils in the Clarno area is not surprising considering the non-calcareous nature of most the paleosols in which shells would not be preserved and their red well-oxidized composition unsuitable for preservation of organic remains (Retallack, 1984a). Nevertheless, insect galls and nibble marks on leaves are known from fossil leaf litters of the Clarno lahars and one piece of permineralized "Nut Beds" preserved a boring beetle within its hole (S. Manchester pers. comm. 1981). In these cases, rarity of invertebrates may be due to the overwhelming abundance of plants among these fossils of lahars.

Fossil terrestrial snails are found in paleosols of the middle John Day Formation, that have yielded also fossil bones and teeth (locality L1541 of Appendix 9). Their occurrence here can be predicted from the calcareous nature of these paleosols (Retallack, 1984a).

A more copious record of invertebrates is known from lacustrine shales of the John Day Formation, which have yielded aquatic snails (L1568, L1354) and a variety of terrestrial insects (L1568, L743; Manchester and Meyer, 1987). These records provide assurance that insects were abundant and diverse despite taphonomic obstacles to their widespread preservation in paleosols.

Burrows and other trace fossils. A variety of burrows and other invertebrate trace fossils were found in many of the paleosols. Their abundance and diversity in some paleosols explains in part their massive bioturbated appearance. For example Lakayx paleosols at the base of the red bed sequence in "Red Hill" include at least three different kinds of structures of probable biogenic origin (Smith, 1988). The most distinctive are near-vertical unbranched tubular burrows some 3-4 mm in diameter, filled with grey silty clay divided by meniscate seams of red clay. These backfill structures are like those of a burrowing insect, and overall these burrows are most like those of burrowing beetles, perhaps a root feeder. Also notable in Lakayx paleosols are rounded clasts of sand to granule size of strongly ferruginized claystone, similar to clayey "pseudosand" and "spherical micropeds" common in tropical soils (Mermut and others, 1984). These structures are commonly interpreted as oral and fecal pellets of ground- dwelling termites (Retallack, 1991c). Both Lakayx and some Sitaxs paleosols include brown to yellow ferruginized ellipsoidal to globose clusters some 2-5 cm in diameter with each nodular unit 4-7 mm in diameter, and commonly associated with slender burrows or drab-haloed root traces. The origin of these distinctive and abundant structures is uncertain: possibilities include calies of fungus-gardening ants or termites, or root nodules from either rhizobial symbionts or fungal mycorrhizae.

In contrast with this distinctive trace fossil assemblage of Clarno red beds are calcareous trace fossils associated with green volcaniclastic paleosols of the middle John Day Formation (at locality L1541 of Appendix 9). These include small calcareous balls some 11-13 mm in diameter, similar to Pallichnus dakotensis from Oligocene paleosols of South Dakota (Retallack, 1984b, 1990b). Pallichnus has been interpreted as the internal mold of a geotrupine dung beetle larval cell, but comparable study of these traces have not been undertaken. Other trace fossils from the John Day Fonnation in the Clarno area are irregular sheets or nodules composed of ellipsoidal units of calcareous siltstone some 5-6 mm in length, similar to Edaphichnium lumbricatum from Eocene paleosols in Wyoming (Bown and Kraus, 1983). Edaphichnium has been interpreted as the chimney of a large earthworm. Much could be learned about these ancient terrestrial ecosystems by further study of their trace fossil assemblages.

Fossil bones. The Clarno area is well known for mammal fossils. Detailed studies of bones in Micay paleosols in the "Mammal Quarry" (L775: Pratt, 1988) showed that the bones had no particular orientation, indicating little or no sorting by water. The bones were disarticulated, cracked and in some cases merely a group of splinters. Several large skulls of titanotheres, rhinoceroses, oreodons and a creodont carnivore were preserved more or less intact. This kind of preservation would be expected during the natural accumulation of dead animals or large carcass fragments in a soil, followed by rotting, weathering and trampling.

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Less is known about bones from the "Nut Beds" (L1359) but our field inspection of such remains and their known sites indicates that they are preserved as clasts in fluvial and laharic conglomerates. The bones are relatively equant, robust teeth, maxillae or fragments. This kind of preservation would be expected from river abrasion and reworking of loose bones washed into streams (Hanson, 1980).

Even in paleochannels of the Clarno Formation most of the fossil vertebrates are of terrestrial creatures. This includes the alligators (Pristichampsus) which belong to an extinct group with distinctive cursorial limb structure (Langston, 1975) and the tortoise (Hadrianus) which is more closely allied to Galapagos tortoises than pond turtles (Hay, 1908). This leaves fish bones and scales in the "Mammal Quarry" as the only definite aquatic vertebrates in the Clarno Formation in its type area.

Fossil fish, including mudminnows are more common in lacustrine shales of the lower John Day Formation (L743, L1568, L1354), but these shales also have yielded terrestrial to semi-terrestrial vertebrates including frogs, salamanders and a bat (Manchester and Meyer, 1987). None of these aquatic elements have been found in paleosols of the John Day Formation. Fossil bone is locally common in calcareous paleosols of the middle and upper John Day Formation (as at L1541), but only a single poorly preserved fragment of a very robust tusk of an extinct hoglike entelodon was found in a non-calcareous paleosol of the lower John Day Formation (L1358). This pattern of preservation has been predicted from general models for fossil preservation in paleosols (Retallack, 1984a), because the calcium apatite of bone is soluble in acidic solutions of non-calcareous soils. The lack of a fossil record of vertebrates in red beds of the lower John Day and Clarno Formations does not reflect a scarcity of game, but merely a lack of preservation in forest soils.

Soil horizons

A second general category of features diagnostic of paleosols, as opposed to other geological phenomena, is gradational alteration down from the ancient land surface, or soil horizons. Soil horizons usually are truncated abruptly at the land surface but show gradational contacts downward into their parent material (Retallack, 1990a). Sedimentary beds, on the other hand, are in general sharply bound and often more numerous and thin. These general differences were used in conjunction with other features, such as root traces and soil structure to recognize paleosols in these mid-Tertiary volcaniclastic sequences (Fig. 3.16, 17). A few paleosols (especially Luquem and Sayayk) are intermediate in showing additions to the surface that include root traces indicating persistence of vegetation. These cumulic horizons (of Soil Survey Staff, 1975) or cumulative horizons (of Birkeland, 1984), nevertheless show sedimentary structures distinctly different from the massive and pedogenically altered material of the ancient soil profile below.

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Figure 3.16. Type Luquem silty clay loam paleosol in the middle Eocene Clarno Formation in the "Fern Quarry". Within the paleosol relict bedding is extensively disrupted by fossil root traces that are not found above its sharp upper surface. This is a weakly developed paleosol. The hammer handle for scale is 25 cm long.

Figure 3.17. Luca clay pisolitic variant paleosol at 87 m in reference section of late Eocene Clarno Formation. The top of the paleosol is the sharp top to the light gray band or A horizon which passes gradationally downward through an horizon of drab- haloed root traces into a red clayey Bt horizon. This is a moderately developed paleosol, with little trace of the relict bedding seen in Fig. 3.14. Tape for scale is graduated in inches.

Clayey surface horizons. In some of the paleosols (Micay, Scat, Patat) the most clayey part of the profile is the uppermost 20 cm or so. Was this clayey layer formed by weathering of a more silty parent material? Or was it a separate clayey bed of a fining-upwards sequence of the parent material? These alternatives are not mutually exclusive: some component of each is likely in a soil, but no weathering in place would be detectable if it were only a sedimentary bed. For these paleosols, the contribution of weathering is most obvious in thin sections, where etched and deeply weathered minerals and rock

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fragments are common.

Although surface clayey horizons are unlikely to be only a fine-grained upper part of a graded bed, some sedimentary additions to them are likely. Chemical analyses, particularly of materials stable in soils such as titania and zirconium, demonstrate that the upper horizon of some of the paleosols had a parent material different from the lower horizon. In the type Patat paleosol, soil formation added a finer grained upper horizon to several distinctly different sandy beds of its parent material. In all these cases, the rate of influx of new material was slow enough for material to be incorporated into the soil fabric. Eolian and fluvial influx are now recognized as common in soils (Brimhall and others, 1988; Muhs and others, 1987).

Subsurface clayey horizons. Many of the paleosols (Lakayx, Luca, Pasct) have a diffuse zone of clay enrichment below the less clayey, truncated top of the profile (Fig. 3.15). These paleosols are all in alluvial to piedmont sequences. Could these clayey zones represent merely finer-grained beds within their parent material? There is no suggestion of this in the field: no stone lines, relict bedding or other sedimentary structures. These clayey subsurface horizons are well homogenized by root traces, burrows, and fecal pellets and have gradational boundaries into coarser-grained material above and below. Nor were any subtle discontinuities revealed by point counting for mineral composition or chemical analysis of trace elements. In thin section, pedogenic clay is visible as thin rims around grains from which it was hydrolyzed and as highly birefringent wisps in a less oriented clayey matrix (Fig. 3.18). Banding and colloform structures in these highly birefringent fine-grained clays are evidence for illuviation from higher horizons in the profiles. Abundant and conspicuous bioturbation in these paleosols has mixed and altered original sedimentary layering and igneous crystal structure beyond recognition, and imposed pedogenic horizonation. This is not to say that there was no clay in the parent materials. Clay was probably at least as abundant in the parent alluvium as it is in associated very weakly developed paleosols (Luquem, Patat and Sayayk paleosols). However, the clay bulge in their depth functions for grain size includes significant amounts of pedogenic clay.

Figure 3.18. Thick illuvial clay skins formed around a volcanic rock fragment to right in the A horizon of the type Scat paleosol in the middle-late Eocene upper Clarno Formation in lower "Red Hill". Scale is 0.1 mm.

Conventionally, the formation of clayey subsurface horizons in soils has been regarded as a process of formation of clay in place by weathering of primary minerals and its washing down into the cracks and root holes in the soil. An alternative view has recently been suggested to accommodate the widespread

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role of eolian dust in soil formation (Muhs and others, 1987). Soils can be considered very slowly accumulating eolian sediments within the zone of weathering, so that subsurface horizons are more clayey because they have weathered for longer than surface horizons. In addition, fine clays transported by wind easily penetrate soil cracks, and their high surface-to-volume ratio allows more thorough weathering than that found in coarser grains of parent material. Not only are these processes widespread in desert soils (McFadden, 1988), but they also have been proposed to produce lateritic and bauxitic soils under humid forests (Brimhall and others, 1988), in a manner analogous to the accumulation of brown clays in the deep ocean (Clauer and Hoffert, 1985). For these Eocene-Oligocene paleosols, there is in addition to wind, a steady input of sediment from flooding and airfall volcanic ash. As indicated by Simonson (1976), such slow sedimentary additions to soils should be considered a process of soil formation rather than of sedimentation. The thorough incorporation of this material in the soil fabric is an indication that it is well under the control of the soil system, as opposed to the wider depositional system that occasionally overwhelms soils with thick deposits or destroys soils by eroding them away.

Evidence of continued sediment influx during formation of those paleosols with subsurface clayey horizons is not difficult to find, in the form of rare fresh feldspars and volcanic rock fragments in otherwise deeply weathered clayey parts of paleosols. Thus it is likely that the subsurface clayey horizons of these paleosols were formed partly by weathering in place and partly by the addition of dust, volcanic ash, and flood-borne silt. There are no indications that these diffuse, clayey, subsurface horizons were inherited from a preexisting clayey bed in the parent material of the paleosols.

Subsurface horizons rich in iron-manganese. Many of the paleosols contain small (1-2 mm), dark brown to bluish-black, opaque patches of noncrystalline iron-manganese on slickensided argillans, as nodules or concretions in the matrix, or as void fills after root traces. They are a minor component of many of the paleosols, which contain low overall amounts of manganese, in some cases depleted from the amount in underlying parent materials. Similar features are common in soils, especially those with clayey texture, free carbonate, or imperfectly drained (Sidhu and others, 1977b; Brewer, Sleeman, and Foster, 1983; Rahmatullah and others, 1990). Considering the virtual absence of carbonate in these paleosols, iron-manganese nodules can be taken as evidence of waterlogging, either during soil formation or burial.

Lakim paleosols are noteworthy in showing unusual accumulations of manganese in prominent septaria and nodules up to 13 cm in diameter (Pratt, 1988). Such extensive mobilization of iron and manganese is evidence for open-system alteration, unlikely during deep burial in such impermeable claystones. These iron-manganese horizons are similar to those found in modern seasonally waterlogged soils (Kanagarh Series of Kooistra, 1982; Gujranwala and Satghara Series of Rahmatullah and others, 1990), and may be an early stage in the development of a manganese-cemented horizon or placic horizon in the terminology of Soil Survey Staff (1975).

Chemical depth functions. Soil horizons, with few exceptions (Retallack, 1988), are distinct from sedimentary or volcanic beds in showing gradational changes in texture, mineral weathering, color, and other features downward from a sharp erosional plane that represents the ancient land surface. Such gradational depth functions also can be seen in chemical data and are particularly well expressed in moderately to strongly developed paleosols (Acas, Lakayx, Pasct, Pswa paleosols) (Fig. 3.19). In contrast, very weakly to weakly developed paleosols show little chemical change or abrupt changes reflecting differences in beds of parent material (Patat paleosols). In most cases these differences are less marked than those between sedimentary beds.

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Figure 3.19. Chemical variation in the type Pswa clay and an overlying Pswa paleosol in the trench below "Black Spur" near Hancock Field Station. (click on image for an enlargement in a new window)

The down-profile variation in most of these elements is probably a function of soil formation, but some elements such as titanium, zirconium, and gold are relatively unaffected by weathering. Their uniformity in most of the paleosols is an indication of a single parent material.

It could be argued that even gradational depth functions reflect parent material variation, such as fining- upwards sequences deposited with waning flood flow in alluvial sequences (Allen, 1965) or the grain size sorting that may accompany emplacement of pyroclastic flows (Gas and Wright, 1987). If these were the cause, however, it is difficult to understand the divergent behavior of easily weathered oxides (lime and soda) versus resistate oxides (titania), and the other details of the variation so much like modern weathering. Also difficult to understand as parent material effects are bulges in chemical abundance.

Another possibility is that the observed chemical depth functions reflect merely porosity-dependent passage of ground-water (Pavich and Obermeier, 1985) or composition-dependent alteration during burial or metamorphism (Palmer and others, 1989). These can be serious objections to interpretation of much older and more altered rocks (Retallack, 1989). Most of these paleosols were clayey and thus low in porosity. Sandy layers within and between paleosols do not show alteration of a kind distinctly different from that in more clayey parts of the profiles. These paleosols also are highly oxidized, as indicated by elevated amounts of ferric iron compared with their parent materials, whereas environments of burial alteration are chemically reducing (Thompson, 1972). Nor are there any unusual high-temperature minerals, recrystallization textures, schistosity, or other features of alteration during deep burial or metamorphism. This is not to say that these paleosols were unaltered by burial. Many changes after burial are outlined in the next chapter. However, the chemical depth functions observed are consistent with evidence from root traces, soil horizons and soil structures that these are indeed paleosols.

Soil structure

Beds now known to be paleosols commonly have been described in geological reports as massive, featureless, blocky, jointy, hackly, nodular, or mottled. Such descriptions make the point well that paleosols lack sedimentary, igneous, and metamorphic structures and have distinctive structures of their own. For an adequate terminology for these structures one must turn to soil science (Brewer, 1976).

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Some structures of soils, such as nodules and mottles, are found also in marine sediments and hydrothermally altered rocks (Retallack, 1990a). Other structures are produced by the randomly oriented expansion and contraction of materials under low confining pressures and temperatures that are virtually unique to soil environments. Such structures include peds and cutans visible in the field, and displacive and sepic plasmic fabric seen in thin section. These structures are diagnostic of soils as opposed to other kinds of geological phenomena, and are richly represented in Eocene and Oligocene paleosols near Clarno.

Cracking and veining. Many of the paleosols show complex systems of clay-filled cracks that have disrupted remains of original bedding and grains of their parent material. For example, hackly surficial clayey layers of Pasct and Micay paleosols in the Clarno area are very distinct from enclosing bedded rocks. The hackly appearance is due to small (6-15 mm in diameter) equant nuclei of claystone surrounded by irregular slickensided and ferruginized clayey surfaces. In soil terminology these are fine granular peds defined by diffusion ferri-argillans. These granular peds are not so well developed, nor so regular in shape and roundness, as those found in some modern grassland soils (Duchafour, 1982). Their formation nevertheless probably reflects similar processes of comminution and weathering of the upper part of the soil by roots of herbaceous plants and activities of a variety of worms, insects and other soil creatures.

Soil peds at a larger scale (5-10 cm) are common in other paleosols (Acas, Lakayx, Luca, Sitaxs). These are similar to coarse angular-blocky peds, defined by slickensided ferri-argillans (Fig. 3.20), and are a typical subsurface structure of soils (Duchafour, 1982). In no case was this expressed in these clayey paleosols to the extent of tepee structures, conjugate shears or mukkara structure found in seasonally cracking soils such as Vertisols (Allen, 1986a; Paton, 1974).

Figure 3.20. Blocky angular ped, broken on top face, but defined on sides by slickensided black surfaces (mangans) from the Sitaxs clay paleosol at 88 m reference section of the late Eocene Clarno Formation. Scale graduated in millimeters and centimeters (Retallack specimen R130).

Claystone grains. In many of the paleosols examined in thin section there are abundant claystone grains of sand to granule size. These vary considerably in the sharpness of their outer boundary and in the degree to which they are darkened by sesquioxide stain. Only those with sharp outer boundaries and staining or other fabric that set them apart from the matrix were counted as clay clasts during petrographic studies. Claystone nuclei with ragged and diffuse margins, on the other hand were counted

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as paleosol peds of the matrix.

In some of the paleosols (Acas), rounded to ellipsoidal claystone grains commonly are ferruginized to a near-opaque reddish-brown color, as seen in thin section under plane light. Some of them include indistinct transparent areas shaped like rectangles, squares, or triangles. These are interpreted as relict or pseudomorphed phenocrysts of feldspar or pyroxene in the highly altered fine-grained groundmass of what was once a granule of andesite. Little-weathered examples of these rock fragments also are widespread in these paleosols and their parent materials. Intermediate stages of granules with moderately fresh cores but a wide ferruginized weathering rind also are found. Not all this weathering necessarily occurred within the paleosol now containing them. Both preweathered and fresh grains were present in the parent materials of some of the paleosols of weak development (such as Patat paleosols). Weathering of volcanic clasts in place within the paleosols also was widespread, as can be seen from the many grains with gradational and irregular, deeply weathered margins (in Acas paleosols). It could be argued that this alteration in place occurred entirely after burial, and was the work of intrastratal solution or hydrothermal injection. This is unlikely because the most highly altered grains are within the most clayey and least porous parts of the profiles. The freshest grains were found in sandy lower parts of the profiles, with fewer roots, burrows, or other signs of soil formation than higher in the profiles. None of these horizons had extensive veining or mineralization with talc, tremolite, pyrrhotite, or other minerals that would be expected in hydrothermally altered rocks. In contrast, the altered grains were smectitic and ferruginized, as is usual during weathering of volcanic rocks.

A striking feature of thin sections of Lakayx paleosols are spheres of sand to granule size of near- opaque ferruginized claystone. Usually they have abrupt outer boundaries. Some sharply broken rounds also were seen. Thus they do not appear to have formed as nodules. Nor do they look like parts of cavities filled with clay or rolled-up parts of thick clay skins, because they show no internal lamination. Some of these spherical claystone grains may be redeposited parts of soils, but clear examples of redeposited soil clasts also are found and are less ferruginized and more varied in size and shape. These "spherical micropeds" (Stoops, 1983) or "claystone pseudosands" (Mohr and Van Baren, 1954) are widespread in tropical soils. Most of them probably formed as fecal and constructional pellets of termites (Mermut and others, 1984). No clear examples of termite mounds were seen, but these may have contributed to claystone breccias found in the uppermost horizons of some Lakayx paleosols.

Destruction of mineral grains. An additional line of evidence for paleosols are mineral grains altered by weathering to a delicate skeleton that could not withstand transport (Fig. 3.21). These are very common in strongly developed paleosols (Acas, Lakayx, Luca). Their skeletal and embayed appearance rule out transport and deposition of the grains in this condition, but not their formation during deep burial (as has been argued for other comparable cases by T. R. Walker and others, 1967). Deep-burial alteration of the grains seems unlikely in this case because altered grains were seen mainly in clayey matrix rather than in sandy or pebbly intervening beds, interpreted as less weathered lower parent material that also would have been more permeable to intrastratal solution. The considerable expansion of some grains would not be expected under the confining pressures in deep burial environments. Ferruginized clay skins around the grains in the Clarno Formation indicate oxidizing conditions, whereas groundwater flowing through rocks as rich in mafic minerals as these volcaniclastics would be chemically reducing. In very deep burial environments, the thermal cracking of organic matter to hydrocarbons and carbon dioxide can generate acidic solutions capable of dissolving grains and matrix to produce secondary porosity (Schmidt and McDonald, 1979). Vuggy, cross-cutting porosity of this kind was not seen in the paleosols. Nor would it be expected considering their likely depth of burial, discussed in detail in a later section.

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Figure 3.21. Deeply weathered crystal of zoned plagioclase in subsurface (Bt) horizon of type Patat clay paleosol near "Hancock Tree" in the middle Eocene Clarno Formation, viewed under crossed nicols. Scale bar is 0.1 mm..

Microfabric of clayey matrix. Additional features of the paleosols seen in thin section under crossed polarizers are highly birefringent streaks of oriented clay within the generally flecked clayey matrix (Fig. 3.22). This distinctive soil microfabric can be called "bright clay" (Retallack, 1990a) or "sepic plasmic fabric" (Brewer, 1976). Many good examples of this were seen in paleosols from Clarno. The concentration of highly birefringent clay around mineral grains could have been due in part to original rolling of the grain during deposition in the parent material, or perhaps rocking of the grain during thin- section preparation, as much as to stresses generated during shrinking and swelling of the original soil. Other more complexly arranged streaks of birefringent clay are indications of a highly deviatoric system of local stresses under low temperature and confining pressure; that is to say, in a soil rather than in a depositional or deep burial environment.

Figure 3.22. Clinobimasepic plasmic fabric, with some areas of bright illuvial clay skins, viewed under crossed nicols of the surface (A) horizon of the type Pswa clay paleosol in the trench below the "Black Spur" in the middle Eocene Clarno Formation. Scale is 1 millimeter (rock specimen JODA5060). http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap3.htm[4/18/2014 12:20:46 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 3)

Sepic plasmic fabrics are best expressed in well or seasonally drained, clayey, and moderately developed soils (Brewer and Sleeman, 1969; Collins and Larney, 1983). Their expression is inhibited in weakly developed or waterlogged soils, in soils dominated by amorphous weathering products of volcanic ash, and in soils whose clayey fabric is masked by abundant near-opaque sesquioxides. These trends also were noted in paleosols of the Clarno area, where weakly developed paleosols (Micay, Patat, Scat) have incipient to streaky bright clay (insepic to mosepic), but moderately developed paleosols (Pasct, Acas) have criss-crossing bright clay (clinobimasepic) and strongly developed paleosols (Lakayx) have criss crossing to woven fabric (masepic to omnisepic).

Clay minerals. The nature of clays in paleosols of alluvial and volcaniclastic sequences are uncertain as guides to whether they actually were soils, because clays from windblown dust or flood-borne alluvium originally present in the parent material of a paleosol also are derived from soils of sedimentary source regions. As a generalization, however, base-poor clays (such as kaolinite) reflect deeper weathering than base-rich clays (illite, smectite: Jackson and others, 1948). These trends are apparent in paleosols near Clarno, with smectite more common in weakly developed paleosols (Micay, Lakim) and kaolinite prominent in strongly developed paleosols (Lakayx, Luca: Fig. 3.23).

Figure 3.23. Broad smectite peak of an x-ray diffractogram of a moderately developed paleosol (B: Luca clay) compared with a weakly developed one (A: type Sitaxs clay). Data from Smith (1988). (click on image for an enlargement in a new window)

In addition, soil clays tend to have broader and less distinct peaks on an x-ray diffractogram, reflecting their finer grain size and poor crystallization compared with metamorphic or hydrothermal clays (Townsend and Reed, 1971). Smectite, and to a lesser extent kaolinite peaks in x-ray diffractograms of Clarno paleosols have this relatively broad and diffuse character of poorly crystallized soil clays.

Conclusions. Interpretation of many of the beds in Eocene and Oligocene sequences near Clarno as paleosols is well supported by many lines of evidence gathered in both the field and the laboratory. For this study, the best indicators of paleosols were root traces, the diffuse contacts, mineral and textural segregations typical of soil horizons, and the cracking, veining, and other soil structures that obliterated preexisting structures of the parent material.

BURIAL ALTERATION OF THE PALEOSOLS

Alteration of paleosols during burial and metamorphism can seriously compromise their recognition and interpretation. The effects of extreme metamorphic alteration are often clear from the development of such structures as schistosity or high-temperature minerals such as garnet. More troublesome in the interpretation of paleosols are modifications during burial that fall short of metamorphism, that is to say, diagenetic changes. Especially problematic are changes that occur soon after burial when the paleosol is

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still within the reach of surficial processes. These modifications in aqueous solutions, with the aid of microbes and under low temperatures and pressures, are not always distinct from soil formation. Indeed, if diagenesis is defined as alteration of sediments after their deposition, then diagenesis includes both soil formation and alteration after burial. Research on the distinction between these two kinds of diagenesis now is progressing apace (Retallack, 1990a, 1991d). The following sections constitute an assessment of the degree to which specific kinds of diagenetic alteration affected the studied paleosols from near Clarno.

Loss of organic matter. Studies of Quaternary paleosols and equivalent surface soils in central North America have shown that soon after burial, soils lose up to an order of magnitude of organic carbon as determined by the Walkley-Black technique, but they preserve the general trend of their depth function for organic matter (Stevenson, 1969). This loss of organic matter has been found in paleosols similar to well drained soils but not in paleosols similar to peaty, waterlogged soils (Retallack, 1983, 1991d, 1994c). The lost organic matter was probably metabolized by aerobic microbial decomposers of the ecosystem from the soil that formed on a sedimentary increment that buried the paleosol.

Loss of organic matter in paleosols from values similar to those in comparable surface soils may have caused changes in color of the paleosols so that they have more pure colors (higher Munsell chroma). Loss of organic matter also would make the paleosols more prone to badlands weathering in the modern outcrop, compared with the original soils stabilized by organic coatings and roots.

Burial gleization. Drab haloes around root traces in some of these paleosols (Fig. 3.12) are best interpreted as products of the anaerobic decay of organic matter buried with the soil. This phenomenon of burial gleization is widespread and well known in paleosols (Retallack, 1976, 1983, 1988, 1990a), soils (de Villiers, 1965), and sediments (Allen, 1986b). In some paleosols (Acas, Sitaxs) there also are drab layers within the profile of a similar greenish-gray or bluish-gray color unusual for surface soils. These may reflect areas chemically reduced in association with anaerobic decay of organic matter buried in the paleosol. More pervasive burial gleization may be responsible for the overall greyish color of some paleosols (Acas, Lakim, Lakayx), but iron-manganese concretions and ferric mottles are evidence that these paleosols were prone to seasonal waterlogging as they formed (Fig. 3.14).

A critical question for interpretation of these paleosols is the extent to which burial gleization has altered more than just the redox state of iron and the color of the paleosols within drab mottles and root haloes. Could it be responsible also for the ferric mottles, concretions, and manganese stringers in these paleosols? This applies especially to Lakim and Acas paleosols, which have these structures. A hallmark of drab-haloed root traces attributed to burial gleization is conservation of amounts of iron and manganese despite their chemically reduced state, compared with amounts of these elements in the surrounding paleosol matrix (Retallack, 1976, 1983). This may be interpreted as evidence of chemical reduction in a closed system, unlike losses of large amounts of iron typical of gleyed soils. Pervasive burial gleization of most of these paleosols also is unlikely in view of their negligible analytical values for ferrous iron compared with ferric iron. Many of these paleosols are very highly oxidized.

There are thus grounds for regarding the effects of gleization as locally restricted to the discolored areas. The bulk of the physical and chemical properties of the paleosols were little affected, even in paleosols originally gleyed. Effects of burial gleization were probably much less in paleosols with only scattered drab-haloed root traces and were negligible in paleosols lacking even these.

Burial reddening. Another widespread effect of burial of paleosols is dehydration of ferric hydroxide minerals such as goethite to oxide minerals such as hematite (Walker, 1967). This change results in reddening of color from yellow or brown to brick red. In the few Quaternary paleosols and comparable surface soils of central North America for which this change has been assessed, the change in color during shallow burial for only a few tens to hundreds of thousands of years amounted to two to three Munsell hue units, from 10YR to 7.5YR or from 7.5YR to 5YR (Ruhe, 1969; Simonson, 1941). No change in hue was noticed in drab-colored (5Y) paleosols compared with similar gleyed surface soils.

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These changes in color compromise the interpretation of paleosols because dehydration of ferric hydroxides to ferric oxides also occurs with increasing age and climatic temperature during the formation of surface soils (Birkeland, 1984). Such changes in hue are especially likely for the red paleosols from Clarno, but other evidence of good drainage from root traces, soil horizons and soil structure, are indications that their oxidation was mainly in the original soil.

Zeolitization. Zeolites are a common component of some of these volcaniclastic paleosols, especially in lower horizons of weakly developed paleosols of the lahars of Hancock Canyon and of the "Nut Beds" (Sayayk and Patat paleosols). Heulandite, laumontite and stilbite have been indentified from the John Day Formation (Hay, 1963). These minerals are common hydrothermal alteration products of tuffs and lavas 1990 (Bargar, 1990, 1994). No zeolites were seen in contact with unqeustionably pedogenic features, such as root traces or burrows. Furthermore, all the paleosols analyzed chemically have low soda/potash ratios that decline up the profile, so that zeolitization during soil formation is unlikely. From these relationships, zeolites probably were formed during warm deposition and local hydrothermal alteration of tuffs and lahars. Zeolites were often progressively destroyed by subsequent soil formation and alteration after burial.

Compaction. Burial of paleosols results in compaction as the void spaces, organisms, and water are crushed by the weight of overburden. The resulting changes in thickness can be of importance for interpreting degree of chemical soil development of paleosols (Brimhall and others, 1991). Fortunately, paleosols from the Clarno area are geologically young enough that their burial history can be reconstructed. The Clarn Formation here has been buried by 929 m of John Day Formation, 305 m of Columbia River Basalt, and potentially as much as 610 m of Mascall Formation, 244 m of Rattlesnake Formation (Oles and others, 1973) for a total of 2088 m. From these data compaction can be calculated using the formula of Sclater and Christie (1980) advocated by Baldwin and Butler (1985) as follows.

C = -0.5/[{0.49/e(D/3.7)}-1]

In this equation C is the degree of compaction as a fraction and D is the depth of burial in km. The constant 0.5 is for solidity (the complement of fractional porosity). This value is representative for soils, which have an average bulk density of 1.3 gm/cm3 (Retallack, 1990a). Computed compaction for the lowermost Scat paleosol in the reference section is 70% of its former thickness and for the uppermost Pasct paleosol in the reference section is 71%. A figure of 70% compaction is reasonable for the entire upper Clarno Formation.

Thermal maturation of organic matter. Coalification and cracking of hydrocarbons at depth can produce acidic reducing brines capable of considerable chemical alteration and the development of secondary porosity in deeply buried sedimentary rocks (Schmidt and McDonald, 1979). This is unlikely to have affected these paleosols at the depths of burial already outlined.

These theoretical predictions of the likely state of organic matter in these paleosols agree with direct observations of what little organic matter remains. Lignites and compressed remains of the woody portions of roots seen in some of the paleosols are dark brown and fibrous in thin section, rather than opaque and broken into coal cleat. None of the paleosols were seen in thin section to have the inflated and invasive vugs with multiple generations of cement that are characteristic of secondary porosity developed during deep burial by carboxylic acid and hydrocarbon cracking. Thus significant alteration of these paleosols due to thermal maturation of organic matter is considered unlikely.

Illitization. Another potential alteration of clayey paleosols is destruction of smectite and growth of illite by transfer of potassium in groundwater from dissolution of potassium-bearing minerals such as microcline and muscovite (Eberl and others, 1990; Weaver, 1989). For marine shales, this mineralogical transformation is common when burial depths reach 1200 to 2300 m and burial temperatures are from 55° to 100°C, but the transformation slows dramatically once easily mobilized pore water is lost (Morton, 1985). Theoretically, however, the transformation of smectite to illite could occur at much

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lower temperatures over very long periods of geological time (Bethke and Altaner, 1986). Indeed, illitization of smectite may occur to a limited extent during shrink-swell behavior of swelling clay soils, such as Vertisols (Robinson and Wright, 1987).

There were traces of potash feldspar in many of the paleosols studied, and thus a potential for illitization of their clays. Several of the paleosols show a slight surficial increase in potash, along with an up-section decline in soda (unlike comparable surface soils). This is much less marked than in profoundly illitized and sericitized paleosols (Feakes and Retallack, 1988; Retallack, 1986a). Taken together with the scarcity of illite in these paleosols, these are indications of negligible illitization of these paleosols.

Feldspathization. Authigenic feldspars form in a variety of rocks during deep burial (Duffin and others, 1989), and replacement of sanidine by K-feldspar has been observed in the John Day Formation in the Painted Hills (Hay, 1963). Enrichment in feldspar by a process called fenitization is commonly associated with the emplacement of carbonatite intrusions (Le Bas, 1977).

None of the feldspars seen in thin sections of paleosols of the Clarno Formation in the Clarno area showed the abrupt, euhedral crystal faces or cut across preexisting textures as is usual for authigenic crystals. Nor was feldspar abundant or associated with the veining and other injection features of fenites. In contrast, the feldspars seen were etched or coated in ferruginized clay (Fig. 3.21), as is usual in soils. Fenitization can extend for a few hundred meters around carbonatite intrusions (Le Bas, 1977), but geological mapping on this fine scale (Fig. 2.2) failed to reveal such intrusions anywhere near the studied paleosols. Alteration of these paleosols of the Clarno Formation by feldspathization is thus unlikely.

Conclusions. From this assessment of the burial alteration of Eocene and Oligocene paleosols near Clarno, these paleosols can be considered little altered by, feldspathization, zeolitization or thermal maturation of organic matter. Their burial depths (2088-2216 m) resulted in compaction that was significant enough (70% percent of original thickness) to make it difficult to follow clastic dikes within these paleosols, but compaction is not always evident from root traces or burrows. The paleosols were not discernably illitized during their burial.

The most profound changes to these paleosols resulted not from deep burial, but from a variety of alterations that occurred soon after burial and near the surface, in part aided by groundwater flow and microbial activity. These changes include depletion of organic matter to as much as a tenth of its original abundance, chemical reduction of oxidized iron in minerals near buried organic matter, and dehydration of ferric hydroxides to oxides. These changes significantly affected the color of the paleosols, altering them to purer color (lower chroma, perhaps by one or two Munsell units), to blue- gray hue in formerly organic parts of the profiles (to Munsell 5Y to 5G from original brownish-gray 10YR to 5Y) and to red hue in weakly organic parts of formerly well-drained paleosols (to Munsell 5YR to 7.5YR from original 10YR to 7.5YR). Some of the profiles once dark brown over orange brown are now red with blue-gray surface horizons and root mottles. Other paleosols once gray now have a distinctive bluish-gray cast. Other paleosols now brown (Munsell 5YR to 10YR) do not seem to have been altered greatly in color, and can be matched with similar surface soils.

DESCRIPTION AND INTERPRETATION OF PEDOTYPES

In the following pages are detailed descriptions and interpretations of the different kinds of paleosols so far recognized in the master sections and selected other sections measured near Hancock Field Station. These have been named as pedotypes, that is, as recognizable kinds of paleosols. Pedotype is a new term used for paleosol series (Retallack, 1990a), which has problematic alternative connotations in both geological and soil science (Retallack, 1994b).

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Pedotypes are named after localities, but many of the local place names are already in use for surface soil series, rock formations, and fossil localities. All of the pedotypes recognized here have been named from simple descriptive terms of the southern Sahaptin Indian language (DeLancey and others, 1988), and particularly the Umatilla dialect (Rigsby, 1965) spoken by the John Day and Tenino bands that foraged during the summer into this region. Sahaptin may be cognate with Cayuse and Nez Perce languages to the east, but is distinct from the Paiute language to the south in the Basin and Range and from the Salishan languages of the Pacific coast and lower Columbia Basin. Names of paleobotanists and flowers have been used for paleosols near Clarno in unpublished theses (Smith, 1988, Pratt, 1988), but this potential confusion is avoided here.

A standardized graphic and descriptive format has been used for representing the salient data and interpretation of each paleosol (following Retallack, 1988a). Colors were estimated by comparison with the charts of Munsell Color (1975), taken within a few minutes of exposure of the naturally moist samples. Lithological sections were logged using a scheme that includes a graphic representation of mean grain size, in order to represent field assessment of likely clayey subsurface (Bt) horizons. The grain size scale of soil science has been used (Soil Survey Staff, 1975), rather than the Wentworth scale commonly used in geological studies. Quantitative grain size and mineral compositional data were obtained from 500 points counted in petrographic thin sections using a Swift Automatic Point Counter by G.J. Retallack, G.S. Smith, J. Pratt, and E.A. Bestland. This gives an abundance of common components with an error (2&gama;) of about 2 percent by volume (Friedman, 1958; van der Plas and Tobi, 1965; Murphy, 1983). The point count data are portrayed in columns that may seem narrow and cramped in some cases, so that only components approaching 2 percent or more can be plotted and only differences of 2 percent or more will appear as significant trends. Clay has been placed to the left in both textural and mineral plots to give visual assessment of how well the two counts agree. In the mineral composition plots, easily weathered minerals in the schemes of Goldich (1938) and M. L. Jackson and others (1948) are placed to the left, and progressively more weather-resistant minerals are placed to the right. In comparing these results with similar data for modern soils it is well to beware of changes during burial, as already discussed. There also is a systematic overestimation of clay in thin sections compared with sieve analysis for grain size of soils (Murphy and Kemp, 1984), because of edge effects in thin sections and the persistence of clay aggregates in sieve analysis commonly used for soils.

A selection of molecular weathering ratios based on whole-rock chemical analyses also are plotted, and their likely pedogenic significance is indicated (following Retallack, 1990a). Chemical analyses were performed using XRF by Diane Johnson (Washington State University, Pullman) and using AA by Christine McBirney (University of Oregon, Eugene), with error calculated from replicate analyses of standard rocks. Bulk density was calculated from weight difference suspended in water of paraffin- coated clods by G.J. Retallack and T. Tate, with error estimated from replicate analyses.

Descriptions of the paleosol profiles follow the conventions and terminology of Roy Brewer (1976) and the Soil Survey Staff (1951, 1962, 1975) of the U.S. Soil Conservation Service. These technical descriptions are important to future classification of these paleosols. Only a concise interpretation of likely alteration of each kind of paleosol after burial is given for each paleosol, because of the general discussion offered above. Other interpretations also are offered in the following pages: a reconstruction of the paleosol as it may have been during formation; attempts to identify the paleosols in classifications for surface soils; their former ecosystem as indicated by their fossil content and other features; and their paleoclimate, topographic setting, parent materials, and duration of soil formation. The pedotypes are listed in alphabetical order.

Acas paleosols

Diagnosis. Purple slickensided clayey (Bt) horizon with red nodules or mottles.

Derivation. Acas is Sahaptin for "eye" (Rigsby, 1965), in reference to the red mottles and nodules

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scattered through these profiles.

Description. The type Acas clay (Fig. 3.24) was measured in a trench excavated on the flanks of the ridge 300 m northeast of the "Hancock Tree" in badlands of "Sienna Ridge" (SW1/4 NE1/4 NW1/4 sect. 26 T7S R19E Clarno 7.5' Quad. UTM zone 10, 704106E 4978605N). This can be correlated to a stratigraphic level of about 113 m in the reference section (Fig. 3.4) through the "Nut Beds" and "Red Hill", in the "claystones of Red Hill" of the upper Clarno Formation, of late Eocene (Uintan) age.

+15 cm: overlying sediment: silty claystone: greenish gray (5GY6/1), weathers light yellowish brown (2.5Y6/4): faint relict bedding: non-calcareous: intertextic skelmosepic in thin section, common feldspar laths: abrupt, smooth contact to

0 cm: A1 horizon: claystone: dark greenish gray (5BG4/1), weathers light yellowish brown (2.5Y6/4): abundant drab-haloed root traces of greenish gray (5GY6/1), common mottles dark reddish gray (10R4/1): abundant slickensides defining crude platy peds: non-calcareous: porphyroskelic clinobimasepic, with deeply-weathered volcanic rock fragments: gradual wavy contact to

-4 cm: A2 horizon: silty claystone: light greenish gray (5GY7/1), weathers light yellowish brown (2.5Y6/4): common mottles dusky red (10R3/2) and deeply weathered volcanic clasts, 3 mm diameter, of reddish brown (5YR4/4): non-calcareous: clinobimasepic porphryoskelic, with deeply-weathered volcanic rock fragments: gradual irregular contact to

-25 cm: Bt horizon: claystone: dark reddish gray (10R4/1), weathered light yellowish brown (2.5Y6/4): common drab haloed root traces of greenish gray (5G5/1): abundant slickensided clay skins defining coarse angular blocky peds: non calcareous; porphyroskelic clinobimasepic in thin section: gradual irregular contact to

-125 cm: C horizon: silty claystone: dusky red (10R3/2), weathers light yellowish brown (2.5Y6/4): common drab-haloed root traces of greenish gray (5GY5/1) to bluish gray (5B5/1): non-calcareous: porphyroskelic mosepic, with ferruginized volcanic rock fragments, scattered clay skins (illuviation argillans): clear smooth contact to

-143 cm: A horizon of another Acas paleosol: greenish gray (5GY6/1), weathers light yellowish brown (2.5Y6/4): prominent mottles of dusky red (10R3/2): scattered sand to granule sized volcanic clasts of bluish gray (5B5/1), greenish gray (5G5/1) and dusky red (10R3/2): non-calcareous.

Figure 3.24. Measured section, Munsell colors, soil horizons, grain size, mineral composition and selected molecular weathering ratios of the type Acas clay paleosol in eastern "Sienna Ridge", which is within the late Eocene Clarno Formation and correlated to a level of 113 m in the reference section (Fig. 3.4). Lithological key as for Fig. 3.3. (click on image for an enlargement in a new window)

Further examples. Additional Acas paleosols were seen within red beds at or above the stratigraphic of the "Nut Beds" in a trench excavated some 500 m to the southwest, but none were seen in the master section through the "Nut Beds" and "Red Hill".

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Alteration after burial. The Acas clay paleosols have probably lost organic matter to burial decomposition and burial gleization, but even burial gleization was not profound considering the high oxidation of iron revealed by ferrous to ferric iron ratios. Burial dehydration of iron oxides also is likely for red mottles, although most of the red patches appear to be deeply weathered volcanic rock fragments reddened during an earlier cycle of soil formation. Each of these changes would have created a purple mottled paleosol from a presumed originally dark grayish brown soil. Compaction also may have been significant: some 70% of original thickness for the type profile using the standard formula of Sclater and Christie (1980).

Reconstructed soil. The original Acas profile was probably a thick (1.5m) clayey soil including common rusty rounded fragments of weathered volcanic rocks. Its A horizon of dark gray loamy clay probably passed down to a dark brown clayey subsurface horizon. Its pH was probably acidic to neutral, which weathered volcanic minerals and leached bases (ratio of alumina/bases). Depth functions are very muted in chemical data on these paleosols, which presumably acquired their chemical and mineralogical composition more from parent alluvium than from soil formation in place. Neither gleization, salinization nor calcification is in evidence from chemical data (soda/potash, alkaline earths/alumina and ferrous/ferric iron ratios).

Classification. Acas paleosols have a marked but irregular subsurface accumulation of clay and common clay skins that qualify as an argillic horizon in the U.S. soil taxonomy (Soil Survey Staff, 1990). They have very few weatherable minerals and the alumina/bases ratio of about 2.5 indicate that they were Ultisols. Despite the somber color of these profiles, the lack of clear mottles, nodules or reduced iron that would indicate waterlogging, rules out Aquults. Acas paleosols with their scattered ferruginized redeposited volcanic rock fragments are best regarded as Plinthic Haplohumults. In the F.A.O. classification (1974), Acas paleosols are most like Ferric Acrisols. In the Australian classification (Stace and others, 1968) they are most like Lateritic Podzolic Soils, and in the Northcote (1974) key Gn3.21.

Paleoclimate. The lack of carbonate and marked leaching of alkalis and alkaline earths from the Acas paleosols are compatible with a humid climate, in excess of a mean annual precipitation of 1000 mm. However, the ratio of alumina/bases is marginally higher in the C than Bt horizon of the type Acas paleosol, as an indication that this chemical indication of humid climate was to a considerable extent inherited with parent material from a pre-existing humid climate soil.

Common ferruginous nodules and ferruginized volcanic rock fragments provide evidence of locally, and perhaps seasonally, oxidizing conditions. If there was a dry season it was not especially marked, and probably much less than 3 months in duration, because Acas paleosols lack the system of cracking and veining found in Vertisols.

The strong bioturbation of these paleosols, despite only moderate textural differentiation and chemical depth functions, is compatible with a productive tropical to subtropical ecosystem. Their sombre color may be due to preservation of organic matter, considering contra-indications against gleization in ferrous/ferric iron ratios. Such organic soils in tropical regions are generally found in the cooler climes of montane sites.

Ancient vegetation. Acas profiles with their stout drab-haloed root traces and subsurface horizon of clay accumulation are most like forested modern soils. The size of root traces and depth of clay illuviation indicate a forest of considerable stature, perhaps 30 m or more. The distinctive sombre color of Acas paleosols and clear burial gleization are evidence of dense ground cover. This did not include grasses or other sod-forming plants, because peds in the surface horizon are platy to angular blocky, rather than granular. Ferns and mosses were more likely ground layer plants. Although these would have required shade, the deep shade of multistratal tropical rain forest is unlikely. Acas paleosols probably supported an oligotrophic tall tropical forest with a single canopy layer.

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No fossil plants were found in Acas paleosols, so that the floristic composition of their forests cannot be known with certainty. Some of these paleosols were found at a stratigraphic level along strike from the "Nut Beds", and could have supported some of the species of plants known from fossil fruits and seeds there (Manchester, 1981, 1994). However, Acas paleosols are not so common in the upper Clarno Formation as other kinds of paleosol, such as Lakayx and Luca, and it is likely that Acas paleosols represent a local unique ecosystem of tropical humic soils.

Former animal life. No fossil animals were found in Acas paleosols, nor in the sedimentary sequence containing them. The chances of finding fossil vertebrates in these non-calcareous paleosols are close to zero (Retallack, 1984a). Fossil mammals of the basal Duchesnean North American Land Mammal "Age" have been found in the disconformably overlying siltstones of the "Mammal Quarry" (Hanson, 1973, 1989), and fossil mammals of the Bridgerian North American Land Mammal "Age" have been found in the underlying "Nut Beds" (C.B. Hanson, pers. comm. 1990). From our sequence stratigraphic correlation and radiometric dating of the lower red beds with Acas paleosols, we predict faunas of the Uintan North American Land Mammal "Age".

Paleotopographic setting. Acas paleosols are deeply weathered with no evidence of gleization and so occupied well drained positions on the landscape. Their granule-sized deeply weathered volcanic rock fragments mixed with silty clay matrix and somewhat irregular grain size distribution are similar to colluvial deposits. The conundrum of very highly oxidized volcanic rock fragments in a somber and probably originally organic-rich soil could be taken as indications of a slowly drained footslope to steeper more highly oxidized soils. Such a geomorphic setting is compatible with the occurrence of Acas paleosols near major erosional breaks within the upper Clarno Formation. The type Acas paleosol is just below the rubbly andesite flow that was locally deeply eroded into gullied topography subsequently filled with the brown siltstones of the "Mammal Quarry". Other Acas paleosols were found near another sedimentological discontinuity between clayey red beds and conglomeratic "Nut Beds." In both cases Acas paleosols formed on hilly landscapes destabilized by soil erosion.

Parent material. Muted depth functions of molecular weathering ratios and deep weathering throughout Acas paleosols, particularly in the ratio of alumina/bases, is evidence that the parent material was deeply weathered soils of humid climates. These were presumably soils further upslope eroded by sheet wash, rainstorm mudflows and creek flooding. This parent material is chemically and mineralogically far evolved from any local primary volcanic ash, flow or lahar. This kind of parentage makes it difficult to determine how much of the observed weathering was in place and how much inherited.

Time for formation. The degree of subsurface enrichment in clay is somewhat irregular and may in part be a reflection of different colluviation events that created the parent material of the type Acas paleosol. Nevertheless, the clay bulge is coincident with the distribution of drab-haloed root traces and abundant clay skins, and relict bedding has been destroyed by bioturbation. From these indications that the creation of the clay bulge or destruction of relict bedding occurred in place, this paleosol can be judged moderately developed, rather than strongly developed as is apparent from its degree of chemical weathering. In well drained Quaternary floodplain soils reviewed by Birkeland (1990) and Walker and Butler (1983), this degree of clay accumulation takes 10,000 to 60,000 years. Even gleyed soils can accumulate as much clay as Acas profiles within 12,000 years (Smith and Wilding, 1972).

Cmuk paleosols

Diagnosis. Black lignite over greenish gray claystone.

Derivation. Cmuk is Sahaptin for "black" (Rigsby, 1965), in reference to the color of the lignite of these paleosols.

Description. The type Cmuk paleosol (Fig. 3.25) was found in a trench below the basalt of "Black Spur" above the trail to the "Mammal Quarry" from Hancock Field Station (NW1/4 NE1/4 NW1/4 Sect. http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap3.htm[4/18/2014 12:20:46 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 3)

27 T7S R19E Clarno 7.5' Quad., UTM zone 10, 703112E 4977736N). In that trench it was at an elevation of 11.6 m, 11 m stratigraphically above the basal porphyritic andesite and 16.6 m below the scoriaceous base of the ridge-forming basalt. This can be correlated to a level of about 20 m in the reference section through the "Nut Beds" and "Red Hill" (Fig. 3.4), in the "conglomerates of Hancock Canyon" of the upper Clarno Formation of Middle Eocene (Bridgerian-Uintan) age.

+80 cm: overlying siltstone: olive (5Y5/3), weathers grayish brown (2.5Y5/2): persistent relict bedding: common fossil leaf impressions (L1757): non-calcareous: clear smooth contact to

+5 cm: overlying siltstone: pale yellow (5Y6/3) to pale olive (5Y7/3), weathers grayish brown (2.5Y5/2): with common coalified logs and twigs in vertical to oblique position: non-calcareous: unistrial porphyroskelic skelmosepic, with clear relict bedding and carbonaceous debris, including fine root traces: abrupt wavy contact to

0 cm: O horizon: clayey lignite: black (5Y2.5/1), with interbeds of yellowish brown (10YR5/8) claystone. weathers grayish brown (2.5Y5/2): common coalified plant debris: non-calcareous: porphyroskelic skelmosepic in thin section, with abundant layered plant cuticle: abrupt smooth contact to

-25 cm: A horizon: sandy claystone: yellowish brown (10YR5/8). weathers grayish brown (2.5Y5.2): common black (5Y2.5/1) root traces and lensoidal relict laminae of sand, including white (5Y8/2) grains of feldspar: non-calcareous: porphyroskelic clinobimasepic in thin section, with clay filled root traces and burrows; clear wavy contact to

-30 cm: Bg horizon: clayey conglomerate: very dark grayish brown (2.5Y3/2), weathers grayish brown (2.5Y5/2): common black (5Y2.5/1) root traces and nodules up to 4 mm diameter of iron-manganese: medium blocky peds defined by sparse slickensided argillans: non-calcareous: porphyroskelic clinobimasepic in thin section, with common volcanic rock fragments: gradual wavy contact to

-50 cm: C horizon: clayey conglomerate: dark gray (5Y4/1), weathers grayish brown (2.5Y5/2): common rounded boulders of porphyritic andesite up to 16 cm diameter: noncalcareous: porphyroskelic clinobimasepic in thin section, with common volcanic rock fragments and feldspars. and clear relict bedding.

Figure 3.25. Measured section, Munsell colors, soil horizons, grain size, and mineral composition of the type Cmuk paleosol below the "Black Spur", which is within the middle Eocene Clarno Formation and correlated to a level of 20 m in the reference section (Fig. 3.4). Lithological key as for Fig. 3.3.

Further examples. Cmuk paleosols were only found in the trench excavated below the basalt of "Black Spur", and are not visible in outcrop because entirely covered by brown silt in addition to the type Cmuk profile at 11.6 m in this trenched section, others were found at 14.9 m, at 16.4 m and at 23.7 m.

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Alteration after burial. This green-gray lignite-bearing paleosol has suffered no obvious loss of organic matter, burial gleization or dehydration of ferric hydroxides. There has been only modest thermal maturation of the coaly surface horizon. Its lignitic rank is apparent from its friable nature, low bulk density and abundant recognizable plant fiber in thin section. Compaction of this clayey profile and especially its surficial lignite was probably considerable. Compaction of black lignites of this kind to 25% of former peat thickness is considered normal (Ryer and Langer, 1980; Cherven and Jacob, 1985), but in this case the lignite is rich in clay which is a little more compaction resistant than pure plant debris.

Reconstructed soil. Cmuk paleosols originally consisted of thick (50 cm or more) impure peat overlying carbonaceous silt with leaves, roots and relict bedding. This surface rooted horizon passed down in some profiles into massive boulder clay of volcanic mudflows little altered by soil formation beyond small local nodules and skins of black amorphous iron-manganese. Their soil reaction was probably acidic and their Eh reducing, and this placed constraints on plant growth despite evidence of nutrients from abundant well easily weathered plagioclase grains.

Classification. Although now thinned by compaction, the peaty surface horizons of these paleosols would formerly have been thicker than 40 cm, and so qualify as Histosols in the U.S. soil taxonomy (Soil Survey Staff, 1990). Abundant planar clay partings within the lignite and preservation of relict bedding in the surface of the mineral horizons are evidence that this was a permanently waterlogged swamp prone to flooding, and so rules out Folists. The mix of decomposed and recognizable plant debris in the lignite is most like that of Hemists. In the F.A.O. classification (1974) Cmuk paleosols were probably Eutric Histosols. These are most similar to Humic Gleys of the Australian classification (Stace and others, 1968). Organic soils are not subdivided in the Northcote (1974) key.

Paleoclimate. Peat accumulation is encouraged by local waterlogging rather than climatic conditions, but in general peat accumulates in non-seasonal climates in which precipitation exceeds evaporation (McCabe and Parrish, 1992). The high clay content of the lignite and numerous claystone partings in one of the Cmuk paleosols indicate conditions marginal for peat accumulation and rule out extremely wet (more than 2000 mm mean annual rainfall) tropical climates of the kind that encourage the development of raised bogs (ombrotrophic mires of Moore and Bellamy, 1971). There is also some evidence of seasonal draining of the swamp, in the form of burrows within both the coal and its underclay. The burrows are simple krotovinas 1-4 mm in diameter and filled with clayey matrix from above (meta-isotubules in the terminology of Brewer, 1976). Such burrows are made by beetles and other air-breathing insects in soils, and show no marginal concretions or internal spreiten of the kind formed by creatures of waterlogged soils.

Also of paleoclimatic significance are fossil plants found within the type Cmuk paleosol. The leaves of Meliosma are of leathery texture and show a clear drip tip as is common in tropical wet climates, where modern relatives of this genus thrive today (Manchester, 1981, 1994). In addition the dominance of this swamp by dicots is most like swamps of central America south of Mexico (Breedlove, 1973; Porter, 1973, Hartshorn, 1983). In northern Mexico and the United States in contrast, swamps are dominated by conifers such as bald cypress (Taxodium distichum: Best and others, 1984), and the dominance of swamps of temperate to subtropical climates by taxodiaceous conifers can be traced back in the fossil record at least into Late Cretaceous times (Retallack, 1994b).

Ancient vegetation. The thick peaty surface horizon, associated fossil logs and tabular systems of thick carbonaceous fossil roots are evidence of swamp forest for Cmuk paleosols. This vegetation was dominated by dictotyledonous angiosperms, which are preserved in the paleosols as compressed leaves with cuticles and include laurels (Litseaphyllum presanguinea) and aguacatilla (Meliosma sp. cf. M simplicfolia), as well as fragments of a broad-leaved grass or sedge (Graminophyllum sp.: from locality L1757). This fossil flora deserves more ambitious collecting because some of the leaves have preserved cuticles, which are rare for the Clarno Formation. Although current understanding of this vegetation is incomplete, its lower diversity and shared elements with the fossil flora of Sayayk paleosols confirm

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that Cmuk paleosols were marginally swampy, and perhaps seasonally drained. Permanent swamps are difficult anaerobic and oligotrophic substrates for plants, and commonly support vegetation distinct from nearby vegetation of dry land (Lind and Morrison, 1974).

Former animal life. No fossil bones were found in Cmuk paleosols, which are in any case insufficiently calcareous to allow bone preservation (Retallack, 1984a). Fossils of the Bridgerian North American Land Mammal Age are known from the "Nut Beds" at this stratigraphic level (Hanson, pers. comm. 1990), and aquatic creatures such as the alligator may have ventured into these swamp woodlands.

Paleotopographic setting. Cmuk paleosols were found within a restricted stratigraphic interval low in the sequence of conglomerates below a marker bed of basalt and above the top of a dome of porphyritic dacite and its colluvial cover of boulders weathered to clayey Pswa paleosols. The dome and its clayey paleosols in the "Mammal Quarry" are at a stratigraphic level less than 10 m below the basal ash-flow tuff of the John Day Formation (Pratt, 1988). Thus some 100 m of sediment overlying the Cmuk paleosol was banked against this ancient hill, which had at least that much topographic relief above the Cmuk swamps. Furthermore this prominent weathered dome would have blocked lahars from the large volcanic edifice to the southwest that supplied mudflows of the "conglomerates of Hancock Canyon". This local barrier appears to have excluded coarse debris from a local swamp or lake, which was presumably impounded by lava flows or other hilly volcanic terrane to the west.

Although there are indications of hilly terrane and even large stratovolcanoes nearby, Cmuk paleosols represent locally waterlogged bottom lands. At least locally these would have been flat and slowly subsiding so that peat could accumulate below water table faster than it could decay.

Parent material. Sandstones and siltstones associated with Cmuk paleosols include abundant grains of little weathered feldspar and volcanic rock fragments of andesitic composition like those associated with Patat and Sayayk paleosols of the "conglomerates of Hancock Canyon". Their ripple marks, plane bedding and lack of large andesitic boulders are similar to fluvial deposits, in contrast to volcanic mudflows responsible for the nearby and coeval "conglomerates of Hancock Canyon" (White and Robinson, 1992). Claystone partings within the Cmuk peats indicate deposition from suspension, probably from ponded floodwaters. Very few weathered clasts derived by erosion of pre-existing strongly developed soils were seen, so that most of this material was either delivered by airfall ash or from very weakly developed soils high on the volcanic edifice, so that its parent material is one of the least weathered of the Clarno paleosols.

Time for formation. These paleosols include well preserved plants and show little evidence of weathering either before or during accumulation of the overlying lignite. The excellent preservation of relict bedding in the underclays is evidence that their sedimentary parent material has been little altered. Better estimates of the time for formation of Cmuk paleosols can be gained from the thickness of their lignites. Peats formed under trees, like the O horizon of the Cmuk paleosol, accumulate at rates of 0.5 to 1 mm/yr (Retallack, 1990a), unlike peats of Sphagnum moss or certain kinds of oligotrophic raised tropical bogs which can accumulate at rates of up to 4 mm/yr (McCabe and Parrish, 1992). Rates of peat accumulation are constrained by the need to bury organic matter beyond the reach of aerobic decay without starving trees roots of oxygen on the one hand, and on the other hand the need to maintain tree growth against inundation by water and clay. Using the more conservative rates and a compaction of peat to lignite of 25% gives estimates of 1,000-2000 years for the type Cmuk paleosol, and 1,000-2000, 400-800 and 2,000-4,000 years for Cmuk profiles successively above that level. These are likely maximum times for formation, considering the high content of clays in these lignites.

Lakayx paleosols

Diagnosis. Red (2.5YR-10R) claystone, thick, abundant shiny slickensided cutans, deeply weathered.

Derivation. Lakayx is Sahaptin for "shine" DeLancey and others, 1988), and refers to the abundant http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap3.htm[4/18/2014 12:20:46 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 3)

slickensided surfaces of these paleosols.

Description. The type Lakayx clay (Fig. 3.26) was found in the lower part of a trench in lower "Red Hill", above the "Nut Beds", Hancock Field Station (NE1/4 SE1/4 SE1/4 SW1/4 Sect. 21 T7S R19E Clarno 7.5' Quad. UTM zone 10, 702695E 4977388N). This is the lowest red paleosol in the measured section and was called the "Chaney red clay paleosol" by Smith (1988). It is at a stratigraphic level of 70.5 m in the reference section (Fig. 3.4) in the claystones of "Red Hill" and in the late Eocene (Bridgerian-Uintan) upper Clarno Formation.

+23 cm: C horizon of overlying Lakayx paleosol: silty claystone; dark red (10R3/6), weathers weak red (10R4/4): sparse fine root trace of dark red (5R3/2) and granules of white (5Y8/1): faint relict bedding: non-calcareous: porphyroskelic isotic in ferruginized areas and clinobimasepic in drab haloes in thin section, with relict volcanic rock fragments and spherical micropeds: abrupt smooth contact to

0 cm: A horizon: silty claystone, a little more clayey than above; dark red (10R3/6), weathers weak red (10R4/4): common drab- haloed root traces of light gray (5Y7/2), with an additional 2 mm diffuse halo of weak red (5YR4/6): very weakly calcareous: porphyroskelic mosepic to isotic in ferruginized areas and clinobimasepic in drab haloes in thin section, with common spherical micropeds and clay skins (illuviation ferriargillans): diffuse wavy contact to

-30 cm: Bt horizon; claystone; dark red (2.5YR3/6), weathers weak red (10R4/4): sparse drab-haloed root traces of olive yellow (2.5Y6/8); coarse blocky subangular structure, defined by abundant slickensided clay skins (ferriargillans) of very dusky red (10R2.5/2) to dark reddish brown (5YR3/5): few relict grains of weak red (10R4/3): non-calcareous: porphyroskelic isotic in ferruginized areas and clinobimasepic in drab haloes in thin section, with common clay skins (illuviation ferriargillans): gradual smooth contact to

-60 cm: C horizon: silty claystone: dusky red 10R3/4), weathers weak red (10R4/4): sparse root traces of light olive gray (5Y6/2) with 1 mm outer halo of dusky red (7.5YR3/2): slickensided argillans less common than above, so that relict bedding is distinct in places: common ferruginous concretions and lithorelicts up to 2-3 mm diameter of dusky red (10R3/4) and reddish black (10R2.5/1): very weakly calcareous: porphyroskelic isotic to mosepic in thin section, with common deeply-weathered volcanic rock fragments.

Figure 3.26. Measured section, Munsell colors, soil horizons, grain size, mineral composition and selected molecular weathering ratios of the type Lakayx and type Scat clay paleosols in lower "Red Hill", which is within the middle-late Eocene Clarno Formation at a level of 70.5 m in the reference section (Fig. 3.4). Lithological key as for Fig. 3.3. (click on image for an enlargement in a new window)

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Further examples. Lakayx paleosols are much more deeply weathered than otherwise similar Luca paleosols, with very few remaining primary minerals and abundant slickensided clay skins. Lakayx paleosols are known primarily from the lower red beds of "Red Hill" and correlative strata of the upper Clarno Formation. There are 10 successive Lakayx paleosols at this level in the reference section in lower "Red Hill". The Lakayx clay manganiferous variant is the last of these paleosols immediately below a major erosional disconformity, and is distinguished by a drab surface horizon and prominent drab-haloed root traces with additional haloes of iron-manganese (Fig. 3.14, 3.27)

Alteration after burial. Lakayx paleosols have probably been modified by burial decomposition and gleization of organic matter and burial reddening. This is indicated by their common drab-haloed root traces, however, no detectable organic matter or fossil leaf litters were found. Some of the drab-haloed root traces in one of these paleosols (Fig. 3.27) immediately below a major erosional disconformity show evidence of manganese accumulation and depletion of iron (Fig. 3.14), indicative of original rather than burial gleization, but even in that profile the effects of waterlogging were local. They are very strongly oxidized, with no detectable ferrous iron and a brick red color (Figs. 3.26, 27). Compaction of these very clayey paleosols was probably some 70% using the standard equation of Sclater and Christie (1980), and this may account in part for the abundant slickensides in Lakayx paleosols. Illitization has not affected these soils which have clays overwhelmingly of kaolinite and smectite (Smith, 1988).

Figure 3.27. Measured section, Munsell colors, soil horizons, grain size, and mineral composition of the Lakayx clay manganiferous variant paleosols in lower "Red Hill", within the middle-late Eocene Clarno Formation at level 85 m in the reference section (Fig. 3.3). Lithological key as for Fig. 3.4.

Reconstructed soil. Lakayx soils were probably thick, clayey, red and low in fertility. There is a marked increase in clay skins and total clay in the subsurface (Bt) horizon. This trend is reflected in

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only a muted bulge in the ratio of alumina/silica (Fig. 3.26). In the case of the type Lakayx clay, profile differentiation may have been limited by a strong contribution of deeply weathered parent material, as indicated by common very deeply ferruginized volcanic rock fragments in the parent material. Such clayey profiles would have been slow to drain, but all appear highly oxidized. Only in the case of the Lakayx clay manganiferous variant is there evidence from iron and manganese mobility around root traces (Fig. 3.14) for local seasonal ponding. High ratios of alumina to bases indicate deep weathering and this is also indicated by the near total lack of weatherable minerals or volcanic rock fragments in thin section (Figs 3.26, 27). Soils of this degree of weathering commonly are red rather than brown (Birkeland, 1984), though a dark brownish red surface horizon is likely considering the abundance of fossil root traces, burrows and other evidence of biological activity. There is no evidence of salinization or calcification from the ratios of soda/potash or alkaline earths/alumina. This together with the mixed smectite and kaolinite clay composition is evidence of mildly acidic pH and low base saturation.

Classification. Spherical micropeds and deep oxidation of Lakayx paleosols are similar to Oxisols of the U.S. soil taxonomy (Soil Survey Staff, 1990), however, their alumina/bases ratio of about 4 is not far beyond that typical for Alfisols. The persistence of smectite in these profiles also indicates base status higher than usual for Oxisols. These features together with abundant clay skins and subsurface increase in total clay make Ultisols the most similar soils to Lakayx paleosols. Among Ultisols, the local gleization of the Lakayx clay manganiferous variant is insufficient for Aquults, nor is there evidence for organic matter of Humults or cracking and carbonate of Ustults and Xerults. Among Udults, the most likely suborder, the persistence of appreciable amounts of smectite rule out Kandiudults or Kanhapludults, nor is there plinthite or fragipans of Plinthudults or Fragiudults. Rhodudults are generally even redder than the paleosol after some burial reddening and Paleudults much thicker than Lakayx paleosols. This leaves typic Hapludults as the most similar soil. In the F.A.O. (1974) classification Lakayx paleosols show some similarity with the Oxisol-like Nitosols and Ferralsols, but their clayey subsurface (Bt) horizons mark them as Ferric Acrisols. In Australia such a soil would be classified as a Krasnozem (Stace and others, 1968) or Gn3.11 in the Northcote (1974) key.

Paleoclimate. Lack of carbonate in Lakayx profiles is an indication of rainfall in excess of 1000 mm per year (Retallack, 1994). Smectite is destroyed in favor of kaolinite and gibbsite in tropical Hawaiian soils in climates of more than 2000 mm mean annual rainfall and in temperate Californian soils more humid than 1500 mm (Sherman, 1952; Barshad, 1966). The coexistence of kaolinite and smectite in Lakayx paleosols thus probably reflects a humid climate of 1000-2000 mm per year.

Tropical paleotemperature is likely considering the spherical micropeds common in Lakayx paleosols. These sand-size clay clasts are generally attributed to the activity of termites (Stoops, 1983; Mermut and others, 1984). Termites today are almost exclusively tropical. "In no case are the climatic areas with cold winters and cool summers occupied by termites. The 49°F [8°C] annual isotherm line of both hemispheres encloses almost all native species" (Emerson, 1952, p. 172). The few termite species penetrating temperate regions are primitive species that nest in wood, rather than in the ground. Termites have been found in middle Eocene lake beds near Republic, Washington (Lewis, 1992), and their fossil record of wings and borings goes back into the Cretaceous (Burnham, 1978; Rohr and others, 1986). A search for termite mounds in Lakayx paleosols would be warranted, as a variety of these distinctive trace fossils are now known (Tessier, 1959; Bown, 1982, Sands, 1987), including examples from early Eocene paleosols of Wyoming (T.M. Bown, pers. comm, 1990) and the late Eocene Interior paleosol of South Dakota (Retallack unpublished field notes and D. Terry, pers. comm., 1989).

Some degree of seasonality could be inferred from pisolitic ironstone concretions in the type Lakayx clay, but observation in thin section confirms that these are volcanic clasts with thick weathering rinds and their distribution in the lowest parts of the profile supports interpretation of these as resorted clasts from pre-existing soils. Nevertheless some degree of seasonality of rainfall is indicated by the abundant slickensided clayskins in these profiles. These are not organized into festooned or radiating structures like those of Vertisols, but a dry period of several weeks a year would be compatible with observed

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cracking of Lakayx paleosols.

Ancient vegetation. The thick, deeply penetrating root traces and well differentiated subsurface clayey horizon with thick clay skins in these paleosols are typical for old growth forest. The high ratios of alumina/bases and pervasive alteration of feldspars and volcanic rock fragments are evidence of oligotrophy of the sort found in rain forest vegetation (Smith, 1988). Also compatible with such an interpretation are the spherical micropeds in Lakayx paleosols (Stoops, 1983) and their high oxidation (negligible values of ferrous/ferric iron: Birkeland, 1984). Nevertheless, there are also indications that these were not so extremely oligotrophic rain forests as many known from modern Amazonia, which unlike Lakayx paleosols are entirely kaolinitic, lack a subsurface zone of clay accumulation and have root traces largely confined to surface horizons (Sanford, 1987; Lucas and others, 1993). Lakayx paleosols thus supported old-growth tropical forest.

No fossil plants have been found in Lakayx paleosols, nor are any likely to be considering their high degree of oxidation (Retallack, 1984a). Nevertheless, Lakayx paleosols are the kinds of profiles expected to support old growth paratropical rain forest assemblages of plants like those known from the underlying Clarno "Nut Beds" (Manchester, 1981, 1994). Red claystones with Lakayx paleosols abruptly overlie conglomeratic paleochannels of the "Nut Beds", and although we are not convinced that there is an angular unconformity separating them (contrary to Hanson, 1973), they do represent a very different sedimentary environment. Nevertheless a number of fossil plants of tropical rain forest affinities are found in the geologically younger Micay paleosols and interbedded fluvial deposits of the "Mammal Quarry" (McKee, 1970; Retallack, 1991a: Manchester, 1994). Because these same species also are known from the "Nut Beds", it is likely that some of them also vegetated Lakayx paleosols.

Former animal life. No vertebrate or invertebrate fossils have been found in Lakayx paleosols which are insufficiently calcareous for preservation of bone and shell (Retallack, 1984a). Fossils of the Bridgerian North American Land Mammal Age are known from the "Nut Beds" which directly underlie the lowest of the Lakayx paleosols (Hanson, pers. comm. 1990). This is generally regarded as a forest adapted fauna and was probably more at home on soils like Lakayx paleosols than the coarse fluvial conglomerates in which the rolled and fragmented bones and teeth were found. As noted above, we do not interpret the contact between Lakayx paleosols and the "Nut Beds" to represent a geologically significant time gap, merely a change in depositional regimen with the cessation of local mudflow deposition.

Paleotopographic setting. Lakayx paleosols are strongly oxidized with deeply penetrating root traces and abundant clay skins, all features of well drained soils. The Lakayx clay manganiferous variant shows some local areas of gleization, but such locally slow drainage would be expected in soils as clayey as these. Thus Lakayx paleosols probably formed in parts of the landscape elevated above regional water table, unlike associated Scat paleosols. The red beds which include Lakayx paleosols thin dramatically to the north and east, and appear to mantle a depression in slopes of the extinct volcano that earlier delivered the thick sequence of mudflows and gravels of the "Nut Beds". Within the sequence of red Lakayx paleosols is a Sitaxs paleosol which developed on ripple-marked silts and claystone breccias similar to those of a small creek channel. The environment of Lakayx paleosols can thus be envisaged as small floodplains and terraces of local creek drainage of a piedmont to an eroding volcanic edifice, or as a post-eruptive volcanic apron in the terminology of Pickford (1986).

The nature of sedimentary processes on this heavily forested piedmont are difficult to discern due to the near total destruction of sedimentary structures by successive buried soils. There are very few fresh volcanic shards or crystals of feldspar in Lakayx paleosols, so that airfall volcanic ash must have been delivered at sufficiently long intervals that it was destroyed by weathering. Thus distant volcanism is not likely to have been an important mechanism of sediment accumulation. There are ferruginized volcanic rock fragments in Lakayx paleosols, derived from pre-existing soils. These observations suggest that creek flooding and colluvial sheetwash, perhaps during unusually destructive storms or earthquakes, were the main mechanism for accumulation of these thick red soils foot slopes of an eroding volcanic

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edifice.

Parent material. Deep weathering of Lakayx paleosols has destroyed much evidence of parent material. The weakly developed type Scat paleosol beneath the type Lakayx clay could be used as a model for earlier stages in the development of Lakayx profiles, and indicates a parent material of sand and gravel of andesitic volcanics, perhaps with some inputs also from volcanic airfall ash. By this standard the degree of development of Lakayx paleosols is extreme, because very little is left of such clasts in Lakayx paleosols. The lower horizons of the type Lakayx paleosol include very deeply weathered ferruginized volcanic clasts that were presumably derived from erosion of pre-existing soils on these forested slopes of a moribund andesitic volcano. By this standard, Lakayx paleosols are not so deeply weathered from their parent material, but have inherited their low fertility from pre-existing soils higher on the volcano. The true parent material of Lakayx paleosols is probably between these extremes a moderately weathered andesitic colluvium.

Time for formation. With their well differentiated subsurface clayey (Bt) horizons and abundant clay skins Lakayx paleosols are strongly developed in the qualitative scheme of Retallack (1990a). Such soils are normally the product of some tens to hundreds of thousands of years of weathering. Comparable Ultisols of the North American States of Georgia and the Carolinas are on high terraces and other landforms thought to be late Pleistocene in age (Buol and others, 1980). Lakayx paleosols show clay enrichment and other characteristic similar to Sangamon paleosols of Illinois, which began forming between 122 Ka and 132 Ka and were covered in many areas by Wisconsinan tills some 50 to 30 Ka (Follmer and others, 1979). Sangamon paleosols that have been exposed for the full 120 Ka or so since inception have much thicker Bt horizons than the 86 cm estimated before burial compaction of the type Lakayx paleosol, and so do lateritic paleosols and Oxisols that represent landscapes stable for millions of years. Even at 100 ka for each Lakayx paleosol, the sequence of 10 such paleosols in the lower part of "Red Hill" represents a million years of soil formation under wet tropical forests.

Lakim paleosols

Diagnosis. Brown to olive with prominent large black iron-manganese nodules.

Derivation. Lakim is Sahaptin for "soot" (DeLancey and others, 1988) and refers to the black iron- manganese nodules that distinguish these paleosols.

Description. The type Lakim paleosol is at a stratigraphic level of 7 m in a trench excavated by G.J. Retallack, A. Mindszenty, E.A. Bestland and T. Fremd on the eastern side of "Painted Ridge" (section no. 10 of the reference section, SE1/4 NE1/4 NW1/4 NW1/4 Sect 6, T11S R21E Painted Hills 7.5' Quad., UTM zone 10, 717417E 4947425N), in the Painted Hills Unit of the John Day Fossil Beds National Monument. This is at 242 m in the reference section of the John Day Formation, and in the upper part of the upper Big Basin Member, which accumulated during the late Oligocene Whitneyan North American Land Mammal "Age."

+18 cm: sandy claystone: pale olive (5Y6/4), weathers yellowish brown (10YR5/4): indistinct relict bedding and common feldspar of white (5Y8/2) and volcanic rock fragments of olive (5Y5/3): few joints stained strong brown (7.5YR5/8): very weakly calcareous: intertextic skelmosepic in thin section, with common volcanic rock fragments, feldspar and quartz: abrupt wavy contact to

0 cm; A horizon: sandy claystone: olive (5Y4/3), weathers yellowish brown (10YR5/4): with abundant fine (1 mm diameter) root traces of pale yellow (2.5Y8/4): fine subangular blocky structure defined by clay skins (argillans) of olive (5Y4/4): common sand-size volcanic rock fragments of dark olive gray (5Y3/2) and pale yellow (5Y7/4): few joints stained strong brown (7.5YR5/6): very weakly calcareous: agglomeroplasmic clinobimasepic in thin section, with fresh rock fragments and common feldspar and opaques: gradual wavy contact to

-26 cm: Bg horizon: silty claystone; dark olive gray (5Y3/2), weathers dark grayish brown (10YR4/2): these dark colors form large (10-20 cm) diffuse mottles and layers in olive (5Y4/3) matrix: common small (2-3 mm) mottles of reddish black (10R2.5/1): few root traces of pale olive (5Y6/4) and yellow (5Y7/6): very weakly calcareous: intertextic skelmosepic, with

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abundant fresh feldspar and volcanic rock fragments: gradual wavy contact to

-35 cm: C horizon: sandy claystone: pale olive (5Y6/4), weathers dark grayish brown (10YR4/2): massive to indistinct bedding: common sand-size volcanic rock fragments of olive (5Y4/4) and yellow (5Y7/6): very weakly calcareous: intertextic skelmosepic, with abundant fresh feldspar and volcanic rock fragments: abrupt wavy contact to

Further examples. These yellow to brown paleosols with their prominent large black mottles and nodules are common in the John Day Formation in the Painted Hills, but rare in the Clarno Formation, and confined to beds of the "Mammal Quarry" both at its type locality and in the reference section. The Lakim clay septarian variant (Fig. 3.28) of the Clarno Formation in the "Mammal Quarry" is distinct from Lakim paleosols of the John Day Formation in its relatively small (2-3 cm diameter) iron- manganese nodules often with the distinctive radial cracks called septaria. Also distinctive for the Clarno paleosols are iron-manganese replacements of root traces.

Figure 3.28. Measured section, Munsell colors, soil horizons, grain size, mineral composition and selected molecular weathering ratios of the Lakim septarian variant and type Micay clay paleosols in the "Mammal Quarry", which is within the late Eocene Clarno Formation and correlated to a level of 124 m in the reference section (Fig. 3.4). Lithological key as for Fig. 3.3. (click on image for an enlargement in a new window)

Alteration after burial. Lakim paleosols have clearly lost organic matter after burial, because their root traces show little remnant of organic carbon and extensive replacement with iron and manganese. No drab haloes or red color were seen so that burial gleization and reddening are unlikely to have been significant. The yellow color of exposures in the "Mammal Quarry" are likely due to oxidation in modern outcrop, but even fresh rock there and in the 1.5 m deep trench excavated into the crest of "Red Hill" has a gray color in relatively warm (Munsell 2.5Y) rather than greenish or blue hues (5Y,5G,5B). These grayish brown siltstones of the "Mammal Quarry" are near the top of the sequence and using the formula of Sclater and Christie (1980) have been compacted to about 71% of their former thickness. There is no mineralogical or chemical evidence for illitization, or zeolitization of these smectitic siltstones with amorphous iron-manganese oxides.

Reconstructed soil. The Lakim soils were probably weakly developed clayey silts with a thin zone of rooting and litter accumulation (A horizon) over bedded siltstone with nodules of iron-manganese (Bg) horizon. Their original color was probably gray with black mottles similar to the paleosols. Iron- manganese nodules form in waterlogged or slowly draining soils. Lakim paleosols were thus prone to waterlogging and stagnation. The lack of red mottled and tabular systems of root traces in Lakim paleosols are indications that water table seldom fell far below the ground surface. Despite these problems for plant growth, Lakim paleosols were relatively fertile, with adequate reserves of nutrient bases and near neutral pH (low values of alumina/bases) and no problems with salt efflorescence or carbonate hardpans (low values of soda/potash and alkaline earths/alumina).

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Classification. Lakim paleosols lack diagnostic horizons of most soil orders of the U.S. taxonomy (Soil Survey Staff, 1990), yet show nodules of iron-manganese indicating a greater degree of soil differentiation than Entisols such as the associated Micay paleosols. This leaves Inceptisols as the most likely order and the waterlogged Inceptisols or Aquepts as the most likely suborder. The iron- manganese nodules indicating waterlogging together with their clear relict bedding distinguish Lakim paleosols as Aquentic Placaquepts. Within the F.A.O. (1974) classification, waterlogged soils like Lakim paleosols are included within the Gleysols, and given their abundance of weatherable minerals and lack of other diagnostic features, Eutric Gleysols are the most similar soils. In the Australian classification (Stace and others, 1968), Lakim paleosols are most like Humic Gleys, but are not typical because there is little evidence in the paleosols of the high levels of organic matter found in some of these Australian soils. In the Northcote (1974) key Lakim soils are Uf6.61.

Paleoclimate. Lakim paleosols are so weakly developed that they were not exposed for long enough to register climatic influences. The septarian nodules of the Lakim paleosol in the "Mammal Quarry" could be taken as evidence of climatic drying and cracking of iron-manganese colloids in the soil. The dry season could not have been severe however, because there is no indication of oxidation of these reduced nodules.

Ancient vegetation. Considering the tabular root systems, iron-manganese nodules and relict bedding of Lakim paleosols, their vegetation can be envisaged as bottomland forest taller than vegetation early in the ecological succession of disturbed ground but not so impressive as old growth forest. Poorly aerated soils like Lakim paleosols commonly support trees with buttressed trunks, peg roots (Jenik, 1978), a relatively open canopy, and thick ground cover of ferns or reeds (Hartshorn, 1983).

The distinctive black nodules of Lakim paleosols may reflect a particular species of manganese accumulating plant, as Pickford (1974) has noted circular areas of manganese staining under trees locally called "kuresstin" in the Lukeino area of Kenya. "Kuresstin" is the so-called toothpick tree (Dobera glabra) in the family Salvadoraceae (Dale and Greenway, 1961; Verdcourt, 1968). This plant may explain paleosols similar to Lakim profiles in the Miocene Ngorora Formation of Kenya (Bishop and Pickford, 1975), but neither this genus nor family has been recognized among fossil plants of the Clarno Formation (Manchester, 1981, 1994).

No plant fossils were found in Lakim paleosol of the "Mammal Quarry". Underlying Micay paleosols and interbedded fluvial deposits have yielded a small fossil flora of fruits and seeds (McKee, 1970; Manchester, 1994). A small fossil flora of leaves also has been found in the surface horizon of the Lakim clay green variant paleosol in the middle Big Basin Member of the John Day Formation below the eastern mound of Chaney's leaf beds (L1871). This included dawn redwood (Metasequoia occidentalis), nutmeg tree (Torreya sp. indet.), grass (Graminophyllum sp. indet.), laurel (Cinnamomophyllum bendirei) and walnut (Juglans cryptata). Remains of walnuts were most common in both the "Mammal Quarry" and Chaney's leaf bed assemblages.

Former animal life. No animal body or trace fossils have been found in Lakim paleosols. The underlying Micay paleosols and fluvial deposits have yielded a diverse mammalian fauna of the early Duchesnean North American Land Mammal "Age" (Mellett, 1969; Hanson, 1973, 1989; Schoch, 1989). Although this assemblage includes fish and alligators, the large fish would have required better aerated waters than those ponded on Lakim paleosols. The alligators are of an extinct type (Pristichampsus) that show more fully terrestrial limb structure than living alligators (Langston, 1975), and may have been well suited to swampy ground like Lakim paleosols.

Paleotopographic setting. Lakim paleosols were poorly drained soils of stagnant ponded bottomlands, where iron and manganese was redistributed into nodules but not oxidized by contact with air. The paleosol in the "Mammal Quarry" overlies a sequence of Micay paleosols interbedded with siltstone and a thick paleochannel conglomerate. Pratt (1988) has plotted the distribution of fossil bones in these Micay paleosols and fluvial deposits and found that the orientation of long bones swung progressively

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up section from east-west to north-south. She interpreted this together with preserved sedimentary structures to reflect the migration and accumulation of a point bar of a meandering stream that filled a local valley into pre-existing volcanic rocks. Within such a setting, Lakim paleosols may have formed in depressions or swales of the point bar system, such as chutes excavated within the upper point bar by flood flow (McGowan and Garner, 1970).

Parent material. Lakim paleosols are not much altered from their parent materials, and associated Micay paleosols and fluvial sediments are altered even less. Both kinds of paleosols in the "Mammal Quarry" developed on silt and sand derived from the erosion of an extinct volcanic center to the east. Both contain common fresh laths of feldspar derived from volcanic ash fall, and there is a bed 20 cm thick of weathered sanidine tuff high in the sequence exposed within the "Mammal Quarry". Both also contain abundant clay and weathered silt grains similar to those seen in Patat paleosols, which may have remained high on the volcanic edifice as a source of sediment. Large volcanic rock fragments are rare and few of them show strongly ferruginized weathering rinds, so that red Pswa paleosols developed on the underlying dacitic dome were probably largely covered as a source of sediment by the time the sequence of the "Mammal Quarry" was accumulating. Even cobbles and pebbles of porphryitic dacite in the basal paleochannel of the "Mammal Quarry" show relatively little weathering and were probably derived from deeply eroded parts of the underlying dome or higher on the volcanic edifice.

Time for formation. Lakim paleosols are weakly developed in the qualitative scale of Retallack (1990a), and thus represent some hundreds to few thousands of years of soil development. Time estimates for Lakim paleosols are tentative because waterlogging evident from iron-manganese nodules can suppress biological activity that would more rapidly form soil from sediment in better drained sites. On the other hand, waterlogging also preserves root traces from aerobic decay, and from this perspective the bedding of Lakim paleosols has not been disrupted by more than a few generations of tree growth.

Luca paleosols

Diagnosis. Red (2.5YR-10YR), thick, claystone, with remnant weatherable minerals.

Derivation. Luca is Sahaptin for "red" (Rigsby, 1965), the color of these paleosols.

Description. The type Luca clay (Fig. 3.29) is the red paleosol immediately below a prominent white tuff, forming a feature here called "Whitecap Knoll", in rolling country between the "Mammal Quarry" and the "Slanting Leaf Beds" 1.2 miles northeast of Hancock Field Station, near Clarno (SE1/4 NW1/4 NE1/4 NW1/4 NW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad. UTM zone 10, 703741E 498852N). The locality and profile has been described by Getahun and Retallack (1991), and the description here includes additional unpublished observations by Paul Drake. Following our current stratigraphic scheme, it is in the upper part of the lower Big Basin Member of the John Day Formation. It probably formed during the Duchesnean North American Land Mammal "Age" considering the single-crystal 40Ar/39Ar radiometric date of 38.19+0.06 Ma obtained by Carl Swisher from the overlying tuff during the course of this work.

+80cm: vitric tuff overlying paleosol: white (5YR8/1), weathers pinkish white (7.5YR8/2): indistinct relict bedding: very weakly calcareous: clear wavy contact to

0 cm: A horizon: clayey siltstone: pale yellow (5Y8/3), weathers pinkish white (7.5YR8/2); common mottles of dark reddish brown (2.5YR3/4) in areas distant from common stout (6-8 mm diameter) woody root traces: few burrows up to 14 mm diameter of white tuff: fine subangular blocky peds defined by slickensided clay skins (sesqui-argillans) of dark reddish brown (2.5YR3/4): porphyroskelic skelinsepic in thin section, with scattered grains of plagioclase, volcanic rock fragments, glass shards and opaques: non-calcareous: diffuse irregular contact to

-47 cm: Bt horizon: silty claystone: dusky red (10R3/4), weathers weak red (10R4/4): common stout (up to 4 mm diameter) root traces of pale yellow (5Y7/4), with drab haloes up to 16 mm diameter of light gray (5Y7/2): angular blocky peds defined by slickensided clay skins (sesqui-argillans) of dark red (10R3/6): few small (1-2 mm diameter) iron-manganese nodules of reddish http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap3.htm[4/18/2014 12:20:46 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 3)

black (10R2.5/1): non-calcareous: porphyroskelic skelmasepic in thin section, with sparse grains of plagioclase, volcanic rocks, opaques and quartz: diffuse irregular contact to

-141 cm: C horizon: clayey siltstone: reddish brown (2.5YR4/4), weathers weak red (10R4/4): few small iron-manganese nodules and dendrites, as above: indistinct relict bedding: non-calcareous: porphyroskelic skelmasepic in thin section, with common grains of plagioclase, volcanic rock fragments, opaques and quartz.

Figure 3.29. Measured section, Munsell colors, soil horizons, grain size, mineral composition and selected molecular weathering ratios of the type Luca clay paleosol in "Whitecap knoll", which is within the late Eocene lower John Day Formation. Lithological key as for Fig. 3.3. (click on image for an enlargement in a new window)

Further examples. These red clayey paleosols differ from Lakayx paleosols primarily in their persistent pyrogenic minerals, as well as a more silty texture and less common slickensided clay skins. Luca paleosols are common in the lower John Day Formation as well as the upper Clarno Formation. There are 15 successive Luca paleosols in the reference section through the upper part of "Red Hill" (Merriam paleosols of Smith, 1988). The lowest of these above a major erosional discontinuity in "Red Hill" is the Luca clay concretionary variant (Fig. 3.30), characterized by redeposited rounded clasts up to 12 mm in diameter of strongly ferruginized red claystone presumably derived from underlying Lakayx paleosols. These clasts are neither so abundant nor dominantly volcanic, as in Acas paleosols.

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Figure 3.30. Measured section, Munsell colors, soil horizons, grain size, mineral composition and selected molecular weathering ratios of the Luca clay pisolitic variant paleosol in central "Red Hill", which is within the late Eocene Clarno Formation and at a level of 87 m in the reference section (Fig. 3.3). Lithological key as for Fig. 3.4. (click on image for an enlargement in a new window)

Alteration after burial. Luca paleosols, like similar Lakayx paleosols, have probably been altered considerably by decomposition of organic matter, gleization, reddening and compaction (at least 70%) during burial. X-ray diffractograms show no evidence of illitization, recrystallization or zeolitization of these paleosols. Thus their chemical and mineralogical composition largely reflects the original soils, even though their color and mottling has been greatly altered.

Reconstructed soil. Luca soils were probably thick reddish brown profiles with clay-enriched subsurface (Bt) and dark gray surface (A) horizons. Included ferruginized volcanic clasts and claystone clasts may have added to red color of these highly oxidized and presumably well drained profiles. Lack of carbonate and generally deep weathering is compatible with acidic pH, but low alumina/bases ratio, smectite and persistent feldspar laths indicate moderate base saturation. In comparison with Lakayx paleosols which have a similar overall profile form, Luca paleosols would have been more fertile and less sticky with clay when wet. There is no evidence from the ratios of soda/potash or alkaline earths/alumina for salinization or calcification.

Classification. Clearly defined subsurface clayey (Bt) horizons together with chemical and petrographic evidence for moderate base status distinguish Luca paleosols as Alfisols of the U.S. soil taxonomy (Soil Survey Staff, 1990). Luca paleosols are best regarded as Hapludalfs, largely on the rather unsatisfactory basis of negative evidence: they lack fragipans, calcareous nodules, deep cracking, abundant kaolinite and other differentiae of other groups. In the F.A.O. (1974) classification, this would have been a Luvisol. Iron and clay enrichment and base depletion are not so marked as in Plinthic and Ferric Luvisols. Orthic Luvisols would be a possibility if much of the current red color were produced by burial reddening that gives the paleosol the appearance of a Chromic Luvisol. The common red claystone clasts in these paleosols inherited from pre-existing soils and their moderate-strong development are most compatible with Chromic Luvisols. Using similar reasoning, they are more likely to have been Red Podzolics than Grey-Brown Podzolics in the Australian classification (Stace and others, 1968) and Gn4.41 in the Northcote (1974) key.

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Paleoclimate. As for Lakayx profiles, the co-occurrence of kaolinite and smectite in Luca paleosols indicates mean annual rainfall between 1000-2000 mm. Unlike the Lakayx clay, however, the Luca clay pisolitic variant has only small amounts of kaolinite, but large amounts of smectite (Smith, 1988). The proportions are so markedly changed that mean annual precipitation in the range 1000-1300 mm is likely. This is not compromised by development of the Lakayx clay, which is comparable with development of the Luca clay pisolitic variant. Furthermore, a Sitaxs paleosol interbedded with Lakayx paleosols has comparable morpholigical development but is more deeply weathered chemically than Sitaxs profiles interbedded with Luca paleosols. Thus there was an abrupt decline in weathering intensity across the major erosional disconformity in the middle of "Red Hill".

No spherical micropeds were noted in Luca paleosols, but it is uncertain whether this means termites inferred for Lakayx paleosols were excluded by lower temperature or other factors. The comparable reddish hue of matrix and redeposited volcanic clasts in the Luca profile immediately above the last Lakayx profile could be taken as an argument for an original color at least as red as Lakayx soils, little reddened during burial. Considering the generally red color of modern tropical soils (Birkeland, 1984), this could be taken as an indication of warm temperatures. The profound bioturbation of Luca paleosols is evidence of high biological productivity found in warm climates.

As in Lakayx paleosols, ferruginized volcanic clasts and patterns of cracking are evidence of a relatively short dry season. This is not expressed as such prominent slickensided clay skins as in Lakayx paleosols, but this difference may be related to a less sticky overall texture of Luca paleosols rejuvenated by volcanic airfall ash.

Ancient vegetation. Luca paleosols show several indications that they supported tall tropical forest: large deeply penetrating drab-haloed root traces, well differentiated clayey subsurface (Bt) horizon with stable (non-slickensided) blocky structure and adequate reserves of nutrient bases and fresh volcanic minerals. The drab surface horizon of many of these profiles may have formed by burial gleization from a reserve of soil humus there, and this is indicated by the finer ped structure in that horizon. These were thus eutrophic forests, so most likely broad-leaved, with good ground cover and thus a single canopy layer. Lakayx paleosols in contrast show little evidence of ground cover or fertility, and true multitiered tropical rain forest grows on soils with even less evidence of ground cover or fertility than Lakayx paleosols (Sanford, 1987; Lucas and others, 1993).

No fossil plants have been found in any Luca paleosols, but a variety of tropical dicotyledonous remains have been found in strata both overlying and underlying the Luca paleosols of "Red Hill" as recounted for Lakayx paleosols. Interpretation of broadleaf semi-evergreen forest with vines and epiphytes is compatible with this local paleobotanical record (Manchester, 1981, 1994). Vegetation may have been different for the geologically younger type Luca clay of the basal Big Basin Member of the John Day Formation on "Whitecap knoll". A small collection of leaves and fruits from late Eocene lake beds (L1568) underlying these red paleosols was dominated by wind-dispersed fruits of walnut-like forms (Cruciptera simsoni, Palaeocarya clarnensis), with common leaves of elm (Ulmus sp. indet.) and dawn redwood (Metasequoia occidentalis). Although this collection is inadequate in size, there are suggestions in this flora of forests more open and deciduous than earlier in the Eocene. Vegetation may have changed again into the early Oligocene Big Basin Member of the John Day Formation, where Luca paleosols are less common among a suite of less deeply weathered soils. Lacustrine beds at this stratigraphic level in several localities (L743, L1352, L1353) have yielded a very different fossil flora similar to that of deciduous single-tiered temperate forests, and dominated by alder (Alnus heterodonta) and dawn redwood (Metasequoia occidentalis; Manchester and Meyer, 1987; Meyer and Manchester, 1994). These lacustrine basins were sampling a variety of vegetation types, as can be seen from our ongoing studies of the Painted Hills where dawn redwood dominated vegetation of swamps on Yanwa paleosols and alder dominated early successional vegetation on Micay paleosols. Nevertheless the lake beds also include a variety of species similar to those found in geologically older deposits associated with Luca paleosols, including walnut (Juglans sp. indet.), laurel (Cinnamomophyllum bendirei) and

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icacina vines (Palaeophytocrene sp. indet.). Although there were clearly changes in regional vegetation sampled by large lakes, the few Luca paleosols found in the early Oligocene may have supported vegetation with a greater component of tropical and evergreen plants.

Former animal life. Only one vertebrate fossil was found from the red slopes of the type Luca clay in the late Eocene lower John Day Formation (locality L1358). It is a fragment of a tusk, probably of the extinct family of hog-like Entelodontidae. Entelodont tusks also have been found in sequences of Luca paleosols in the lower Big Basin Member on Cant Ranch near Dayville (Coleman, 1949a,b). Such non- calcareous paleosols are unlikely to preserve bone (Retallack, 1984a), but massive enamel of tusks is relatively more resistant to dissolution in soils than most kinds of bone.

Animal life of Luca paleosols at lower stratigraphic levels can be inferred from fossils found in interbedded stream deposits and from geological dating using radiometry and sequence stratigraphy. Carl Swisher has determined a geological age of the 38.19±0.06 Ma for the ash above the type Luca clay and 39.22±0.03 Ma for the basal ash-flow tuff of the John Day Formation overlying the Clarno "Mammal Quarry". Thus the stratigraphic interval from the tuff above the type Luca clay to the base of the beds of the "Mammal Quarry" was deposited during the Duchesnean North American Land Mammal "Age", as dated elsewhere in North America (Swisher and Prothero, 1990). Thus Luca paleosols of the lower Big Basin Member of the John Day Formation probably supported a Duchesnean fauna like that of the "Mammal Quarry" (Mellett, 1969; Hanson, 1973, 1989; Schoch, 1989). This is the geologically most ancient fauna of the "White River Chronofauna" (of Clark and others, 1967), a fauna including many Asiatic immigrants that displaced archaic North American creatures (Retallack, 1985). The "Mammal Quarry" is the geologically most ancient known example of the Duchesnean faunas (Lucas, 1992) and these brown siltstones disconformably overlie a sequence of Luca paleosols. Thus Luca paleosols of the upper Clarno Formation probably supported Uintan faunas with greater similarity to the Bridgerian-Uintan fossil mammals found in the Clarno "Nut Beds" than to the Duchesnean mammals of the "Mammal Quarry" (Retallack, 1991a).

Paleotopographic setting. Luca paleosols were well drained and formed in geomorphic settings well above the water table, as can be seen from their thorough oxidation (low ferrous/ferric iron ratios) and subsurface clay enrichment. As for Lakayx paleosols, we could find little evidence of fluvial paleochannels within the sequence of Luca paleosols in the upper Clarno Formation or lower John Day Formation. There is a unit of fossiliferous lacustrine brown shale within the sequence of Luca paleosols in the lower John Day Formation. There are also several volcanic tuff beds within these shales and between Luca paleosols. The Luca clay pisolitic variant and many other Luca paleosols include common ferruginized clasts redeposited from pre-existing red soils, indicating that colluvial slope wash remained important in these soils. In general however, these are less prominent than feldspars and other indications of additions from volcanic airfall. Thus Luca paleosols formed on volcanic ash and colluvium accumulating on toeslopes of hilly country and terraces of small creek systems. Slopes were probably quite gentle during accumulation of the John Day Formation, because its basal ashflow tuff shows little local thickness change and overlying sequences of Luca paleosols included lakes. These gentle slopes of thick red soils presumably were drained by a local network of creeks unconnected to different source terrains that would have delivered lithologically distinctive materials to form recognizable paleochannels.

Parent material. Luca profiles developed on a mix of colluvially resorted soil and volcanic airfall ash, with more emphasis on the latter than generally comparable Lakayx paleosols. Because some ash beds are preserved with little weathering within sequences of Luca paleosols, their composition can be evaluated with greater accuracy than for sequences of Lakayx paleosols. Especially notable is a thick lithic tuff in the upper Clarno Formation in "Red Hill" and the basal ash flow tuff of the John Day Formation that caps "Red Hill". These appear to be rhyolitic to dacitic in composition (Walker and Robinson, 1990), unlike the andesitic ultimate source of the colluvial component of Luca paleosols.

Time for formation. Luca paleosols show comparable to greater textural differentiation of subsurface

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clayey (Bt) horizon than Lakayx paleosols. This is moderately to strongly developed in the qualitative scale of Retallack (1990a), and represents tens to perhaps hundreds of thousands of years for each profile. On terraces of the Merced River in the San Joaquin Valley of California, under mean annual precipitation of 410 mm and mean annual temperature of 16°C, Alfisols with subsurface clay accumulation comparable to Luca paleosols are found in lower Modesto and upper Riverbank geomorphic surfaces dated at between 40,000 and 130,000 years old (Harden, 1982, 1990). Similar age can be inferred by comparison with Alfisols of more humid and cool climate (943 mean annual precipitation and 9.8°C mean annual temperature) near Millport, Ohio (Lessig, 1961). Also comparable are Alfisols on phonolitic colluvium less than 40,000 years old in the cool humid climate high on the Kenyan volcano, Mt Kenya (Mahaney, 1989; Mahaney and Boyer, 1989). None of these are ideal comparisons because of differences in climate and parent material, but the consistency of estimates indicates that they are within the correct order of magnitude.

Luquem paleosols

Diagnosis. White bedded volcanic ash with root traces.

Derivation. Luquem is Sahaptin for a fire that has gone out (DeLancey and others, 1988), and refers to the volcanic ash parent material of this paleosol.

Description. The type Luquem (Fig. 3.31) silty clay loam is exposed for some 100 m in the "Fern Quarry", on the hill south of a stock pond 0.5 miles northeast of Hancock Field Station, near Clarno (SE1/4 NW1/4 SE1/4 SW1/4 Sect. 26 Clarno 7.5' Quad. UTM zone 10, 702748E 4977295N). This locality correlates to a level of 18 m in the reference section (Fig. 3.4) and is in the "conglomerates of Hancock Canyon" of the upper Clarno Formation of middle-late Eocene age or Bridgerian-Uintan North American Land Mammal "Ages". This age is supported by a fission track age of 43.0 Ma from a pumice in the Luquem paleosol in the "Fern Quarry" and of 44.3 Ma from a dacite cobble from an overlying lahar (Vance, 1988, pers. comm. 1990).

+93 cm: overlying silty tuff: pale yellow (2.5Y7/4), weathers strong brown (7.5YR5/6): clear relict bedding, with common fossil leaves of pale brown (10YR6/3) and brownish yellow (10YR6/8), arching up from paleosol below: fossil plants mainly fern (Saccoloma gardneri) with some horsetail (Equisetum clarnoi): non-calcareous: intertextic silasepic in thin section, with abundant feldspar and altered shards, and scattered ferri-organans after fossil plants: abrupt slightly wavy contact to

0 cm: A1 horizon: siltstone: pale yellow (2.5Y7/4), weathers yellow (10YR7/6): common plant fragments, including fragmented debris as well as complete rhizomes and roots of dark yellowish brown (10YR4/4): clear relict bedding: non-calcareous: intertextic silasepic in thin section, with abundant plagioclase and altered shards, and scattered ferri-organans after plant debris and ferrans along fine-grained relict laminae: clear smooth contact to

-13 cm: A2 horizon: siltstone: white (10YR8/2), weathers yellow (10YR7/8): sparse root traces and iron stain (ferrans) of yellowish brown (10YR5/8): clear relict bedding: non-calcareous: intertextic silasepic in thin section of sandy laminae grading up to shaly laminae that are insepic agglomeroplasmic some fine ferri-organans after root traces: abrupt wavy contact to

-22 cm: C horizon: siltstone: white (10YR8/2), weathers yellow (10YR7/8): sparse iron stain (ferrans) of yellowish brown (10YR5/8): non-calcareous: intertextic silasepic in thin section, with common feldspar and devitrified volcanic shards, faint relict bedding.

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Figure 3.31. Measured section, Munsell colors, soil horizons, grain size, and mineral composition of the type Luquem silty clay loam and Sayayk paleosol in the "Fern Quarry", within the middle Eocene Clarno Formation and correlated to level of 18 m in the reference section (Fig. 3.4).

Further examples. The tuff that buried the type Luquem silty clay loam paleosol shows no signs of rooting or soil formation in the reference section, which includes the Luquem silty clay paleosol at 56 m (Fig. 3.32). This other profile contains horsetails (Equisetum clarnoi) in place of growth and is strongly permineralized with silica, so crops out strongly within the central exposure of the "Nut Beds."

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Figure 3.32. Measured section, Munsell colors, soil horizons, grain size, and mineral composition of a Luquem silty clay loam and the type Sayayk silty clay loam paleosol in the "Nut Beds", which is within the middle Eocene Clarno Formation and correlated to a level of 54 m in the reference section (Fig. 3.4). Lithological key as for Fig. 3.3.

Alteration after burial. Luquem paleosols have the appearance of volcanic tuffs not much altered from their original condition. The accumulation of organic matter, clay and iron hydroxides was not sufficient for burial decomposition, gleization, illitization or reddening to have been important processes. They are however now hard rocks, rather than loose tuffs and this change can be attributed to compaction and cementation after burial. The compaction of such crystal rich silty and sandy materials is evident at some grain contacts in thin section and from small-scale concertinalike deformation of included fossil ferns and horsetails, but was not nearly so marked as the 70% compaction calculated for clayey paleosols such as Luca and Lakayx. Luquem paleosols are also cemented with silica, which clearly post dated the growth of fossil horsetails preserved as cellular permineralizations in the "Nut Beds". However, permineralization could not have been long after plant growth, or tissue structure would have decayed substantially. Thus permineralization within a silica charged hot spring is likely, rather than silicification entirely during burial. Silicification late during burial is also negated by the uncompacted form of permineralized plant remains. Nevertheless some addition of silica during burial is a likely explanation for chalcedony filling pores and vugs in these paleosols, and these soils were certainly not cemented to the hard rocks of today when they supported the growth of ferns and horsetails.

Reconstructed soil. Luquem soils were probably white volcanic crystal tuffs, with limited accumulation of litter and penetration of roots in the surface (A horizon) and much relict bedding in a little-altered subsurface (C horizon). Root traces are generally deeply penetrating, indicating good drainage. The abundance of little weathered minerals indicate potentially high fertility and alkaline to neutral pH. Fossil plant debris is well preserved and for the most part identifiable, so that these soils had not fully exploited their potential mineral reserves or built humus and clay reserves to dampen fluctuations in water availability.

Classification. Volcanic ash soils are Andisols in the U.S. soil taxonomy, and those with abundant recognizable volcanic clasts are the Vitrands (Soil Survey Staff, 1990). Given the lush growth of pteridophytes in Luquem soils, they were presumably well supplied with moisture, and thus most likely Typic Udivitrands. Similar arguments can be used to identify Luquem paleosols as Vitric Andosols in the F.A.O. (1974) classification. Such volcanic soils are not well accommodated within the Australian classification (Stace and others, 1968), but best accommodated as Alluvial Soils because of the relict bedding that is evidence of some fluvial redeposition after volcanic airfall. In the Northcote (1974) key Luquem paleosols are Um1.21.

Paleoclimate. These paleosols are too weakly developed to be regarded as reliable indicators of paleoclimate. The lush growth of fossil horsetails and large-leaved ferns in them is however an indication of a warm wet climate.

Ancient vegetation. Vegetation of Luquem paleosols is unusually well preserved in growth position within the paleosols themselves and arching up into overlying tuffaceous sediments. This extraordinary preservation can be attributed to what Seilacher and others (1985) have called obrution, or rapid burial, in these cases by volcanic airfall ash. In the "Nut Beds" the fossil plants have been preserved as cellular permineralizations, perhaps by silica-charged volcanic hot springs. The type Luquem silty clay loam paleosol supported vegetation mainly of large ferns (Saccoloma gardneri) with lesser amounts of horsetails (Equisetum clarnoi), and the Luquem paleosol in the "Nut Beds" has yielded only horsetails. These particular plants and low specific diversity of these assemblages are typical for vegetation early in the successional colonization of disturbed surfaces (Burnham and Spicer, 1986). Luquem paleosols preserve the very earliest stages in plant succession around these middle Eocene tropical volcanoes.

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Later stages in the colonization of disturbed ground are recorded in the fossil plant assemblages of Sayayk paleosols which represent pole woodlands and even later stages by Patat paleosols with their fossil stumps and leaf litters of forest.

Former animal life. No animal fossils have yet been found in Luquem paleosols. Fossil mammals are known from paleochannel deposits in the "Nut Beds" overlying the Luquem paleosol there. Although the type Luquem silty clay loam paleosol is stratigraphically 50 m lower in the sequence, it probably is not greatly different in geological age, considering the generally weak development of paleosols and other evidence for rapid accumulation of this sequence of volcanic mudflows. The known fauna includes forest-adapted archaic mammals of the Bridgerian North American Land Mammal "Age" (Retallack, 1991a).

Paleotopographic setting. Both known Luquem paleosols are in sequences of sandstones and grain- supported conglomerates that show cross bedding, ripple marks and graded bedding characteristic of fluvial depositional environments (Retallack, 1991a). They are within thick sequences of such rocks, representing deposition by high energy streams with gravel bedload during periods between influx of sequences of massive volcanic mudflows. Some of the energy of these streams may have been boosted by distal outwash of lahar, though the immediate facies surrounding Luquem paleosols do not have the character of deposits from hyperconcentrated flow (as described by Scott, 1988). The coarse-grained nature of associated paleochannels may be more related to a geomorphic position on foot slopes flanking steep volcanic stratocones. Low angle heterolithic cross-stratification including a Luquem paleosol exposed laterally for several hundred meters of the "Nut Beds" can be interpreted as a deposit of a levee of a moderately sinuous stream (Retallack, 1991a). A similar paleotopographic setting is compatible with what can be observed around the type Luquem paleosol in the "Fern Quarry", where a cross-bedded fluvial paleochannel overlies ash covering the type Luquem silty clay loam. This would imply a lowland near-stream setting within a floodway relatively barren of forest vegetation that would disrupt and disperse ash.

Parent material. The parent volcanic ash of Luquem paleosols is a relatively well preserved mix of silt-sized crystals of sanidine and partly devitrified volcanic shards. The shards are much less abundant in the surface compared with subsurface of the type Luquem silty clay loam, and both shards and crystals are locally obscured by silicification in the Luquem horsetail variant paleosols. Nevertheless these materials remain very similar to other rhyolitic to dacitic tuffs from both the upper Clarno and John Day Formations (Walker and Robinson, 1990).

Time for formation. These soils of minimal profile development are very weakly developed in the relative scale of Retallack (1990a). Their low diversity fossil plant assemblages indicate that they were buried at a very early stage in the successional recolonization of the volcanic ash beds. In a tropical climate that supported regional vegetation as lush as indicated by fossil plants in the Clarno Formation (Manchester, 1981, 1994) and the various paleosols described here, this would be a matter of only a few years. Luquem paleosols show comparable development to Chova paleosols of Guatemala, which formed on thick pumiceous ash from the October 1902 eruption of Volcan Santa Maria (Simmons and others, 1959).

Micay paleosols

Diagnosis. Brown to olive claystone with root traces and relict bedding.

Derivation. Micay is Sahaptin for plant root (Rigsby, 1965), traces of which distinguish these paleosols from sedimentary rocks.

Description. The type Micay clay (Fig. 3.28) is the upper profile in a measured section made by Pratt (1988) in the west wall of the "Mammal Quarry," 0.8 miles north of Hancock Field Station, Clarno area (SW1/4 NW1/4 NE1/4 NE1/4 SW1/4 Sect. 27 T7S R19E Clarno 7.5' Quad., UTM zone 10, 703283E 4978117N). Micay is a new name for the "Chaenactis clay paleosol" of Pratt (1988). This is 400 m north http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap3.htm[4/18/2014 12:20:46 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 3)

of the reference section of the upper Clarno Formation, but can be correlated to a level of about 126 m in that section. Associated mammal fossils in the quarry indicate that this paleosol formed during the late Eocene Duchesnean North American Land Mammal "Age" (Hanson, 1973, 1989; Lucas, 1992). It is only a few meters stratigraphically below the welded tuff of member A of the John Day Formation dated here using the single-crystal 40Ar/39Ar technique by Carl Swisher at 39.22±0.03 Ma.

+15 cm; clayey siltstone overlying paleosol; pale olive (5Y6/3), weathers light olive brown (2.5Y5/4); indistinct relict bedding; non-calcareous; porphyroskelic argillasepic in thin section; abrupt wavy contact to

0 cm; A1 horizon; silty claystone; pale yellow (5Y7/4), weathers light olive brown (2.5Y5/4); with common stout (up to 5 mm) dark gray (5YR4/1) woody root traces; medium platy peds outlined by few clay skins (sesqui-argillans) of reddish brown (5YR4/4); porphyroskelic skelinsepic in thin section, with abundant (30%) fecal pellets and common large volcanic rock fragments with pilotaxitic andesine (An35) laths; non calcareous; gradual wavy contact to

-6 cm; A2 horizon; clayey siltstone; pale yellow (5Y7/3), weathers light olive brown (2.5Y5/4); with few stout dark gray (5YR5/4) root traces; indistinct relict bedding, broken by sparse clay skins (sesqui-argillans of strong brown (7.5YR4/6) and yellowish red (5YR5/8); non-calcareous; porphyroskelic skelinsepic in thin section, with common volcanic rock fragments and rare quartz; gradual wavy contact to

-10 cm; C horizon; siltstone; pale yellow (5Y7/3), weathers light olive brown (2.5Y5/4); relict bedding; weakly calcareous; argillasepic skelinsepic in thin section with common volcanic rock fragments.

Further examples. Micay paleosols were found also in the uppermost Clarno Formation within the reference section, and are common in the overlying John Day Formation. Micay paleosols are weakly developed like Scat paleosols, which are comparable gray paleosols interbedded with lahars in the Clarno Formation. Unlike Scat paleosols however, Micay profiles are developed on silty to clayey redeposited tuffs, rather than volcaniclastic gravels.

Alteration after burial. The green-gray color of Micay paleosols may be due in part to burial gleization of organic matter that probably decomposed during burial to leave clayey to manganiferous root traces. These clayey paleosols probably also were compacted by 70% typical for paleosols in this area. There is no indication from color or mineral composition for burial reddening or illitization.

Reconstructed soil. Micay paleosols would originally have been gray clays with some surface accumulation of organic matter and root penetration of the surface (A horizon) above a massive to faintly bedded subsoil (C horizon). This subsoil was not so clearly ashy as in Luquem paleosols, and shows weathering of a mixed volcanic airfall component that has largely destroyed evidence of volcanic shards. Considering its relatively fresh feldspar crystals and fluvially redeposited andesitic rock fragments, Micay paleosols probably had relatively low bulk density, high base saturation, near neutral pH and other andic properties. Root traces, though fine are deeply penetrating, as in well drained soils. There is no mottling or mineral accumulations suggestive of waterlogging, calcification, or salinization.

Classification. In the U.S. soil taxonomy (Soil Survey Staff, 1990) such very weakly developed soils are best classified as Entisols. Micay profiles are drab colored with shallow root traces, indicating some waterlogging, so are best identified as Aquandic Fluvaquents. In the F.A.O. (1974) classification, Micay paleosols are most like Eutric Fluvisols. In the Australian classification (Stace and others, 1968), they are similar to Alluvial Soils. They can also be described as Uf1.41 in the Northcote (1974) key.

Paleoclimate. Micay paleosols are insufficiently developed to be useful indicators of paleoclimate, although the evident deep weathering of volcanic shards in them is compatible with a warm humid climate.

Ancient vegetation. The fine root traces found within Micay paleosols and their persistent relict bedding are features of soils that support vegetation early in ecological succession of disturbed ground. However, weathering of Micay paleosols is clearly in excess of that seen in Luquem paleosols and short of that seen in Scat and Pasct paleosols. The vegetation of Micay paleosols can be envisaged as open

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mid-successional pole woodlands with good herbaceous ground cover.

Micay paleosols and underlying fluvial deposits of the "Mammal Quarry" have yielded a small fossil flora of fruits and seeds (McKee, 1970; Manchester, 1994), including a variety of tropical vines (Odontocaryoidea nodulosa, Diploclisia sp. indet., Eohypserpa sp. indet., Iodes sp. indet., Palaeophytocrene sp. cf. P. foveolata, Vitis sp. indet., Tetrastigma sp.), sycamores (Platananthus synandrus), dogwoods (Mastixioidiocarpum oregonense), alangiums (Alangium sp. indet.), cashews (Pentoperculum minimus), and walnuts (Juglans clarnensis). Some of these fossils may have been derived from the Pswa paleosol at the base of the sequence exposed in the Clarno "Mammal Quarry" (Pratt, 1988). In open near-stream settings envisaged for Micay paleosols, many of these seeds could also have been derived from other nearby communities. However, living sycamore is known to be an early successional colonizer of streamsides and such a role is likely also for the extinct Clarno species (Peattie, 1950; Manchester, 1986; Retallack, 1991a).

Former animal life. Micay paleosols and closely associated fluvial deposits in the Clarno "Mammal Quarry" have yielded an array of fossil animals: alligators (Pristichampsus sp. indet.), creodont carnivores (Hemipsalodon grandis), sabre-tooth cats (Nimravinae gen. et sp. indet.), rodents (gen. et sp. indet.), anthracotheres (Heptacodon sp. indet), oreodons (Diplobunops sp. indet.), rhinoceroses (Teletaceras radinskyi and Procadurcodon sp. indet.), tapirs (Plesiocolopirus hancocki and Protapirus sp. indet.) and horses (Epihippus gracilis and Haplohippus texanus: Mellet, 1969; Hanson, 1973, 1989; Schoch, 1989). Some of these creatures, particularly the common small rhinoceros (Teletaceras radinskyi) evidently lived on Micay paleosols, because they are represented by moderately complete though disarticulated specimens. One could make similar arguments for the alligator, creodont and oreodon which are represented by complete and fragile skulls that would not withstand long-distance transport. The other taxa could have come from further afield, considering Pratt's (1988) conclusion that they accumulated on a fluvial point bar as isolated elements or groups of bones still united by flesh.

Paleotopographic setting. Pratt (1988) has shown that Micay paleosols of the Clarno "Mammal Quarry" formed on siltstones capping an overall fining-upwards sequence from a basal conglomerate. This thin (10-35 cm) basal clast-supported conglomerate of porphyritic andesite pebbles (0.8-9 cm diamter) and well rounded fossil bone and wood, is similar to the channel lag of a mountain stream. It is overlain by 10-45 cm of massive silty sand with up-section decrease in pebbles and increase in bedding. This and the overlying bedded silty sands with carbonaceous stringers yielded most of the fossil bone and plants. Fossils persist, but are less common in an overlying sequence of Micay and Lakim paleosols. The orientation of fossil long bones in Micay paleosols and underlying fluvial deposits swings progressively up section from east-west to north-south. This can be explained by migration and accumulation of a point bar of a meandering stream that filled a local valley into pre-existing volcanic rocks. Micay soils would have formed the better drained vegetated surfaces of the point bar, only slightly elevated from Lakim soils of local swales.

Parent material. Micay paleosols formed on silt and sand derived from the erosion of an extinct volcanic center to the east as well as from volcanic ash fall. They contain abundant fresh laths of feldspar but only rare volcanic shards, and there is a bed 20 cm thick of white little-weathered rhyodacitic tuff high in the sequence exposed within the "Mammal Quarry". Compared with the tuffaceous component, grains of porphyritic andesite are less common, and few of them have ferruginized weathering rinds. Although both components were probably mixed and redeposited by river action, the rhyodacitic tuffaceous component dominated the andesitic alluvial component.

Time for formation. Micay paleosols are weakly developed in the qualitative scale of Retallack (1990), lacking clear relict bedding as well as diagnostic horizons of soils more differentiated than Inceptisols of the U.S. soil taxonomy (Soil Survey Staff, 1990). Volcanic soils in humid tropical New Guinea form fine crumb structure and discernible pedogenic clay within 300-2000 years (Bleeker and Parfitt, 1974; Bleeker, 1983) and have completely lost volcanic glass by 8,000 to 27,000 years (Ruxton, 1968). These are upper limits on the time for formation of Micay which have relict shards and little pedogenic clay.

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On the other hand, Micay paleosols represent more than just a few growing seasons as for Luquem paleosols. Micay profiles probably formed over a few hundred years.

Pasct paleosols

Diagnosis. Olive-gray to orange, thick, slickensided, subsurface, clayey (Bt) horizon.

Derivation. Pasct is Sahaptin for "cloud" (Rigsby, 1965), and refers to the gray subsurface horizon of these paleosols.

Description. The type Pasct clay paleosol (Fig. 3.33) is high in the reference section (128 m) immediately below the basal ash-flow tuff (member A) of the John Day Formation in the northern corner of "Red Hill", Hancock Field Station, near Clarno (SW1/4 NW1/4 NW1/4 SE1/4 Sect. 27 T7S R19E Clarno 7.5' Quad. UTM zone 10, 702783E 497753N). The brown clays including it can be correlated with similar deposits in the nearby "Mammal Quarry", which has yielded fossils of the late Eocene, Duchesnean North American Land Mammal "Age" (Hanson, 1973, 1989; Lucas, 1992). This paleosol is immediately below the welded tuff using the single-crystal 40Ar/39Ar technique by Carl Swisher at 39.22±0.03 Ma.

+930 cm: granule tuff: pale yellow (2.5Y7/4), weathers brown (10YR5/3); with common small (2 mm) bipyramidal quartz crystals and rock fragments of brownish yellow (10YR6/6) and red (10YR4/6): weakly calcareous: agglomeroplasmic argillasepic in thin section, with sand-size grains of volcanic quartz and feldspar, each with a thick oxidation rind (diffusion sesquan): abrupt smooth contact to

0 cm: A1 horizon: silty claystone: dark brown (7.5YR3/2), weathers brown (10YR5/3): common carbonaceous plant debris very dark brown (7.5YR3/1), including root traces and twigs up to 3 cm wide: non-calcareous: fine granular peds, with dark clay skins (organans) in places: porphyroskelic mosepic in thin section, with root traces lined with carbonaceous and ferruginous clay: gradual irregular contact to

-2 cm: A2 horizon: silty claystone: light gray (5Y6/1), weathers brown (10YR5/3): common carbonaceous root traces of dark brown (7.5YR3/2): medium granular peds, defined by clay skins of brownish yellow (10YR6/6): few krotovinas up to 20 cm diameter filled with sandy ash from above: non-calcareous: porphyroskelic mosepic in thin section, with common clay skins (ferri-argillans) defining granular peds and clasts mainly of feldspar: gradual irregular to

-18 cm: Bt horizon: claystone: dark gray (5Y4/1), weathers brown (10YR5/3); common carbonaceous root traces of dark brown (7.5YR3/2) and sesquioxide mottles of brownish yellow (10YR6/6): coarse blocky angular peds, defined by slickensided clay skins of dark gray (5Y4/1) or brownish yellow (10YR6/6): non-calcareous: porphyroskelic clinobimasepic in thin section, with scattered feldspar and deeply weathered porphyritic volcanic rock fragments: gradual irregular contact to

-72 cm: C horizon: silty claystone: dark gray (5Y4/1), weathers brown (10YR4/3): common clay skins of light yellowish brown (10YR6/4): non-calcareous: porphyroskelic clinobimasepic in thin section, with common feldspar and volcanic rock fragments.

Figure 3.33. Measured section, Munsell colors, soil horizons, grain size, mineral

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composition and selected molecular weathering ratios of the type Pasct clay paleosol in upper "Red Hill", which is within the late Eocene Clarno Formation and at a level of 128 m in the reference section (Fig. 3.4). Lithological key as for Fig. 3.3. (click on image for an enlargement in a new window)

Further examples. There is another Pasct paleosol in the claystones of the "Mammal Quarry" immediately below the type Pasct clay paleosol, but none within the underlying red beds of the upper Clarno Formation. Pasct paleosols also are found at various levels of the "Nut Beds" and in the "conglomerates of Hancock Canyon" within the reference section, and these range from middle to late Eocene or Bridgerian-Uintan North American Land Mammal "Age." For example the Pasct clay brown variant is within the reference section in the sequence of lahars underlying the "Nut Beds" (Fig. 3.34).

Figure 3.34. Measured section, Munsell colors, soil horizons, grain size, mineral composition and selected molecular weathering ratios of the Pasct clay brown variant paleosol in the conglomerates underlying the "Nut Beds", of the middle Eocene Clarno Formation at a level of 18 m in the reference section (Fig. 3.4). Lithological key as for Fig. 3.3.

Alteration after burial. Pasct paleosols present a conundrum of clay illuviation, base loss and low ferrous/ferric ratios of a well drained soil but have dark gray color of a gleyed soil. The color of the profile may be in part a product of burial gleization and decomposition of soil organic matter. Some Pasct profiles have orange-stained slickensided clay skins, but these do not persist into the outcrop with further excavation. Their orange to yellow hue is indicative of goethite or other iron hydroxides from weathering in the modern outcrop. There are few dark red mottles or other color that would indicate burial reddening. These clayey profiles probably suffered at least 70% compaction calculated from the formula of Sclater and Christie (1980). No mineral or chemical evidence of recrystallization or illitization was seen.

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Reconstructed soil. Pasct paleosols were probably clayey soils with dark gray loamy surface (A) horizons over brownish gray subsurface (Bt) horizons, with substantial accumulations of pedogenic clay (alumina/bases ratios). They were moderately well drained as indicated by dominance of oxidized iron (ferrous/ferric iron ratios), and yet not strongly leached except near the surface (Ba/Sr ratios). Nevertheless, some reduced iron near the surface may indicate slow drainage of these clayey soils. The dark clay skins seen in thin section indicate illuviation of humus as well as clay, as in seasonally waterlogged soils. These paleosols have been significantly leached of nutrients (alumina to base ratios are moderate), and were probably acidic to neutral in pH. Abundant feldspar crystals indicate a tuffaceous parentage, but the lack of preserved shards is evidence against andic properties. Ratios of both soda/potash and alkaline earths/alumina show simple leaching depth-functions, and no evidence of salinization or calcification.

Classification. The type Pasct paleosol shows subsurface differentiation of alumina and clay sufficient to qualify as the argillic horizon of the U.S. soil taxonomy (Soil Survey Staff, 1990). Alumina/bases ratios of 1.5-2.4 straddle the Alfisol-Ultisols dividing line, but the abundance of feldspar is more like Alfisols. Pasct paleosols with their tuffaceous parent materials and gray color are best regarded as Aquandic Umbraqualfs. In the F.A.O. (1974) classification they are matched best by Gleyic Luvisols. In the Australian classification (Stace and others, 1968) Pasct paleosols are most like Humus Podzols. In the Northcote (1974) key they are Gn3.94.

Paleoclimate. The leaching of alkalis and alkaline earths and total destruction of volcanic shards leaving only feldspars of pyrogenic origin are compatible with a humid climate, in excess of a mean annual precipitation of 800 mm (Retallack, 1994a). Extremely rainy climates are unlikely considering moderate leaching and hydrolysis indicated by low barium/strontium ratios and moderate alumina/bases ratios.

Banded dark clay skins evident in thin section provide evidence for climatic seasonality. If there was a dry season it was not especially marked, and probably much less than 3 months in duration, because Pasct paleosols lack the system of cracking and veining found in Vertisols.

The strong bioturbation of these paleosols, despite moderate textural differentiation and chemical depth functions, is compatible with a productive tropical to subtropical ecosystem. The somber color of Pasct paleosols may be due to preservation of organic matter, considering ferrous/ferric iron ratios that are too low for permanently waterlogged soils. Pasct paleosols were probably much richer in organic matter than for Acas paleosols, which share this feature of drab color without associated evidence of waterlogging. In tropical regions such well drained organic soils are found in the cooler climatic belts of mountain plateaus.

Ancient vegetation. Carbonaceous debris and root traces in the type Pasct clay are evidence of forest vegetation. The degree of chemical weathering and textural differentiation of the paleosol is compatible with old-growth forest. The somber color and humus-clay skins of Pasct profiles indicate a lush and productive forest with thick well decomposed litter and probably also a good ground cover of the sort found in cool moist areas under abundant herbaceous angiosperms or ferns.

No recognizable plant fossils were found in Pasct paleosols. A small assemblage of fossil fruits and seeds of tropical vines and mesophytic trees was found in and associated with Micay paleosols of the late Eocene Clarno "Mammal Quarry", along strike from the type Pasct clay (McKee, 1970; Manchester, 1994). Among these fossils the tropical moonseed vines (Diploclisia sp. indet.) and black walnuts (Juglans clarnensis) have living relatives that do well on humic fertile soils like Pasct paleosols (Peattie, 1950; Manchester, 1987). These taxa also are common in the "Nut Beds" (Manchester, 1981, 1994), and may have colonized Pasct paleosols within the middle Eocene conglomeratic sequence of the Clarno Formation. Interestingly, Pasct paleosols of the "Nut Beds" and "Mammal Quarry" do not appear greatly different, despite indications of paleoclimatic change from middle to late Eocene time in Lakayx compared with Luca paleosols. Pasct paleosols may have supported vegetation of local cool moist sites

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that were found at high elevation around the footslopes of volcanoes during middle Eocene time, but at lower elevation as the volcanic edifice was eroded during the cooler and drier climates of the late Eocene. Such middle Eocene montane origins of much of the latest Eocene and Oligocene flora of North America has been postulated on floristic grounds by Wolfe (1987).

Former animal life. No animal fossils were found in Pasct paleosols, nor would any be expected in such non-calcareous paleosols (Retallack, 1984a). Nevertheless Pasct paleosols represent the lushest forest ecosystems at both the stratigraphic level of the Clarno "Mammal Quarry" and the "Nut Beds" where fluvial deposits and associated weakly developed paleosols (Micay and Sayayk) have yielded a variety of forest-adapted mammals. In the middle Eocene "Nut Beds", forest-adapted forms include small four-toed horses (Orohippus major) and tapirs (Hyrachyus eximius: Retallack, 1991a). In the late Eocene "Mammal Quarry", forest-adapted forms include agriochoere oreodon (Diplobunops sp. indet.), tapir (Plesiocolopirus radinskyi) and four-toed horse (Haplohippus texanus). This is not to say that such creatures definitely lived on Pasct paleosols, but merely that Pasct paleosols represent forest ecosystems for which they appear well suited by virtue of their relatively small size, non-cursorial limb structure and low-crowned molars.

Paleotopographic setting. Pasct paleosols probably occupied geomorphic positions above water table, as indicated by their textural and chemical differentiation and overall lack of unoxidized iron. On the other hand, the drab color and inferred high content of humus together with ferrous iron near the surface as evidence of local puddling or slow drainage are indications of flat imperfectly-drained surfaces, such as fluvial terraces. Such an interpretation is in accord with the likely parent material of Pasct paleosols and the occurrence of Pasct paleosols at similar stratigraphic levels with paleochannel grain-supported conglomerates both in the "Nut Beds" and "Mammal Quarry". Two Pasct profiles in the southern outcrop of "Nut Beds" are sandwiched between paleochannel conglomerates. Within the conglomeratic sequence below the "Nut Beds" Pasct paleosols are found in clayey and tuffaceous intervals, whereas the thick volcanic mudflows are associated with Patat and Scat paleosols. No Pasct paleosols were found in the Clarno "Mammal Quarry", which was evidently a channelway with both paleochannel conglomerates and point bar deposits (Pratt, 1988). At this stratigraphic level two Pasct paleosols were found 400 m to the south in the uppermost part of the reference section through "Red Hill". Compared with paleochannel conglomerates along strike, Pasct paleosols have fine grained lower horizons, indicating deposition from gentle currents and from suspension by largely ponded floodwaters, rather than the raging torrents of river channelways.

Parent material. Pasct paleosols contain a mix of feldspars probably derived from volcanic ash fall and andesitic rock fragments derived from fluvial deposition of eroded volcanic rocks. Their lower horizons also contain a large proportion of clay and show clear relict bedding as evidence of deposition of these materials by flood waters. Because point counted amounts of feldspar dominate those of volcanic rock fragments, the composition of this alluvium was probably more like rhyodacitic airfall than andesitic volcanics.

Time for formation. Pasct paleosols are moderately developed in the qualitative scale of Retallack (1990a), a degree of differentiation that usually corresponds to tens of thousands of years. Such time spans are indicated by comparison with generally similar floodplain soils (Walker and Butler, 1983; Birkeland, 1990), as outlined for Acas paleosols. Another indication of age is the lack of volcanic shards in Pasct paleosols despite their abundant feldspars of tuffaceous airfall origin. In cool humid volcanic highlands of New Guinea the complete destruction of volcanic shards by weathering takes about 8,000 to 27,000 years (Ruxton, 1968).

Patat paleosols

Diagnosis. Sandstone with root traces, thick, mildly leached and ferruginized.

Derivation. Patat is Sahaptin for "tree" (Rigsby, 1965), the permineralized stumps of which have been

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found rooted in several of these paleosols.

Description. The type Patat clay paleosol (Fig. 3.35) is the paleosol in which the "Hancock Tree" is rooted, but 10 m north of that landmark permineralized trunk, in Hancock Canyon, 0.8 miles north east of Hancock Field Station, near Clarno (SW1/4 NE1/4 SW1/4 NW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad. UTM zone 10, 704022E 4978153N). This paleosol and the overlying Sayayk paleosol was overwhelmed by a thick (10 m) lahar and this sequence can be correlated to a level of 30 m in the reference section, within the "conglomerates of Hancock Canyon" of the upper Clarno Formation of middle to late Eocene age or Bridgerian-Uintan North American Land Mammal "Age."

+6 cm: siltstone overlying paleosol: pale yellow (2.5Y7/4), weathers yellow (10YR7/6): common folded leaf impressions of yellowish brown (10YR5/6), mainly sycamore (Macginitea angustiloba) and katsura (Joffrea speirsii): scattered twigs up to 2 cm across of dark brown (10YR3/3): also large stump 39 cm in diameter and 60 cm high: weakly calcareous: agglomeroplasmic insepic in thin section, with common feldspar laths: abrupt smooth contact to

0 cm: A1 horizon: clayey siltstone: light gray (2.5Y7/2), weathers dark brown (10YR3/3): common root traces of yellowish brown (10YR5/6): abundant iron-stained joints (diffusion ferrans) of yellowish brown (10YR5/6) and light olive brown (2.5Y5/4): uppermost surface shows impressions of leaves like those in overlying sediment: non-calcareous: agglomeroplasmic insepic in thin section, with common volcanic clasts, both fresh and deeply weathered with ferruginized rinds (diffusion sesquans): gradual smooth contact to

-10 cm: A2 horizon: siltstone: yellow (2.5Y7/6), weathers dark brown (10YR3/3): common root traces up to 11 mm wide of yellowish brown (10YR5/6): coarse angular blocky peds defined by ferruginized joints (diffusion ferrans) of dark yellowish brown (10YR4/4) and brownish yellow (10YR6/8): non-calcareous: intertextic skelmosepic in thin section, with common feldspar and volcanic rock fragments: clear smooth contact to

-21 cm: Bw horizon: medium-grained sandstone: light yellowish brown (2.5Y6/4), weathers yellowish brown (10YR5/2) and dark brown (10YR6/4): common root traces of yellowish brown (10YR5/6): scattered volcanic rock fragments up to 3 mm diameter of light olive brown (2.5Y5/4): very coarse blocky peds defined by ferruginized joints (diffusion ferrans) of dark yellowish brown (10YR4/4) and yellowish brown (10YR5/4): non-calcareous: intertextic insepic in thin section with abundant volcanic rock fragments, commonly surrounded with irregular skins of iron-manganese: gradual smooth contact to

-35 cm: BC horizon: coarse-grained sandstone: pale yellow (2.5Y7/4), weathers very pale brown (10YR7/4): weak relict bedding: scattered volcanic rock fragments up to 5 mm in diameter of light yellowish brown (2.5Y6/4): some iron-manganese skins (mangans) of very dark grayish brown (10YR3/2): weakly calcareous: intertextic insepic in thin section, with abundant volcanic rock fragments showing weathering rinds (diffusion sesquans): abrupt wavy contact to

-51 cm: C horizon: granule conglomerate: light yellowish brown (2.5Y6/4), weathers very pale brown (10YR7/3): common volcanic rock fragments of grayish brown (2.5Y5/2) and iron manganese skins of very dark gray (10YR3/1): reverse graded bedding near the base and normally graded bedding near the top enclose an interval of bedding defined by pebble trains: weakly calcareous: intertextic skelmosepic in thin section, with abundant porphyritic andesite volcanic rock fragments, commonly with weathering rinds (diffusion sesquans).

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Figure 3.35. Measured section, Munsell colors, soil horizons, grain size, mineral composition and selected molecular weathering ratios of the type Patat clay paleosol near the "Hancock Tree", which is within the middle Eocene Clarno Formation and correlated to a level of 30 m in the reference section (Fig. 3.4). Lithological key as for Fig. 3.3. (click on image for an enlargement in a new window)

Further examples. Patat paleosols show weak development beyond that found in the more common Sayayk sandy paleosols. Patat paleosols were found only within the "conglomerates of Hancock Canyon" along with Sayayk paleosols.

Alteration after burial. Despite the permineralized stumps in overlying lahars, common leaf impressions in A horizons and woody root traces throughout these profiles, carbonaceous material was not seen in the Patat, and presumably decayed during burial, and perhaps also during oxidation in modern outcrop. This may have been accompanied by burial gleization, because both these and Sayayk paleosols have a distinctive green hue in thicker outcrops of Clarno conglomerates along the John Day River to the south of Hancock Field Station. On the Field Station however, Patat paleosols are yellow to orange in color with ferric hydroxides that may be the result of oxidation in the modern outcrop. Patat paleosols do not have the red hues that result from burial reddening of ferric hydroxides. Compaction of these sandy paleosols was probably minimal, judging from the little deformed fossil stumps and root traces in some of them. However they have been lithified by cementation with silica. The uppermost horizon of the type Patat clay is strongly silicified as are the permineralized trunks rooted within it. Some of this silicification may be related to warm alkaline water associated with emplacement of the overlying 11 m volcanic mudflow. The silicified upper portion of type Patat clay is extensively fractured, with the fractures oxidized with orange to brown ferric hydroxides more likely to have been produced by weathering in outcrop than by Eocene weathering and burial dehydration. This part of the profile has evidently suffered local brittle deformation during unroofing and exposure.

Reconstructed soil. Patat soils probably had sandy surface (A) horizons over subsurface (Bw) horizons only weakly oxidized weathered to clay and with much relict bedding preserved. Weathering had leached alkaline earths from the upper part of the profile (low alkaline earth/alumina ratios), but there is a weak reaction with acid in the lower part. Its pH was probably weakly acidic to neutral. Patat soils were rich in nutrient bases, as is evident from common feldspar and volcanic rock fragments and low alumina/bases ratio. They were also well drained judging from their deeply penetrating root traces, scarce reduced iron and overall profile differentiation. There is no evidence from soda/potash ratios or alkaline earths/alumina for either salinization or calcification.

Classification. Patat paleosols lack clear profile differentiation of soil orders other than Inceptisols and

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Entisols (of Soil Survey Staff, 1990), but are more weathered than Entisols such as associated Sayayk paleosols and lack feldspar laths and shards of primary volcanic ash falls like Micay paleosols. Tropepts and Ochrepts are the most likely suborders for Patat paleosols, and are usually difficult to distinguish because they are distinguished on the basis of isomesic versus seasonal temperature regime respectively. Fortunately Patat paleosols include permineralized stumps with clear growth rings and identifiable as plants of temperate climatic affinities, such as katsura (Joffrea speirsii) and sycamore (Macginitea angustiloba: Manchester, 1986). In the absence of evidence for deep weathering, fragipans, frost heave structures or aridland caliche, Patat paleosols are best identified as Psammentic Eutrochrepts. In the F.A.O. (1974) classification these are Eutric Cambisols. In the Australian classification (Stace and others, 1968) Patat paleosols are most like Brown Earth soils, although such soils of Australia like the Patat paleosol are more weakly developed than the original European concept of Braunerde. In the Northcote (1974) key Patat paleosols, are best described by Um5.51.

Paleoclimate. Patat paleosols are too weakly developed to be good indicators of paleoclimate. Nevertheless, a humid climate is indicated by the degree of weathering of bases and barium, which is modest but impressive for profiles with such clear relict bedding. Similarly the size of the fossil stumps (up to 39 cm diameter) indicates a substantial forest for such weakly developed soils, and such productivity is found in warm climates. Productivity is even more impressive in view of the evidence from marked growth rings preserved in the stumps for seasonal interruption of growth. This is unlikely to have been a response to a dry season for several reasons. The growth rings are more clearly marked than the nearby ring porous condition of some fossil woods from the Clarno "Nut Beds" (Manchester, 1979, 1994), and the fossil woods of Patat paleosols are similar to temperate climate trees such as katsura (Joffrea spiersii) and sycamore (Macginitea angustiloba: Manchester, 1986). No carbonate or cracking is apparent from the paleosols, which have leaf litters better preserved and are much less oxidized and reddened than would be expected for forests subject to a dry season. The growth rings therefore reflect a cool season of leaf fall among these deciduous forests.

Ancient vegetation. Patat paleosols show much relict bedding and only weak weathering of subsurface (Bw) horizons, as in soils supporting vegetation early in the successional colonization of disturbed ground. It is therefore surprising to find common large permineralized stumps rooted in Patat paleosols. A large stump near type Patat clay is 39 cm in diameter and 60 cm high. The "Hancock Tree" also is rooted in this paleosol to the south. It is 39 cm in diameter and shows a 279 cm length of exposed trunk above a concealed basal portion of 115 cm to the base of the lahar and 28 cm to the top of the Patat paleosol: a total preserved length of 322 cm. Other prone fossil logs within the lahar had diameters of 32, 9, 7, 6, 6, and 3 cm. These were thus colonizing forests, intermediate between secondary regrowth and old-growth forest.

Fossil leaf litters have also have been recovered from Patat paleosols both to the east near the "Hancock Tree" and to the west below the "Nut Beds", where they have a few more tropical elements. Near the "Hancock Tree" (L750, L1731, L1733, L1754) Patat leaf litters consist mainly of temperate elements such as sycamore (Macginitea angustiloba), katsura (Joffrea speirsii), and alder (Alnus clarnoensis), with few tropical elements such as laurel (Cinnamomophyllum sp. cf. "Cryptocarya" eocenica). In contrast, Patat leaf litters in the conglomerates below the "Nut Beds" to the east (L1756) yielded mainly tropical elements such as aguacatilla (Meliosma sp. cf. M simplicifolia) and magnolia (Magnolia sp. cf. M leei), with less common temperate elements walnut (Juglans sp. indet.) and sycamore (Macginitea angustiloba). The climatic significance of these taxa is limited because both sycamore and alder can also be considered pioneering trees that tend to dominate early in ecological succession (Burger, 1983; Peattie, 1950; Manchester, 1986). Nevertheless, these leaf litters may represent an ecotone between two distinct kinds of ancient forest. Vegetation comparable to the eastern Patat Macginitea-dominated fossil leaf litters is deciduous tropical forests dominated by Liquidambar macrophylla found at elevations of 1000-2000 m in tropical Mexico (Gomez-Pompa, 1973). Meliosma- dominated assemblages of eastern Patat paleosols would have been comparable to pioneering forests of lowland evergreen rain forest of Mexico ("selva" of Lauraceae of Gomez-Pompa, 1973). Such a reconstruction of deciduous forest on volcanic footslopes to the west and semi-evergreen forest on volcanic toeslopes to the west is

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compatible with a reconstructed Clarno paleogeography of an andesitic stratocone source for lahars to the east of the study area (White and Robinson, 1992).

Former animal life. No fossil animals have been found in Patat paleosols and none would be expected in such non-calcareous paleosols (Retallack, 1984a). A small mammalian fauna found in the "Nut Beds" is stratigraphically 35 m higher than the type Patat clay, but this probably represents not more than a few tens of thousands of years considering the thick intervening mudflow deposits and weakly developed paleosols. The Bridgerian-Uintan assemblage of forest-adapted animals known from the "Nut Beds" (Retallack, 1991a) probably lived during the time Patat paleosols were formed, but whether they ranged into these cooler upland deciduous forests is unknown, and unlikely in the case of the large tortoises (Hadrianus sp. indet.).

Paleotopographic setting. The type Patat clay was evidently well drained considering the reach of its woody root traces and lack of ferrous iron. The preserved tree trunks also lack buttresses, knee roots or air roots found in tropical plants of waterlogged ground (Jenik, 1978). There is also evidence for upland habitats from the temperate deciduous nature of its leaf litters dominated by sycamore and katsura, which would have been restricted to higher elevations in a landscape with tropical rain forest of the type preserved in the "Nut Beds".

A variety of grain-supported conglomerates, sandstones with parting lineation, graded beds, and ripple marked siltstones are preserved in an around Patat paleosols and are evidence of a nearstream fluvial environment dominated by traction flow. These largely sandy deposits are interbedded with thick (up to 11 m) mudflows with scattered large boulders of porphyritic andesite, typical for volcanic lahars (White and Robinson, 1992). The bed overlying the type Patat paleosol and the bed forming its Bw horizon are massive clayey sands with scattered pebbles and may be deposits from the hyperconcentrated runout waters of volcanic mudflows, like those described from Mt St Helens by Scott (1988). Their environment can be envisaged as the fluvial braidplain on the toeslopes of a large andesitic stratovolcano with gullies coursed by mudflows. In this kind of environment periodic high flow from especially destructive mudflows and outwash create lowland flood terraces, that are colonized by vegetation to create soils like Patat paleosols during periods of lower discharge.

Parent material. The parent material of Patat paleosols is clayey sand of andesitic composition. Despite evidence of deposition from streams and from distal flow triggered by lahars that drained a forested stratovolcano, the volcanic clasts in lower horizons of these paleosols are little weathered. Although probably derived from soils high on the volcanic edifice, these source soils were also little modified from their parent material, as is usual for soils within cool climate zones of large composite volcanoes, even in tropical regions (Simmons and others, 1959; Mahaney, 1989; Mahaney and Spence, 1989).

Time for formation. Patat paleosols are weakly developed in the qualitative scale of Retallack (1990a), with clear evidence of relict bedding little disrupted by plant growth and mineral weathering. Soils developed on the cool humid volcanoes of New Guinea have considerably more clay skins and ped development than seen in Patat paleosols over only 300 to 2000 radiocarbon years (Bleeker and Parfitt, 1974; Bleeker, 1983). A few hundred years is a likely upper limit for time of formation of Patat soils, and is compatible with information from the annual growth rings of their fossil stumps. A large stump near the type profile is 39 cm in diameter and included 32 annual rings toward the rather deformed center. The "Hancock Tree" also is rooted in this paleosol and shows 59 rings as well as another 12 mm too deformed to count within its 39 cm diameter. To this figure should be added several years or tens of years for development of early successional vegetation comparable to that preserved in Luquem and Sayayk paleosols. Thus it is likely that the preserved fossil trunks represent the first tree crop in these paleosols over the first century or so of plant colonization of these disturbed volcanic land surfaces.

Pswa paleosols

Diagnosis. Purple clayey subsurface (Bt), with corestones and gradational contact down to andesitic

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breccia.

Derivation. Pswa is Sahaptin for "stone" or "clay" (Rigsby, 1965; Delancey and others, 1988), which form a mixture in these colluvial soils.

Description. The type Pswa clay (Fig. 3.36) paleosol is not exposed, but can be revealed by trenching above the track that links Hancock Field Station and the "Mammal Quarry," below "Black Spur" at a point 0.5 miles north of Hancock Field Station, near Clarno (NW1/4 SW1/4 NW1/4 SW1/4 SE1/4 Sect. 27 T7S R19E Clarno 7.5" Quad. UTM zone 10, 703112E 4977736N). The type profile is developed on a talus of large boulders of porphyritic dacite, and is overlain by boulder breccia of dacite with an additional Pswa paleosol. The dacitic parent material may also have yielded the dacite cobble in the lahar above the "Fern Quarry" dated by fission track at 43.6 Ma (Vance, 1988; pers. comm., 1990). This is at a stratigraphic horizon 25 m below the columnar basalt that forms the ridge of "Black Spur", and thus correlates to a level of about 16 m in the reference section. It is within the "conglomerates of Hancock Canyon" of the upper Clarno Formation, and of middle to late Eocene age, or Bridgerian- Uintan North American Land Mammal "Age".

+90 cm: boulder breccia overlying paleosol: light gray (5Y7/1), weathers grayish brown (2.5Y5/2): has angular boulders of porphyritic andesite up to 50 cm across of pale yellow (2.5Y8/4) and olive (5Y5/2) with slickensided weathering rinds (diffusion sesquans) up to 1 cm thick of brownish yellow (10YR6/8): non calcareous: intertextic mosepic in thin section, with deeply weathered clasts of dacite including phenocrysts altered to clay and partly altered pilotaxitic groundmass: abrupt irregular contact to

0 cm: A horizon: silty claystone: light brownish gray (2.5Y6/2), weathers grayish brown (2.5Y5/2): with sparse drab-haloed root traces up to 1 cm diameter of greenish gray (5G6/1): common distinct coarse mottles of dark reddish gray (10R4/1): few irregular ferruginous nodules of brownish yellow (10YR6/8): coarse angular blocky peds defined by slickensided clay skins (illuviation argillans) of brownish yellow (10YR6/8): non-calcareous: porphyroskelic skelmosepic in thin section, with abundant fine root traces and weathered volcanic rock fragments: gradual irregular contact to

-19 cm: Bt horizon: claystone: dark reddish gray (10R3/1), weathers grayish brown (2.5Y5/2): common large (up to 30 cm) deeply weathered boulders of porphyritic dacite of olive yellow (2.5Y6/6): coarse angular blocky peds defined by slickensided clay skins (illuviation argillans) of brownish yellow (10YR6/8): non-calcareous: porphyroskelic clinobimasepic in thin section, common deeply weathered volcanic rock fragments with clay skins (diffusion argillans): gradual irregular contact to

-120 cm: BC horizon: boulder breccia: gray (5Y6/1), weathers grayish brown (2.5Y5/2): common large (up to 70 cm) deeply weathered boulders of porphyritic dacite of olive (5Y5/4) with weathering rinds (diffusion sesquans) of brownish yellow (10YR6/8): non-calcareous: porphryoskelic skelmosepic in thin section, abundant volcanic rock fragments with clay skins (diffusion argillans): gradual irregular contact to

-150 cm: C horizon: boulder breccia: light gray (5Y7/1), weathers grayish brown (2.5Y5/2): common large (up to 90 cm) deeply weathered boulders of porphyritic dacite of olive (5Y5/4) with weathering rinds (diffusion sesquans) of brownish yellow base (10YR6/8): non-calcareous: porphryoskelic skelmosepic in thin section, abundant volcanic rock fragments with clay skins (diffusion argillans): gradual irregular contact to

-170 cm: R horizon: porphyritic dacite: greenish gray (5Y5/1), weathers grayish brown (2.5Y5/2): non-calcareous: intertextic crystic in thin section, with relict pilotaxitic groundmass and large zoned phenocrysts of plagioclase and hornblende all altered in part to clay and opaque oxides.

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Figure 3.36. Measured section, Munsell colors, soil horizons, grain size, mineral composition and selected molecular weathering ratios of the type Pswa clay paleosol below "Black Spur", which is within the middle Eocene Clarno Formation and correlated to a level of 16 m in the reference section (Fig. 3.4). Lithological key as for Fig. 3.3. (click on image for an enlargement in a new window)

Further examples. The type Pswa paleosol is buried by boulder breccia that includes another Pswa paleosol. These are the only profiles of this kind seen during this study, although one would expect similar profiles to be common on other porphyritic dacite or andesite flows of the Clarno Formation, given the long time of formation necessary for this pedotype.

Alteration after burial. Pswa paleosols are purple-red, mottled and low in organic matter and so probably discolored substantially by burial decomposition and gleization of organic matter and burial reddening of ferric hydroxides. Also likely is compaction of clayey parts of the profile to 70% of their former thickness calculated from the equation of Sclater and Christie (1980). The boulders of weathered dacite on the other hand show little evidence of deformation by compaction of their relict crystal structure, and in some cases the clayey horizon boundaries have been disrupted by slickensided boulders. There is little indication of illitization from soda/potash ratios which have remained very similar to those of the parent andesite.

Reconstructed soil. The original Pswa soil can be envisaged as a thick (1m) soil with a dark gray clayey surface (A) horizon over a bouldery reddish brown clayey subsurface (Bt) horizon. Although there are numerous relict andesitic boulders the matrix of the subsurface horizon is markedly enriched in both clay skins and total clay. Low ratios of barium/strontium and alumina/bases and persistent volcanogenic minerals indicate weakly acidic to neutral pH and moderate fertility. The type profile has some reduced iron remaining in its clayey subsurface horizon as evidence for impeded drainage, and this is compatible with the gray to purple hue. The thickness of the profiles, thoroughness of their weathering and deep penetration of root traces are evidence of well drained conditions. Soda/potash ratios are high throughout these profiles as in their andesitic parent materials, but there is no up-profile increase as would be expected in a salinized soil. Neither is there any sign of calcification from ratios of alkaline earths/alumina.

Classification. Pswa paleosols show clay enrichment of the subsurface horizon sufficient for argillic horizons found in Alfisols and Ultisols of the U.S. soil taxonomy (Soil Survey Staff, 1990). There alumina/bases ratios of 1-2 and barium/strontium ratios of generally less than 1 are evidence of only

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modest hydrolysis and leaching, as found in Alfisols rather than Ultisols. Pswa paleosols are most like Lithic Hapludalfs, largely because they lack the red color, iron content, fragipans, deep cracks or other features of other divisions. In the F.A.O. (1974) classification this corresponds to an Orthic Luvisol. In the Australian classification (Stace and others, 1968) Pswa paleosols are like Brown Podzolic soils and in the Northcote (1974) key they are most like Gn2.01.

Paleoclimate. A humid climate is indicated by the way in which Pswa paleosols have been leached of alkalis, alkaline earths and barium compared with their andesitic parent material. At no level on the profiles was there accumulation of carbonate or salts as found in soils formed under mean annual rain fall of less than 1000 mm (Birkeland, 1984; Retallack, 1994a).

The pervasiveness and deep alteration of Pswa paleosols is impressive considering the relict crystal structure of andesitic corestone and only moderate chemical weathering revealed by alumina/bases and barium/strontium ratios. These indications of deep weathering are compatible with a warm climate, but not compelling evidence (Birkeland, 1984; Retallack, 1990a).

No clear cracking patterns or concretions were found that would indicate strong climatic seasonality. However, the reduction spots and ferrous iron low in the Bt horizon of the type Pswa clay may be evidence of slow drainage at that level during a wet season. This was probably not a place of permanent seepage because Pswa paleosols lack rusty mottles or spots of iron manganese like those found in waterlogged soils and Lakim paleosols.

Ancient vegetation. The overall profile form of a subsurface clay enrichment together with large drab- haloed root traces are evidence for old growth forest vegetation on Pswa paleosols. These forests were not so rich in humus and presumed ground cover as those on Pasct paleosols at the same stratigraphic level. Nor were they so low in humus and ground cover deep within the shade of multiple canopy layers interpreted for Lakayx paleosols. Nor were they as low in nutrient bases as Pasct, Acas or Lakayx paleosols. Pswa paleosols probably supported eutrophic well drained tropical forests.

No fossil plants have been found preserved in Pswa paleosols, which were too oxidized to permit preservation of plant material. Interpretation here as soils of tropical forests is consistent with the abundant fossil plants found at comparable stratigraphic levels within Luquem, Sayayk and Patat paleosols and within fluvial conglomerates of the Clarno "Nut Beds" (Manchester, 1981, 1994). However, Pswa paleosols of steep well drained slopes of a tall volcanic dome are not likely to have contributed a great deal of plant material to rivers and mudflows within the nearby heavily forested lowland.

Former animal life. No fossil animals have been found in Pswa profiles, nor would any shell or bone be expected in such acidic paleosols (Retallack, 1984a). Forest-adapted fossil mammals are known from the Clarno "Nut Beds" at about the same stratigraphic level (Retallack, 1991a), but it is uncertain if and which of these creatures ventured from the fluvial lowlands in which they were buried to the steep forested slopes of Pswa paleosols.

Paleotopographic setting. Pswa paleosols developed on the steep slopes of a dacitic volcanic dome, intruded on the flanks of a large stratovolcano that shed the thick sequence of conglomerates exposed in Hancock Canyon and the Palisades (White and Robinson, 1992). This dome of deeply weathered porphyritic dacite had a topographic relief of at least 100 m, because that thickness of Clarno Formation conglomerates and red beds onlap its southern side. The deeply penetrating root traces and deep weathering of Pswa paleosols are both compatible with a well drained land surface. The enormous angular boulders of andesite within the profile, together with abundant small matrix-supported cobbles and granules are most like talus deposits from a steep hillside emplaced by a combination of soil creep, mudflows and rock fall. The second Pswa paleosol formed after a significant episode of slope failure that covered the type Pswa clay with colluvial debris. Pswa profiles were probably in a footslope position, because the overlying sequence of sandstones and shales include Cmuk paleosols of a swampy

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poorly drained lowland.

Parent material. The parent material of both Pswa paleosols is a porphyritic dacite intrusion, which is exposed at the base of the type Pswa clay. Both Pswa paleosols are littered with large blocks of this rock, presumably derived from cliffs and steep slopes nearby. Even the sand and silt size grains seen in thin section appear to be mostly this same porphyritic dacite. The bulk of both profiles appears to have been a colluvial deposit derived from this volcanic dome. However, there could have been minor additions from airfall volcanic tuff, and one pebble of silicified sandstone (Fig. 3.10) similar to those of the Clarno "Nut Beds" was found in the colluvial sandstone C horizon of the upper Pswa profile.

Time for formation. The Pswa paleosols are moderately developed in the qualitative scale of Retallack (1990a), and this generally corresponds to several tens of thousands of years of soil development (Birkeland, 1990). Brown weathering rinds preserved on andesitic boulders in these paleosols are generally a millimeter or less thick, and this has been found by Colman (1986) to take about 65,000 years in the cool humid climate of Mt Rainier in Washington state, but as much as 150,000 years in the cool dry climate of Truckee in Nevada. In wet and cool parts of Mt Kenya in Kenya, phonolitic lavas that are comparably porphyritic to the Clarno andesite, have been noticeably weathered within 1,940 years, but accumulation of clay to levels that would qualify as argillic has taken 40,000 years or longer (Mahaney, 1989; Mahaney and Boyer, 1989).

Sayayk paleosols

Diagnosis. Sandstone with root traces and clear relict bedding.

Derivation. Sayayk is Sahaptin for "sand" (Rigsby, 1965), which is common in these paleosols.

Description. The type Sayayk clay loam paleosol (Fig. 3.32) is in the southern outcrop of the "Nut Beds," 0.5 miles west of Hancock Field Station, near Clarno (SE1/4 SE1/4 SE1/4 SW1/4 Sect 27 T7S R19E Clarno 7.5' Quad. UTM zone 10, 702744E 4977294N). This is the third in a sequence of comparable partly silicified paleosols above the base of the "Nut Beds" and is at the level extensively quarried for fossil leaves, fruits and wood (Manchester, 1981, 1994). It is within the "Nut Beds" of the upper Clarno Formation. Fossil mammals from overlying strata south along strike have been identified with those of the middle Eocene, Bridgerian North American Land Mammal "Age" (Hanson, 1989). Pumice from the overlying tuffaceous sandstone has yielded a fission track age of 43.0 Ma (Vance, 1988), which is currently regarded as the age of the late Eocene Uintan North American Land Mammal "Age" (Prothero and Swisher, 1992).

+9 cm: siltstone overlying paleosol: light gray (10YR6/1), weathers yellowish brown (10YR5/6): irregular laminae of white (10YR8/1) pumiceous sandstone: sparse fine root traces of yellowish brown (10YR5/4): weakly calcareous: insepic intertextic in thin section, with relict beds of porphryoskelic argillasepic shale, few vugs filled with cavity-lining chalcedony: abrupt smooth contact to

0 cm: A horizon: clayey siltstone: pale brown (10YR6/3), weathers reddish brown (5YR4/4) and yellowish brown (10YR5/6): abundant fossil roots and logs up to 3 cm wide of very dark grayish brown (1OYR3/2) and fossil leaves of yellowish brown (10YR5/6), dominated by aguacatilla (Meliosma sp. cf. M. simplicifolia): weakly calcareous: crystic Porphyroskelic in thin section, with scattered feldspar and volcanic fragments: the fine crystal structure in thin section is due to pervasive silicification, that also preserves in three dimensions some of the cellular structure of fossil root traces: gradual smooth contact to

-10 cm: C horizon: fine-grained sandstone: white (10YR8/2), weathers very pale brown (10YR7/4): stout root traces up to 4 mm diameter of pale brown (10YR6/3), in places replaced with white (10YR8/2): flaggy bedding and local ripple drift cross- lamination in upper part of the bed, lower part is massive with parting lineation: weakly calcareous: crystic porphyroskelic in thin section with interbedded laminae of insepic intertextic sandstone, rich in feldspar and volcanic rock fragments.

Further examples. These sandy weakly developed paleosols are common in the "Nut Beds", which includes 9 of them in addition to the type Sayayk clay loam. Additional profiles of this kind are common in the "conglomerates of Hancock Canyon" of the upper Clarno Formation.

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Alteration after burial. Sayayk paleosols are volcaniclastic sandstones little altered from their original condition. The accumulation of organic matter, clay and iron hydroxides was not sufficient for burial decomposition, gleization, illitization or reddening to have been important processes. Compaction is not obvious in thin section, or from preservation of permineralized fossil wood, fruits and leaves with considerable relief. Compaction of these paleosols was certainly much less than the 70% calculated for clayey paleosols such as Luca and Lakayx. Sayayk paleosols are cemented with silica, which must have postdated the growth of plants so abundantly represented by roots and leaves preserved in them. However, permineralization could not have been long after plant growth, or tissue structure would have decayed substantially. Permineralization within a silica charged hot spring is likely, rather than silicification entirely during burial. Some addition of silica during burial may explain chalcedony filling pores and vugs in these paleosols.

Reconstructed soil. Sayayk soils were little more than rooted sands, in which plant growth, animal burrowing and other soil building processes had not proceeded to obliterate bedding of their parent material. They consisted of a surface (A) horizon of roots and leaf litter over a subsurface (C horizon) of bedded volcaniclastic sand. They were probably poorly drained considering the good preservation of fossil leaves in successions of these thin paleosols, but were not permanently waterlogged as their leaf litters were not as thick and carbonaceous as peats inferred for Cmuk paleosols. With their abundant little weathered volcanic clasts, including scoria, pumice and shards, they would have been fertile soils with neutral to mildly acidic pH.

Classification. Such weakly developed soils in the U.S. taxonomy (Soil Survey Staff, 1990) are best matched by Fluvents, considering the great variation in grain size of their parent materials and close association with fluvial paleochannels. Fluvents are subdivided on the basis of climatic criteria which are not evident from such weakly developed paleosols. However, the abundant fossil wood with its diffuse growth rings and diverse, large leaves with drip tips in Sayayk paleosols provide evidence of isothermic tropical climates (Manchester, 1994), as in Tropofluvents. In the F.A.O. (1974) classification Sayayk paleosols would be Eutric Fluvisols. In Australia such profiles are called Alluvial Soils (Stace and others, 1968) or Um1.21 of the Northcote (1974) key.

Paleoclimate. Sayayk paleosols are not sufficiently developed to be indicators of paleoclimate. These paleosols have been the focus of intensive collection of fossil wood, fruits, seeds and leaves (Scott, 1954, 1955, 1956; Manchester, 1981, 1994a, 1994b; Scott and Wheeler, 1982; Manchester and Kress, 1993). A humid rainfall regime is indicated by the dominance of large, entire-margined leaves, many of which include drip tips, as well as by the numerous bars on sclariform perforations of vessels in fossil woods. A tropical temperature regime is indicated by the presence of frost sensitive plants such as cycads, palms and Ensete. Another tropical indicator is the abundance of vines (43% of species with known affinities), which is typical of tropical forest with a multitiered canopy. Growth rings in the fossil woods indicate climatic seasonality, but this was not marked (Scott and Wheeler, 1982). Wolfe (1978) envisages climate for the similar Eocene floras of the nearby Puget Group of Washington with a mean annual temperature of 21-25° and a mean annual range of temperature of 3-7°.

Ancient vegetation. Sayayk paleosols show little disruption of primary bedding by root traces which are generally preserved in part by cellular permineralization with silica of possible hydrothermal origin. Such hot spring fluids can be scalding and caustic, so that vegetation in the vicinity is sparse and is best characterized as ecologically stress tolerant. In the hot springs of Yellowstone National Park, Wyoming, for example, bare terraces of tufa and sinter are colonized largely by cyanobacteria (Ward and others, 1992). Sayayk paleosols lack such massive sinters, tufas and microbial lamination, and contain abundant and diverse broadleaf angiosperm leaves, fruits and wood (Manchester, 1981). Although the preservation of some of these fossils may have been favored by hydrothermal water, these communities are best regarded as early in ecological succession of young land surfaces created by flooding, including catastrophic runout of volcanic lahars. These shrublands or pole woodlands would have been intermediate in ecological succession between the early colonizing fern brakes of Luquem paleosols and the tropical forests of Patat paleosols.

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Most Sayayk paleosols have beautifully preserved fossil leaves, and sometimes also fossil fruits and wood. The floristic composition of these early successional pole woodlands could be reconstructed in detail by systematic exposure and census of fossils in the surface horizons of these paleosols. Such studies are beyond the scope this study, but reconnaissance collecting of numerous Sayayk paleosols demonstrated a lateral variation in fossil content that may reflect an ecotonal boundary between two distinct kinds of ancient vegetation. Unlike lacustrine leaf beds in which leaves can be transported and mixed, Sayayk paleosols preserve leaves near their place of growth, as can be seen from the penetrating root traces as well as variation in skeletonization, insect nibbling and folding of fossil leaves comparable to that found in leaf litters of modern soils. A very diverse flora of tropical affinities is found in Sayayk paleosols of the "Nut Beds" (L1359) and western lahars (L1730, L1759, L1761, L1854, L1855, L1856, L1857, L1859, L1860, L1861, L1873); including aguacatilla (Meliosma sp. cf. M. simplicifolia), moonseed (Diploclisia), icacina vine (Goweria dilleri), magnolia (Magnolia leei), laurels (Litseaphyllum praesanguinea, L. praelingue, L. sp. cf. "Laurophyllum" merrilli, Cinnamomophyllum sp. cf. "Cryptocarya" eocenica), tree fern (Cyathea pinnata), horsetail (Equisetum clarnoi), walnut (Juglans sp.), maple (Acer clarnoense), alder (Alnus clarnoensis), katsura (Joffrea speirsii) and sycamore (Macginitea angustiloba). In contrast, a limited fossil flora of temperate affinities is found in lahars to the east (L1650, L1732, L1753, L1760, L1858); including sycamore (Macginitea angustiloba), katsura (Joffrea speirsii), alder (Alnus clarnoensis), laurel (Litseaphyllum presanguinea), and horsetail (Equisetum clarnoi).

The diverse tropical flora is also known from fluvial conglomerates of the "Nut Beds", where botanical affinities, leaf sizes and other indicators have been used to argue that it represents multistratal paratropical rain forest (Manchester, 1981, 1994). This allochthonous flora largely of fruits and seeds is probably in part derived from old-growth forest communities of the type envisaged for Lakayx and Pasct paleosols. Sycamore-katsura floras like those of the eastern Sayayk paleosols are also known from allochthonous Eocene lake beds of the Clarno Formation and elsewhere in the western United States (Manchester, 1986; Crane and Stockey, 1985) and from late successional forest soils such as the Patat paleosols of the Clarno area. The fossil floras of early successional Sayayk paleosols may reflect an ecotone between these two distinctive ecosystem types. Comparable vegetation types of tropical Mexico today include the high evergreen selva of lowlands and the deciduous tropical forests dominated by Liquidambar macrophylla found at elevations of 1000-2000 m (Gomez-Pompa, 1973). Interpretation of Meliosma-dominated assemblages of Sayayk paleosols as early successional lowland rain forest and Macginitea-dominated assemblages of Sayayk paleosols as early successional upland deciduous forests is compatible with a reconstructed paleogeography of an andesitic stratocone source for lahars to the east of the study area (White and Robinson, 1992). Meliosma today includes species of colonizing forests (van Busekom and van de Water, 1989), as does living sycamore (Platanus: Peattie, 1950; Manchester, 1986).

Former animal life. Nibbled and decayed fossil leaves in Sayayk paleosols attest to a varied biota of invertebrate and microbial decomposers in Sayayk paleosols. No vertebrates have been recorded from Sayayk paleosols, but it is likely that the variety of vertebrates known from fluvial conglomerates of the "Nut Beds" traversed these streamside paleosols. Large depressions (13 cm diameter by 7 cm deep) in Sayayk paleosols of the central outcrop of the "Nut Beds" are similar in cross-section to fossil footprints of large mammals found elsewhere in Cenozoic rocks (Loope, 1986). Mammal fossils found in the conglomerates of the "Nut Beds" include a graviportal titanothere (Telmatherium sp. indet.) large enough to have made such tracks, as well as smaller turtles (Hadrianus sp. indet), four-toed horses (Orohippus major), extinct tapirs (Hyrachyus eximius) and lion-like extinct carnivores (Patriofelis ferox).

Paleotopographic setting. There is little indication of paleotopography in Sayayk paleosols other than their weak development compatible with naturally disturbed sites. Sayayk paleosols were found within sandy sequences associated with grain-supported conglomerates interpreted as fluvial paleochannels, both in the "Nut Beds" and near the "Hancock Tree". These paleochannels are within the thick sequence

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of volcanic mudflows, and in some cases may represent the outflow of these lahars, as discussed for Patat paleosols. Sayayk paleosols were thus a part of this braidplain outwash of a large andesitic stratovolcano. Within such a depositional setting Sayayk soils probably formed on streamsides prone to disturbance on decadal time scales by catastrophic flooding and mudflows.

Parent material. The parent material of Sayayk paleosols is well preserved in their layered C horizons. It includes silt and clay, but composition is more readily apparent from associated volcaniclastic sandstone and granule conglomerate. Most of the clasts are of porphyritic andesite and were presumably derived from volcanic flows of a nearby stratovolcano. Less common are feldspar laths, volcanic shards and there also are some thin layers of pumice, derived from volcanic airfall of rhyodacitic composition. Most of these rock and mineral fragments are relatively fresh, but some show weathering rinds and even pervasive ferruginization, indicating that some were derived from deeply weathered soils perhaps similar to Lakayx and Pswa paleosols. Such soils could also be a source for silty and clayey beds within Sayayk paleosols. Both soil and airfall components appear overwhelmed compositionally by the andesitic volcaniclastic component.

Time for formation. Sayayk paleosols show very weak soil development in the qualitative scale of Retallack (1990a), and represent a stage of soil development intermediate between those of Luquem and Patat paleosols. Similarly the fossil plants preserved in Sayayk paleosols represent colonizing forests intermediate between early successional herbaceous vegetation preserved in Luquem paleosols and the more substantial forests preserved as stumps in Patat paleosols. Luquem paleosols represent a few growing seasons or years of soil development and Patat paleosols represent centuries. Sayayk paleosols therefore represent decades of soil development.

Scat paleosols

Diagnosis. Thin gray claystone with relict gravel.

Derivation. Scat is Sahaptin for "dark" and "night" (Rigsby, 1965; DeLancey and others, 1988), in reference to the gray surface horizons of these paleosols.

Description. The type Scat clay paleosol (Fig. 3.26) was found in the lower part of a trench in lower "Red Hill", above the "Nut Beds", Hancock Field Station (NE1/4 SE1/4 SE1/4 SW1/4 Sect. 21 T7S R19E Clarno 7.5' Quad. UTM zone 10, 702695E 4977388N). It is immediately below the lowest red paleosol in the measured section and was called the "Pine Creek clay paleosol" by G.S. Smith (1988). It is at a stratigraphic level of 69 m in the reference section of the claystones of "Red Hill" and in the late Eocene (Bridgerian-Uintan) upper Clarno Formation.

+5 cm; claystone overlying paleosol; light olive gray (5Y6/2); weathers weak red (10R4/4); indistinct relict bedding; very weakly calcareous: abrupt wavy contact to

0 cm; A1 horizon; claystone; gray (2.5Y5/1), weathers light brown (7.5YR6/4); common stout (9 mm diameter) root traces of dark gray (2.5Y4/1), with mottles of light olive gray (5Y6/2); few granules (up to 3 mm diameter) of deeply weathered, rounded, volcanic rock fragments, olive gray (5Y5/2) and clay skins (ferri-argillans) of reddish brown (2.5YR4/4); very weakly calcareous: gradual irregular contact to

-4 cm; A2 horizon; granule bearing claystone; gray (7.5YR5/1), weathers light brown (7.5YR6/4); common rounded clasts up to 10 mm in diameter of volcanic rock fragments, of light olive gray (5Y6/2), olive yellow (5Y6/8) and strong brown (7.5YR5/6); very weakly calcareous; gradual irregular contact to

-34 cm; C horizon; clayey conglomerate; gray (2.5Y6/1) to bluish gray (5B5/1); rounded, fresh to deeply weathered volcanic clasts of dark bluish gray (5B4/1), reddish brown (2.5YR4/4), and dark red (7.5R3/8); indistinct relict bedding; very weakly calcareous.

Further examples. Scat paleosols are common in the lahars of the Palisades and of Hancock Canyon. Nine of them were found in the reference section below the "Nut Beds". Additional examples can be

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seen in lahars cropping out in the cliffs facing the John Day River south of Hancock Field Station. Here, however, they have a distinctive greenish gray (5G5/2) color, which is probably their true color. Like Patat, Pasct and Sayayk paleosols in these coarse grained lahars, Scat paleosols also may have been oxidized in outcrop.

Scat paleosols vary considerably in thickness and clayeyness of the surface horizons. Those thicker than 20 cm and with horizons of subsurface clay enrichment grade into Patat and Pasct paleosols. Unlike sandy Sayayk and Patat paleosols, Scat and Pasct paleosols are clayey, and even their included volcanic rock fragments are weathered to clay.

Alteration after burial. Scat paleosols are dark gray so have not been reddened by soil formation or burial. They are without recognizable plant material but do have drab-haloed root traces, so probably suffered burial gleization and decomposition of soil organic matter. Some Scat paleosols have orange- stained slickensided clay skins, but these do not persist into the outcrop with further excavation. Their orange to yellow hue is indicative of goethite or other iron hydroxides from weathering in the modern outcrop. These clayey profiles probably suffered at least 70% compaction calculated from the formula of Sclater and Christie (1980). No mineral or chemical evidence of recrystallization or illitization was seen.

Reconstructed soil. Scat paleosols can be envisaged as thin clayey and humic surface (A) horizons over little altered andesitic conglomerates (C horizons). The type Scat clay is almost as deeply weathered chemically as the overlying type Lakayx clay and other Scat paleosols of the Clarno Formation conglomerates are comparably clayey and unreactive to acid. Their high alumina/bases ratio is an indication of low fertility and acidic pH. Their gray color could be taken as an indication of waterlogging, but such an interpretation is contradicted by their deep weathering and deeply penetrating root traces. Despite evidence of considerable weathering and clay formation that would have taken at least tens to hundreds of years, Scat paleosols lack any ferric mottles or iron-manganese nodules of the sort found in waterlogged soils. They are better regarded as humic soils of moderately well drained alluvial terraces and mudflow mounds. There is no evidence from soda/potash or alkaline earth/alumina ratios for salinization or calcification.

Classification. Scat paleosols are best identified as Inceptisols, because they lack diagnostic subsurface horizons of most orders of the U.S. soil taxonomy (Soil Survey Staff, 1990), and are more deeply weathered than both Entisols and Andisols. In view of the dark color of their surface horizon and lack of evidence for a dry or cold climate or for fragipans, Scat paleosols are best identified as Entic Haplumbrepts. In the F.A.O. (1974) classification these are Humic Cambisols. Within the Australian classification (Stace and others, 1968), Scat paleosols are most like Alpine Humus Soils, which are found at elevations of 366-2,228 m, which is not as high as the name would imply. In the Northcote (1974) key Scat paleosols are best described as Uf1.41.

Paleoclimate. Scat paleosols are too weakly developed to be useful indicators of paleoclimate. Nevertheless their deep chemical weathering together with limited physical weathering is compatible with a humid tropical climate. Thick layered clay skins in some Scat paleosols (Fig. 3.18) are evidence of climatic seasonality. The banding of these argillans is not as marked as it could be and is compatible with a short dry season, as discussed for Lakayx paleosols.

Ancient vegetation. No fossil plants were found in Scat paleosols, and this gives further support to the idea that they were not waterlogged despite their gray color. Their thin surface horizons over little altered andesitic conglomerates and thick woody root traces are evidence of colonizing forests intermediate in ecological succession between pioneering herbaceous vegetation and old-growth forest. Scat paleosols can be envisaged as intermediate in development between Patat paleosols on the one hand and Pasct paleosols on the other. Fossil stumps, leaves and fruits of forests of tropical to temperate affinities have been found in Patat paleosols, but the fossil flora of Pasct paleosols is unknown. Scat paleosols were found mainly in the eastern outcrops of the conglomerates, where the flora of both Patat

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and Sayayk paleosols was dominated by Meliosma and other plants of tropical affinities. Presumably its vegetation was intermediate between these early successional pole woodlands and a more diverse old growth rain forest.

Former animal life. No fossil animals were found in Scat paleosols, but a forest-adapted fauna has been collected from Sayayk paleosols and associated fluvial conglomerates at this stratigraphic level (Retallack, 1991a). Considering the close association of Scat paleosols with Sayayk and Pasct paleosols, and the absence of any obvious paleotopographic barriers, it is likely these many of these animals ranged beyond the nearstream Sayayk paleosols and into the nearby forests envisaged for Scat and Pasct paleosols.

Paleotopographic setting. Scat paleosols are drab with deeply penetrating root traces and without clear nodules, mottles or chemical evidence of waterlogging. Thus they were probably well drained humic soils that would have developed into Pasct profiles given sufficient time.

Most Scat profiles were found developed on both clast-supported conglomerates interpreted as fluvial paleochannel deposits as well as on thick matrix-supported conglomerates interpreted as volcanic mudflows. The fluvial gravels probably formed low alluvial terraces within the outwash plain of a nearby andesitic stratovolcano (White and Robinson, 1992). Volcanic mudflows tend to follow stream drainages, and can be initiated by heavy rainstorms as well as by volcanic eruptions and associated earth movements and atmospheric turbulence (Rodolfo, 1989). Mudflows coursing down the gullied flanks of a large volcano can gather considerable momentum that is dissipated rapidly near the toeslopes of the volcano so that large boulders fall out to nucleate a characteristic hummocky topography (Cas and Wright, 1987). Other parts of the mudflow may produce a broad valley fill that is subsequently incised into gullies and alluvial terraces by normal stream flow. Thus Scat paleosols probably formed on young landscapes created by periodic catastrophic floods and mudflows.

Some Scat paleosols (for example at 20 and 28 m in reference section Fig. 3.3) were found developed on lapilli tuff of rhyodacitic composition. The bedding and stones up to 14 mm across in this tuff are evidence for a component of base surge, probably driven by eruptive column collapse, in addition to passive airfall, judging from studies of modern high silica eruptions (Cas and Wright, 1987). These tuffs were thus additional catastrophic deposits that formed somewhat elevated young land surfaces later colonized by forests forming Scat paleosols as local watertable was lowered by stream gullies and terraces nearby.

Parent material. Scat paleosols are weakly developed and their parent materials are well preserved within their lower horizons. For the most part these are conglomerates rich in clasts of porphyritic andesite, of both fluvial and mudflow origins, as outline above. Contributions of airfall volcanic ash and of soils of the drainage are minor components in most Scat paleosols, judging from the dominance of fresh clasts of porphyritic andesite over feldspar laths of deeply weathered clasts. The type Scat clay has the highest proportion of weathered clasts seen in thin sections of Scat paleosols. Exceptions to this andesitic volcaniclastic parent material are the two profiles (at 20 and 28 m in reference section) developed on rhyodacitic lapilli tuff. No alluvial or soil contribution to their parent material was noted.

Time for formation. Weak development of the kind seen in Scat paleosols generally forms over periods of hundreds to a few thousands of years (Retallack, 1990a). Porphyritic phonolite lavas and colluvium in wet and cool Mt Kenya in Kenya show comparable weathering and humic surface horizons comparable to that in Scat paleosols within 1,940 years (Mahaney, 1989; Mahaney and Boyer, 1989). Soils on volcanic ash in humid tropical New Guinea form fine crumb structure and discernible pedogenic clay in amounts comparable with Scat paleosols within 300-2000 years (Bleeker and Parfitt, 1974; Bleeker, 1983). Scat paleosols are better developed than soils compared with Luquem paleosols and less developed than soils compared with Pasct paleosols. Some 100-1000 years is a reasonable estimate of time represented by Scat paleosols.

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Sitaxs paleosols

Diagnosis. Olive-purple silty claystone with relict bedding, prominent red to orange nodules and mangans on blocky peds.

Derivation. Sitaxs is Sahaptin for "liver" (Rigsby, 1965), in reference to the distinctive purple and mottled color of these paleosols.

Description. The type Sitaxs clay paleosol (Fig. 3.37) is at the top of the prominent thick (6 m) gray band at 97 m in the reference section within "Red Hill," above the "Nut Beds," 0.6 miles west of Hancock Field Station, near Clarno (NE1/4 SE1/4 SE1/4 SW1/4 Sect. 27 T7S R19E Clarno 7.5' Quad. UTM zone 10, 702695E 4977388N). The type profile is the one described as the Knowlton clay paleosol by Smith (1988) in the top of the lower Red Hill trench. Two of these profiles 100 m to a long strike to the north were sampled again during this study in the base of the upper Red Hill trench. This level is within the upper red beds of the upper Clarno Formation and is of late Eocene age, probably corresponding to the Uintan North American Land Mammal "Age".

+27 cm: clayey siltstone overlying paleosol: dusky red (10R3/4), weathers dark reddish brown (2.5YR4/4): faint relict bedding: scattered grained of feldspar light gray (5Y7/1), claystone clasts of dark reddish brown (5YR3/2), and mottles of dusky red (10R3/2) and pale yellow (5YR3/2): non-calcareous: porphyroskelic clinobimasepic in thin section, with common feldspar and volcanic rock fragments: abrupt smooth contact to

0 cm: A horizon: silty sandstone: dark gray (2.5Y4/1), weathers dark reddish brown (2.5YR4/4): common root traces up to 5 mm diameter of light gray (5Y7/2) and pale yellow (5Y8/3): few clay skins (mangano-argillans) of very dark gray (5Y3/1), defining weak course angular blocky peds: scattered volcanic rock fragments of light greenish gray (5GY7/1) and black (7.5YR2/0): non-calcareous: agglomeroplasmic skelmosepic in thin section, with common volcanic rock fragments and root traces: gradual irregular contact to

-36 cm: Bw horizon: sandy claystone: gray (5Y5/1), weathers dark reddish brown (2.5YR4/4) due to slope wash: faint drab haloed root traces of light olive gray (5Y6/2): slickensided iron-manganese skins (mangans) of black (2.5Y2/1) define coarse angular blocky peds: small irregular round white (2.5Y8/1) calcareous nodules, only weakly calcareous, with mammillated iron crusts (diffusion ferrans) of brownish yellow (10YR6/8): weakly calcareous matrix: agglomeroplasmic clinobimasepic in thin section, with common volcanic clasts of porphrytic andesite: gradual irregular contact to

-49 cm: C horizon: silty sandstone: pale olive (5Y6/3), weathers light gray (5Y7/1): faint relict bedding: common volcanic rock fragments up to 3 mm diameter of very dark gray (5Y3/1) and white (5Y8/1): weakly calcareous: intertextic skelmosepic in thin section, with both fresh and ferruginized and clayey volcanic rock fragments.

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Figure 3.37. Measured section, Munsell colors, soil horizons, grain size, mineral composition and selected molecular weathering ratios of the type Sitaxs clay paleosol in central "Red Hill", in the late Eocene Clarno Formation and at level of 97 m in the reference section (Fig. 3.4). Lithological key as for Fig. 3.3. (click on image for an enlargement in a new window)

Further examples. Three additional Sitaxs paleosols were found in both the upper and lower parts of the red bed succession of the reference section of the upper Clarno Formation. Each is associated with gray tuffaceous beds that stand out in the red bed sequence, and each has characteristic differences. The type Sitaxs clay is near the crest of the ridge and its carbonate content may be due to modern soil formation, because the irregular ferruginous nodules of two laterally equivalent Sitaxs paleosols 100 m to the north are not so calcareous. The Sitaxs clay gravelly variant (at 77 m in reference section) is a purple mottled green and gray profile. The Sitaxs clay manganiferous variant (at 88 m) has especially striking slickensided mangans (Fig. 3.20). The Sitaxs clay ferruginized variant (at 114m) is more oxidized than the others, though still a purplish color (dusky red, 10R3/4), and still with the relict bedding and subsurface horizon of irregular ferruginized nodules.

Alteration after burial. Sitaxs paleosols have evidently suffered burial decomposition of organic matter. This is indicated by their clayey root traces, and in one case a claystone natural cast of a twig 2 cm in diameter, lacking any remaining organic matter. Burial gleization also is likely considering their common drab-haloed root traces. Although manganese clay skins and nodules of these paleosols are evidence of original waterlogging as well, the manganese oxides are on the surfaces of internally unoxidized peds and in root channels as is usual in groundwater gley. The drab-haloed root traces in contrast are reduced within the root channel but not in surrounding matrix as in surface water gley (Retallack, 1990a): these phenomena were more likely produced during burial. The dark purplish hue of

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Sitaxs paleosols may not be original either, and was probably created by burial dehydration from a reddish brown hue, similar to that of nodules in Sitaxs profiles that appear soft and oxidized in the modern outcrop. These are moderately clayey paleosols and may have suffered compaction to 70% of their former thickness, as estimated from the formula of Sclater and Christie (1980). Sitaxs paleosols are markedly more indurated than enclosing red claystones, presumably because of cementation during burial by silica that was able to permeate their granular structure better than that of surrounding claystones. No trace of illite or illitization is evidence from chemical analysis of x-ray diffraction of Sitaxs paleosols (Smith, 1988).

Reconstructed soil. Sitaxs soils can be envisaged as humic gray surface (A) horizons over a clayey subsurface (Bg) horizons with red mottles and skins and nodules of reddish black iron-manganese. These mottles, skins and nodules reflect a periodically waterlogged soil in which reduced iron and manganese was mobilized into solution, only to be oxidized during the dry season. Waterlogging as well as a short time for formation may explain the modest chemical differentiation of these profiles, as well as their relict bedding and other indications of weak development. The degree of base depletion, indicated by alumina/bases ratios, is low, as would be expected for a soil so rich in feldspar crystals and volcanic rock fragments. Thus it was a fertile soil with pH mildly acidic to neutral, and may have had andic properties. There is no evidence from soda/potash ratios or alkaline earths/alumina for either salinization or calcification.

Classification. Weakly to moderately developed soils formed on volcanic ash are mostly assigned to Andisols in the U.S. soil taxonomy (Soil Survey Staff, 1990). Although very few volcanic shards remain in these paleosols or their tuffaceous parent materials, these paleosols are commonly markedly more indurated than surrounding claystones, as if more permeable to cementation during burial and also more friable and lower in density than nearby clayey soils. Within Andisols, Placaquands have a combination of subsurface iron-manganese due to waterlogging that best describes Sitaxs paleosols. In the F.A.O. (1974) classification, waterlogging is regarded as more important than andic properties, and Sitaxs paleosols are best identified as Eutric Gleysols. In the Australian classification also (Stace and others, 1968) gleization has more emphasis than andic properties and Sitaxs paleosols are most like Humic Gley. In the Northcote (1974) key Sitaxs paleosols are like Uf6.41.

Paleoclimate. Both waterlogging and weak development limit the usefulness of Sitaxs paleosols as climatic indicators. Nevertheless, their smectite dominated clay, lack of carbonate and degree of weathering for paleosols with much relict bedding is compatible with a humid warm climate. Their nodules and skins of iron-manganese (mangans) are indications of waterlogging that can be contrasted with their mostly oxidized iron (low ferrous/ferric iron ratios) and deeply penetrating root traces indicative of well drained soils. Some additional gleization during burial may have produced the drab- haloed root traces as noted above, but the complex fracture of slickensided mangans around peds clearly predate burial and compaction (Fig. 3.18). Presumably, waterlogging was during a wet season and oxidation during a dry season. There is no systematic cracking pattern in Sitaxs paleosols like that of Vertisols that would indicate severe seasonality.

Ancient vegetation. Only a claystone cast of a woody twig was found in a Sitaxs paleosol. Their degree of drainage was evidently sufficient to allow aerobic decay of most leaf litter. Nevertheless seasonally-waterlogged lowland forest vegetation is indicated by the large fossil root traces and iron- manganese nodules and other evidence for waterlogging. There may have been some differences in vegetation of Sitaxs paleosols through time, because the profile found within the sequence of Lakayx paleosols in lower "Red Hill" is much more deeply weathered and so may have supported lusher vegetation, than the Sitaxs paleosols including the type profile found within the sequence of Luca paleosols in upper "Red Hill".

Lowland forest also is in evidence from fossil plant assemblages found in strata both overlying and underlying the Sitaxs paleosols of "Red Hill" (McKee, 1970; Manchester, 1981, 1994), as recounted for Lakayx and Luca paleosols. Permanently waterlogged peaty Cmuk paleosols in the middle Eocene

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conglomerates of the Clarno Formation have yielded identifiable fossil leaves laurel (Litseaphyllum presanguinea) and aguacatilla (Meliosma sp. cf. M. simplicifolia), as well as fragments of a broad- leaved grass or sedge (Graminophyllum sp.: from locality L1757). A small collection of leaves and fruits from late Eocene lake beds of the John Day Formation (L1568) above the red paleosols includes walnut-like forms (Cruciptera simsoni, Palaeocarya clarnensis), elm (Ulmus sp. indet.) and a swamp conifer (Metasequoia occidentalis) which dominates peaty waterlogged paleosols of the lower John Day Formation in the Painted Hills. Vegetation of the Sitaxs paleosol in middle to late Eocene red beds of lower "Red Hill" probably included dicots tolerant of waterlogging like Meliosma. At some time within the late Eocene however the vegetatuon of swampy lowlands changed because of a cooler climate and were dominated by dawn redwood. Dicot dominance of swamps is found in central America (Breedlove, 1973; Porter, 1973, Hartshorn, 1983). In northern Mexico and the United States in contrast, swamps are dominated by taxodiaceous conifers such as bald cypress (Taxodium distichum: Best and others, 1984). Change from dicot to conifer dominance had been effected by latest Eocene deposition of the lower John Day Formation. It is unlikely that this shift had occurred before deposition of red beds including Sitaxs paleosols of upper "Red Hill", considering the absence of dawn redwood in the small assemblage of fruits and seeds in the "Mammal Quarry" of the uppermost Clarno Formation and the relatively unleached nature of Sitaxs paleosols compared with Yanwa paleosols associated with Metasequoia in the Painted Hills.

Former animal life. No fossil animals were found in Sitaxs paleosols or in associated Lakayx and Luca paleosols. An Uintan/Bridgerian assemblage of mammals has been found in the underlying "Nut Beds" (Retallack, 1991a) and a Duchesnean assemblage of mammals in the overlying "Mammal Quarry" (Mellett, 1969; Hanson, 1973, 1989; Schoch, 1989). These kinds of forest adapted faunas would probably not have been excluded from lowland forests with seasonal waterlogging as envisaged for Sitaxs paleosols.

Paleotopographic setting. The iron-manganese skins on the exterior of internally-unoxidized peds, ferrunginized nodules and modest chemical differentiation of Sitaxs paleosols indicate groundwater gleization and a lowland topographic setting susceptible to seasonal waterlogging. All the Sitaxs paleosols formed on tuffaceous parent materials that are little weathered or oxidized compared with enclosing red and deeply weathered Lakayx and Luca paleosols. Thus Sitaxs paleosols record periods of impeded weathering and drainage associated with volcanic eruptions. The type Sitaxs clay formed on a particularly massive tuff some 6 m thick, which has the appearance of a pyroclastic flow from collapse of a Plinian eruptive column (Cas and Wright, 1987). Settling and cementation of this flow downstream may have created a locally perched water table for the time it took Sitaxs paleosols to form, followed by gullying and lowered water table for formation of successive Luca paleosols. The other Sitaxs paleosols (at 77 and 114 m in reference section) are on thinner pyroclastic beds and are more oxidized, perhaps because of less disruption of local drainage patterns.

Parent material. Sitaxs paleosols developed on lithic tuffs of rhyodacitic composition, with little contribution from weathered andesitic volcanic rocks or pre-existing soils. The parent material is well preserved in the thick (6 m) pyroclastic flow under the type Sitaxs paleosol, but more deeply weathered in other examples on thinner pyroclastic units. Luquem and some Scat paleosols also are developed on such parent materials and yet developed in a very different direction, without waterlogging.

Time for formation. Sitaxs paleosols are weakly developed in the qualitative scheme of Retallack (1990a), and this degree of profile differentiation usually takes some hundreds to a few thousands of years (Retallack, 1994a). Waterlogging tends to arrest weathering and profile development so that it is possible that Sitaxs paleosols represent more time than is apparent from their degree of destruction of relict bedding. With this limitation in mind, the development of Sitaxs paleosols is comparable to that of Scat paleosols, and probably represents 100-1000 years.

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

CHAPTER IV: PALEOENVIRONMENTAL SUMMARY OF THE CLARNO AREA

Each paleosol has something to offer in terms of paleoenvironmental information, as summarized in Tables 3.1 and 4.1, but much can also be gained by considering assemblages of paleosols from different levels of the sequence as parts of a sequence of varied ancient landscapes. These reconstructed landscapes can then be compared with modern landscapes and their soils. The potential interrelationship between paleosols can be explored by plotting them in two dimensions with hue as the dependent variable and degree of development as the independent variable (Fig. 4.1). Broad classes of hue reflect degree of drainage and humification. Development on the other hand reflects time for formation of the paleosol and stage of ecological succession of its vegetation. Thus weakly developed paleosols can be considered precursors to better developed paleosols on the same general parent material and in the same general paleotopographic setting. Although weakly developed soils dominate many depositional settings, the less-common better-developed paleosols probably reflect more accurately conditions over most of the landscape.

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Figure 4.1. Interpretive relationships between late Eocene paleosols from (A) "Nut Beds" and conglomerates, (B) lower red beds, (C) upper red beds and (D) brown siltstones of "Mammal Quarry" in the upper Clarno Formation, in terms of likely former degree of drainage and humification (red versus drab hue) and duration of soil development (weak versus strong development), and likely direction of ecological succession of plants and of soil development (arrows).

TABLE 4.1 - INTERPRETED MID-TERTIARY PALEOENVIRONMENTS OF NAMED PEDOTYPES

PALEOSOL PALEOCLIMATE ANCIENT VEGETATION

Acas Humid (>1000 mm m.a.p.), Lowland well-drained old-growth forest: no fossils found seasonally dry Cmuk Not sufficiently Swamp woodland: from "Black Spur" (L1757) including well drained to laurel (Litseaphyllum presanguinea), aguacatilla (Meliosma reflect sp. cf. M simplicfolia), and broadleaf grass

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paleoclimate (Graminophyllum sp. indet.) Lakayx Humid (1000- Lowland well-drained old-growth rain forest: no fossils 2000 mm m.a.p.) found Lakim Insufficiently Lowland seasonally inundated swamp forest: no fossils developed found indicator Luca Humid (1000- Lowland well-drained old-growth forest: at "Whitecap 1500 mm m.a.p.), Knoll" (L1358) charred wood of dicotyledonous seasonally dry angiosperm Luquem Insufficiently Early successional herbs: in "Fern Quarry" (L1099) and developed "Nut Beds" (L748) mainly fern (Saccoloma gardneri) with indicator some horsetail (Equisetum clarnoi) Micay Early successional vegetation: in "Mammal Quarry" (L775) Insufficiently may have yielded assemblage of tropical fruits and seeds developed and in John Day Formation (L1777) yields coniferalean indicator wood Pasct Humid (>1000 Lowland poorly-drained forest: no fossils found mm m.a.p.) Patat Mid-successional colonizing forest: in lahars to west (L750, L1731, L1733, L1754) includes sycamore (Macginitea angustiloba), katsura (Joffrea speirsii), alder (Alnus Insufficiently clarnoensis) and laurel (Cinnamomophyllum sp. cf. developed "Cryptocarya" eocenica): but in "Nut Beds" and lahars to indicator east (L1756) includes aguacatilla (Meliosma sp. cf. M. simplicifolia), magnolia (Magnolia sp. cf. M. leei), walnut (Juglans sp. indet.) and sycamore (Macginitea angustiloba) Pswa Humid (>1000 mm m.a.p.), Well-drained old-growth forest: no fossils found seasonally dry Sayayk Early successional pole woodland: many localities in "Nut Beds" (L1359) and western lahars (L1730, L1759, L1761, L1854, L1855, L1856, L1857, L1859, L1860, L1861, L1873) with diverse flora of tropical affinities including aguacatilla (Meliosma sp. cf. M. simplicifolia), moonseed (Diploclisia), icacina vine (Goweria dilleri), magnolia (Magnolia leei), laurels (Litseaphyllum praesanguinea, L. praelingue, L. sp. cf. "Laurophyllum" merrilli, Insufficiently Cinnamomophyllum sp. cf. "Cryptocarya" eocenica). tree developed fern (Cyathea pinnata), horsetail (Equisetum clarnoi) indicator walnut (Juglans sp.), maple (Acer clarnoense), alder (Alnus clarnoensis), katsura (Joffrea speirsii) and sycamore (Macginitea angustoloba); but in lahars to east (L1650, L1732, L1753, L1760, L1858) have limited flora of temperate affinities including sycamore (Macginitea angustiloba), katsura (Joffrea speirsii), alder (Alnus clarnoensis), laurel (Litseaphyllum presanguinea), and horsetail (Equisetum clarnoi) Scat Insufficiently developed Humic mid-successional woodland indicator Sitaxs Insufficiently

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developed Seasonally waterlogged lowland colonizing forest. indicator

PARENT TIME FOR FORMER ANIMALS TOPOGRAPHY PALEOSOL MATERIAL FORMATION

No fossils found Seasonally Weathered 10-60 Ka Acas inundated andesitic lowland gravel and volcanic ash No fossils found Swampy Andesitic 0.4-4 Ka Cmuk lowland, water sand and silt impounded around local andesitic dome Burrows of beetles and termites Well drained Andesitic 30-150 Ka Lakayx terraces of gravel and alluvial lowland rhyodacitic to lower slopes volcanic ash of an old volcano No fossils found Seasonally Fluvially 0.5-1 Ka Lakim inundated redeposited alluvial levee andesitic and lowland gravel and rhyodacitic volcanic ash "Whitecap Knoll" (L1358): hog Well drained Rhyodacitic 40-130 Ka Luca (Entelodontidae gen. et sp. terraces of volcanic ash indet.) alluvial lowland No fossils found Well drained Rhyodacitic 1-10 yr Luquem near stream volcanic ash terraces of volcanic apron "Mammal Quarry" (L775): fish, Levee of stream Fluvially 0.1-2 Ka Micay alligator (Pristichampsus sp.), draining apron redeposited bearlike creodont (Hemipsalodon of moribund andesitic grandis), sabre-tooth cat volcanic edifice gravel and (Nimravinae), rodent, rhyodacitic anthracothere (Heptacodon sp.), volcanic ash oreodon (Diplobunops sp.), rhinoceroses (Teletaceras radinskyi, Procadurcodon sp.), tapir (Plesiocolopirus hancocki, Protapirus sp.) and horses (Epihippus gracilis, Haplophippus texanus) No fossils found Imperfectly Fluvially 10-60 Ka Pasct drained redeposited

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floodplain of andesitic volcanic apron gravel and rhyodacitic volcanic ash No fossils found Levee of lahar Fluvially 50-100 yr Patat runout streams redeposited on volcanic porphyritic apron andesite gravel and sand No fossils found Colluvial talus Breccia of 40-150 Ka Pswa of old volcanic porphyritic dome of andesite porphyritic andesite No fossils found Levee of Fluvially 1 - 10 yr Sayayk volcanic lahar redeposited runout streams andesite gravel and sand No fossils found Alluvial terraces Andesitic 0.1-1 Ka Scat and volcanic gravel and mudflows sand, also rhyodacitic tuffs No fossils found Low lying Rhyodacitic 0.1-1 Ka Sitaxs volcanic tuffs tuffs

Deposition of Clarno volcaniclastic deposits

From this perspective the suite of paleosols within Clarno Formation conglomerates some 44 million years ago (Fig. 4.2) is comparable with soils forming now around central American andesitic stratovolcanoes. Volcanoes south of Mexico and into Guatemala and Nicaragua are associated with soils more strongly weathered (Nitosols and Ferralsols of F.A.O, 1975) than those of the Clarno Formation (Acrisols and Luvisols), whereas in northern Mexico the best developed soils are less deeply weathered (Luvisols and Cambisols). Soils around the volcanoes of the Transmexican Volcanic Belt match Clarno paleosols well, and particularly those around San Martin Volcano in the Sierra de los Tuxtlas near the Gulf of Mexico in Veracruz state, Mexico (F.A.O. 1975 map unit Tv 17-2ab). The volcano is on the boundary between two climatic and vegetation zones. At low elevations climate is seasonally dry humid tropical, with mean annual rainfall of more than 2500 mm and a dry season of up to 3 months. Mean annual temperature is more than 23°C and mean annual range of temperature is 8°C. At higher elevations and to the north climate is humid tropical with a more marked dry season of 4-6 months, mean annual rainfall of 1250-2000 mm, mean annual temperature of more than 23°C and mean annual range of temperature of 8°C. This climatic boundary is also the boundary between evergreen tropical forest and semideciduous forest ("selva alta perennifolia" and "selva alta subperennifolia" of Mata and others, 1971). The most conspicuous elements of the evergreen lowland forest are ramon breadnut tree (Brosimum alicastrum), sapodilla (Manilkara zapota), tempisque (Sideroxylon tempisque), mahogany (Swietenia macrophylla), white mangrove (Bucida buceras), capiri (Masticodendron capiri), Mirandaceltis monoica and Carpodiptera floribunda (F.A.O. 1975). This lowland vegetation

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passes upwards at elevations of 700-900 m to a diverse tropical forest rich in species of the family Lauraceae, hence the term "selva of Lauraceae". Common in this semi-evergreen forest are Christmas tree (Alchornea latifolia), bolly gum (Beilschmiedia anay, B. mexicana), icaeina vine (Calatola laevigata), cycad (Ceratozamia mexicana), tree fern (Cyathea mexicana), indigo bush (Dalea elata), leguminaceous tree (Dussia mexicana), fig (Ficus lapathifolia), cocoa-relative (Hampea integerrima), tropical laurel (Licaria peckii), melastoma-relative (Miconia trinervis), tropical hackberry (Mirandaceltis monoica), silverballi (Nectandra salicifolia), louro (Ocotea veraguensis), avocado (Persea scheideana), clearweed (Pileapubescens), pepper (Piper sanctum), fig-relative (Poulsenia armata), oaks (Quercus corrugata, Q. sp. indet. aff. Q. gracilior, Quercus skinneri), kiwi-fruit-relative (Saurauia laevigata), tree fern (Sphaeropteris horrida), cashew-relative (Tapiriria mexicana), iris-relative (Trimeza martinicensis), nutmeg-relative (Virola guatemalensis), and elm (Ulmus mexicana). Like many tropical forests of the type called "selva" in Mexico, there is no clearly dominant species. From 1000-1500 m elevation on San Martin volcano these diverse forests pass into deciduous forests dominated by sweet gum (Liquidambar styraciflua) and oak (Quercus affnis: Gomez-Pompa 1973: "bosques caducifolia" of Mata and others, 1971). The "selva of Lauraceae" with its cycads, tree ferns, diverse laurels and mix of temperate and tropical affinities is a good modern analog for the fossil flora of the "Nut Beds" and Sayayk and Patat paleosols in the western portion of the Clarno Unit of the John Day Fossil Beds with its common large leaves with drip tips (Fig. 4.3). Such laurel forests have persisted today in only limited areas of the tropics and Canary Islands, but were once very widespread, judging from early Tertiary fossil floras (Axelrod, 1975). The sweet gum-oak deciduous forests of higher elevations with their more temperate elements are a good modern analog for the sycamore-katsura fossil floras (Fig. 4.4) found around the "Hancock Tree" and Hancock Canyon in the eastern portion of the Clarno Unit closer to the source stratovolcano for the thick volcanic lahars. Such a vegetation reconstruction also tallies well with the known fossil fauna of forest-adapted four-toed horses, tapirs, titanotheres, and creodonts known from the "Nut Beds" (Fig. 4.5).

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Figure 4.2. A reconstruction of landscapes, vegetation and soils during the middle-late Eocene deposition of the Clarno "Nut Beds" and conglomerates some 44 million years ago. (click on image for an enlargement in a new window)

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Figure 4.3. Reconstruction of a fossil aquacatella (Meliosma beusekomu) from the middle-late Eocene "Nut Beds" of the Clarno Formation at Hancock Field Station, Oregon (data from Bones, 1979, Manchester, 1981, pers. comm. 1993; van Beusekom and van der Water, 1989). (click on image for an enlargement in a new window)

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Figure 4.4. Reconstruction of a fossil plane or sycamore (Macginitea angustiloba) from the middle-late Eocene conglomerates of Hancock Canyon of the Clarno Formation at Hancock Field Station, Oregon (data from Wheeler and others, 1977; Scott and Wheeler, 1982; Manchester, 1986). (click on image for an enlargement in a new window)

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Figure 4.5. Reconstructions of middle-late Eocene (Bridgerian-Uintan) animals from the "Nut Beds" of the Clarno Formation at Hancock Field Station, Oregon (A and scale from R.B. Horstall for Scott, 1913; B, from E.M. Fulda for Osborn, 1929; E, from C.E. Knight for Osborn, 1910; others original with data from Hay, 1908). (click on image for an enlargement in a new window)

Deposition of "Red Hill" claystones

The lower red beds of "Red Hill", overlying the "Nut Beds", consist mainly of deeply weathered red soils (Ferric Acrisols: Fig. 4.6), but these have retained some smectite, a differentiated clayey subsurface horizon and are not so deeply weathered as the soils (Nitosols and Ferralsols) of humid tropical central America. Similar soils to the Lakayx paleosols of lower "Red Hill" are found in metamorphic basement near a rhyolitic volcanic center on the Sierra Madre del Sur near Punta Escondido, Mexico (map unit Af20-2ab of F.A.O., 1975). Here the climate is seasonally dry humid tropical, with a mean annual temperature of more than 23°C, mean annual range of temperature of up to 7°C dry season of 4-6 months and mean annual precipitation of 1250-2000 mm. Vegetation is a medium (15-20 m tall) semi-evergreen forest ("selva mediana subperennifolia" of Mata and others, 1971), which is a mix of deciduous elements with evergreen elements. Breadnut (Brosimum) and other species of tropical evergreen forest remain common in gullies. Common deciduous elements ranging into drier climatic belts are coyole palm (Acrocomia mexicana), surette (Byrsonima crassifolia), dillenia-relative (Curatella americana), guava (Psidium guajava), calabash tree (Crescentia cujete) and Jamaican kino (Coccoloba barbadensis: Gomez- Pompa, 1973). This transitional flora between tall evergreen rain forest and deciduous forest is similar physiognomically to the "selva of Lauraceae" found on volcanoes of Veracruz. This may be a better model for the vegetation of Lakayx paleosols, because similar plant fossils have been found in the overlying "Mammal Quarry" and underlying "Nut Beds".

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Figure 4.6. A reconstruction of landscapes, vegetation and soils during middle-late Eocene deposition of the lower "red beds" of the Clarno Formation some 43 million years ago. (click on image for an enlargement in a new window)

The upper red beds of "Red Hill" have mainly Luca paleosols that are strongly developed but less deeply weathered than those in the lower part of "Red Hill" (Fig. 4.7). These paleosols are mainly Chromic Luvisols which are widespread on metamorphic and volcanic rocks of the Pacific slope of Mexico from Chiapas to Jalisco states (map units Lc26-3ab, Lc28-3bc, Lc29-3bc, Lc34-2b of F.A.O., 1975). The climate of all these areas is seasonally dry subtropical, with mean annual temperature of 19-23°C mean annual range of temperature up to 10°C, dry season of 4-6 months and mean annual precipitation of 950-2500 mm. The upper altitudinal limit of this climatic zone is at the frost line, so that frosts are infrequent. Vegetation in this region is a low (15 m or less) deciduous forest ("selva baja caducifolia" of Mata and others, 1971). Most, but not all, trees loose their leaves in the dry season. Diversity is high, with the commonest species including Jamaican dogwood (Piscidia piscipula), wild tamarind (Lysiloma bahamensis), copite (Cordia dodecandra), simarouba-relative (Alvaradoa amorphoides), brazilwood (Haematoxylon brasiletto), tropical legume tree (Lysiloma gellermanni, L. acapulcensis), silk-cotton tree (Ceiba acuminata), copal (Bursera excelsa), pistachio (Pistacia mexicana), cuachalala (Amphipterygium adstringens), linaloe (Bursera http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap4.htm[4/18/2014 12:20:53 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 4)

spp.), copalcocote (Cyrtocarpa procera), morning glory (Ipomoea spp.) and navio (Conzattia sericea: F.A.O. 1975). No fossil plants have been found in the Luca paleosols of "Red Hill", nor are many of these genera known from the Eocene fossil record of the Pacific Northwest. Nevertheless, physiognomically similar vegetation can be envisaged composed mainly of deciduous elements within the fossil flora of the "Nut Beds" and "Mammal Quarry".

Figure 4.7. A reconstruction of landscapes, vegetation and soils during late Eocene deposition of the upper "red beds" of the Clarno Formation some 41 million years ago. (click on image for an enlargement in a new window)

Deposition of the "Mammal Quarry" siltstones

The grey-orange siltstones of the Clarno "Mammal Quarry" have a low diversity of paleosols (Fig. 4.8), the best developed of which are Gleyic Luvisols. This suite of paleosols is comparable to the Gleyic Luvisols with associated Mollic Gleysols and Eutric Fluvisols of the Rio Verde Delta of Oaxaca, Mexico (map units Lg29-3a of F.A.O., 1975). This area has a seasonally dry tropical climate, with mean annual temperature of more than 23° C, mean annual range of temperature of 4-10° C, mean annual rainfall of 550-1000 mm, and a dry season of 4-6 months. Vegetation in this part of Mexico is a low deciduous forest ("selva baja

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caducifolia" of Mata and others, 1971). Grasses such as blue grama (Bouteloua curtipendula, B. rothrocki), tobosa (Hilaria semplei) and Cathestecum spp. may be common in the understorey (F.A.O., 1975). The fine root traces and humification of Micay paleosols in the "Mammal Quarry" may reflect this more open vegetation.

Figure 4.8. A reconstruction of landscapes, vegetation and soils during late Eocene deposition of the "Mammal Quarry" beds of the Clarno Formation some 39 million years ago. (click on image for an enlargement in a new window)

The fossil mammal fauna (Fig. 4.9) of the quarry is distinctly different from pre-existing forest-adapted faunas, and represents the earliest fauna of the Duchesnean North American Land Mammal "Age" (Lucas, 1992). This was the earliest of the so-called "White River chronofauna", a more modern fauna that appeared in North America largely as a result of immigration from Asia (Hanson, 1989; Lucas, 1992). The more modern aspects of this fauna include the appearance of groups such as true cats and rhinoceroses, as well as more elongate (cursorial) limb structure that may have been selected by more open habitats. Evidence from paleosols corroborates the existence of these more open forests in the volcanic ranges of Oregon during late Eocene time. http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/chap4.htm[4/18/2014 12:20:53 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Chapter 4)

Figure 4.9. Reconstruction of late Eocene (Duchesnean) animals from the "Mammal Quarry" of the upper Clarno Formation at Hancock Field Station, Oregon (scale from R.B. Horstalle for Scott, 1913; others original with inspiration from Stock, 1936; Russell, 1938; Scott, 1945; McGrew, 1953; Radinsky, 1963; Mellett, 1969; Langston, 1975; Hanson, 1989; Savage and Long, 1986; Dixon and others, 1992). (click on image for an enlargement in a new window)

Summary

Paleosols have served several uses in this reconstruction of life and landscapes of the middle to late Eocene. Because they are in place they have helped to group some of the fossil floras into natural assemblages. Paleosols also have served as indicators of vegetation at stratigraphic levels that have not yielded plant fossils, and that are unlikely to do so. Thus a picture has emerged of a landscape and vegetation more varied in time and space than was apparent from prior paleontological work. Although an image of tall tropical rain forest similar to that of lowland Taiwan and Panama has been evoked from prior studies of the fossil flora of the "Nut Beds" (Chaney, 1948; Manchester, 1981), more recent work has revealed a more complex mix of tropical and temperate elements (Manchester, 1994). The anomalously high diversity of the Clarno "Nut Beds" flora has been thought to be a product of mixing of plant assemblages (Manchester, 1994), and this supposition is confirmed by our interpretation of these beds as a stream channel lag near the ecotone between upland tropical

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forest and high elevation woodland. Furthermore there is evidence of stepwise climatic drying and cooling from late Eocene floras of the western United States (Wolfe, 1978, 1992). Our research on paleosols advances the idea that the middle Eocene forests of Oregon were marginally tropical, and that the late Eocene was a time of maximal warmth. Unlike the fossil floras which are found at intervals corresponding to 10 million years or so, paleosols constitute a near-continuous narrative of middle to late Eocene paleoenvironment change.

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joda/bestland-retallack1/chap4.htm Last Updated: 21-Aug-2007

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

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Zachos, J.C., Lohmann, K.C., Walker, J.C.G., and Wise, S.W., 1993. Abrupt climate change and transient climates during the Paleogene: a marine perspective. Journal of Geology, v. 101, p. 191-213.

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 1: Individual named paleosols in the Clarno area

Level Section Number Name (m)

"Black Spur" ca.16 ca.2 type Pswa clay "Black Spur" ca.20 ca.5 type Cmuk peat lower conglomerates 22 6 Pasct clay brown variant "Fern Quarry" ca.21 ca.5 Sayayk silty clay loam "Fern Quarry" ca.22 ca.6 type Luquem silty clay loam Hancock Canyon ca.29 ca.7 Sayayk clay Hancock Canyon ca.30 ca.8 type Patat clay Hancock Canyon ca.31 ca.9 Sayayk clay lower "Nut Beds" 51 20 Sayayk clay lower "Nut Beds" 52 21 type Sayayk clay loam lower "Nut Beds" 52.5 22 Sayayk silty clay lower "Nut Beds" 53 23 Sayayk silty clay lower "Nut Beds" 53.5 24 Sayayk silty clay lower "Nut Beds" 54 25 Luquem silty clay loam lower red beds 69 35 type Scat clay lower red beds 71 36 type Lakayx clay lower red beds 77 41 Sitaxs clay gravelly variant lower red beds 85 46 Lakayx clay manganiferous variant lower red beds 87 47 Luca clay concretionary variant lower red beds 88 48 Sitaxs clay gravelly variant lower red beds 97 52 type Sitaxs clay "Sienna Ridge" east ca.113 ca.64 type Acas clay upper red beds 114 64 Sitaxs clay ferruginized variant "Mammal Quarry" ca.124 ca.72 Lakim clay septarian variant "Mammal Quarry" ca.125 ca.73 type Micay clay upper red beds 128 75 type Pasct clay "Whitecap knoll" ca.300 ca.150 type Luca clay

Note: Meter levels and consecutive number of paleosols refer to the reference section, with approximate correlations indicated "ca." for sections off the reference section.

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 2: Textures (volume percent) from point counting petrographic thin sections and calcareousness from reaction with dilute acid of paleosols in the Clarno area

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 3: Mineral composition (volume percent) by point counting of petrographic thin sections of Eocene paleosols in the Clarno Unit of the John Day Fossil Beds National Monument, Oregon

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 4: Major element chemical analyses by AA and XRF, loss on ignition (LOI), all weight percent, and bulk density (g/cc) of Eocene paleosols from the Clarno area

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 5: Trace element analyses (ppm) by AA and XRF of paleosols from the Clarno area

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 6: Molecular weathering ratios of paleosols in the Clarno area

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 7: 40Ar/39Ar radiometric age determination data (from C. Swisher)

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 8: XRF whole rock chemical analyses of igneous rocks

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JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 9: New collections of fossils from near Clarno, Wheeler County, Oregon

L685 Uppermost central "Nut Beds"

This is the original "Nut Beds" locality collected extensively by Thomas Bones, conglomerates forming a bench on top of the central outcrop of the Clarno "nut beds", 0.5 miles northwest of Hancock Field Station, near Clarno (NE1/4 SE1/4 SE1/4 SW1/4 Sect 27, T7S R19E, Clarno 7.5' Quad., UTM zone 10 702738E 4977378N). The central outcrop of the "Nut Beds" is defined by two gullies which divide this exposure of indurated conglomerates and sandstones from similar exposures to the south and north along strike. This locality continues to yield in surface debris and would produce well with quarrying, but yields have always been low. This fossiliferous conglomerate is at a stratigraphic level of 62 m in the master section of Clarno Formation measured here, and is in the "Nut Beds" of the Clarno Formation and of Middle Eocene (Bridgerian-Uintan) age.

Juglans clarnensis: fruit (P9385A,B=JODA3800)

L743 "Slanting leaf beds"

This locality for fossil leaves of the so-called "Bridge Creek flora" is often visited by campers at Hancock Field Station, and is on Maurer's Ranch below Iron Mountain, near Clarno (SE1/4 NE1/4 SE1/4 SE1/4 sect. 22 T7S R19E Clarno 7.5' Quad., UTM zone 10 703435E 497946N). It is a prominent band of white lacustrine shales forming the brow of a ridge low in the foothills of Iron Mountain, reached by foot trails to 1.5 miles north of Hancock Field Station. This large exposure should produce fossils indefinitely. The preservation is of impressions only, and specimens in most layers are limited in size by extensive jointing of the rock. This is in the middle Big Basin Member or Member F of the John Day Formation, of early Oligocene (Orellan) age. Metasequoia occidentalis: foliar spur (P6172=JODA3849) Alnus heterodonta: leaf (P6172=JODA3841, P11397A,B=JODA3838)

Crataegus merriami: leaf (P6728=JODA3839)

Folindusia sp.: caddis fly case (P9587=JODA3819)

Novumbra oregonensis: fish (P8155A,B=JODA3848)

L748 Middle central "Nut Beds"

This locality in the central outcrop of the Clarno "Nut Beds" is a band of cherty siltstone with remains of fossil horsetails in place of growth 2 m above the basal excavation, 0.5 miles northwest of Hancock Field Station, near Clarno (NE1/4 SE1/4 SE1/4 SW1/4 Sect 27, T7S R19E, Clarno 7.5' Quad., UTM zone 10 702741E 4977378N). The central outcrop of the "Nut Beds" is defined by two gullies which divide this exposure of indurated conglomerates and http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/app9.htm[4/18/2014 12:21:13 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Appendix 9)

sandstones from similar exposures to the south and north along strike. This layer forms an attractive field display in the central part of the outcrop, where sampling should be discouraged, but it can be collected at several places along its 150 m of strike. The fossil horsetails are rooted in Luquem paleosols. This is at 54 m in the master section, and in the "Nut Beds" of the Clarno Formation, of middle Eocene (Bridgerian-Uintan) age.

Equisetum clarnoi: stem (P9748=JODA3850)

L750 South "Hancock Tree"

This locality on the southern side of the gully across from the "Hancock Tree", a prominent permineralized trunk within a lahar, in a tributary of Hancock Canyon, but from the southern side of the gully across from the fossil tree, 0.6 miles northeast of Hancock Field Station (NW1/4 SE1/4 SW1/4 NW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad., UTM zone 10 704008E 4978149N). This is a bed of cherty siltstone that crops out beneath the lahar, and represents the leaf litter of the Patat paleosol in which the "Hancock Tree" is rooted. The fossil leaf-bearing horizon is thin and has been sampled at only a few places, but has thick overburden that limits ease of quarrying. This locality is probably correlative with locality L1756, which is at 38 m in the master section, in the "lahars of Hancock Canyon" of the Clarno Formation, of middle Eocene (Bridgerian-Uintan) age.

Macginitea angustiloba: leaf (P6274=JODA3851)

L775 "Mammal Quarry"

This large quarry was excavated primarily between 1955 and 1959 by Lon Hancock, Arnold Shotwell and Malcolm McKenna, and from 1969-1972 by teams from the Oregon Museum of Science and Industry. The weathered quarry now and forms a large (50x50 m) depression in the upper part of a gully 0.8 miles north of Hancock Field Station (SW1/4 NW1/4 NE1/4 NE1/4 SW1/4 Sect. 27 T7S R19E Clarno 7.5' Quad., UTM zone 10 703283E 4978117N). The quarry is at the end of a vehicular track and along the main foot trail from Hancock Field Station to the "Slanting Leaf Beds" (locality L743). Fossil bones were found within a 1 m thickness of grey to olive siltstones between calcareous conglomerates of the quarry floor and olive siltstones of the weathered and slumped quarry face. Jennifer Pratt reopened the quarry in 1987 and found additional material in place. Further excavation would be worthwhile as the overburden is only about 3-4 meters of soft claystones that are easily moved. The specimen collected for this work was found loose in the debris pile east of the excavation. This horizon correlates to a stratigraphic level of 122 m in the master section, and is in the "Mammal Beds" of the uppermost Clarno Formation, of late Eocene (Duchesnean) age.

Diplobunops sp.: partial molar (P8248=JODA3852)

L977 Upper central "Nut Beds"

This locality is the base of the cliff-forming conglomerate that caps the central outcrop of the Clarno "Nut Beds", 0.5 miles northwest of Hancock Field Station, near Clarno (NE1/4 SE1/4 SE1/4 SW1/4 Sect 27, T7S R19E, Clarno 7.5' Quad., UTM zone 10 702741E 477328N). The upper portion of this conglomerate bed is locality L685, and the productive conglomerate layer is about 1 m above the layer of L748. The basal 0.5 m of this conglomerate is full of permineralized wood, fruits and seeds in a jumbled arrangement. The surface is well picked over by collectors, but loosened blocks sometimes still yield worthwhile fossils. This locality is too steep and the rock too hard for a productive quarrying. This locality is at 67 m in the master section, and is in the "Nut Beds" of the Clarno Formation, of middle Eocene age (Bridgerian-Uintan)

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Juglans clarnensis: fruit (P10189A=JODA3853)

L1052 Hancock Canyon packrat midden

This small overhang full of packrat debris is at the base of the thick lahar entombing the "Hancock Tree", and 3 m northeast along the trail from the fossil tree, 0.6 miles northeast of Hancock Field Station (NW1/4 SE1/4 SW1/4 NW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad., UTM zone 10 704023E 4778148N). Only about 0.5 m3 of midden material is present in this small cave. The age of the material is probably middle Holocene (W.G. Spaulding personal communication, 1985).

Juniperus occidentalis: fragments in midden matrix (P9047=JODA3854)

L1099 Upper fern quarry

This extensive (100m long) quarry can be seen at a distance from abundant white blocks on the hillside above Hancock Canyon, between the two stock ponds, 0.4 miles northeast of Hancock Field Station, near Clarno (SW1/4 NW1/4 SW1/4 SW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad., UTM zone 10 703786E 497765N). The headwall of the quarry is formed by a thick white tuff that has buried fossil vegetation largely of ferns. This locality is for material in the uppermost Luquem paleosol dominated by ferns. A more diverse angiosperm-dominated flora is found in a Sayayk paleosol 40 cm below the tuff (L1755). Quarrying is becoming increasingly difficult because of the hardness of the rock and rapidly increasing depth of overburden. This quarry correlates to a level of 18 m in the master section and is in the "lahars of Hancock Canyon" of the Clarno Formation, of middle Eocene age (Bridgerian-Uintan)

Equisetum clarnoi: stem (P12130=JODA3802)

Saccoloma gardneri: fern (P12129A-D=JODA3807)

L1352 Lower Knox Ranch

This locality is a small roadcut revealing white leaf-bearing shale south of the road and 0.5 miles west of Knox Ranch, near Clarno (SW1/4 SW1/4 NW1/4 SE1/4 NE1/4 Sect. 20 T7S R20E Porcupine Butte 7.5' Quad., UTM zone 10 709315E 4976820N). The road to Knox Ranch leaves highway 218 along Pine Creek at the abandoned Pine Creek School building, some 2 miles east of the turnoff to Hancock Field Station. This outcrop is shaded by a large juniper tree. The fossil leaves are impressions only, but the fossils have pleasing coloration on the lacustrine white shale. This locality would repay additional collecting. This is in the middle Big Basin Member, of the lower John Day Formation of early Oligocene (Orellan) age.

Monocotyledonae sp. indet.: broad leaf (P9732=JODA3803)

Metasequoia occidentalis: foliar shoots (P9728A,B=JODA3808)

Alnus hollandiana: leaf (P9731=JODA3813)

Craigia oregonensis: fruit (P9729A,B=JODA3811, P9730=JODA3812)

L1353 Upper Knox Ranch

This locality is another roadcut south of the same road as L1352, but only 0.3 miles west of Knox Ranch, near Clarno (NW1/4 SE1/4 NW1/4 SE1/4 NE1/4 Sect. 20 T7S R20E Porcupine

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Butte 7.5' Quad., zone 10, UTM 709496E 4979926N). This is a more extensive outcrop higher in elevation, but at about the same stratigraphic level. The white shales here dip steeply east. The fossil leaf impressions here are white like their matrix, but well defined. This is in the middle Big Basin Member of the lower John Day Formation of early Oligocene (Orellan) age.

Metasequoia occidentalis: foliar shoot (P9741=JODA3814)

Pinus sp.: seed (P9738=JODA3814)

Alnus hollandiana: leaves (P9736=JODA3804)

"Tilia" circularis: leaf (P9740=JODA3810)

Acer osmonti: seed (P9739=JODA3805)

Craigia oregonensis: fruit (P9735A,B=JODA3809)

L1354 Knox Ranch north

This locality consists of outcrops of green tuffaceous sandstone in a gully draining a hill 0.5 miles north of Knox Ranch, near Clarno (SE1/4 NW1/4 NW1/4 SE1/4 SW1/4 Sect. 16 T7S R20E Porcupine Butte 7.5' Quad., UTM zone 10 710818E 4980885N). This is at an elevation of 3340' on a steep ridge that forms the northern boundary to the flat pastures accessible by a rough track northeast from the ranch-house. This ridge forms the northern boundary to the relatively flat terrain around the ranch-house. The green tuffaceous sandstone here is full of small aquatic snails. There also are common bones of very large fish, which although disarticulated, would repay further collecting. This is in the lower Turtle Cove Member of the lower John Day Formation, of late Oligocene (lower Arikareean) age.

Ammonitella lunata: snails (P9743A-J=JODA3855)

Lymnaea stearnsi: snails (P9744A-F=JODA3856)

L1358 "Whitecap Knoll"

This prominent knoll of red claystone is capped by a thick white tuff, and is in the rolling country of Maurer's Ranch between the "Mammal Quarry" (L775) and the "Slanting Leaf Beds" (L743), 1.2 miles northeast of Hancock Field Station, near Clarno (SE1/4 NW1/4 NE1/4 NW1/4 NW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad., UTM zone 10 703741E 4978852N). The knoll is east of the main foot trail between Hancock Field Station and the "Slanting Leaf Beds", but can be seen clearly from various points along the trail north of the ridge formed by the welded tuff of the basal John Day Formation. Only two fossils were found loose on the surface at the foot of the knoll. Considering their reddish staining but dark color, they are presumed to have come from the drab upper portion of the type example of the Luca paleosol exposed here. It is possible that they came from further upslope and higher in the formation, because the surface here is littered with small clasts of basalt from Iron Mountain. No other fossils have been found here and the potential for further discoveries is low. The tuff here has been dated by Carl Swisher at 38.2 Ma. This is in the lower Big Basin Member of the John Day Formation, of latest Eocene (Duchesnean) age.

Angiospermae gen. et sp. indet.: charcoalified wood (P9757=JODA3855)

Entelodontidae gen. et sp. indet.: portion of tusk (P9756=JODA3856)

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L1359 Southern "Nut Beds"

This is the southernmost exposure of the Clarno "Nut Beds" which have yielded most of the fossil vertebrates from this horizon, some 300 m south of the main "Nut Beds" locality (L685), 0.5 miles northwest of Hancock Field Station, near Clarno (SE1/4 SE1/4 SE1/4 SW1/4 Sect 27, T7S R19E, Clarno 7.5' Quad., UTM zone 10 702748E 4977295N). These cherty siltstones form a cliff here as in the main "Nut Beds" exposure. The fossil leaves are from a sequence of weakly developed Sayayk paleosols exposed in the lower part of the exposure, collected mainly from large bounders that have rolled down the slope here. These large boulders have been largely exhausted as a supply of complete leaves, but there is a potential to quarry here. As in the main excavation into the lower "Nut Beds", quarrying is made difficult by the hardness of the rock and by extensive jointing. This is at a level of 53 m in the master section, and is in the "Nut Beds" of the Clarno Formation, of middle Eocene (Bridgerian-Uintan) age.

Litseaphyllum sp. cf. "Laurophyllum" merrilli: leaf (P11528=JODA3832)

Diploclisia sp.: leaf (P11526=JODA3828)

Meliosma sp. cf. M simplicifolia: leaf (P11525=JODA3829)

L1541 Sorefoot Creek

This locality is in green badlands 300 m north of Sorefoot Creek and 200 m east of the John Day River, 3 miles north along its left bank from Clarno (SE1/4 SW1/4 NE1/4 NW1/4 NE1/4 Sect. 19 T7S R19E Clarno 7.5' Quad., UTM zone 10 69789E 4980244N). These mammal fossils, snails and trace fossils weathered out loose from green Xaxus paleosols in the gully between a green knoll and higher green spur here. The green beds overly red badlands in this area. This locality has been collected continuously by students from Hancock Field Station, but still yields useful fossils. This is in the basal Turtle Cove Member of the John Day Formation of late Oligocene (early Arikareean) age.

Edaphichnium sp. indet: earthworm chimney (P12141A,B=JODA3825)

Polygyra dalli (Stearns) Steams: shell (P10401=JODA3823)

Pallichnus sp. indet: dung beetle bolus (P12140A-E=JODA3824)

Perchoerus sp. indet.: molar (P12138=JODA3826)

Hypertragulidae gen. et sp. indet.: astragalus (P12139=JODA3827)

L1568 South "Whitecap Knoll"

This locality is a thin (4 cm) white volcanic ash cropping out as chips on the slope 100 m south of a prominent knoll of red claystone is capped by a thick white tuff (L1358), and is in the rolling country of Maurer's Ranch between the "Mammal Quarry" (L775) and the "Slanting Leaf Beds" (L743), 1.2 miles northeast of Hancock Field Station, near Clarno (SE1/4 SW1/4 NE1/4 NW1/4 NW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad, UTM zone 10 703752E 4978795N). Most of the few tuff bed fragments on the surface have been collected, and about half of them contained well preserved compressions of cones, fruits and leaves. The tuff bed lies within a sequence of dark brown shales with abundant fish scales and plant debris. Because of the abundance of material and the paucity of information about fossil floras at this straigraphic level, this locality deserves more extensive quarrying. This is in the lower Big Basin Member of the John Day Formation, of latest Eocene (Duchesnean) age.

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Metasequoia occidentalis: cone (P10482=JODA3857)

Palaeocarya clarnensis: fruit (P10481A,B=JODA3858)

Cruciptera simsoni: fruit (P10481A,B=JODA3859)

Viviparus sp.: snail (P11399=JODA3860)

Coleoptera sp. indet.: elytron (P10483=JODA3861)

L1650 Creek near "Hancock Tree"

This locality is in the north bank of the gully 10 m northwest of the "Hancock Tree", a prominent permineralized trunk within a lahar, in a tributary of Hancock Canyon, 0.6 miles northeast of Hancock Field Station (SW1/4 NE1/4 SW1/4 NW1/4 SW1/4 Sect. 26 T7S R19E, Clarno 7.5' Quad., UTM zone 10 704022E 4978148N). This locality is a Sayayk paleosol about 1 m lower stratigraphically than the paleosol in which the "Hancock Tree" is rooted. The leaves are found within a narrow zone as a leaf litter and some of the horsetails arch up into overlying beds as if infiltrated then overwhelmed with sediment. The matrix is an orange cherty siltstone and the fossils are stained reddish brown. This locality could sustain further collecting, but large scale quarrying would be limited by nearby walls of lahar. This level can be correlated to 28 m in the master section and is in the "lahars of Hancock Canyon" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Equisetum clarnoi: stems (P10887A=JODA3862)

Joffrea speirsii: leaf (P10884B=JODA3863)

Macginitea angustiloba: leaf (P10885E=JODA3864)

L1730 Uppermost Hancock Canyon

This locality is a small ledge of sandstone between lahars at the head of Hancock Canyon, 0.8 miles northeast of Hancock Field Station, near Clarno (SE1/4 NW1/4 SE1/4 NW1/4 NW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad., UTM zone 10 703984E 497288N). The locality is about 300 m north along the gully from the "Hancock Tree" (L750), and is at a stratigraphic level above the thick lahar than entombed the "Hancock Tree", and also above an overlying basalt flow. The fossil leaves form a leaf litter in the surface of a Sayayk paleosol between lahars. The leaves form a matlike accumulation within a thin seam in the cliff face and prospects for further collection and quarrying are limited. This locality can be correlated to 66 m in the master section, and is in the "lahars of Hancock Canyon" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Alnus clarnoensis: leaf (P11462=JODA3833)

Meliosma sp.: leaf (P11462=JODA3834)

L1731 Spur of Hancock Canyon

This locality is within the thick (11 m) lahar forming south-facing outcrops in a spur 0.5 miles northeast of Hancock Field Station, near Clarno (NW1/4 NW1/4 SW1/4 NW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad., UTM zone 10 703908E 4978047N). This thick lahar is the same one entombing the "Hancock tree" (L750). A single leaf impression was found 1 m above the base of the lahar and was the only fossil found in this area, so potential for other fossils is very low. The fossil is a fragmentary impression preserved with some relief,

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presumably because of curling of a dry leaf from a leaf litter. This locality correlates to a level of 31 m in the master section. It is in the "lahars of Hancock Canyon" of the Clarno Formation, of middle Eocene (Bridgerian-Uintan) age.

Macginitea angustiloba: leaf (P11463=JODA3830)

L1732 East "Hancock Tree"

From a low overhanging lahar bed within the main portion of Hancock Canyon 0.7 miles northeast of Hancock Field Station, near Clarno (NE1/4 NW1/4 NW1/4 NE1/4 SW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad., UTM zone 10 704147E 4978086N). This locality is in the main portion of Hancock Canyon before the tributary gully that leads to the "Hancock Tree" (L750), which is 200 m to the west. Leaves can be found on the sole of the lahar which forms an overhang about 20 m above the base of the gully. This lahar is stratigraphically above the thick lahar that entombed the "Hancock Tree" and the overlying basalt flow, and represents the last of the lahar beds here. The leaves are impressions only, and occur within a thin zone that was probably a leaf litter of a Sayayk paleosol. Because the layer is already the site of a cave and the productive layer is thin, potential for further collecting is limited. This locality can he correlated to a level near 66 m in the master section, and is in the "lahars of Hancock Canyon" of the Clarno Formation, of middle Eocene (Bridgerian-Uintan) age.

Alnus clarnoensis: leaf (P11464=JODA3801)

L1733 South "Hancock Tree"

This locality is high on a spur and is the source of a prominent landslide of blocks into Hancock Canyon, 0.5 miles northeast of Hancock Field Station, near Clarno (NE1/4 NW1/4 NW1/4 SW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad., UTM zone 10 704012E 4977968N). The locality is directly above a point in the main foot trail up Hancock Canyon almost blocked by several large boulders that fell from the high spur to the north. The productive layer is at the base of the same thick (11 m) lahar that entombed the "Hancock Tree" at an elevation of about 1800 feet. At this locality also are several permineralized stumps, including one showing spreading basal roots and the conspicuous rays of sycamore wood. Fossil leaf impressions are in a cherty siltstone parting and have the appearance of a fossil leaf litter in a Patat paleosol. These specimens were collected from boulders of the landslide here, and potential for further collection from this steep face is limited. This locality is correlative with locality L1756 in the master section at 38 m, and is in the "lahars of Hancock Canyon" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Cinnamomophyllum sp. cf. "Cryptocarya" eocenica: leaf (P11467=JODA3845)

Joffrea speirsii: leaf (P11465=JODA3831)

Macginitea angustiloba: leaves (P11466B=JODA3875, P11467=JODA3835)

L1753 Upper north "Hancock Tree"

This is from an overhang beneath the thick lahar entombing the "Hancock Tree", some 8 m northwest along the trail from the tree in this tributary gully of Hancock Canyon, 0.6 miles northeast of Hancock Field Station, near Clarno (SW1/4 NE1/4 SW1/4 NW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad, UTM zone 10 704023E 4978150N). This is not from the same paleosol in which the "Hancock Tree" is rooted, but from a Sayayk paleosol 25 cm above it. The leaves are compressions that form a thin zone and have the appearance of a fossil leaf litter. A few sizeable blocks could be pried out of this overhang, but the potential

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for further collecting is limited. This locality also is correlative with locality L1756 in the master section at 38 m, and is in the "lahars of Hancock Canyon" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Joffrea speirsii: leaves (P11662A=JODA3868)

Litseaphyllum presanguinea: leaves (P11665=JODA3867, P11667=JODA3869, P11668=JODA3870)

Alnus clarnoensis: leaf (P11663=JODA3865, P11664=JODA3866)

L1754 Lower north "Hancock Tree"

This is from a ledge beneath the thick lahar entombing the "Hancock tree", some 12 m northwest along the trail from the tree in this tributary gully of Hancock Canyon, 0.6 miles northeast of Hancock Field Station, near Clarno (SW1/4 NE1/4 SW1/4 NW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad., UTM zone 10 704023E 4978150N). This is from the same paleosol in which the "Hancock Tree" is rooted, and from the type Patat paleosol. The leaves are variably ferruginized compressions that form a thin zone and have the appearance of a fossil leaf litter. Because of overlying thick lahar, the potential for further collecting is limited. This locality also is correlative with locality L1756 in the master section at 38 m, and is in the "lahars of Hancock Canyon" of the Clarno Formation of middle Eocene (Bridgerian- Uintan) age.

Alnus clarnoensis: leaf (P11669=JODA3871)

L1755 Lower Fern Quarry

This extensive (100m long) quarry can be seen at a distance from abundant white blocks on the hillside above Hancock Canyon, between the two stock ponds, 0.4 miles northeast of Hancock Field Station, near Clarno (SW1/4 NW1/4 SW1/4 SW1/4 SW1/4 Sect. 26 T7S R19E Clarno 7.5' Quad., UTM zone 10 703786E 4977651N). The headwall of the quarry is formed by a thick white tuff that has buried vegetation largely of fossil ferns (L1099). This locality is for a more diverse angiosperm-dominated flora found in a Sayayk paleosol 40 cm below the tuff. Quarrying is becoming increasingly difficult because of the hardness of the rock and rapidly increasing depth of overburden. This quarry correlates to a level of 18 m in the master section and is in the "lahars of Hancock Canyon" of the Clarno Formation, of middle Eocene age (Bridgerian-Uintan)

Joffrea speirsii: leaf (P11671=JODA3872)

Quercus sp.: leaf (P12132A,B=JODA3818)

Cinnamomophyllum sp. cf. "Cryptocarya" eocenica: leaf (P11670=JODA3873, P11974=JODA3847, P12131=JODA3820)

Goweria dilleri: leaf (P11671=JODA3874, P11974=JODA3846)

L1756 "Nut Beds" trench

This locality was found in a long stratigraphic trench in the slope below the southern outcrop of the "Nut Beds" (L1395), some 300 m south of the main "Nut Beds" locality (L685), 0.5 miles northwest of Hancock Field Station, near Clarno (SE1/4 SE1/4 SE1/4 SW1/4 Sect 27, T7S R19E, Clarno 7.5' Quad., UTM zone 10 702782E 4977306N). The locality is no longer exposed because the trench was filled. It is located directly beneath a thick lahar that crops

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out poorly, but does create a somewhat steeper hillslope. A better guide to this locality is its position 2m above a distinctive white tuff with small (cm size) angular black stones that form a lag deposit on the badlands slopes near the base of the exposures here. The leaves are impressions in a sandstone surface of a Patat paleosol. This locality would repay quarrying as the overburden is soft, and the collection includes an interesting mix of temperate and tropical elements. This is at a stratigraphic level of 30 m in the master section, and is in the "lahars of Hancock Canyon" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Magnolia sp. cf. M. leei: leaf (P11678=JODA3876)

Macginitea angustiloba: leaf (P11676=JODA3877) Juglans sp.: leaf (P11675A,B=JODA3878)

Meliosma sp. cf. M. simplicfolia: leaves (P11677A,B=JODA3879)

L1757 Lower "Black Spur" trench

These fossils were found in a trench excavated into claystones and coal measures on the south facing hillside below a prominent basalt flow of "Black Spur" and above the underlying porphyritic andesite intrusion, 0.5 miles northwest of Hancock Field Station, near Clarno (NW1/4 SW1/4 NW1/4 SW1/4 SE1/4 Sect. 27 T7S R19E Clarno 7.5' Quad., UTM zone 10 703112E 497736N). The locality is 100 m to the north and above the foot trail from Hancock Field Station to the mammal quarry (L775). It is no longer exposed because the trench was filled. It is 13 m stratigraphically above the underlying intrusion and 14 m below the overlying columnar-jointed basalt flow. These leaves were found in the underclay to the thickest (60 cm) of several seams of lignite, here designated as Cmuk paleosols. The leaves were impressions only, but this locality holds promise like no other in the Clarno Formation for preservation of cuticles. This locality may correlate to somewhere near 28 m in the master section, and is in "lahars of Hancock Canyon" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Graminophyllum sp.: leaf (P11680A,B=JODA3880)

Litseaphyllum presanguinea: leaf (P11681=JODA3881)

Meliosma sp. cf. M simplicfolia: leaf (P11679=JODA3882)

L1758 Upper "Black Spur" trench

These fossils were found in a trench excavated into claystones and coal measures on the south facing hillside below a prominent basalt flow of "Black Spur", 0.5 miles northwest of Hancock Field Station, near Clarno (NW1/4 SW1/4 NW1/4 SW1/4 SE1/4 Sect. 27 T7S R19E Clarno 7.5' Quad., UTM zone 10 703118E 497732N). The locality is 150 m to the north and above the foot trail from Hancock Field Station to the mammal quarry (L775). It is no longer exposed because the trench was filled, but is 1 m stratigraphically below the scoriaceous base of the overlying basalt flow. These root-like markings were found in a weakly bedded white claystone bed, that appears to be a Pasct paleosol developed on a lacustrine shale. Only fragmentary plant remains were found and all are preserved as impressions only. This locality may correlate to somewhere near 38 m in the master section, and is in the "lahars of Hancock Canyon" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Tracheophyta gen. et sp. indet.: woody root traces (P11682=JODA3883)

L1759 Middle cave east Bat Barn

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This locality is on a knoll overlooking highway 218 in the hills north of an old barn frequented for the study of bats and owls, 0.8 miles southwest of Hancock Field Station, near Clarno (SW1/4 NW1/4 SW1/4 NW1/4 SW1/4 Sect. 34 T7S R19E Clarno 7.5' Quad., UTM zone 10 702406E 4976263N). The fossils are in a small overhang on the western brow of the rocky knoll. The leaf impression carne from a 20 cm thickness of siltstones overlying a Sayayk paleosol developed on a lahar. Potential for further collection is limited by overburden. Other localities very close at hand are L1854, L1855, and L1856, which are from different strata in and around the overhang. This siltstone has been eroded out to create the local overhang here. This locality correlates to 8 m or lower in the master section, and is in the "lahars of the Palisades" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Litseaphyllum praesanguinea: leaf (P11683=JODA3884)

L1760 Upper Palisades

This locality is in a gully of the Palisades, overlooking Indian Canyon and highway 218, 0.8 miles southeast of Hancock Field Station, near Clarno (SW1/4 SW1/4 SE1/4 NE1/4 SW1/4 Sect. 35 T7S R19E Clarno 7.5' Quad., UTM zone 10 705208E 496295N). This horizon is high in south-facing cliffs (elevation 1700') about 50 m west of the point where the cliff line changes orientation to east facing. Fossil leaf impressions are common in a thin seam of purple and green silstone at the top of a lahar. This is probably a leaf litter of a Sayayk paleosol. This locality correlates to 8 m or lower in the master section, and is in "lahars of the Palisades" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Alnus clarnoensis: leaf (P11684=JODA3885)

L1761 Lower north "Indian Maiden Knolls"

This locality is the base of an extensive overhanging lahar in the head of a gully draining west from "Indian Maiden Knolls", 0.6 miles southeast of Hancock Field Station, near Clarno (NW1/4 NW1/4 SW1/4 SE1/4 NW1/4 Sect. 35 T7S R19E Clarno 7.5' Quad., UTM zone 10 703942E 4926833N). This is the last lahar in this area and forms an extensive overhang surrounding the head of the steep gully south of "Equisetum Canyon" and north of a gully largely formed in andesite close to highway 218 to the south. This gully and the southerly gully give the appearance of a reclining woman when as viewed from the west, and thus the name "Indian Maiden Knolls". The fossil leaves are ferruginized impressions that form a foliar roof to the overhang, which has eroded a Sayayk paleosol. They can be collected from large blocks in the gully bed, but some larger overturned blocks covered with leaves make a spectacular display in place. Potential for further collection of this horizon is limited. Fossil leaves also occur up to 40 cm above this level in the lahar (as locality L1861). This locality may correlate to a level of 17 m in the master section. It is in the "lahars of the Palisades" of the Clarno Formation, middle Eocene (Bridgerian-Uintan) age.

Litseaphyllum sp. cf. "Laurophyllum" merrilli; leaf (P11988=JODA3886)

Cinnamomophyllum sp. cf. "Cryptocarya" eocenica: leaf (P11987=JODA3887)

Meliosma sp. cf. M. simplicfolia: leaf (P11986=JODA3888)

L1777 Iron Mountain

This locality is an area of badlands high on the western face of Iron Mountain, 3 miles north of Hancock Field Station, near Clarno (SW1/4 SW1/4 NE1/4 NW1/4 Sect 15 T7S R19E

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Clarno 7.5' Quad., UTM zone 10 702218E 497626 1N). The locality is at an elevation of 2900 feet. A single fossil collected is a sample of a large permineralized log, at least 1 m long and 60 cm in diameter, lying prone in a cherty tan Micay paleosol within the light brown claystones here. This level is above the basalts of Member F of the John Day Formation and below the Columbia River Basalts. It is from the Turtle Cove Member of the John Day Formation, and late Oligocene (lower Arikareean) in age.

Coniferales gen. et sp. indet.: permineralized wood (P11794=JODA3889)

L1854 Middle knoll east "Bat Barn"

This locality is on a knoll overlooking highway 218 in the hills north of an old barn frequented for the study of bats and owls, 0.8 miles southwest of Hancock Field Station, near Clarno (SW1/4 NW1/4 SW1/4 NW1/4 SW1/4 Sect. 34 T7S R19E Clarno 7.5' Quad., UTM zone 10 702406E 4976261N). These leaf impressions are from a low exposure of a 20 cm thickness of siltstones 2 m south along strike from the overhang on the eastern brow of the knoll (L1759), and perhaps 10 cm higher within the siltstones than at that locality. This is a weathered surface exposure of the siltstone suitable for extensive further quarrying. The siltstones overlie a Sayayk paleosol developed on a lahar. Other localities very close at hand are L1855, and L1856. This locality correlates to 8 m or lower in the master section, and is in the "lahars of the Palisades" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Cyathea pinnata: leaf (P11976=JODA3842) Magnolia leei: leaf (P11977=JODA3843)

Litseaphyllum sp. cf. "Laurophyllum" merrilli: leaf (P11978=JODA3840)

Macginitea angustiloba: leaf (P11975=JODA3844)

L1855 Upper cave east "Bat Barn"

This locality is on a knoll overlooking highway 218 in the hills north of an old barn frequented for the study of bats and owls, 0.8 miles southwest of Hancock Field Station, near Clarno (SW1/4 NW1/4 SW1/4 NW1/4 SW1/4 Sect. 34 T7S R19E Clarno 7.5' Quad., UTM zone 10 702406E 4976263N). These leaf impressions are from a sandy conglomerate seam in rocks forming the roof of the overhang, 20 cm above the stratigraphic level of fossiliferous silstones (L1759, L1854) that have weathered to form the overhang. These fossils are in a Sayayk paleosols and the potential for further collecting is limited. Another locality very close at hand is L1856. This locality correlates to 8 m or lower in the master section, and is in the "lahars of the Palisades" of the Clarno Formation of middle Eocene (Bridgerian- Uintan) age.

Goweria dilleri sp.: leaf (P11979A,B=JODA3890)

Meliosma sp. cf. M. simplicfolia: leaf (P11980=JODA3836, P11981=JODA3837)

L1856 Lower cave east "Bat Barn"

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difficult to collect within the recess of the overhang. This locality correlates to 8 m or lower in the master section, and is in the "lahars of the Palisades" of the Clarno Formation of middle Eocene (Bridgerian-Uintan) age.

Litseaphyllum praelingue: leaf (P11982=JODA3891)

L1857 Knoll north "Bat Barn"

This locality is high on the eastern face of a hill 300 m north of the abandoned barn frequented as a haunt of bats and owls, 200 north of highway 218 near the turnoff of the road leading south along the John Day River and 0.8 miles southwest of Hancock Field Station, near Clarno (SE1/4 NE1/4 SW1/4 NW1/4 NW1/4 SW1/4 Sect. 34 T7S R19E Clarno 7.5' Quad., UTM zone 10 702151E 4976417N). Leaf impressions are in a silty seam, representing the surface of a Sayayk paleosol, between thick lahars. It is probably the same horizon that yielded fossils on the knoll to the east (L1759, L1854, L1655, L1856) and correlated to 8 m or lower in the master section. Potential for further fossils is limited by steepness and thickness of overburden. This is from the "lahars of the Palisades" of the Clarno Formation, and is middle Eocene (Bridgerian-Uintan) in age.

Acer clarnoense: leaf (P11983A,B=JODA3892)

L1858 Upper "Equisetum Canyon"

This locality is blocks of siltstone on top of the last lahar, which forms a small waterfall in the upper part of the southern fork of "Equisetum Canyon", 0.7 miles east of Hancock Field Station, Clarno (SW1/4 SE1/4 SW1/4 NW1/4 NE1/4 NW1/4 Sect. 35 T7S R19E Clarno 7.5' Quad., UTM zone 10 703978E 4977174N). The fossiliferous horizon is a thin seam of leaf impressions in sandstones and siltstone capping the last lahar in this area. It represents a leaf litter of a Sayayk paleosol. The top of the waterfall exposes extensive bedding planes below the fossiliferous layer, which is amenable to quarrying here. This horizon can be correlated to a level of 18 m in the master section. It is in the "lahars of the Palisades" of the Clarno Formation, and is of middle Eocene (Bridgerian-Uintan) age.

Macginitea angustiloba: leaf (P11984=JODA3893)

L1859 Central "Equisetum Canyon"

This locality consists of large blocks littering "Equisetum Canyon" near the junction of its north and south forks, 0.4 miles east of Hancock Field Station, near Clarno (NW1/4 NE1/4 SW1/4 SE1/4 NW1/4 NW1/4 Sect. 35. T7S R19E Clarno 7.5' Quad., UTM zone 10 703804E 4977056N). The boulders show a spectacular array of leaf impressions within thin layers between lahar beds, here interpreted as leaf litters of Sayayk paleosols. The original position of the fossiliferous layer is in the walls of the canyon, at an elevation of about 1700', where collection is difficult because of steepness and thickness of overburden. The fallen blocks are a source of large slabs of museum display quality, although helicopter support would be needed to move them. This horizon probably correlates to 8 m or lower in the master section. It is in the "lahars of the Palisades" of the Clarno Formation, and is middle Eocene (Bridgerian-Uintan) in age)

Joffrea speirsii: leaf (P11985=JODA3894)

Goweria dilleri: leaf (P11985=JODA3895)

Juglans sp.: leaflet (P11985=JODA3896)

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L1860 Upper north "Equisetum Canyon"

This locality is a high bench formed by the highest lahar on the spur, northwest of "Equisetum Canyon", 300 m east of Hancock Field Station (SE1/4 SW1/4 NE1/4 NW1/4 NW1/4 Sect. 35 T7S R19E Clarno 7.5' Quad., UTM zone 10 703687E 4977222N). Fossil leaves are in silty beds of a Sayayk paleosol on top of the lahar that forms this high bench. The matrix is strongly jointed so that complete leaves are difficult to obtain, although the site would be easy to quarry. This locality correlates to about 55 m in the master section and correlates with the "Nut Beds" of the Clarno Formation of middle Eocene (Bridgerian- Uintan) age.

Equisetum clarnoi: stem (P12135=JODA3817)

Litseaphyllum praelingue: leaf (P12133=JODA3806, P12124=JODA3904)

Goweria dilleri: leaf (P12135=JODA3816)

L1861 Upper north "Indian Maiden Knolls"

This locality is an overhanging lahar in the head of a gully draining west from "Indian Maiden Knolls", 0.6 miles southeast of Hancock Field Station, near Clarno (NW1/4 NW1/4 SW1/4 SE1/4 NW1/4 Sect. 35 T7S R19E Clarno 7.5' Quad., UTM zone 10 703942E 4976833N). This is the last lahar in this area and forms an extensive overhang surrounding the head of the steep gully south of "Equisetum Canyon" and north of a gully largely formed in andesite close to highway 218 to the south. This gully and the southerly gully give the appearance of a reclining woman when viewed from the west, and thus the name "Indian Maiden Knolls". Fragmentary leaf impressions, often curled as if dry, can be collected from large blocks in the gully bed. Potential for further collection of this horizon is limited. Fossil leaves also occur up to 40 cm above the base of the lahar (which is locality L1761). This locality may correlate to a level of 17 m in the master section. It is in the "lahars of the Palisades" of the Clarno Formation, middle Eocene (Bridgerian) age.

Litseaphyllum sp. cf. "Laurophyllum" merrilli: leaf (P11990=JODA3897)

Diploclisia sp.: leaf (P11993=JODA3898)

Goweria dilleri: leaf (P11989=JODA3899)

Meliosma sp. cf. M. simplicfolia: leaf (P11991=JODA3900)

Juglans sp.: leaflets (P11992=JODA3901)

1873 Lower north "Equisetum Canyon"

This locality is a silty bed beneath a thick lahar on a knoll northwest of "Equisetum Canyon", 300 m east of Hancock Field Station, near Clarno (NE1/4 NW1/4 SW1/4 NW1/4 NW1/4 Sect. 35 T7S R19E Clarno 7.5' Quad., UTM zone 10 703627E 4977213N). The silty bed preserves a fossil leaf litter of leaves in a Sayayk paleosol beneath the massive lahar that forms the knoll here. The horizon is about 5 m below the top of the knoll and nearby locality L1860. I can be correlated to a level of about 50 m in the master section, or the "Nut Beds" of the Clarno Formation, of middle Eocene (Bridgerian) age.

Goweria dilleri; leaf (P12173=JODA3902)

Meliosma sp. cf. M. simplicifolia: leaf (P12174=JODA3903)

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Note: Place names and rock units in quotation marks have not been approved by the U.S. Geological Survey, and are names informally proposed here or in wide use at Hancock Field Station. These collections are not comprehensive, and of a reconnaissance nature only, representing no more than an hour or so of collecting at each. Some localities, such as the "Nut Beds" (L685, L977), "Mammal Quarry" (L775) and "Slanting Leaf Beds" (L743), have yielded large collections of fossils beyond those reported here, and now housed in the Condon Collection of the University of Oregon, Florida State Museum, University of California at Berkeley and John Day Fossil Beds National Monument.

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joda/bestland-retallack1/app9.htm Last Updated: 21-Aug-2007

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/app9.htm[4/18/2014 12:21:13 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Appendix 10)

JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 10: A checklist of middle Eocene (Bridgerian- Uintan) fossils in nut beds and lahars of the Clarno Formation near Clarno and paleosols in which they have been found

ASPERGILLIACEAE (wood-rotting fungi)

Cryptocolax clarnensis Scott: cleistothecia, hyphae (large spored dry rot) Cryptocolax parvula Scott: cleistothecia, hyphae (small-spored dry rot)

EQUISETALES (horsetails)

Equisetum clarnoi (Brown): stem, rhizome, cone (scouring rush) - Sayayk

FILICALES (ferns)

Cyathea (Hemitelia) pinnata (MacGinitie) Lamotte: leaves (bipinnate tree fern) - Sayayk Saccoloma gardneri (Lesquereux) Knowlton: leaves (large pinnate fern) - Luquem

CYCADALES (cycads)

Dioon sp.: leaf (cycad)

CONIFERALES (conifers)

Pinus sp. indet.: seed, wood, pollen (pine) Torreya sp. indet.: seed (nutmeg tree) Taxodiaceae gen. et sp. indet.: wood (redwood) Taxus sp. indet.: seed (yew)

GINKGOALES (maiden hair trees)

Ginkgo bonesi Scott et al.: wood, leaf (ginkgo)

MONOCOTYLEDONAE (palms and grasses)

Ensete oregonense Manchester & Kress: seed (bananalike herb) Graminophyllum sp. indet.: leaf (grass) - Cmuk Sabal bracknellensis (Chandler) Mai: seed (palmetto) Sabaljenkinsi Reid & Chandler: seed (palmetto) Sabalites eocenica (Lesa) Dorf: leaf, wood (as Palmoxylon) (palm)

MAGNOLIACEAE (magnolias)

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Liriodendroxylon multiporosum Scott & Wheeler: wood (tulip tree) Magnolia angulata Scott & Wheeler: wood, leaf, seed (New World magnolia) Magnolia leei Knowlton: leaf (bigleaf magnolia) - Patat, Sayayk Magnolia longiradiata Scott & Wheeler: wood, seed (Asiatic magnolia) Magnolia spp. indet.: seeds (magnolias)

ANNONACEAE (custard apples)

Annonaspermum cf. A. pulchrum Reid & Chandler: seed (custard apple) Annonaspermum spp. indet: seed (custard apples)

SCHISANDRACEAE (schisandras)

Schisandraceae gen. et sp. indet: seed

LAURACEAE (laurels)

Cinnamomophyllum sp. cf. "Cryptocarya" eocenica Hergert: leaf (nutmeg) - Sayayk, Patat Laurocarpum spp.: seeds (extinct laurels) Lindera sp. indet.: seeds (wild allspice) Litseaphyllum praelingue (Sanborn) Wolfe: leaf (avocadolike laurel) - Sayayk Litseaphyllum presanguinea (Chaney & Sanborn) Wolfe: leaf (silverballi) - Sayayk, Cmuk Litseaphyllum sp. cf. "Laurophyllum" merrilli Chaney & Sanborn: leaf (extinct laurel) - Sayayk Ulminium scalariforme Scott & Wheeler: wood (laurel wood)

MENISPERMACEAE (moonseeds)

Anamirta sp. indet.: fruit (fish berry) Atriaecarpum sp. indet: fruit (extinct moonseed) Calycocarpum sp.: fruit (North American vine) Chandlera lacunosa Scott: fruit (extinct hollowed moonseed fruit) Daviscarpum sp.: fruit (extinct moonseed) Diploclisia auriformis (Hollick) Manchester: fruit, leaf (Paleotropical vine) - Sayayk Eohypserpa sp. indet: fruit (extinct moonseed) Odontocaryoidea nodulosa Scott: fruit (extinct nodular moonseed fruit) Palaeosinomenium venablesii Chandler: fruit (extinct moonseed) Tinospora spp.: fruit (Indomalesian tropical vine) Tinomiscoidea sp. indet: fruit (extinct moonseed) Menispermaceae gen. et spp. indet.: fruits (extinct moonseeds)

TROCHODENDRACEAE

Trochodendron becki (Hergert & Phinney) Scott & Wheeler: wood (Japanese vessel-less tree) Euptelea baileyana Scott & Barghoorn: wood (Japanese vessel-less shrub)

CERCIDIPHYLLACEAE (katsura)

Joffrea spiersii Crane & Stockey: fruit, wood (as Cercidiphyllum alalongum), leaf (as Cercidi-phyllum crenatum) (extinct katsura) - Sayayk, Patat

PLATANACEAE (sycamores)

Macginicarpa glabra Manchester: ovulate fruits, flowering heads (as Platananthus synandrus), anthers (as Macginistemon mikanoides), leaves (as Macginitea angustiloba), http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/app10.htm[4/18/2014 12:21:14 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Appendix 10)

wood (as Plataninium haydenii) (Clarno plane) - Sayayk, Patat Platanus sp.: fruit (sycamore)

HAMAMELIDACEAE (witch hazel family)

Hamamelidaceae gen. et sp. indet.: fruit

BETULACEAE (birches)

Alnus clarnoensis Klucking: leaf (alder) - Sayayk, Patat Betula clarnoensis Scott & Wheeler: wood (birch) Betulaceae gen. et sp. indet.: fruits (birch)

FAGACEAE (oaks)

Quercus palaeocarpa Manchester; leaf: acorn, wood (as Quercinium crystallifera) (oak) Castanopsis sp.: fruit, wood (as Fagaceoxylon ostryopsoides) (chestnut)

ACTINIDIACEAE (kiwi fruit family)

Actinidia sp.: seed (kiwi fruit)

THEACEAE (tea family)

Cleyera sp. indet.: fruit (cleyera)

SYMPLOCACEAE (lodh bark family)

Symplocus sp.: seed (lodh bark)

STERCULIACEAE (cocoa family)

Triplochitioxylon oregonensis Manchester: wood (whitewood) Chattawaya paliformis Manchester: wood (extinct pterospermumlike wood)

ULMACEAE (elms)

Aphananthe sp. indet.: fruit (Indomalesian tree) Cedrelospermum lineatum (Lesquereux) Manchester: fruit (extinct elm) Celtis sp. indet.: fruit (hackberry) Trema sp. indet.: fruit (guacimilla) Ulmaceae gen et sp. indet.: seed, wood, leaf

MORACEAE (figs)

Castilla sp. indet.: leaf, wood (as Ficoxylon) (fig)

FLACOURTIACEAE (West Indian boxwoods)

Saxifragispermum sp. indet.: seed (extinct dicot)

SAPOTACEAE (chicle family)

Bumelia spp.: seeds (neotropical hardwood)

SAXIFRAGACEAE (saxifrages and hydrangeas)

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Hydrangea sp. indet.: fruit (hydrangea)

LEGUMINOSAE (acacias)

Leguminicarpon sp. indet.: pod, wood (as Tetrapleuroxylon) (African legume wood)

NYSSACEAE (tupelos)

Nyssa spatulata (Scott) Manchester: seed (extinct tupelo) Nyssa spp.: seeds (tupelos)

ALANGIACEAE (alangiums)

Alangium oregonensis Scott & Wheeler: wood, fruit (alangium) Alangium sp.: fruit (alangium)

CORNACEAE (dogwoods)

Cornus sp. indet: fruit (dogwood) Langtonia bisulcata Reid & Chandler: fruit (extinct large fruit) Mastixia sp. indet.: fruit (Indomalesian dogwood) Mastixiocarpum sp. indet.: fruit (extinct dogwood) Mastixioidiocarpum oregonense Scott: fruit (extinct dogwood fruit)

ICACINACEAE (tropical vines)

Iodes multireticulata Reid & Chandler: seeds (Paleotropical vine) Iodes sp. indet.: seeds (Paleotropical vine) Goweria dilleri (Knowlton) Wolfe: leaf - Luquem, Sayayk Palaeophytocrene pseudopersica Scott: fruit (extinct discoid icacina vine fruit) Palaeophytocrene hancocki Scott: fruit (extinct large inflated icacina vine fruit) Pyrenacantha sp. indet.: fruit (Paleotropical vine) Icacinaceae gen. et spp. nov.: fruits and seeds

RHAMNACEAE (buckthorns)

Berhamnophyllum sp. indet.: leaf (buckthorn)

VITACEAE (grapes)

Ampelopsis sp. indet: seed (tropical climber) Ampelocissus spp. indet: seeds (tropical climber) Parthenocissus angustisulcata Scott: seed (Virginia creeper) Parthenocissus spp.: seeds (Virginia creeper) Vitis magnisperma Chandler: seed (grape) Vitis sp.: seed (grape)

STAPHYLEACEAE (bladdernuts)

Tapiscia occidentalis Manchester: seed (bladdernut)

SAPINDACEAE (soapberry family)

Deviacer sp. indet.: seed (soapberry) Palaeoallophyllus sp. indet: seed (tropical tree)

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SABIACEAE (aguacatilla)

Meliosma sp. cf. M. jenkinsii Reid & Chandler: seed (aguacatilla) Meliosma sp. cf. M. simplicifolia: leaf, wood, fruit (aguacatilla) - Sayak, Cmuk Meliosma spp.: seeds (aguacatilla) Sabia sp.: seed (sabia)

ACERACEAE (maples)

Acer clarnoense Wolfe and Tanai: leaf (maple) - Sayayk

BURSERACEAE (torchwoods)

Bursericarpum spp. indet.: fruit (torchwood)

ANACARDIACEAE (cashews)

Astronium sp. indet.: wood (kingwood) Pentoperculum minimus (Reid & Chandler) Manchester: fruit (extinct dicot) Rhus sp. indet: fruit (sumac) Tapiriria clarnoensis Manchester: wood (Neotropical tree)

JUGLANDACEAE (walnuts)

Cruciptera simsoni (Brown) Manchester: fruit (extinct four-lobed wingnut) - Sayayk, Patat cf. Hooleya lata Wing and Hickey: fruits, wood (as Clarnoxylon blanchardi Manchester & Wheeler) (extinct two-lobed wingnut) Juglans clarnensis Scott: fruit, leaf (Clarno black walnut) - Patat Palaeocarya clarnensis Manchester: fruit, wood (as Engelhardioxylon nutbedensis) (extinct three-lobed wingnut) Palaeoplatycarya sp.: fruit (extinct wingnut)

ARALIACEAE (ivy and ginseng family)

Araliaceae gen. et sp. indet.: seed (ivy)

RUBIACEAE (coffee and gardenia family)

Emmenopterys sp. indet.: seed (gardenia)

COLEOPTERA (beetles)

Buprestidae gen. et sp. nov.: beetle (wood borer)

CROCODYLIA (alligators)

Crocodylia gen, et sp. indet.: teeth (alligator)

CHELONIA (turtles)

Hadrianus sp. indet.: carapace fragments (box turtle)

EQUIDAE (horses)

Orohippus major Marsh: teeth (small four-toed horse)

BRONTOTHERIIDAE (extinct titanotheres)

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Telmatherium sp. indet.: teeth (large hornless titanothere)

HELATETIDAE (extinct tapirs)

Hyrachyus eximius Leidy: teeth (small cursorial rhinolike tapir)

OXYAENIDAE (catlike extinct carnivores)

Patriofelis ferox Marsh: teeth (lionlike carnivore)

Note: Sources of names are Chaney (1937), Scott (1954, 1955, 1956), Klucking (1956), Scott and Barghoorn (1955), Hergert, 1961; Scott and others (1962), Gregory (1969), Brown (1975), Manchester (1977, 1979, 1980a, 1980b. 1981, 1983, 1986, 1987, 1988, 1991, 1994), Bones (1979), Scott and Wheeler (1982), Crane and Stockey (1985), Wolfe and Tanai (1987), C.B. Hanson (personal communication, 1990), Retallack (1991a), and Manchester and Wheeler (1993), and Manchester and Kress (1993). This list does not include 74 additional problematic fruits and seeds of uncertain familial affinities listed by Manchester (1994).

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joda/bestland-retallack1/app10.htm Last Updated: 21-Aug-2007

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/app10.htm[4/18/2014 12:21:14 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Appendix 11)

JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 11: A checklist of late Eocene (early Duchesaean) fossils in the mammal quarry of the upper Clarno Formation near Clarno and paleosols in which they are found

MENISPERMACEAE (moonseeds)

Diploclisia sp.: fruit (Indomalesian moonseed) Eohypserpa sp. indet.: fruit (extinct moonseed) Odontocaryoidea nodulosa Scott: fruit (extinct nodular moonseed fruit)

PLATANACEAE (sycamores)

Platananthus synandrus Manchester (for "angiosperm incertae sedis" of McKee, 1970): flowering head (Clarno plane)

CORNACEAE (dogwoods)

Mastixioidiocarpum oregonense Scott: fruit (extinct tropical dogwood)

ALANGIACEAE (alangium family)

Alangium sp. indet.: fruit (alangium)

ICACINACEAE (tropical vines)

Iodes sp. indet.: seed (Paleotropical vine) Jodicarpa sp. indet.: fruit (extinct icacina vine) Palaeophytocrene sp. cf. P. foveolata Reid and Chandler: fruits (extinct icacina vine)

VITACEAE (grapes)

Ampelocissus sp: seed (tropical climber) Vitis sp.: seed (grape) Tetrastigma sp.: seed (Indomalesian vine)

JUGLANDACEAE (walnuts)

Juglans clarnensis Scott: fruits (Clarno black walnut)

ANACARDIACEAE (cashew family)

Pentoperculum minimus Reid & Chandler: seed (extinct cashewlike plant)

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CROCODYLIA (alligators)

Pristichampsus sp. indet.: skull (land alligator)

HYAENODONTIDAE (extinct carnivores)

Hemipsalodon grandis: skull (large bearlike carnivore)

FELIDAE (cats)

Nimravinae gen. et sp. indet.: skull (sabre-tooth cat)

RODENTIA (rats and mice)

Rodentia gen et sp. indet.: tooth (extinct squirrellike rodent)

ANTHRACOTHERIIDAE (extinct river hogs)

Heptacodon sp. indet.: teeth (small river hog)

AGRIOCHOERIDAE (early oreodons)

Diplobunops sp. indet.: skull (fanged oreodon)

AMYNODONTIDAE (extinct rhinos)

Procadurcodon sp. indet.: skull (large tapirlike rhino)

RHINOCEROTIDAE (rhinoceroses)

Teletaceras radinskyi Hanson: skull, limbs (small hornless rhino)

HELATETIDAE (extinct tapirs)

Plesiocolopirus hancocki (Radinsky) Schoch: teeth (tapir)

TAPIRIDAE (tapirs)

Protapirus sp. indet.: teeth (tapir ancestor)

EQUIDAE (horses)

Epihippus gracilis Marsh: teeth (three-toed horse) Haplohippus texanus McGrew: teeth (four-toed horse)

PISCES (fish)

Pisces gen. et sp. indet.: bones, scales (freshwater fish)

Note: Sources of names from Russell (1938), McKee (1970), Mellett (1969), Hanson (1973, 1989), Pratt (1988), Schoch (1989), Retallack (1991a), Lucas (1992) and Manchester (1994).

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http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/app11.htm[4/18/2014 12:21:15 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Appendix 11)

joda/bestland-retallack1/app11.htm Last Updated: 21-Aug-2007

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/app11.htm[4/18/2014 12:21:15 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Appendix 12)

JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

APPENDIX 12: A checklist of late Eocene (late Duchesaean) fossils in the lower John Day Formation near Clarno and paleosols in which they have been found

CONIFERALES (evergreens)

Metasequoia occidentalis (Newberry) Chaney: cone (dawn redwood)

ANGIOSPERMAE (flowering plants)

Angiospermae gen. et sp. indet.: wood (vessel bearing angiosperm) - Luca

ULMACEAE (elms)

Ulmus sp. indet.: leaf (elm)

JUGLANDACEAE (walnuts)

Cruciptera simsoni (Brown) Manchester: fruit (extinct four-lobed wingnut) Palaeocarya clarnensis Manchester: fruit (extinct three-lobed wingnut)

COLEOPTERA (beetles)

Coleoptera sp. indet.: elytron (small beetle)

GASTROPODA (snails)

Viviparus sp.: snail (freshwater snail)

PISCES (fish)

Pisces gen. et sp. indet. disarticulated scales and bones (freshwater fish)

ENTELODONTIDAE (extinct hogs)

Entelodontidae gen. et sp. indet.: tusk (large hog) - Luca

Note: Source of names is Getahun and Retallack (1991) and Manchester (1991).

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http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/app12.htm[4/18/2014 12:21:16 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Appendix 12)

joda/bestland-retallack1/app12.htm Last Updated: 21-Aug-2007

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/app12.htm[4/18/2014 12:21:16 PM] http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/app13.htm[4/18/2014 12:21:17 PM] http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/app14.htm[4/18/2014 12:21:18 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Glossary)

JOHN DAY FOSSIL BEDS

Geology and Paleoenvironments of the Clarno Unit John Day Fossil Beds National Monument, Oregon

GLOSSARY

acidic - with a low pH (<7), or abundance of hydronium ion (H+) in solution

aging upwards sequence - sedimentary succession including paleosols whose degree of development is generally stronger for paleosols higher within the succession than for those near the base

agglomeroplasmic - soil microfabric in which there is an incomplete or local fine-grained matrix to skeleton grains

agrotubule - tubular feature of soil filled with pellet-like clasts of and clastic grains

A horizon - surface horizon of a soil, commonly including organic matter

Albaqualf - kind of Alfisol that shows gley features and a sandy near surface horizon above the clayey subsurface horizon

albic horizon - light colored soil horizon characterized by less organic matter, less sesquioxides (Fe2O3 and Al2O3), or less clay than the underlying horizon. Its light color is due largely to quartz and feldspar.

Alfisol - fertile forest soil, with subsurface clayey, ferruginized or humic horizon

alkali elements - sodium (Na) and potassium (K)

alkaline - with a high pH (>7), and low activity of hydronium (H+) ions in solution

alkaline earth elements - calcium (Ca) and magnesium (Mg)

allophane - poorly ordered hydrous aluminum silicate

alluvial fan - large conical landform deposited by streams entering intermontane basins from narrow mountain valleys

alluvium - sedimentary deposits of rivers

alumina - aluminum oxide (Al2O3)

alveolar-septal structure - micromorphology of calcareous soils, with thin micritic compartments filled with sparry calcite, thought to form around fungi associated with roots

anaerobic decay - a metabolic reaction in which organic matter is broken down in the absence of oxygen into simpler compounds, including CO

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andesite - silica saturated volcanic rock, often porphyritic with large crystals commonly plagioclase and groundmass; characteristic of volcanic arcs associated with subduction zones

andic - with properties like that of an Andisol

Andisol - Inceptisol-like soils formed on volcanic ash, with low bulk density, high porosity and great fertility

anthropic epipedon - surface horizon of a soil altered by human activity, such as habitation

Ap horizon - A horizon disrupted by plowing or other comparable disturbance

Aqualf - kind of Alfisol with gley features

Aquent - kind of Entisol with gley features

Aquept - kind of Inceptisol with gley features

aquic - showing gley features

Aquod - kind of Spodosol with gley features

Aquoll - kind of Mollisol with gley features

Aquox - kind of Oxisol with gley features

Aquult - kind of Ultisol with gley features

aragonite - mineral with the same chemical composition as calcite, but a different crystal structure, primarily found in skeletons of molluscs

Arent - kind of Entisol, with surface layers mixed by plowing or other human activity

Argid - kind of Andisol with argillic or natric horizons

argillan - cutan consisting of clay

argillasepic - soil microfabric mainly of clay and lacking highly birefringent streaks when viewed in thin section under crossed nicols

argillic horizons - soil horizon of clay enrichment, recognized in the field by oriented clay films that coat either mineral grains, small channels or ped surfaces. Compared with eluvial horizons argillic horizons have 3% more clay if eluvial horizon clay is 10-15%, 12% more clay if eluvial horizon clay is 15-40%, or 8% more if eluvial horizon clay is 40-100%.

Argiustoll - kind of Ustoll with a clayey subsurface horizon

Andisol - desert soil, usually thin profiles, commonly with calcareous nodules or salt crystals within a meter of the surface

anthropod - phylum of jointed legged animals, such as insects, spiders, and crayfish

asepic - soil microfabric lacking highly birefringent streaks (plasma separations) when viewed under crossed nicols

atomic absorption spectrometry - method of chemical analysis using light absorption

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wavelengths of flaming aerosol of sample

backfill structure - sinuous or simply curved layering within the filling sediment of a burrow produced by movement of an animal

badlands - erosional landform of deeply gullied sedimentary rocks too unstable and in too dry a climate to support a cover of vegetation

basaltic rocks - rocks like basalt, that are rich in iron and magnesium, fined grained and generally produced as volcanic flows

base - principal cations of soil solutions (Ca2+, Mg2+, Na+, K+)

base saturation - percentage of the cation exchange capacity due to bases

basket podzol - locally thickened sandy subsurface (E or eluvial) horizon under an individual tree

bauxite - highly weathered material rich in aluminum, and poor in humus, silica and bases, consisting mainly of gibbsite or similar minerals

Bc horizon - B horizon with concretions or nodules

Bg horizon - B horizon with strong gleying

B horizon - subsurface horizon of soil, often enriched in clay or carbonate

billet - small sawn slab of rock used to prepare a petrographic thin section

bimasepic - sepic plasmic fabric with a network of highly birefringent streaks in two preferred directions

biofunction - mathematical relationship between soil features and soil biota

biosequence - set of soils formed under similar climate, topographic setting, parent material and time, but different vegetation or other organisms

bioturbated - mixed and moved by the burrowing, rooting and other activities of organisms

birefringence - iridescent appearance of minerals when viewed in a microscope under cross- polarized light

birnessite - poorly crystalline mineral of dark iron and manganese oxides

Bk horizon - B horizon with accumulation of carbonates, usually calcite nodules

blocky peds - a form of ped that is polygonal and nearly equant in shape

Bn horizon - B horizon with accumulation of sodium

bog - general term for wetland vegetation, used especially for vegetation of mosses

Bo horizon - B horizon with residual accumulation of sesquioxides

Bonalf - a kind of Alfisol of cool to cold climates

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Boroll - a kind of Mollisol of cool to cold climates

breccia - coarse grained rock with angular clasts

Bs horizon - B horizon with illuvial accumulation of sesquioxides

Bt horizon - B horizon with illuvial accumulation of clay

bulk density - a measure of mass in a given volume (grams per cubic centimeter); usually indicated by symbol ρ

burrow - tunnel or other excavation of a soil animal

butte - isolated hill or mountain with steep sides, usually having a smaller summit area than a mesa

Bw horizon - with colored or structural B horizon

By horizon - B horizon with accumulation of gypsum

Bz horizon - B horizon with accumulation of salts

calcareous - consisting largely of calcite

calciasepic - soil microfabric dominated by a mixture of clay and clay-sized carbonate, and lacking highly birefringent streaks when viewed in thin section under crossed nicols

calcic horizon - subsurface soil horizon enriched in calcite or dolomite in the form of coatings, wisps or nodules, and at least 15 cm thick with at least 5% more carbonate than underlying horizons.

calcification - soil building process of the accumulation of carbonate, usually as nodules in subsurface horizons

calcite - carbonate mineral (CaCO3)

calcrete - rock cemented with calcium carbonate

caliche - pedogenic calcium carbonate nodules or layers

cambic horizon - subsurface soil horizon with at least enough pedogenic alteration to eradicate some rock structure, form some soil structure, and remove or redistribute primary carbonate. Their color has higher chroma or redder hue than does the color of the underlying horizons.

capillary action - tendency of fluids to rise in a small cylinder due to surface tension

carbonaceous - with abundant organic matter

2- carbonate - common anion (CO3 ) in soil solution and component of carbonate minerals such as calcite and siderite and skeletons such as mollusc shells

carboxyl - common radical of organic acids (COOH+)

caries texture - soil microfabric in which grains are deeply embayed because of local

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dissolution or hydrolysis

carnivore - animal that eats meat

carr - wetland vegetation of trees with alkaline groundwater

cation exchange capacity - measure of a soils exchangeable cations (mainly H+, Al3+, Ca2+, Mg2+, Na+, K+), usually by displacement with ammonium chloride and titration for its abundance

catena - A sequence of soils developed from similar parent material under similar climatic conditions but whose characteristics differ because of variations in relief and drainage.

3+ 2+ celadonite - clay mineral {(K,Ca,Na)-1.6(Fe , Al, Mg, Fe )4Si7.3Al0.7O20(OH)4}

cement - fine grained binding substance that holds together rocks and firm parts of soil, typically silica or calcium carbonate

C horizon - subsurface soil horizon, excluding bedrock, with slightly more weathered material from which the soil formed or is presumed to have formed. Lacks properties of A and B horizons, but includes weathering as shown by mineral oxidation, accumulation of silica, carbonates or more soluble salts, and gleying.

chalcedony - microcrystalline quartz (SiO2)

chaparral - synonym of fireprone shrubland, used mainly in California

charcoal - charred wood

chelate - a chemical compound capable of transporting elements or compounds by means of a particularly favorable site of attachment (from Greek chela for claw)

2+ 3+ chlorite - clay like mineral {(Mg,Fe , Fe , Mn, Al)12[(Si,Al)8O20](OH)16}

chroma - purity of color, or degree to which a color is not masked by darkness or lightness in the Munsell system of color

Chromudert - a kind of Vertisol of humid seasonally dry climates, which has some horizons that are not black

chronofunction - mathematical relationship between soil features and the time over which they develop

chronosequence - set of soils formed under similar climate vegetation, topographic position and parent material but over varying lengths of time

clastic dike - crack in soil or sediment filled with contrasting material: silan in terminology of Brewer

clay skin - coating of clay along cracks or grains within a soil: argillan in terminology of Brewer

clinobimasepic - sepic plasmic farbic with a network of highly birefringent streaks in two preferred directions and at a low angle

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clinometer - device for measuring angular deviation from horizontal

coal - black carbon-rich rock formed by burial alteration of peat

coalification - process forming coal from peat by expulsion of volatile materials and enrichment in carbon due to heat and pressure of deep burial

colloid - material that is too fine grained to be visible under the optical microscope, includes soil iron stain and clay colluvium. Soil materials that accumulate on and at the base of slopes by gravitational action.

complex-response - Change of the bedload transport rate in a fluvial system in response to a single external perturbation.

compression - form of fossil preservation in which the organic remains of the fossil are crushed and coalified between bedding planes

concretion - glaebule with concentric internal fabric, usually because of periodic addition of material. These are hard, locally cemented lumps of material with onion-skin internal layering.

cone - ellipsoidal structure of helically arranged reproductive organs of plants, found in conifers, lycopods and clubmosses

coprolite - fossil feces

corestone - spheroidally weathered remnant of parent material, least weathered toward the center, and usually within the C horizon of deep weathering profiles

cornstone - pedogenic calcium carbonate nodules of paleosols

cover slip - thin glass cover glued on top of a petrographic thin section

Cretaceous - period of geological time about 146-65 million years ago

cross bedding - sedimentary layering that is inclined to regional layering, commonly due to the formation of dunes with slip-faces at an angle to the ground surface

crystal chamber - irregular nodular masses of crystals

crystallaria - single crystals or groups of crystals in soils

crystallinity - degree of perfection of crystal structure, free of defects or other less regular arrangement of chemical constituents

crystallite - small crystal, beyond the size resolvable by optical microscopy

crystic - a soil microfabric dominated by crystals

cuirasse - indurated hardpan or crust exposed at the surface, usually lateritic

cumulic horizon - soil horizon that shows bedding or other evidence that it is accumulating in a sedimentary fashion on top of the soil

cutan - modified surface within a soil, formed at surface of a ped channel, grain or other feature of the soil http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/glossary.htm[4/18/2014 12:21:20 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Glossary)

cuticle - tough, coating of hydroxy fatty acids and waxes that covers the leaves and other aerial parts of land plants

cutinite - a kind of exinite, formed from plant cuticles

Cv horizon - C horizon with plinthite

decalcification - soil-building process of leaching out carbonate from surface horizons

decarboxylation - chemical reaction removing carboxyl radical from organic matter

decomposition - decay, or breaking down of organic matter to simpler compounds such as carbon dioxide by decomposer microbes

dehydration - chemical reaction involving loss of water or hydroxyl

depth unction - common graphical presentation of chemical and petrographic data on soils and paleosols as a plot with one axis the depth from the surface of the profile

desert pavement - surface layer of stones, sometimes as closely interlocking as a cobblestone street

desert scrub - vegetation of widely scattered thorny shrubs and succulents such as cactus, with patches of bare ground

deviatoric - aligned in unpredictable and random directions

diagenesis - alteration of sediments after burial but before metamorphism: includes soil formation

diaspore - aluminum-rich mineral [AlO(OH)].

diffractogram - plot of the x-ray reflections produced for identification of minerals from an x-ray diffractometer

diffusion cutan - cutan formed by concentration at the surface of a material which becomes less prominent away from the surface for example the strong oxidation of the margins but not interior of peds

displacive fabric - a soil microfabric in which one mineral (usually calcite) fills cavities opened by the expansion or rotation of large clods of soil or the cracking out of clods or grains

dolomite - carbonate mineral (CaMg(CO3)2]

domed-columnar ped - ped in the form of a vertically-oriented prism, usually as thick as the whole B horizon and with its upper surface hemispherical: common in salt affected soils

drab-haloed root traces - root traces that are surrounded by soil of a gray and often also bluish or greenish color, compared with the yellow to red soil or paleosol away from the root trace

duricrust - hard cemented horizon of soil or deep weathering profile, includes laterite, bauxite, calcrete and silcrete

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duripan - subsurface soil horizon cemented firmly by clay and silica

Dystrochrept - kind of Ochrept soil that is very low in weatherable bases

ecosystem - the complex of a community and its environment functioning as a unit in nature

Eh - electrode potential (usually in millivolts): for soils a measure of the degree of oxidation of the soil. Oxidized soils have a high positive Eh and reduced soils have a low negative Eh.

E horizon - soil horizon underlying O or A horizon, characterized by less organic matter, less sesquioxides (Fe2O3 and Al2O3) or less underlying horizon. Its light color is due largely to quartz and feldspar. Also known as an eluvial or albic horizon.

eluvial horizon - soil horizon characterized by less organic matter, less sesquioxides (Fe2O3 and Al2O3), or less clay than the underlying horizon. Its light color is due largely to quartz and feldspar

endocarp - interior woody part of a seed or fruit coat of plants, also known as a pit or stone, as in cherries and peaches

endolithic microrelief - system of surface cavities formed by microbes living within and on rocks

endoskeleton - internal skeleton, as in mammals

energy dispersive x-ray spectrometry - method of chemical analysis using x-rays emitted from sample in scanning electron microscope (EDAX)

Entisol - very weakly developed soils, usually with abundant sedimentary, igneous or metamorphic relicts from their parent material

Eocene - epoch of geological time about 57-33 million years ago

Ephemeral Stream - A stream that flows only briefly in direct response to rainfall or snowmelt.

epidermis - outer covering of cells of a plant or animal

estuary - that part of a river mouth that is influenced by marine tides

Eutrochrept - kind of Ochrept rich in bases

evaporite - sedimentary rock that forms by the accumulation of the evaporation of water, includes rock salt and gypsum

exoskeleton - skeleton, as in arthropods

extinction angle - angular difference between the orientation of a crystal and the point at which it can no longer transmit polarized light as viewed in petrographic thin section under a microscope, useful for identifying minerals such as feldspars

facies - an informal an rock unit, usually designated by features thought to be significant for interpreting sedimentary paleoenvironment

factor-function approach - study of environmental control in the expression of soil features,

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can be used also to infer paleoenvironmental conditions from paleosols

fecal pellet - small ovoid to spherical feces produced by small animals

feldspar - group of minerals including microcline and plagioclase

fen - wetland vegetation of grasses and other herbs with alkaline groundwater

ferran - cutan consisting of sesquioxides of iron

ferric iron - iron in the Fe3+ valence state, usually within red or yellow minerals or compounds

ferrous iron - iron in the Fe2+ valence state, usually within gray to green minerals or compounds

ferruginous rhizoconcretion - rhizoconcretion cemented by goethite, hematite or other iron hydroxides or oxides

fibric peat - peat with abundant recognizable plant material, not completely decayed

Fibrist - kind of Histosol consisting largely of plant remains so little decomposed that their botanical origin can be determined

fibrous roots - numerous fine (usually less than 2 mm diameter) roots radiating from the base of a plant, as in palms and grasses

fining upwards sequence - sedimentary layer that varies toward smaller grain size from the bottom to the top

fireprone shrubland - closely spaced woody shrubs, less than 2 m tall adapted to frequent burning

fission tracks - Imperfections in minerals and volcanic glass caused by spontaneous fission of unstable atomic nucleus, which propels energy particles through surrounding material. The density of tracks is a function of numbers of atoms that have undergone fission, and thus also of age.

flocculation - aggregation into a coherent mass from fine suspended particles, as can happen to clay particles in turbid water with changes in salinity

floodplain - frequently flooded, low lying region flanking large rivers

fluorescence - emission of electromagnetic radiation usually as a response to absorption of another form of radiation

Fluvent - kind of Entisol, those formed on silt and clay with conspicuous relict bedding

fluvial - relating to rivers

Folist - kind of Histosol, freely-drained, consisting primarily of organic horizons derived from leaf litter, twigs and branches resting on rock, gravel or boulders, the interstices of which are filled with organic material

footslope - lower convex part of a hill slope, between steeper backslope and more level

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toeslope

foraminfer - marine microorganisms that secrete or manufacture a small shell

forb - herbaceous plant other than grasses, found typically in rangeland

forest - vegetation of closely spaced trees more than 8 m tall

formation - The most fundamental local, rock division of stratigraphic classification, which has some distinctive homogeneity of lithology (color, texture, fossil content, etc.); generally named formally for some geographic locality (e.g. John Day Formation for the John Day region of Oregon).

fragipan - A hard and brittle subsoil horizon commonly cemented with amorphous silica and/or aluminum.

framboid - minute (10 microm to 1 mm diameter) round spherules or groups of spherules of pyrite, usually produced by anaerobic bacteria

freeze-thaw banding - structure of cracks and silty seams in pattern of brickwork, produced by frost heaving of soils

friable - easy to break into constituent grains: opposite of cemented or indurated

ganister - silicified sandstone, commonly containing root traces and underlying a coal seam. These are in most cases paleosol E or eluvial horizons.

geothermal gradient - variation in temperature of the Earth with depth into the crust

gibbsite - mineral rich in aluminum [Al2(OH)3]

gilgai microrelief - soil surface of ridges and swales or potholes produced by the shrinking and swelling of Vertisols

glaebule - segregations of materials distinct from other parts of the soil, including nodules, concretions, and septaria

gleization - process of gley formation

gley - soil that is blue-gray or green-gray colored, strongly mottled or with abundant iron- manganese nodules, usually due to waterlogging, but sometimes produced also by burial

glossic features - locally penetrating tongues or tubes of light-colored sandy material deep within a soil profile

glycolation - experimental, treatment of clays by exposure to open container of ethylene glycol at 80°C for 4 hours, used to study expansion of smectite clays

goethite - yellow to brown iron hydroxide mineral Fe2O3•H2O)

graded bed - sedimentary bed that varies in gram size from the bottom to the top of the bed. Normally graded beds are finer grained to the top, and inversely, graded beds are coarser grained toward the top.

granotubule - tubular feature of soil filled with clastic grains and little clay

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granular microfabric - soil microfabric in which skeleton grains are touching with little or fine grained matrix in the interstices

granular ped - a form of ped or clod that is small and rounded

grassland - vegetation of mainly grasses

"Green Clay" - kind of paleosol I found in Precambrian rocks, with unusual combination of indications of deep weathering (corestones, cracks) and gley colors (green gray with chemically reduced iron minerals)

groundwater calcrete - calcrete formed by precipitation of carbonate cement from groundwater

groundwater gley - gley features formed by the ponding of groundwater from an elevated water table

groveland - vegetation of clumps of trees separated by open grassland

guano - excrement of birds and bats

gypsic horizon - subsurface soil horizon with accumulation of gypsum

gypsum - evaporite mineral (CaSO4•2H2O)

hackly - having the appearance of something chopped or cut up

Haplaquept - typical Aquept, lacking distinguishing features of other kinds of Aquepts

Haplohumult - typical Humult, lacking distinguishing features of other kinds of Humults

Haplorthod - typical Orthod, lacking distinguishing features of other kinds of Orthod

Haploxerand - typical Xerand, lacking an especially dark surface horizon

Hapludalf - typical Udalf, lacking distinguishing features of other

Hapludoll - typical Udoll, lacking distinguishing features of other kinds of Udolls

Haplustalf - typeical Ustalf, lacking distinguishing features of other kinds of Ustalfs

Haplustoll - typical Ustoll, lacking distinguishing features of other kinds of Ustolls

halite - mineral of desert soils (NaCl)

halloysite - hydrated form of kaolinite

Harden index - quantitative measure of the degree of soil development, calculated by addition of scores for a variety of soil features thought to vary with time of formation

hardpan - A soil horizon cemented with silica, sesquioxides, calcium carbonate or organic matter.

hematite - red iron oxide mineral (Fe2O3)

hemic peat - peat in which some but not all of the plant material is so decayed as to be

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unrecognizable

Hemist - a kind of Histosoll in which organic matter is decomposed to the extent that as much as two-thirds of the plant material is unidentifiable

herbivore - animal that eats plants

histic epipedon - peat: a soil surface horizon with at least 18% organic matter if the mineral fraction contains more than 60% clay or 12% organic matter if the mineral fraction has no clay, for a depth of 20 cm.

Histosol - soil with peaty surface, which must be at least 40 cm thick if composed mainly of woody material

Holocene - epoch of geological time from 10,000 years ago to present

2+ 3+ hornblende - a mineral of igneous and metamorphic rocks [(Na,K)0-1Ca2(Mg,Fe ,Fe , Al)5Si6-7.5Al2-0.5O22(OH)2]

hue - color, such as red, yellow or green, independent of lightness or darkness of the color, in the Munsell system of color classification

Humult - kind of Ultisol with a surface horizon rich in organic matter

humus - The well-dcomposed, relatively stable part of the organic matter found in aerobic soils.

hydrocarbon - compound mainly of hydrogen and carbon, including methane and paraffin

hydrolysis - common weathering reaction in soil solutions, converting aluminosilicate minerals to clay and cations in solution

hydronium - hydrogen ion (H+)

hydrothermal - related to groundwater of elevated temperature, commonly associated with volcanic activity

hydroxide - compound including hydroxyl

hydroxyl - chemical anion (OH-)

ice wedge - vertical wedgelike disruption of a soil filled with horizontally layered material after melting of the ice that created it

ichnogenus - formal taxonomic category for a specific kind of trace fossil, similar to a genus of biological classification

ICP - inductively-coupled plasma emission spectrometry

illite - potassium-rich clay mineral {K1.5-1.0Al4[Si6.5-7.0Al1.5-1.0O20](OH)4}

illitization - common process during deep burial that converts smectite clays to illite

illuvial horizon - soil horizon enriched in clay by illuviation

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illuviation - soil building process of enrichment of clay washed in from higher horizons

illuviation cutan - cutan formed by washing down of material from higher within a soil

impression - form of fossil preservation in which only an outline of the fossil remains with none of the original organic material

INAA - instrumental neutron activation analysis

Inceptisol - soils with some weathering and incipient development of a variety of different kinds of horizons, but none well-enough developed that the soil could be identified with another order

incisor - front tooth of mammals, greatly elongated in rodents

indurated - firm, hard, cemented

insepic - sepic plasmic fabric with small isolated patches of highly birefringent plasma

intercalary crystal - single crystal embedded in soil matrix

interstratified clays - clays with crystal layers of differing chemical composition

intertextic - soil microfabric in which skeleton grains are more prominent than fine grained matrix, which forms intergranular braces and fills local pockets

inundulic - soil microfabric similar to undulic, but cloudy, with large irregular isotropic patches which appear dark when viewed under crossed nicols

isotic - soil microfabric that is dark when viewed under crossed nicols because either isotropic, like opal, or opaque, like hematite

isotope - alternative forms of a chemical element that differ slightly in mass and sometimes also in other properties. Common isotopes of carbon are the very heavy radiogenic isotope 14C used for carbon dating, and the stable isotopes 13C and 12C.

isotopic dating - Mineral or rock dating using radioactive isotopes. Radioactive isotopes decay at constant rates therefore the ratio of daughter isotope to its unstable parent determines how long the radioactive parent has been in the mineral or rock.

isotropic mineral - a mineral whose crystal structure shows no preferred orientations: appears black in thin section under cross polarized light

isotubule - tubular feature of soil filled with mixed clay and clastic grains without any preferred orientation

Jacob staff - survey pole used for taking angular differences in elevation and horizontal differences in distance with clinometer

jarosite - powdery, yellow mineral smelling of rotten eggs [KFe3(OH6)(SO4)2], forms by oxidative weathering of pyrite

kandic horizon - subsurface soil horizon similar to argillic horizon in clay enrichment, but clays are kaolinitic and there are very few weatherable minerals remaining

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kaolinite - base-poor clay mineral {Al4{Si4O14](OH)8}

karst - landform formed from the weathering and dissolution of limestone, often rugged with caves and pinnacles

karst bauxite - kind of bauxite formed within depressions of karst landscapes

kerogen - particulate organic matter lacking regular chemical structure and insoluble in organic solvents and mineral acids, present in sedimentary rocks

K horizon - subsurface soil horizon so impregnated with carbonate that its morphology is determined by the carbonate. Authigenic carbonate coats or engulfs all primary grains in a continuous medium and makes up 50% or more by volume of the horizon. The uppermost part of the horizon commonly is laminated. If cemented, the horizon corresponds with some caliches and calcretes.

krotovina - tubular feature in a soil filled with material from a higher soil horizon

Kubler index - measure of clay crystallinity using the width of x-ray diffractometer peaks

kunkar - pedogenic calcium carbonate nodules or layers

labile minerals - minerals such as olivine and pyroxene that are relatively easily weathered

lacustrine - relating to lakes

larval cell - chamber used for rearing young in the complex nests of social insects such as termites, bees and ants

laterite - highly weathered material rich in iron, and poor in humus, silica and bases

lattisepic - sepic plasmic fabric with a network of highly birefringent streaks in two preferred directions that are at a right angle

lentil ped - soil clods that are shaped like an elongate parallellogram, usually with slickensided faces and characteristic of Vertisols

lessivage - soil-building process of washing down of clay into subsurface cracks

lichen - plantlike organism formed by the symbiotic association of fungi and algae

ligament - tough tissue that connects bones or supports internal organs of animals

lime - calcium oxide (CaO)

limestone - rock formed mainly of calcite

linear gilgai - gilgai microrelief of elongate ridges and swales, usually running downslope

lithic sandstone - sandstone whose clasts are mainly rock fragments

lithofunction - mathematical relationship between soil features and parent material of the soil

lithorelict - rock fragment in a soil remaining from its parent material

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lithosequence - set of soils formed under similar climate, vegetation, topographic setting and time, but varying parent material

litter - accumulation of leaves, wood and other decaying organic matter on the surface of soil

loess - deposits of wind-blown glacial dust

macronutrients - elements needed in large amounts for the nourishment of plants, including hydrogen (H), carbon (C), nitrogen (N), oxygen (0), magnesium (Mg), phosphorus (P), sulfur (S), potassium and calcium (Ca)

magnesia - magnesium oxide (MgO)

2+ 3+ magnetite - an iron-rich mineral [Fe Fe 2O4]

mangal - vegetation consisting of mangroves

mangan - cutan consisting of oxides or hydroxides of iron and manganese

mangrove - tree capable of living within the intertidal zone of the ocean

maquis - synonym of fireprone shrublands, used mainly for vegetation around the Mediterranean Sea

marsh - wetland vegetation of grasses and other herbs with acidic to neutral groundwater

masepic - sepic plasmic fabric with highly birefringent streaks forming an extensive criss- crossing network

megaspore - large (usually more than 60 microm diameter) spores of some kinds of ferns, lycopods and similar plants

member - Formal stratigraphic subdivisions of formations.

mesa - hill with a flat top

metaranotubule - tubular feature in a soil filled with sandy material from a higher soil horizon

metamorphism - alteration of rocks during deep burial and heating, generally to more than 200°C or greater than 7 km, whichever comes first

metasediment - metamorphosed sedimentary rock

metatubule - tubular feature of soil filled with material different from soil matrix and derived from some other soil horizon

micrite - very fine grained sediment of calcite and clay minerals

micritization - soil forming process whereby coarsely crystalline calcite or other materials are converted to micrite

microarthropod - microscopic arthropod, including springtails and mites

microbe - microscopic organism

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microbial earth - vegetation of microbes living on and within a friable soil

microfabric - arrangement of constituents visible by microscopy

Milankovitch effect - Cyclic change of temperature of the earths surface due to combined effects of variations in the tilt of axis, wobble of axis (p recession), and ellipticity of the orbits.

mineral - Naturally occuring chemical element or compound with a definite composition, a characteristic crystal form, and other distinctive physical properties.

ministromatolite - small (often microscopic) domed structure with internal lamination, formed by the growth of microbial colonies

Miocene - epoch of geological time about 23-5 million years ago

moderately developed soil or paleosol - with surface rooted zone and obvious subsu ace clayey, sesquioxidic, humic or calcareous or surface organic horizons, qualifying as argillic, spodic or calcic horizons or Histosol and developed at least to the extent of nodules for calcic horizons

moder humus - organic matter consisting of a mix of recognizable plant material and other organic material completely decayed: intermediate between mor and mull humus

moisture equivalent - percentage moisture in a soil at "field capacity", which is the point at which water is no longer moving through or filling soil pores, but bound in immobile films to grains and roots

mole - mass in grams of Avogadro's number (6.022x1023) of atoms or molecules of an element of compound, calculated by dividing weight percent of analyzed element or compound by its atomic weight

molecular weathering ratio - ratio of chemical constituents in moles, calculated in order to understand changing chemical proportions due to weathering

mollic epipedon - soil surface horizon of grassland soils, with fine structure (usually granular peds), dark color (chroma of 3 or less, value darker than 5 when dry), contains at least 1% organic matter (0.58% organic carbon), and has a base saturation of over 50%

Mollisol - grassland soil with a mollic epipedon at least 18 cm thick

monsoonal climate - climate of very marked seasonal rain fall, as in the Indian subcontinent

mor humus - organic material consisting of little decayed plant material, such as the dried pine needles commonly preserved under conifer forest

mosepic - sepic plasmic fabric with partly adjoining highly birefringent streaks

mottle - glaebules of very irregular shade and diffuse boundaries, usually expressed as different ore areas of soil

mucigel - gelatinous zone within the rhizosphere, rich in bacteria and fungi

mudflow - rapid downslope movement of a slurry of mud and boulders after rain storms or volcanic eruptions

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mukkara structure - subsurface deformation of soil horizons, usually with the surface horizon festooned between ridges of exposed cracked subsurface horizon, produced by shrinking and swelling of Vertisols

mull humus - organic matter decayed so that plant structure is no longer visible, as in the surface horizon of grassland soils or Mollisols

murram - loose aggregate of pea-sized lateritic gravel used for road building

natric horizon - soil subsurface horizon more than 15% saturated with exchangeable sodium, commonly also with salts and prismatic or domed columnar peds

Natrustoll - kind of Ustoll, with abundant sodium or other indications of salt accumulation such as domed-columnar peds

needle fiber calcite - calcite crystals in the form of microscopic needles, commonly precipitated by soil fungi

neocutan - altered area within a soil at a surface as well as some distance in from the surface. These are unusually thick cutans.

neoferran - neocutan of iron oxides of hydroxides

neomorphism - change in form of crystals, including recrystallization

neutron activation analysis - method of chemical analysis using radiation induced after neutron irradiation in a nuclear reactor

nicols - polarizing light filters on a petrographic microscope

Nitosol - Ultisol or Oxisol with abundant slickensided clay skins in the F.A.O. soil classification

nodule - glaebule with an undifferentiated, massive internal fabric. These are usually local hard, cemented lumps of soil material.

normal fault - Fault along which the upper block has moved down relative to the lower block along a steeply inclined surface; characteristic of crust that has been subjected to tension.

normative mineral composition - estimate of the proportions of minerals present in a specimen calculated from the chemical composition of the specimen and ideal compositions of the minerals

Ochrept - kind of Inceptisol with ochric and cambic horizons, and sometimes also, poorly developed calcic horizons, fragipans or duripans.

ochric epipedon - soil surface horizon too light in color and low in organic matter to be mollic or umbric.

O horizon - surface accumulation of organic material overlying mineral soil

Oligocene - epoch of geological time about 33-23 million years

oligotrophic forest - forest living in low nutrient soil such as a Sodosol

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olivine - a mineral of igneous rocks {Mg,Fe)2[SiO4]}

omnisepic - sepic plasmic fabric dominated by highly birefringent, oriented plasma, with a "woven" appearance

omnivore - animal that eats meat and plants

ooid - small (1-2 mm diameter) round grain with internal concentric structure

opal - silica mineral (SiO2•nH2O)

opalite - silica cemented shale or claystone

opaque - not pervious to light, and so black when viewed in a petrographic thin section

optical axis figure - arrangement of light interference bands seen when minerals are viewed in particular orientations within petrographic thin sections and useful for mineral identification

organan - cutan consisting of organic matter

Orthent - kind of Entisol, formed on erosional remnants such that hard bedrock, or relict soil material, is within 25 cm of the surface

Orthid - kind of Aridisol, lacking an argillic horizon

Orthod - kind of Spodosol, with a subsurface horizon including both sesquioxides and organic matter

orthotubule - tubular feature of soil filled with material of very similar fabric and composition to soil matrix

oxidation - chemical reaction in which electrons are lost to valence of elements with multiple valence states, for example Fe2+ to Fe3+, which commonly is achieved by means of oxygen as a electron sink

oxic horizon - highly weathered subsurface horizon characterized by hydrated oxides of iron and aluminum, 1:1 lattice clays, and low cation-exchange capacity. Few primary silicate minerals remain with the exception of quartz, which is quite resistant to weathering.

oxidized groundwater - water within soils and rocks that is rich in oxygen. Oxidizing groundwaters are rare, and largely found within actively-recharged, sandy aquifers, because of oxygen scavenging by microbes and by minerals

Oxisol - deeply weathered soils with kaolinitic clays, quartz and few weatherable minerals

18 16 oxygen-isotope analysis - Ration of O to O in shells composed of CaCO3 provides indication of paleotemperature of seawater when the shell was formed.

Paleocene - epoch of geological time about 65-57 million years ago

paleochannel - former river channel, usually marked by an elongate deposit broadly lenticular in cross section, of cross bedded sandstone or conglomerate

paleoecology - study of the ecology of fossil organisms http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/glossary.htm[4/18/2014 12:21:20 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Glossary)

paleomagnetism - former orientation of Earth's magnetic field as recorded in magnetic minerals in rocks

paleopedology - study of paleosols

paleosol - soil of a landscape of the past: a surficial region of a planet or similar body altered in place by biological, chemical or physical processes, or a combination of these

Paleudalf - kind of Udalf that is very strongly developed, usually over a long period of time (hundreds of thousands of years)

Paleudult - kind of Udult that is very strongly developed, usually over a long period of time (hundreds of thousands of years)

Paleustalf - kind of Ustalf that is very strongly developed, commonly with a continuous subsurface calcareous horizon

pallid zone - horizon of white clay and bleached or mottled rock beneath laterite in a deep weathering profile

palygorskite - mineral of desert soils [(OH2)4Mg5Si8O20•4H2O]

pampas - synonym of grassland, used mainly in South America

papule - glaebule of clay, a useful non-genetic term if one is not sure whether they are clay galls of the original parent material, void fills or segregations of clay

paratubule - tubular feature of soil filled with material different from soil matrix and unlike anything else within the profile

parent material - Initial material of a soil.

parkland - vegetation of woodland with numerous large grassy clearings

ped - natural aggregate of soil; that is, stable lumps or clods of soil between cracks, roots, burrows or other planes of weakness

pediment - An erosion surface formed by the retreat of an escarpment.

pedofacies - kind of sedimentary facies containing one or more paleosols and dominated by pedogenic features such as nodules, mottles and root traces

pedogenic - formed in association with soil

pedolith - sedimentary deposit composed of clasts that are clearly derived from soils, such as talus slopes of lateritic clasts below a laterite scarp

pedon - A single soil profile in a landscape; it is the smallest soil descriptive unit.

pedorelict - soil structure that formed in a different soil than the one in which it is found, for example a calcareous nodule within the gravelly parent material of a non-calcareous soil

pedotubule - tubular features of soils, including roots and burrows

pedotype - reference profile for definition of a soil or paleosol mapping unit

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pegmatite - coarsely crystalline rock mainly of quatz and feldspar, usually forming veins within granitic rocks

peg root - short, bluntly-ending roots that protrude from the ground, as in mangroves

Pennsylvanian - period of geological time about 323-290 million years ago

perched water table - level of water ponded in soil by an impermeable subsurface layer

peridotite - rock formed mainly of olivine

periostracum - outer, thin, brown organic layer covering the shells of some molluscs, such as snails and freshwater clams

Permian - period of geological time about 290-250 million years ago

permineralized - infiltrated with cementing minerals, as in the silica that fills woody cell contents to create permineralized wood. Such wood is often incorrectly referred to as petrified, but the cellulose cell walls remain, and have not been turned to stone.

petrocalcic horizon - subsurface soil horizon cemented firmly with calcium carbonate

petroferric horizon - subsurface soil horizon cemented firmly with iron oxides and hydroxides

petrography - description of rocks, usually including study in thin section

petrogypsic horizon - subsurface soil horizon cemented firmly with gypsum

pH - negative logarithm of the activity of the hydronium ion (H+): soils a measure of acidity. Acidic soils have a low pH (<7) and alkaline soils have a high pH (>7), with a total observed range of 4.5-11, from a theoretical 1-14.

phenocryst - large crystals in a prophritic rock

phytolith - mineral particle made by a plant, such as opal bodies of grasses

pisolite - spherical concretions usually about 2 to 15 mm in diameter.

plagioclase - mineral of igneous rocks [Na(AlSi3O8)—Ca(AlSi3O8)]

plasma - fine grained material of soil microfabric, making up peds, including amorphous clay and iron stain

platy ped - form of ped that is thin but wide, often formed by weathering of sedimentary layers

playa lake - desert basin, rarely inundated, usually dry and covered in salt and clay

Pleistocene - epoch of geological time about 1.6 million to 10,000 years ago

plinthite - iron-rich, humus-poor clayey part of a soil, usually mottled red and yellow, and with the distinctive property of hardening irreversibly to an iron hardpan upon drying. This term is used or those kinds of laterites that are found within soil

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Pliocene - epoch of geological time about 5 to 1.6 million years ago

podzolization - soil building process of acidic leaching into subsurface horizon of sesquioxides, organic matter or combinations of these

point-counting - systematic search and record of grain type or size made to determine mineral composition or grain size of paleosols

polygenetic Soil - A soil that has been formed by two or more different and contrasting processes so that the horizons are not genetically related.

porcellanous - with the appearance of china or porcelain

porosity - percent void space between grains and peds of soil; complement to solidity

porphyritic - crystalline texture of large crystals isolated within a fine grrained matrix

poyroskelic - soil microfabric in which grains are dispersed fine grained matrix, like phenocrysts in a porphyritic rock

potash - potassium oxide ([K2O])

prairie - synonym of grassland, used mainly for vegetation in North America temperatures of about

pressure solution - process of dissolution of grains of rock by the pressures of deep burial focused at grain contacts

primary porosity - proportion of void space between grains and peds in the original soil or sediment

profile - A vertical section through a soil from the surface into the relatively unaltered material.

productivity - a measure of biological accumulation of organic matter, measured as grams of carbon or of dry organic matter per meter per year

"Protorendzina" - weakly developed soil with mollic surface horizon on limestone bedrock

Psamment - kind of Entisol, formed on sand, especially eolian dunes, with relict bedding

pseudoanticline - uparched bedding planes that are confined to a particular layer, and so thought to be due to local clay heave or crystallization rather than regional folding that produces anticlines

pseudomorph - mineral grain that has adopted the form of another mineral, usually as a result of replacement of that mineral, for example, chalcedony pseudomorphs of gypsum

pseudomycelium - fine irregular filaments of calcium carbonate in soil

ptygmatic - folded back on itself in a complex way

pyrite - common mineral of mangal and salt marsh soils (FeS2)

pyroxene - mineral of igneous rocks {(Mg,Fe)Si2O6}

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quartz - common mineral of soils (SiO2)

quasicutan - altered area within a soil that is thick and shows a relationship to a surface, but is not right at the surface. Quasicutans form a kind of halo following the outline peds, grains and other features.

quasimangan - quasicutan of iron-manganese

Quaternary - period of geological time from 1.6 million years ago to present

radiogenic - prone to decay with the release of radioactivity

rain forest - forest living in a very humid climate

rangeland - region of open vegetation, including wooded grassland, grassland and desert scrub

rare earth elements - elements with atomic number 57-71, also known as lanthanides, of which lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), ytterbium (Yb), and lutetium (Lu) are commonly analyzed in rocks and soils

recrystallization - process of forming new crystals without a change in chemical composition

red beds - sediments or sedimentary rocks that are largely red in color

reddening - change in color from brownish red (Munsell 10YR) to brick red (Munsell 5R) that occurs during soil formation and during burial of soils

reductant - chemical compound capable of inducing reduction

reduction - a chemical reaction in which electrons are donated to change the valence of elements with multiple valence states, for example converting ferric iron (Fe3+) to ferrous iron (Fe2+)

REE - rare earth elements

regolith - The unconsolidated mantle of weathered rock, soil and superficial deposits overlying solid rock.

relict structures - features persisting in soil from its parent material, including bedding, crystalline structure and schishosity

relief - degree to which the margins of a mineral grain stand out from its surroundings as viewed in thin section under a microscope

Rendoll - kind of Mollisol formed on limestone bedrock

replacive fabric - microfabric of soils in which one mineral is converted incompletely and over an irregular front into another mineral

residuum - material remaining after a long period of weathering

resistate minerals - minerals such as quartz and microcline that are resistant to weathering

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and tend to persist as other minerals are destroyed in soils

respiration - metabolic process of organisms, whereby organic food is converted into energy and carbon dioxide

reverse fault - Fault along which the upper block has moved down relative to the lower block; characteristic of crust that has been subjected to compression.

R horizon - consolidated or weathered bedrock underlying the soil

rhizoconcretion - concretion that forms by cementation of soil around a root

rhizoid - elongated epidermal cell that functions as a root, as in mosses, liverworts and primitive land plants

rhizome - a rootlike structure of plants which lies along or within the ground, but which is really a stem, as revealed anatomically and in its pattern of branching and budding

rizosphere - area of influence a root in the soil

rhyolite - silica rich volcanic rock

ripple mark - sedimentary structure of small scale undulations of a bedding plane: miniature dunelike forms produced by wind or water currents

rock varnish - thin crust of red to black iron and manganese oxides and clay formed on the surface of rocks in deserts, lakes and streams, largely as a result of microbial activity

root - branching subterranean structure of plants, often with some woody internal thickening

root hair - elongate cell erect on the surface of roots, most common a short distance behind the growing tip of roots.

rootlet - side branch from roots.

root trace - tubular cavity or irregular marking left in soils and paleosols by roots, recognized by irregular tubular shape, tapering downwards branching downward or outward from a center, and (for deeply buried paleosols) concertina-like shape due to compaction of surrounding sediment around the main lateral rootlets

saccharoidal - like sugar crystals

salic horizons - subsurface soil horizon with accumulations of salt

salinized - affected by salt accumulation

Salorthid - kind of desert soil or Aridisol, which has salts such as gypsum within the profile and lacks a subsurface horizon of clay enrichment

salt marsh - wetland vegetation of grasses and other herbs with saline groundwater, usually within the intertidal zone of bays

sand crystal - sand cemented into the shape of a crystal of cementing material, usually gypsum

sand wedge - vertically oriented wedgelike disruption of a soil filled with vertically banded

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/glossary.htm[4/18/2014 12:21:20 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Glossary)

sediments from opening and closing with freezing and thawing

sapric peat - peat in which organic matter has decayed to such an extent that little if any of the original plant components are recognizable

Saprist - kind of Histosol, consisting mainly of decomposed and unrecognizable plant mattes

saprolite - less altered lower portion of weathering profiles, showing some weathering, but much relict bedding, schistosity or crystalline structure remaining from parent material

savanna - commonly used as a synonym of wooded grassland, but also widely taken to include grassy woodland

scanning electron microscope - microscope that uses electron beams to create images

schist - metamorphic rock of clay grain size showing pronounced schistosity

schistosity - degree of development of planes of fissility and foliation characteristic of fine rained metamorphic rocks

sclerotia - rounded, woody bodies, with interlaced, elongate, hollows produced by the resting stages of fungi

secondary porosity - a system of tubes and vesicles developed in rock during deep burial associated with maturation of buried organic matter

sedimentary facies - Overall lithology of strata reflecting environment of deposition; characteristics of one environment such as beach sand, grade laterally into facies of another environment.

SEM - scanning electron microscope

sepic plasmic fabric - appearance of soil thin sections viewed under cross-polarized light of wisps or streaks of highly oriented and highly birefringent clay in a less organized dark matrix: a characteristic micro fabric of soils

sepiolite - mineral of desert soils [(OH2)4Mg5Si12O30·8H2O]

septarium (plural septaria) - glaebule with a complex system of internal cracks, usually due to shrinkage

sesquan - cutan consisting of sesquioxides of iron and aluminum

sesquioxides - alumina (Al2O3) and ferric iron (FeO3)

shrubland - vegetation of low-growing woody shrubs, such as sagebrush and saltbush

siderite - carbonate mineral of waterlogged and organic rich soils (FeCO3)

silan - cutan consisting of silica

silasepic - soil microfabric dominated by silt and sand grains, and lacking highly birefringent streaks when viewed under crossed nicols

silcrete - a silica cemented material associated with weathering profiles

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/glossary.htm[4/18/2014 12:21:20 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Glossary)

silica - silicon dioxide (SiO2)

siliceous - composed mainly of silica

silicified - cemented by silica

sinker - deeply-penetrating large root, that takes advantage of deep groundwater

sinter - silica-rich, often vuggy, deposits formed around volcanic hot springs

skeletan - cutan consisting of clastic grains such as quartz or feldspar

skeleton grains - clastic grains such as quartz and feldspar within the soil microfabric

skeletonized leaf - plant leaf decayed in such a way that cuticle and soft tissues have been removed to reveal the woody vascular traces or veins

skelsepic - sepic plasmic fabric with highly birefringent plasma associated with the outer surface of skeleton grains

slickenside - smooth to striated surface of a rock produced by shearing within soils, during burial crushing of soil peds and during faulting

slide - small glass pane used for supporting thin section of rock or soil

smectite - a base-rich clay mineral {1/2Ca,Na)0.7(Al,Mg,Fe)4-6[(Si,Al)8O20](OH)4•nH2O}

soil - The subaerial surface of the earth; a membrane between the lithosphere and atmosphere.

soil creep - downslope movement of hillside soils, as revealed by bending into the surface of near vertical veins and bedding planes

soil horizons - gradational changes in texture or mineral content down into parent material of a soil or paleosol from the truncated land surface

soil structure - three dimensional features characteristic of soils

solidity - percent solid grains or ped in a soil: complement to porosity

soluan - cutan consisting of soluble salts such as gypsum or calcite

solum - altered upper part of a weathering profile, including the various named soil horizons

sparry calcite - calcite crystals large enough to be discernable under an optical microscope

spherical microped - microscopic sphere-shaped soil clod, typical of tropical soils and produced as oral and fecal pellets of termites

spherulite - spherical aggregate of radiating crystals

spicule - small pointed mineral body made by an animal as part of its skeletal support, such as the opal bodies of freshwater sponges

spodic horizon - subsurface soil horizon formed by concentration of organic matter and sesquioxides that have been translocated downward from an E horizon http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/glossary.htm[4/18/2014 12:21:20 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Glossary)

Spodosol - acidic sandy soil with B horizons enriched in organic matter, iron and aluminum or combinations of these, but not clay

sporinite - kind of exinite coal maceral, formed from spores and pollen

standard error - measure of the variation of a set of data points around a mean value or fitted curve, defined as the square root of variance after division by the number of data points

stele - central conducting strand of tracheids or xylem found within roots and stems of plants

steppe - synonym of grassland, used mainly for grasslands of Asia

stoichiometry - measurement of proportions of components for conservation of matter and energy in chemical equations and formulae

stone line - layer of pebbles or other large rock fragments confined to a narrow horizon, commonly an erosional plane, and conspicuous as the only large clasts in an otherwise one grained soil

stratovolcano - steep volcanic cone constructed by successive layers of ash and lava

stratigraphic sequences - Intervals of conformable strata bounded by unconformities.

stream terrace - Former level of a broad valley floor that was created by aggradation or by lateral fluvial erosion, but now is above the present floodplain because of incision by the stream. A terrace consists of a tread and a riser, which separates the tread from the stream or a lower terrace.

stress cutan - cutan formed by differential forces within the soil such as shearing due to swelling and shrinking induced by wetting and drying

striotubule - tubular feature of soil filled with mixed clay and clastic grains with curved internal layering

strongly developed soil or paleosol - with especially thick (2-3 m), sea, clayey or humic subsurface (B) horizons or surface organic horizons (coal or lignites) or especially well developed soil structure or calcic horizons as a continuous layer

subcutanic features - modifications of soil material that show a relationship to a surface, but do not occur only at that surface

Sulfaquent - kind of Aquent with common sulfur minerals such as pyrite or jarosite, commonly formed under salt marsh and mangal vegetation

Sulfaquept - kind of Aquept with common sulfur minerals such as pyrite or jarosite, commonly formed under salt marsh and mangal vegetation

2- sulfate - common anion (SO4 ) in soils, found in minerals such as gypsum

surface water gley - gley features formed by the ponding of water by impermeable soil layers above drier subsoil

swale - local elongate depression on the landscape, typically from abandoned flood channels

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/glossary.htm[4/18/2014 12:21:20 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Glossary)

swamp - wetland vegetation of trees with acidic to neutral ground water

tap root - single, thick, vertical root, like that of a carrot

taxonomic uniformitarianism - assumption that soil types of the past formed under similar environmental conditions to taxonomically similar soils of the present

taxonomy - classification: for soils, used to distinguish the soil classification of the U.S. Soil Conservation Service (originally entitled "Soil Taxonomy") from other classifications

telinite - kind of vitrinite coal maceral, formed from wood fragments with some crushed, cellular structure remaining

tepee structure - inverted V-shaped local disruption of layering within a bed, due to action of roots or clay swelling

terrace - flat geomorphic surface representing the erosional remnant of a former land surface

Tertiary - period of geological time about 65-1.6 million years ago

thin section - transparent slice of rock or soil mounted between glass covers, used for microscopic examination

topofunction - mathematical relationship between soil features and topographic setting of soil

toposequence - set of soils formed under similar climate, vegetation, parent material and time, but varying topographic setting

Torrand - kind of Andisol of very dry climate, with little clay or colloidal material, and abundant salts and carbonate at shallow levels within the profile.

Torrox - kind of Oxisol of very dry climates

trace fossil - fossilized evidence of the activity of an organism, such as a fossil footprint or burrow

trachyte - volcanic intrusive and flow rock close to saturation with silica, consisting mainly of alkali feldspar

transform fault - A lateral or strike-slip fault characteristic of spreading ridges, which offsets the ridge axes as spreading progresses.

transpiration - evaporative by loss of water from leaves of plants

trimasepic - sepic plasmic fabric with a network of highly birefringent streaks in threep referred directions

Tropept - kind of Inceptisol found in intertropical regions.

tuber - potatolike underground storage organ of plants

Udifluvent - kind of Entisol, discernably decalcified and with clear relict bedding remaining from clayey alluvial parent material

Udalf - kind of Alfisol formed in a humid climate, usually non-calcareous

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/glossary.htm[4/18/2014 12:21:20 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Glossary)

Udoll - kind of Mollisol formed in a humid climate, usually non-calcareous

Udult - kind of Ultisol formed in a humid climate, so deeply weathered and non-calcareous

Ultisol - acidic, deeply weathered forest soil, with clayey, ferric, aluminous or humic subsurface horizon

umbric epipedon - soil surface horizon similar to mollic except for platy to massive structure and base saturation less than 50%. They are generally associated with forest vegetation

unconformity - major temporal break in the accumulation of a sedimentary rock sequence, as indicated by fossils as evidence of age or by deformation of underlying layers before deposition of overlying layers

underclay - clayey paleosol beneath a coal seam

undulic - soil micro fabric that is almost but not quite isotropic, so very dark when viewed in thin section under crossed nicols

Ustalf - kind of Alfisol of dry summer-wet climates

Ustand - kind of Andisol of dry summer-wet climates

Ustochrept - kind of Ochrept formed in a dry climate, usually with carbonate nodules

Ustoll - kind of Mollisol of dry summer-wet climates

Ustox - kind of Oxisol of seasonally dry climates

Ustropept - kind of Tropept formed in a dry climate

valley calcrete - form of groundwater calcrete formed by precipitation from the water table near streams

value - the degree of lightness of a color in the Munsell system of color classification

vein - a narrow crack through rock, commonly filled with minerals such as quartz or calcite

vermicular - wormy, full of elongate cavities

vertic - showing some properties of Vertisols, such as slickensides and deep cracks

Vertisol - thick, very clayey, slickensided soil, often with internal deformation of horizons

very strongly developed - with unusually thick (3 or more m) subsurface (B) horizons or surface horizons (coal or lignites): such a degree of development is found mainly at major geological unconformities

very weakly developed soil or paleosol - with little evidence of soil development apart from root traces and abundant sedimentary, metamorphic or igneous textures remaining from parent material

vesicular - full of small, near-spherical cavities

Vitrand - kind of Andisol rich in glassy volcanic shards

http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/glossary.htm[4/18/2014 12:21:20 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Glossary)

vitrinite reflectance - measure of the shininess of the coal maceral vitrinite, the percentage of light reflected from the maceral

vitrain - bright coal: brilliant, black, non-laminated coal, clean to the touch and breaking with conchoidal fracture

vivianite - blue to white mineral of marsh soils [Fe3(PO4)2&busll;8H2O]

void - small open spaces within soil microfabric, generally crushed out of buried paleosols

volatile matter - easily moved materials: for coal, volatile material includes water, sulfur and nitrogen

volcanic arc - An arcuate chain of volcanic islands or volcanoes which erupt mainly andesitic lavas and ash but also including basalts and rhyolites; generally associated with trenches, seismicity and subduction.

volcanic ash - particles of volcanic sock, crystals and glass that settle out through the atmosphere after volcanic eruptions

volcaniclastic - formed from particles of volcanic rock

vosepic - sepic plasmic fabric with highly birefringent plasma associated with the walls of voids. May be difficult to recognize in paleosols with voids crushed during burial

vug - small unfilled cavity in rock or soil

Walkley-Black method - wet chemical titration method for the determination of abundance (weight percent) of soil organic carbon

waterlogged soil - soil that is saturated with water

water potential - negative water pressure maintained within tracheids that transports water through a plant

weakly developed soil or paleosol - with a surface rooted zone (A horizon), as well as incipient subsurface clayey, calcareous, sesquioxidic or humic or surface organic horizons, but none of these developed to the extent that they would qualify as argillic, spodic or calcic horizons or histic epipedons

weathering rind - thin outer zone of weathering found on rock and mineral grains within a soil.

Weaver index - measure of clay crystallinity using height of x-ray diffractometer peak

Weber index - measure of clay crystallinity using width of x-ray diffractometer peak of clay compared with that of quartz

wetland - part of the landscape that is waterlogged or inundated for a substantial part of the year

wooded grassland - trees giving 10-40% cover, isolated and scattered among grasses

wooded shrub land - trees giving 10-40% cover, isolated and scattered among grasses

woodland - vegetation of closely spaced trees 2-8 m tall http://www.nps.gov/history/history/online_books/joda/bestland-retallack1/glossary.htm[4/18/2014 12:21:20 PM] John Day Fossil Beds NM: Geology and Paleoenvironments of the Clarno Unit (Glossary)

Xeralf - a kind of Alfisol of dry winter-wet climates

Xerand - a kind of Andisol of dry winter-wet climates

xeric - of dry winter-wet climates

Xeroll - kind of Mollisol of dry winter-wet climates

x-ray diffractometer - machine used to identify mineral by the angles at which their crystal faces reflect a focused beam of x-rays

x-ray fluorescence spectrometry - method of chemical analysis using wavelengths of secondary radiation.

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joda/bestland-retallack1/glossary.htm Last Updated: 21-Aug-2007

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