Cenozoic Cooling and Grassland Expansion in Oregon and Washington

GREGORY J. RETALLACK Department of Geological Sciences, University of Oregon, Eugene, OR 97403; [email protected]

Many different kinds of paleosols are common in Cenozoic badlands of the high deserts of eastern Oregon and Washington. Pedotypes, taxonomic orders, and climofunctions are three distinct approaches that use paleosol data to reconstruct past climate, ecosystems, topography, parent materials, and landscape stability. Because the back-arc paleotopographic setting, rhyolitic parent material, and rate of subsidence changed little for paleosols of eastern Oregon and Washington over the past 45 million years, these paleosols record primarily changing climate and vegetation. Paleosols of Oregon and Washington are evidence of the transition from a late Eocene (35 Ma) peak of warm, humid forests to cool, desert shrublands in the Oligocene. The reversion to warm-wet forests in the middle Miocene (16 Ma) was followed by general cooling and spread of sod grasslands that culminated in the last ice age (>1.8 Ma). These records are compatible with a greenhouse model for climate change of cooling induced by coevolutionary advances in carbon sequestration and consumption by grassland soils and sediments, punctuated by warming from volcano-tectonic and extraterrestrial perturbations. The abundant Cenozoic paleosols in the Pacific Northwest are multifaceted guides to past global change.

INTRODUCTION soil structures (angular blocky peds and sesqui-argillans), soil Oregon’s Painted Hills of red-streaked badlands are the microfabrics (porphyroskelic skelmasepic), grain-size distri- best known of colorful badlands scattered throughout the bution (subsurface clay enrichment) and chemical composi- high desert of eastern Oregon and Washington (Figs. 1, 2B). tion (alkali depletion and iron oxidation). The Painted Hills In the Painted Hills, the prominent red bands are clayey includes at least ten paleosols of this Luca pedotype, as well subsurface (Bt) horizons of forest soils (Alfisols) representing as 14 other kinds of paleosols that are among 435 paleosols successive humid-climate ecosystems that colonized tuffa- in a composite stratigraphic section (430 m thick) of the ceous alluvial terraces over periods of tens of thousands of lower John Day Formation. The abundance and diversity of years (Retallack et al. 2000). Evidence for this interpretation paleosols in the Painted Hills is not unusual (Retallack et al. comes from studies of root traces (drab-haloed claystone), 2002a, Bestland and Forbes 2003, Sheldon 2003, Retallack 2004a, b, Retallack et al. 2004, Sheldon 2006), and calls for a systematic approach to classifying, naming, and interpret- ing the thousands of paleosols known from the Cenozoic of the Pacific Northwest. This paper reviews the long record of paleosols in Oregon and Washington, comparing different approaches of: (1) their field classification (2) their interpretation within modern soil taxonomies; and (3) the application of transfer functions derived from study of modern soils. Such varied approaches to paleosol archives have implications for understanding long-term changes in climate and vegetation, both locally and globally (Retallack 2007). This paper emphasizes the paleosol record and different approaches to its interpretation.

COMMON PALEOSOLS OF THE PACIFIC NORTHWEST Cenozoic fossils of Oregon have been famous since Thomas Condon’s discovery in 1865 of fossil leaves and mammal bones in what is now known as the Painted Hills Unit of the John Day Fossil Beds National Monument (Clark 1989). University of California paleontologists John Merriam (1906, 1916, Merriam and Sinclair 1907), Ralph Chaney and Dan Axelrod (Chaney, 1924, 1948, Chaney and Axelrod 1959) subsequently collected rich fossil floras and Figure 1. Localities of paleosols examined in Oregon and Wash- faunas from Eocene, Oligocene, and Miocene rocks nearby, ington. and geologists Hay (1962) and Fisher (1964) were the first 90 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009 to note paleosols in these rocks. The temporal resolution preserve abundant mammal bones and teeth (Retallack and completeness of this paleosol record recently became 1998). Orellan(?), Arikareean, and Hemingfordian mammals apparent when the geochronology of these strata was refined (Coombs et al. 2001, Hunt and Stepleton 2004), radiometric by magnetostratigraphy (Prothero and Rensberger 1985, dates of tuffs (Fremd et al. 1994), and magnetostratigraphy Prothero et al. 2006a, b) and by radiometric dating of nu- (Prothero and Rensberger 1985) indicate that this sequence merous interbedded volcanic tuffs and lava flows (Fremd et ranges in age from 29–17 Ma (middle Oligocene to early al. 1994, Streck et al. 1999). With these new data has come Miocene). Beginning at top of tuff H on Longview Ranch, an appreciation of the abundance and diversity of paleosols, recent 40Ar/39Ar single-crystal laser dates include 28.7 ± 0.07 outlined below. Ma at 0 m, 27.89 ± 0.57 Ma at 67 m, 27.18 ± 9,13 Ma at 106 m, 25.9 ± 0.31 Ma at 177.5 m, and 19.6 ± 0.13 Ma at 497 m Clarno Formation (Fremd et al. 1994, Retallack 2004a, Tedford et al., 2004). The Hancock Field Station near Clarno has a sequence of at least 76 successive paleosols of 11 different types de- Columbia River Basalt veloped within volcaniclastic conglomerates and tuffaceous The Middle Miocene (16 Ma) Columbia River Basalt red beds of the Clarno Formation that accumulated on the Group includes numerous paleosols between the flood ba- margins of a large andesitic stratovolcano (Retallack et al. salts. These have been studied extensively in Picture Gorge 2000). The Nut Beds Member of the Clarno Formation has (Sheldon 2003, 2006). Although these red paleosols have yielded a middle Eocene flora of 173 species of fossil fruits been regarded as baked zones from the heat of overlying and seeds from tropical forest plants, including magnolia, flows, the vitrinite reflectance of peaty interbasaltic paleosols palms, and vines (Manchester 1994). Fossils from near Clarno and the degree of ceramicization of red clayey inter basaltic also include permineralized wood (Wheeler and Manchester paleosols both indicate that only the top few centimeters of 2002) and middle Eocene (Bridgerian) mammals, as well as the meter-thick paleosols have been thermally altered (Sheldon a later Eocene (Duchesnean) bone bed yielding titanotheres, 2003). Vaporization of vegetation thoroughly vesiculated and creodonts, and other mammals (Hanson 1996). Radiometric zeolitized the flows, rather than altering underlying paleosols. dating of andesitic and basaltic flows and rhyodacitic tuffs Tie points for ages within the section beginning 300 m north at the Clarno Nut Beds locality allows age determination by of Picture Gorge include a 16.01 Ma magnetic reversal at 50 linear interpolation from the following tie points: 43.8 ± 0.5 m, and the 15.77 ± 0.04 Ma Mascall tuff at 280 m (Watkins Ma basalt at 38 m, 43.0 ± 3.5 Ma tuff at 52 m, 42.7 ± 0.3 and Baksi 1974, Bailey, 1989, Tedford et al., 2004). Ma tuff at 90 m, 39.2 ± 0.03 Ma tuff at 128 m (Bestland et al. 1999, Retallack et al. 2000). Mascall Formation The middle Miocene Mascall Formation near Dayville is John Day Formation well known for a fossil flora of oak and bald cypress within The Painted Hills Unit of the John Day Fossil Beds Na- diatomaceous lake beds (Chaney and Axelrod 1959). Paleo- tional Monument exposes the lower John Day Formation, sol-rich overbank deposits of the Mascall Formation yield with hundreds of paleosols ranging from deeply weathered, Barstovian mammal assemblages in the type section near Day- red claystones, to little-weathered volcanic siltstones (Figs. ville, through Rock Creek and Antone, and west to Paulina 1A–B). Only calcareous volcanic soils and associated sedi- (Downs 1956). Bones and teeth are rare because paleosols ments have yielded Oligocene (early Arikareean) mammals of the Mascall Formation are clayey and non-calcareous, (Retallack et al. 2000). Bridge Creek near the Painted Hills more like those of the lower than upper John Day Forma- has lent its name to fossil floras of temperate paleoclimatic tion (Bestland and Forbes 2003). Chronostratigraphic ages affinities, dominated by dawn redwood, alder and oak (Meyer of paleosols for the lower part of the formation in the type and Manchester 1997). High quality 40Ar/39Ar single-crystal area include a 16.2 ± 1.4 Ma ash at 35 m, 15.77 ± 0.04 Ma laser radiometric dates of tuffs in the Painted Hills range from ash at 119 m, 15.2 Ma magnetic reversal at 120 m, 15.0 Ma 40–29 Ma (late Eocene to middle Oligocene): 39.7 ± 0.03 Ma reversal at 129 m, 14.9 Ma reversal at 165 m, and 14.8 Ma at 0 m, 32.99 ± 0.11 Ma at 98 m, 32.66 ± 0.03 Ma at 137 m, reversal at 190 m (Tedford et al., 2004, Prothero et al. 2006a, 29.75 ± 0.02 Ma at 329 m, 29.70 ± 0.06 Ma at 381 m, and Prothero et al. 2006b). Other Barstovian (middle Miocene) 28.65 ± 0.05 Ma at 427 m (Retallack et al. 2000). There are paleosols are known from fossil mammal sites near Gateway hundreds more unstudied paleosols in the upper John Day (Downs 1956, Ashwill 1983, Smith 1986) and Beatty Buttes Formation in this area, which continues from Bridge Creek (Wallace 1946, Hutchison 1968). north into the canyons south of Sutton Mountain. Paleosols and mammal fossils of the upper John Day Ironside and Juntura Formations Formation are best known from the Sheep Rock and Blue Late Miocene plant, bird, and mammal fossils of the Basin units of the John Day Fossil Beds north to Longview Clarendonian land mammal age have been reported from Ranch, Johnson Canyon, Kimberly and Spray (Retallack the Unity, Ironside, and Juntura formations (Bowen et al. 2004a). These paleosols contain calcareous nodules and 1963, Shotwell 1963, Shotwell and Russell 1963, Retallack, RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 91

2004b). A sequence of tuffs in the Ironside Formation of White Cliffs, Taunton, and Sutton Mountain include crumb- upper Windlass Gulch, north of Unity have been correlated structured soils like those of grasslands, as well as calcareous with tuffs radiometrically dated as 11.8 Ma at 49.5 m, 11.8 nodular soils like those of sagebrush steppe. Ma at 60.0 m, 11.7 Ma at 73.6 m, 11.7 Ma at 83.3 m, 11.6 Ma at 100.5 m, 11.6 Ma at 110 m, 11.5 Ma at 115.5 m, and Palouse Loess 11.3 Ma at 173 m (Perkins et al. 1998, Retallack 2004b). The Palouse Loess is an eolian deposit of redeposited Radiometrically dated rocks in the Juntura Formation west rhyodacitic ash and quartzofeldspathic fluvial silt . It forms a of Juntura include a 12.4 ± 0.5 Ma basalt at 0 m, 11.5 ± 0.6 thick and agriculturally fertile veneer on the Columbia River Ma tuff at 230 m, and 9.7 ± 0.22 Ma ash-flow tuff at 259 m Basalts throughout much of the Columbia River basin in (Bowen et al. 1963, Evernden and James 1964, Fiebelkorn eastern Oregon and Washington. Dating by magnetostratig- et al. 1982, Johnson et al. 1996, Retallack 2004b, Tedford et raphy, tephrochronology, and thermoluminescence of the al., 2004). Unity, Ironside, and Juntura paleosols are weakly road cut west of Helix, Oregon, includes ages of 0.0636 Ma calcareous and siliceous like soils found in the summer dry at 4 m and 0.158 Ma at 6 m from the top (Tate 1998). An grassy woodlands of northern California today (Retallack outcrop near Washtucna, Washington yielded a paleomagnetic 2004b). age of 0.788 Ma at 12 m and a radiometric age 0.055 Ma for an ash layer at 3 m from the top (Busacca 1989, 1991). Rattlesnake, Deschutes, Shutler, and Drewsey The best known sections near Helix and Washtucna show Formations Milankovich cyclicity (41–100 ka) alternating between two The latest Miocene Rattlesnake Formation near Dayville distinct pedotypes: (1) crumb-textured paleosols with abun- yields Hemphillian mammals, including large grazing horses dant earthworm microfabrics like those in grassland soils, and (Merriam et al. 1925), and chronostratigraphic ages that (2) massive calcareous paleosols riddled with cicada burrows include a 7.14 Ma magnetic reversal at 25 m, a 7.05 ± 0.01 like those of sagebrush steppe soils (Tate 1998, O’Geen and Ma tuff at 77 m, and a 7.0 Ma reversal at 101 m (Streck et Busacca 2002, Blinnikov et al. 2002). al. 1999, Prothero et al. 2006b). Paleosols of the Rattlesnake Formation reveal a transition from woodland through tall CLASSIFICATION OF PALEOSOLS grassland to sagebrush steppe (Retallack et al. 2002a). The Paleosols can be classified by field pedotypes or taxonomic Rattlesnake Ash-Flow Tuff is widespread beyond the type orders. Pedotypes are different kinds of paleosols based on area near Dayville, and overlies paleosols at Logan Butte and specified type sections, and recognizable from field charac- in Spanish Gulch (Retallack 2007). Paleosol sequences of the teristics. In contrast, taxonomic orders are categories of clas- Deschutes Formation near Prineville have the 7.05 ± 0.01 Ma sification based on modern soils, which can only be applied ash-flow tuff at 0 m, and a 3.3 ± 0.2 Ma basalt rimrock at 103 to paleosols after consideration of laboratory data obtained m (Bishop and Smith 1990, Streck et al. 1999). as proxies for taxonomic criteria (Retallack 1997a). Other Hemphillian mammals found near Rome are correlated with the section at Juntura, for which radiometric dates Pedotypes are 9.7 ± 0.22 Ma at the base of the Drewsey Formation and The general paleosol type, or pedotype, is a non-genetic 8.08 ± 0.56 Ma for a basalt at 100 m (Wolf and Ellison 1971, field mapping designation (Retallack 1994), comparable with Fiebelkorn et al. 1982, Sheppard and Gude 1987). The Shut- “series” of soil maps (Soil Survey Staff 1993). Each pedotype ler Formation at McKay Reservoir yields a late Hemphillian is based on a specified type profile (Retallack et al. 2000, mammal assemblage (Shotwell 1956, 1958). 2002a, Retallack 2004a, b). Cenozoic pedotypes in Oregon and Washington have been named using simple descriptive Ringold Formation terms from the Sahaptin Native American language (Figs. The Miocene-Pliocene Ringold Formation yields fragmen- 2–3), which was widely spoken throughout the southern Co- tary Blancan fossil mammals, and is well exposed in White lumbia River basin (Rigsby 1965, De Lancey et al. 1988). Cliffs along the Columbia River near Richland, and in road The purpose of pedotype naming and description is to and railway cuts near Taunton, Washington (Gustafson 1978, facilitate precise description and characterization of paleo- Smith et al. 2000). The White Cliffs section records the fol- sols as natural objects in their own right. Conventions of lowing paleomagnetic reversals: 5.23 Ma at 2.81 m, 4.98 Ma naming and definition, such as nomination of type sections, at 32 m, 4.89 Ma at 40 m, 4.8 Ma at 44 m, 4.62 Ma at 63.1 are needed to facilitate the growth of descriptive databases m, 4.48 Ma at 61.1 m, and 4.29 Ma at 142 m (Gustafson through the efforts of successive investigators. These conven- 1985). Near Taunton, the formation records the Pliocene tions follow standard procedures of soil survey (Soil Survey paleomagnetic reversal at 3.040–3.110 Ma between 0–9.9 m Staff 1993). Differences between pedotypes need to be in a local section above a railway siding (Morgan and Morgan documented (Fig. 3) before their environmental significance 1995, Smith et al. 2000). Plio-Pleistocene paleosols are pres- is interpreted. Although interpretations of paleoclimate, fossil ent in the 2-Ma Huckleberry Tuff exposed on high terraces flora and fauna, paleotopographic position, parent material, south of Sutton Mountain (Perkins et al. 1998). Paleosols at and time for formation differ between pedotypes, they can 92 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

Figure 2. Field photographs of selected paleosols: A. Ultisols and Alfisols above the Nut Beds near Clarno.B. Alfisols and Gleyed Incep- tisols in the central Painted Hills. C. Aridisols and Andisols at Foree north of Kimberly. D. Caprock Aridisols south of Kimberly. be generalized to different individual paleosols of the same forming conditions. pedotype (Retallack et al. 2000). Diversity, overturn, appearances, and disappearances of pedotypes through time can be estimated (Fig. 5) in the same Pedotype interpretation way as evolutionary metrics of mammal fossils (Alroy et al. Each pedotype represents a particular combination of 2000, Janis et al. 2002). Unlike biological species, which persist soil-forming influences; i.e., a particular ecosystem formed from evolution to extinction, ecosystems and their soils can be in a particular climate, on a particular parent material, in dispersed and reconstituted as conditions allow (Bernabo and a particular landscape setting, and over a particular period Webb 1977). Thus, Skwiskwi paleosols in the upper Big Basin of time. As with paleontological data, pedotypes have lo- Member (30 Ma) and the Mascall (15 Ma) and Rattlesnake cal stratigraphic ranges and can be useful in stratigraphic formations (7 Ma) all represent subhumid woodland communi- correlation and paleoenvironmental reconstruction (Fig. ties, even though their taxonomic compositions were probably 4). As with trace fossils (Seilacher 1970) and stromatolites quite different. With these few exceptions, stratigraphic ranges (Bertrand-Sarfati and Walter 1981), pedotypes do not need defined by the first and last occurrences of pedotypes are temporal and genetic continuity to be useful in stratigraphy comparable in duration with stratigraphic ranges of associated and paleoecology. There is a general progression of differ- mammals (Alroy et al. 2000, Janis et al. 2002). In addition, ent pedotypes in the Cenozoic of Oregon (Fig. 4), aside both pedotype and mammalian diversity and turnover were from a few repetitions, such as the return of green (Xaxus) generally greater during the warm-wet late Eocene (34–45 pedotypes after brown (Plas) pedotypes in the Haystack Ma) and middle Miocene (19–12 Ma) than during the cold- Valley Member of the upper John Day Formation, and the dry late Oligocene and late Miocene-Pleistocene (Alroy et al. return of brown clayey (Skwiskwi) pedotypes from the Big 2000, Janis et al. 2000; Fig. 5). Basin Member of the John Day Formation in the Mascall Each pedotype also represents a particular kind of vegetation, and Rattlesnake Formations. Each formation has a unique geomorphic setting, parent material, and time for formation (see sequence of pedotypes that reflects temporal changes in soil- Retallack et al. 2000, 2002a, Retallack 2004a, b). The relative RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 93

Figure 3. Chemical and petrographic data on selected Oregon paleosols. A. Xaxus and Xaxuspa paleosols (revised section) from Foree. B. Luca paleosol from Whitecap Knoll near Clarno. C. Lakayx and Scat paleosols above Nut Beds near Clarno (data from Re- tallack et al. 2000). 94 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009 importance of these paleoenvironmental factors through time can be assessed from the relative abundance of pedotypes for two million year bins centered on each million-year increment (Fig. 6). Forest pedotypes were common in the Eocene (35–45 Ma), woodland pedotypes in early Oligocene (30–35 Ma) and the middle Miocene (19–12 Ma), and desert shrubland (probably sagebrush) pedotypes at other times. Forest and woodland paleosols have large root traces and differ in the degree of chemical and mineral weathering of the clayey subsurface (Bt) horizons (Retallack et al. 2000), whereas shrubland paleosols

Figure 5. Richness (A), appearances (B), disappearances (C), overturn (D), calcareous paleosols or pedocals (E) and taxonomic orders (F) through time of pedotypes of paleosols from Oregon and Washington. Bin size is 1 million years either side of each million year increment. Data source is 1856 paleosols in 50 described pedotypes (Retallack et al. 2000, 2002a, Bestland and Forbes 2003, Retallack 2004a,b).

Figure 4. Stratigraphic range of named pedotypes of paleosols from Oregon and Washington. RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 95 have shallow calcareous nodules (Bk) and common cicada burrows (Retallack 2004a). There has also been a steady increase in bunch grasslands with granular-ped paleosols since the early Oligocene (30 Ma), and sod grasslands with crumb-ped paleosols since the early Miocene (19 Ma: Fig. 6A). Streamside habitats with very weakly developed pedotypes were most common during the warm-wet Eocene-early Oligocene (>30 Ma) and middle Miocene (19–12 Ma), whereas chemically oxidized paleosols of well-drained floodplains were common at other times (Fig. 6B). Although coarse-grained fluvial sediments and volcanic lahars are common in the Eocene-early Oligocene and middle Miocene, most of the paleosol record was formed on claystones weathered from redeposited rhyodacitic airfall tuffs (Fig. 6C; Bestland 2000, Retallack et al. 2000). Some quantifiable aspects of paleosols reflect vegetation and the activities of soil-dwelling animals. Modern soils of eastern Washington have large (1–2 cm in diameter) burrows of cica- das in sagebrush soils, abundant small (0.5 mm in diameter) earthworm pellets in grasslands, and medium to coarse (1–5 cm) blocky peds in forests (O’Geen and Busacca 2002). The fine crumb structure of sod grassland soils, granular structure of bunch grassland soils, and blocky structure of woodland soils can also be recognized in paleosols (Retallack 2004a,b). The decline in minimum size of peds in paleosol surface horizons over the past 45 Ma in Oregon (lower envelope to Fig. 7A) produces a corresponding increase in internal surface area of paleosols (upper envelope of Fig. 7B). Internal surface area was calculated from the number of approximating cubes to the average ped size in the thickness of A horizons, added to a comparable calculation for Bt or Bw horizons when present. These measurements support an early Oligocene (30 Ma) advent of bunch grassland, early Miocene (19 Ma) appearance of sod grassland, and late Miocene (7 Ma) appearance of tall sod grassland in Oregon from pedotypes (Fig. 6A). Despite these innovations, both average ped size and internal surface Figure 6. Variation in soil forming factors of vegetation (A), geo- area have changed little over the past 45 Ma. morphic setting (B), parent material (C) and degree of develop- Soil Taxonomy ment (D) through time of pedotypes of paleosols from Oregon and Washington. Bin size and data source are same as for Figure 5. There are 12 orders in the soil taxonomy of the US Soil Conservation Service (Soil Survey Staff 1999). Identification of soils and paleosols in this classification system requires but a guide to key criteria is presented here. Many paleosols laboratory analyses (Fig. 2). For paleosols, there are petro- dominated by volcanic shards (Fig. 3A) have non-crystalline graphic and chemical proxies that accommodate alterations colloids that have been partly recrystallized to clinoptilolite to soil during burial (Retallack 1997a, 2001a). Comparable and celadonite (Retallack et al. 2000, 2002a, Bestland 2002), laboratory data also is needed for identification of paleosols as in Andisols (suffix “-and” of Soil Survey Staff 1999) and in other soil classifications, such as map units of the United Andosols (Food and Agriculture Organization 1974). Some Nations Educational Scientific and Cultural Organization’s paleosols have the crumb texture, thin root traces, and thick- soil maps of the world (Food and Agriculture Organiza- ness of this fine soil fabric to qualify as Mollisols (suffix “-oll” tion 1974), and traditional soil names (Stace et al. 1968). of Soil Survey Staff 1999) and Kastanozems (of Food and A simplified field classification (Mack et al. 1993) is useful Agriculture Organization 1974). Other paleosols have high for labelling paleosols, but not for paleoenvironmental in- soda/potash ratios, and shallow nodules and concretions of terpretation (Retallack 1993, Mack and James 1994), which calcite and chalcedony, which are characteristic of Aridisols is emphasized in the present study. (suffix “-id” of Soil Survey Staff 1999) and Xerosols, Solon- Details of soil taxonomic determinations are published chak, and Solonetz (of Food and Agriculture Organization elsewhere (Retallack et al. 2000, 2002a, Retallack 2004a,b), 1974). Paleosols that are weakly developed with bedding 96 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

ing the vast array of modern soil descriptions in county and regional soil surveys. The Food and Agriculture Organization (1974) soil maps of the world are especially useful in this regard because they are global in coverage. It is primarily taxonomic considerations that enable comparison of the suite of paleosols from the middle Eocene Clarno Nut Beds (Figs. 2A, 3A) with soils now forming under the tropical forest (“selva of Lauraceae”) on Volcán San Martin, Mexico, and the suite of paleosols from the middle Oligocene Turtle Cove Member of the John Day Formation (Figs. 2C, 3C) with soils now forming under deciduous grassy woodland near Tehuacán, Mexico (Retallack et al. 2000). Also informative is the relative abundance through time of soil orders (Fig. 5F) and Marbut’s (1935) simpler classification of calcareous soils (pedocals) versus non-calcareous soils (pe- dalfers: Fig. 5E). The onset of pedocals in the early Oligocene (30 Ma) is striking, as is their rarity in the middle Miocene (19–12 Ma). Pedocals reflect dry and seasonal climates with insufficient moisture to leach carbonate from soils. Forest soils (Oxisols, Ultisols, Alfisols) are common in the Eocene and Figure 7. Variability in (A) ped size (cm) within surface horizons and (B) in calculated internal surface area versus land surface area early Oligocene (30–45 Ma), and Alfisols reappear during the (mm2/mm2) in paleosols of Oregon and Washington through middle Miocene (19–12 Ma) when woodland and highly sea- time. Each plotted point represents one paleosol. sonal soils (Andisols and Vertisols) are common. Desert soils (Aridisols) have been common at other times, with a fluctuating but increasing abundance of grassland soils (Mollisols) since planes of sedimentary parent material little disrupted by root the early Miocene (19 Ma). traces are classified as Entisols (suffix “-ent” of Soil Survey Staff 1999) and Fluvisols (Food and Agriculture Organization TRANSFER FUNCTIONS 1974). These can be contrasted with moderately developed paleosols in which all traces of sedimentary organization have Paleoenvironmental interpretations can be quantified for been obliterated by the activity of worms and roots, and which paleosols by applying the experimental designs of Jenny have a subsurface horizon that has been enriched (by at least (1941). His space-for-climate approach to quantifying soil 8%) in clay washed down into the profiles, as in Alfisols (Fig. formation uses a collection of modern soils from different 3B; suffix “-alf” of Soil Survey Staff 1999) and Luvisols (Food climates, but that are comparable in other soil-forming and Agriculture Organization 1974). All of the paleosols factors, including vegetation, parent material, topographic noted above are rich in cationic nutrients (Ca2+, Mg2+, Na+, setting, and time for formation. From this set of soils (a K+); however, the paleosols were significantly less fertile if climosequence) can be extracted mathematical relationships the molar sum of these bases divided by molar alumina is less (climofunctions) between soil variables (such as base deple- than 0.5 (Sheldon et al. 2002). Such base-depleted paleosols tion) and climatic variables (such as mean annual precipita- with a subsurface clay-enriched horizon can be regarded as tion). Similarly, biofunctions for vegetation or other biotic Ultisols (Fig. 3A; suffix “-ult” of Soil Survey Staff 1999) and effects can be extracted from biosequences, topofunctions Acrisols (Food and Agriculture Organization 1974). Strongly for geomorphic changes from toposequences, lithofunc- base-depleted, uniformly clayey, and often ferruginous and tions for parent material effects from lithosequences, and bauxitic paleosols can be identified as Oxisols (suffix “-ox” of chronofunctions for time of soil development from chrono- Soil Survey Staff 1999), Ferralsols, and Nitosols (Food and sequences (Retallack 2005). Generally applicable biofunc- Agriculture Organization 1974, Bestland et al. 1996). tions, topofunctions, lithofunctions and chronofunctions for paleosols have yet to be devised, and for those aspects of Taxonomic interpretation paleoenvironmental interpretation, pedotype and taxonomic The primary purpose for identifying paleosols within modern approaches are most useful (Fig. 6). soil taxonomies is to find modern soils analogous to paleosols. In contrast, there are several climofunctions from which to Fossil soils, like other fossils, have lost much of their original choose (Sheldon et al. 2002, Retallack 2005). Several features form and function during burial and other alterations (Retallack of modern soils show significant relationships with mean an- 1997a). In the same way that behavior and ecology of fossil nual precipitation (P in mm) and mean annual temperature snails and mammals can be inferred from their nearest living (T in oC): (1) depth to calcareous nodules (D in cm) in the relatives, much can be learned by comparison of paleosols with soil profiles (Retallack 2005); (2) chemical index of alteration comparable soils. Soil classification is a simple way of navigat- without potash (C, which is the molar ratio of alumina over RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 97 alumina plus lime, magnesia, and soda times 100) of paleosol subsurface (Bt or Bw) horizons (Sheldon et al. 2002), and (3) alkalies index (S which is molar potash plus soda over alumina) of paleosol subsurface (Bt or Bw) horizons (Sheldon et al. 2002) , according to the equations: P = 139.6 + 6.39D + 0.013D2 , where S.E. = ± 141 mm; R2 = 0.62 P = 221.12e0.0197C, where S.E. = ± 182 mm; R2 = 0.72 T = -18.52S + 17.3, where S.E. = ± 4.4oC; R2 = 0.37 Depth to calcareous nodules can be corrected for burial compaction (using Inceptisol physical constants of Sheldon and Retallack 2001), but atmospheric CO2 levels and erosion of the paleosols before burial were not considered sufficiently significant to require correction (Retallack et al. 2000, Retal- lack 2004a,b).

Climofunction application When applied to calcic and chemical data from Oregon paleosols, each paleoclimatic transfer function indicates long term oscillations between arid-cool and humid-warm paleoclimate. The covariance of paleotemperature and paleoprecipitation is striking from chemical climofunctions (Fig. 8A). Paleoprecipitation estimated from depth to carbonate (Fig. 8B) is comparable with that estimated from chemical composition. There are limitations to carbonate data, because carbonate-bearing paleosols appeared in Oregon only after 30 Ma, and such paleosols cannot record high precipitation, which creates non-calcareous soils (Retallack 2005). Some parts of Oregon’s fossil soil record show exceptional temporal resolution. During the late Oligocene (28.6–23.4 Ma) accumulation of the upper Turtle Cove Member on Longview Ranch near Kimberly there are 105 climatic fluctua- Figure 8. Cenozoic variation in mean annual precipitation (A) tions recorded by depth to carbonate in 358 paleosols, as well and mean annual temperature (B) inferred from paleosol chem- as by the oxygen and carbon isotopic composition of their istry (A, B) and depth to calcic horizons (B), compared with pedogenic carbonate (Fig. 9). These variations principally oxygen and carbon isotopic composition of marine foraminifera record paleoclimatic cycles paced with changes in obliquity (C–D), and CO2 levels inferred from stomatal index (E). Data (41 k.yr) of the Earth’s orbit, a temporal resolution generally of A and B from Retallack (2004a,b) and Retallack et al. (2000), associated with Quaternary paleoclimatic records (Retallack with flanking curves one standard error from the transfer func- et al. 2004). tion; data of C and D from Zachos et al. (2001); data of E from Retallack (2001b, 2002) with flanking curves one standard devia- Paleosol-based paleoclimatic curves are comparable with tion of the stomatal index measurement, using transfer function long-term variation in oxygen and carbon isotopic compo- of Wynn (2003). sition of benthic marine foraminifera (Fig. 8D), and with variation in atmospheric CO2 estimated from stomatal index of Ginkgo leaves (Fig. 8E). Also comparable are time series floral estimates, which require large collections and are scat- of North American mammalian diversity, origination and tered in time, paleosol data are easier to obtain and much extinction (Alroy et al. 2000, Janis et al. 2002), and diversity more abundant through time. and floristic affinities of broadleaf forest vegetation in the An unexpected result, also found in comparable studies in lacustrine deposits of Oregon and Washington (Graham Montana and Nebraska (Retallack 2007), is that paleoclimatic 1999). Paleosol data confirm Meyer and Manchester’s (1994) drying encouraged the spread of desert shrubland rather than estimate of a mean annual precipitation of 1000-1500 mm and grasslands (Fig. 6A). Grasslands appear for the first time and mean annual temperature of 3–9oC for the early Oligocene then spread at times of warm-wet climate (Figs. 6, 8) and (32 Ma) Bridge Creek floras of central Oregon, and Chaney high soilscape diversity (Fig. 5) in the early (30 Ma) Oligo- and Axelrod’s (1959) estimate of a mean annual precipitation cene and early (19 Ma) and late (7 Ma) Miocene. Ancient of about 1270 mm and mean annual temperature of about grasslands are here inferred from paleosol data (Figs. 6, 7, 17oC for the middle Miocene (15 Ma) Mascall flora. Unlike 10), although there is a record of grass pollen (Leopold and 98 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

Denton 1987), phytoliths (Strömberg 2002, 2004, 2005, gocene and Pleistocene shifts in oxygen isotope values in the Blinnikov et al. 2002) and a few megafossils (Graham 1999, deep ocean are due to growth and decay of the Antarctic and Retallack 2004b). Most of the fossil record of plants comes Arctic ice caps, which abstracted large volumes of isotopically from swampy lowland deposits, whereas grasslands were light oxygen from the ocean-atmosphere system (Zachos et mainly a phenomenon of dry, well drained soils (Retallack al. 2001). Long term drift of marine oxygen isotopic values 1998). The evolution of grasslands can be inferred from to lower values also is well known, and is attributed to crustal root traces and aggregate size in paleosols. Soil aggregates recycling (Veizer et al. 2000, Kasting et al. 2006) or burial (peds) are small in grassland soils because defined by a net- diagenesis (Mii et al. 1997). Other theoretically plausible, work of fine roots, and because produced as fecal pellets by but quantitatively unlikely reasons for mismatches of oceanic earthworms, both characteristic of grassland soils (Retallack oxygen and Oregon paleosol records include evolution of C4

1997a, 2001c). These highly coevolved ecosystems did not photosynthetic pathways in grasses which select CO2 heavy simply fill in arid inland regions, which were occupied then, for either carbon or oxygen, and Rayleigh distillation to lower as now, by desert shrublands. oxygen isotope values on land increasingly elevated and isolated Surprisingly, the uplifting of the Cascade, Klamath, and from the sea by mountains (Retallack 2007). Less surprising is Olympic mountain ranges does not appear to correspond the carbon isotope value of the same deep marine foraminifera, to the spread of rain-shadows, as traditionally inferred from which matches Oregon paleoclimatic records well (Fig. 8D), fossil floras (Chaney 1948, Ashwill 1983), and more recently apart from Plio-Pleistocene deviation attributable to the rise from declining isotopic values of oxygen in tooth enamel of C4 vegetation on land (Cerling et al. 1997). and pedogenic carbon (Kohn et al. 2002, Kohn and Fremd 2007). Growth of the Oregon Cascades inferred from radio- IMPLICATIONS FOR CENOZOIC metrically dated eruptions (McBirney et al. 1974, Priest 1990) GLOBAL CHANGE shows peaks of volcanic activity at 35, 25, 16, 10 and 4 Ma, The Cenozoic Oregon paleosol record is unusually long but these are all times of warm-humid rather than cold-dry and detailed. Oregon’s back-arc paleotopography, rate of paleoclimate (Fig. 8A–B). Re-evaluation of the physiog- basinal subsidence, and rhyolitic parent materials changed nomy of fossil floras from the northern Great Basin indicate little over the past 45 Ma, but Oregon’s changing climate high altitudes since at least the early Miocene, for example and vegetation reflects a global paleoclimate signal for several 2100 m for the middle Miocene (16 Ma) 49 Camp flora of reasons. Annual variation in oxygen isotopic composition northwestern Nevada (Wolfe et al. 1997), again at a time of of growth bands within Miocene mammalian tooth enamel warm-humid paleoclimate (Fig. 8A–B) and high atmospheric reflect planetary revolutions (Fox 2001, Kohn et al. 2002). CO2 (Retallack 2001b, 2002). Eastern Oregon was broadly Also, temporal variations in depth to carbonate and its stable elevated during middle Miocene (16 Ma) initial eruptions of isotopic composition (Fig. 9) have the same periodicity (41- the Yellowstone hot spot, then subsided subsequently (Hum- 100 ka) as orbital variations in obliquity and eccentricity phreys et al. 2000), with the exception of remarkably focused (Retallack et al. 2004). Late Eocene and middle Miocene uplift of the Wallowa Mountains (Hales et al. 2006). Cascades peaks in temperature and precipitation in Oregon paleosols and Klamath Mountain rain shadows have been important in (Fig. 8A–C) correspond to highs in global atmospheric creating generally dry long-term climate in eastern Oregon, CO2 revealed by stomatal index of fossil Ginkgo (Fig. 8E) with loessial sediments and calcareous paleosols starting and peaks in deep ocean temperature inferred from marine during the Oligocene (30 Ma: Retallack et al. 2000). Rocky oxygen isotopic values (Fig. 8D). Cenozoic global cooling Mountain barriers also promoted summer-dry climate due to from late Eocene (35 Ma) and middle Miocene (16 Ma) peaks a cool nearby ocean by isolation of eastern Oregon from Gulf of warmth has been explained by mountain uplift (Raymo Coast cyclonic circulation starting during the early Miocene and Ruddiman 1992), changing oceanic currents (Kennett (19 Ma: Retallack 2004a). Orographic rain shadows were 1982, Broecker 1989) and grassland coevolution (Retallack thus long-term boundary conditions to circulation since at 2001c), and the Oregon paleosol record is relevant to each least 50 Ma (Kent-Corson et al. 2006), but do not explain of these hypotheses. observed short-term paleoclimatic variation such as middle Miocene warm-wet spikes (Retallack 2007). Mountain uplift Also surprising are mismatches between broadly compa- Raymo and Ruddiman (1992) proposed that Himalayan rable paleoclimatic records of Oregon paleosols and oxygen and other mountain uplift promoted deep weathering by and carbon isotopic composition of deep marine benthic carbonic acid and was thus a sink for atmospheric carbon foraminifera (Fig. 8C–D). Abrupt terminal Eocene, late dioxide promoting Cenozoic climatic cooling after about 40 Oligocene and Pleistocene change in oxygen isotopic data Ma. Their argument was based largely on the temporal in- contrast with ramps in paleosol data (Sheldon et al. 2002, crease of 87Sr/86Sr ratios, now attributed largely to carbonate Sheldon and Retallack 2004), and the general trend of oxygen weathering, which does not appreciably affect atmospheric isotope records is sloping whereas paleosol records are level redox, unlike silicate weathering (Jacobson et al. 2002, Ja- with deviations (Fig. 8C). Abrupt terminal Eocene, late Oli- cobson and Blum 2003). There are additional fundamental RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 99

Figure 9. Milankovitch-scale fluctuations in mean annual paleoprecipitation inferred from depth to calcic (Bk) horizon within paleosols of the upper John Day Formation on Longview Ranch, near Kimberly. problems with Raymo and Ruddiman’s (1992) hypothesis be- lowed by warming effects of carbon dioxide from destroyed cause metamorphic and volcanic emissions of carbon dioxide soils and biomass (Poag et al. 2003). together with reduced chemical weathering at high altitude In the Oregon paleosol record, which includes the Colum- make mountain uplift a force not for global cooling, but for bia River basalts (Sheldon 2003, 2006), the most chemically global warming (Zeitler et al. 2001). Himalayan and other weathered paleosols are those least disturbed by volcanism, mountain uplift promotes physical weathering, especially by uplift and sedimentation (Bestland et al. 1996, Retallack et means of glaciation, but not carbon-consuming chemical al. 2000). These paleosols would have consumed significant weathering of silicates (Jacobson and Blum 2003). Warm-wet amounts of carbon dioxide by hydrolysis, especially at times spikes at 35 and 16 Ma in climate records of Oregon (Fig. 8) of high atmospheric carbon dioxide and warm-wet weath- and elsewhere around the world (Retallack 2007) coincide ering (Fig. 8). Thus, times of volcano-tectonic quiescence with peaks in volcanic activity in the western US (McBirney et promote cooling, by consuming atmospheric carbon dioxide al. 1974, Priest 1990), and in globally significant eruptions of during hydrolytic weathering and fertilizing the ocean with Ethiopia-Yemen and Columbia River flood basalts (Courtillot bicarbonate and nutrients for deep oceanic storage of reduced 2002). Some of these eruptions may have intruded coal (such carbon largely from phytoplankton (Retallack 2001c). In as Oregon’s Herren Formation) and released to the atmo- contrast, perturbations of mountain uplift, volcanism, and sphere large amounts of thermogenic methane, which then bolide impact are forces for planetary warming. oxidized to atmospheric CO2, as has been argued for other global warming events (Retallack and Jahren 2008). These Ocean gateways warm-wet spikes also coincide with the Chesapeake impact Ocean current reorganization as a result of continental crater at 35 Ma (Poag et al. 2003), and Ries and Steinheim drift has also been proposed as a force for Cenozoic global craters at 16 Ma (Stoeffler et al. 2002), which would induce cooling. Kennett (1982) argued that cooling across the Eo- initial cooling from particulate ejecta in the atmosphere fol- cene-Oligocene transition was caused by continental drift of 100 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

Australia and South America away from Antarctica, so that and small trees (Juniperus occidentalis) (see Blinnikov et al. the ice continent was then thermally isolated by the Circum- 2002) and may also be from arid shrubland communities Antarctic current. Broecker (1989) argued that Panamanian indicated by paleosols. isthmus closure created a warm salty Caribbean and stimu- Considering the combined evidence from paleosols and lated thermohaline circulation into North Atlantic bottom phytoliths, grasslands did not merely adapt to climate change, water formation to bring on the Pleistocene ice age. Problems but were a biological force for global change. Compared with with timing and mechanism have emerged for both ideas. The preexisting woodland soils, grasses created soils richer in re- Circum-Antarctic current was initiated at 37 Ma rather than duced carbon and finer in structure deeper within the profile the 33.9 Ma Eocene-Oligocene boundary (Exon et al. 2004) (Figs. 7, 10), thus promoting carbon sequestration in soils and and completed by 25 Ma (Lyle et al. 2007) when Oregon derived sediments, as well as carbon dioxide consumption by and other isotopic data indicate warming and deglaciation in hydrolytic weathering. Woodlands create moist air and dry a reversal of the proposed effect (Zachos et al. 2001). Pana- soils by active transpiration, but grasslands create moist soil manian isthmus closure was at 2.8–3.1 Ma rather than the and dry air, which is cooler without greenhouse-inducing 1.8 Ma Plio-Pleistocene boundary (Bartoli et al. 2005), also water vapor. Finally albedo of grasses is higher than that of a time of warming. More problematic is modeling indicating woodlands, reflecting much solar warmth back into space warming rather than cooling by diminution of the Humboldt (Retallack 2001c). Thus, grasslands and their soils (Molli- Current as Chile drifted north (DeConto and Pollard 2003), sols) became a force for planetary glaciation comparable with and by Gulf Stream redistribution into the North Atlantic of Late Devonian to Carboniferous (300-390 Ma) evolution of warmth from an enclosed Caribbean Sea (Lund et al. 2006). trees (Berner 1997) and soils of forests (Alfisols) and swamps Thermal transport modeling now suggests a more important (Histosols: Retallack 2001a, 2004c). role for global carbon dioxide than southern ocean currents Unlike ocean gateways or mountain uplift, this mecha- in Cenozoic cooling (Huber and Nof 2007). nism of global cooling is biological not physicochemical. In Southern and central American oceanic gateways are re- the long term, weedy reproduction and abrasive phytoliths mote from Oregon records (Fig. 8A–B) which show general of grasses withstood the onslaught of increasingly large, similarity with oceanic isotopic records (Fig. 8C–D) domi- hypsodont and hard-hooved mammals more effectively than nated by cores from the Southern Ocean (Zachos et al. 2001). pre-existing woody plants, but key stages in the process are Eocene-Oligocene cooling in the northern Pacific Ocean was evident in Oregon (Fig. 10). An early stage appearing by 35 synchronous with that in the southern hemisphere, yet not Ma in Nebraska and 30 Ma in Oregon is marked by abundant accompanied by changes in northern oceanic basin configura- opal phytoliths of grasses, cursorial and lophodont mixed tion (Scholl et al. 2003), lending support to climate-change browser-grazer rhinos and horses, and granular-structured mechanisms of global reach such as the greenhouse effect of calcareous paleosols (Retallack 1983, Retallack et al. 2000, atmospheric carbon dioxide. Janis et al 2002, Strömberg 2002, 2004) A likely biological adaptation triggering the appearance of these fossils and Grassland coevolution paleosols is the origin of rumination (cud chewing) dated A third suggested cause of Cenozoic climatic cooling is to 34–35 Ma by molecular clock techniques on digestive stepwise coevolution of grassland grasses and grazers into ribonucleases of ruminants (Jermann et al. 2001). Another novel ecosystems (sod grasslands) and soils (Mollisols) over coevolutionary advance at a time of warm-wet climate was the past 35 Ma (Retallack 2001a). Evidence for this view is appearance of hypsodont horses, abundant open country well documented in Oregon (Fig. 10), where it has a long phytoliths and crumb-structured paleosols (Mollisols) of pedigree back to Thomas Huxley’s insights on horse evolu- short sod grasslands in Oregon, Montana and Nebraska at tion from his 1876 examination of the collection of Oregon about 19 Ma (early Miocene: Retallack 2007). The seminal fossils O.C. Marsh at Yale obtained from Thomas Condon evolutionary innovation for these communities may have (Clark 1989). The coeval appearance of hypsodont horses been pack-hunting, indicated by the prorean gyrus in brain and Mollisols in Oregon reflects grass-grazer coevolution that casts of fossil carnivores (Van Valkenburgh et al. 2003), is also evident in Montana, Nebraska, Pakistan, and Kenya which in turn promoted herding, intensive “cell grazing” (Retallack 1995, 1997b, 2007, Retallack et al. 2002b). The and sod development (Savory and Butterfield 1999). A final appearance of open-country grass phytoliths 4 Ma.earlier than coevolutionary advance, again at a time of warm-wet climate hypsodont horses in the Great Plains (Strömberg 2006) does at about 7 Ma, was the appearance of large horses, along not contradict this conclusion because the open country grass with deep-calcic, crumb structured paleosols (Mollisols) phytoliths come from desert and rangeland soils (Aridisols of subhumid climates and tall-grasslands (Retallack et al. and Inceptisols) comparable with those now supporting 2002a). The seminal evolutionary adaptations in this case sagebrush and bunch grassland (Retallack 2007). Other phy- may have been monodactyl hard hooves and highly hypso- toliths in these paleosols are considered by Strömberg (2004, dont teeth, harder on seedlings of trees than grasses, so that 2006) as forest indicators, but they are indistinguishable from the grassland-woodland ecotone rolled outward into more phytoliths of modern desert shrubs (Artemisia tridentata) humid regions (Retallack 1997b). The 7 Ma coevolutionary RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 101

Figure 10. Coevolution of grasses and grazers. Although only examples of paleosols and fossil horses from Oregon are shown, comparable evolutionary change is known from all continents except Australia and Antarctica, and may have had global change consequences.

advances marked the onset of the C4 photosynthetic pathway consumption and sequestration, water vapor reduction and as a global carbon isotopic perturbation (Cerling et al. 1997), albedo increases of grasslands arrested tectono-volcanic and although the pathway itself may be older; an origin of 40 extraterrestrial warmings at 35, 16 and 7 Ma to create the Ma is estimated from paleosol carbon isotopic studies (Fox bumpy ride of Oregon and global climate over the past 45 and Koch 2003), 25 Ma from phylogenetic analyses (Kellogg million years (Fig. 8). 1999), and 12.5 Ma from isotopic and anatomical studies of fossil grasses (Nambudiri et al. 1978, see Whistler and Bur- CONCLUSIONS bank 1992, for revised age). There is as yet no evidence of The multifaceted Cenozoic paleosol record of Oregon and

C4 grasses in Oregon before their agricultural introduction, Washington undoubtedly has more to reveal about global and such summer-dry climates have mainly C3 grasses today change beyond the interpretations of changing vegetation (Sage et al.1999). Cooling coevolutionary advances in carbon and climate reviewed here. Especially promising is the role of 102 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009 past weathering in atmospheric carbon dioxide consumption of Sedimentary Research A72:673–686. (Bestland 2000) and mammalian community dynamics of Bestland, E.A., and M.S. Forbes. 2003. Stratigraphy and geochem- different pedotypes (Retallack et al. 2004). New approaches istry of the mid-Miocene Mascall Formation (upper part) in its to research can be expected beyond those of pedotypes, type areas. Unpublished Report John Day Fossil Beds National taxonomy, and transfer functions outlined here. Oregon Monument, Kimberly. 50 pp. and Washington’s Cenozoic paleosol record is continuous Bestland, E.A., P.E. Hammond, D.L.S. Blackwell, M.A. Kays, back to at least 45 Ma, and some parts of it are comparable G.J. Retallack, and J. Stimac. 1999. Geologic framework of the in temporal resolution with deep-sea cores (Retallack et Clarno Unit, John Day Fossil Beds National Monument, central al. 2004). Comparable paleosol records are developing for Oregon. Oregon Geology 61:3–19. Montana, Nebraska (Retallack 2007), and elsewhere (Retal- Bestland, E.A., G.J. Retallack, E.A. Rice, and A. Mindszenty. 1996. lack 2001a). Paleoenvironmental information from paleosols Late Eocene detrital laterites in central Oregon: mass balance now supports evidence from fossil phytoliths and bones in geochemistry, depositional setting, and landscape evolution. paleosols at many localities, and provides new evidence for Geological Society of America Bulletin 108:285–302. theories of global change. Bishop, E.M., and G.A. Smith. 1990. A field guide to the geology of Cove Palisades State Park and the Deschutes Basin in central ACKNOWLEDGMENTS Oregon. Oregon Geology 52:3–12. I thank Ted Fremd, Scott Foss, and Mary Oman for Blinnikov, M., A. Busacca, and C. Whitlock. 2002. Reconstruction funding, research clearance, and curatorial assistance. Erick of the late Pleistocene grassland of the Columbia Basin, Washing- Bestland, Evelyn Krull, Jonathan Wynn, Megan Smith, ton, USA, based on phytolith records in loess. Palaeogeography Russell Hunt, and Nathan Sheldon helped with fieldwork Palaeoclimatology Palaeoecology 177:77–101. Bowen, R.G., W.L. Gray, and D.C. Gregory. 1963. General geology and fossil collection. Ken Finger and Randall Irmis greatly of the northern Juntura Basin. American Philosophical Society improved the manuscript by diligent editing. Work was Transactions 53:22–34. funded by National Park Service Contracts CX-9000-1-1009, Broecker, W.S. 1989. The salinity contrast between the Atlan- 144-PX9345-99-005, and P1325010503, Bureau of Land tic and Pacific Ocean during glacial time. Paleoceanography Management cooperative agreement 8/21/01, and National 4:207–212. Science Foundation grant EAR-0000953. Busacca, A.J. 1989. Long Quaternary record in eastern Washington, USA, interpreted from multiple paleosols in loess. Geoderma LITERATURE CITED 45:105–122. Alroy, J., P.L. Koch, and J.C. Zachos. 2000. Global climate change Busacca, A.J. 1991. Loess deposits and soils of the Palouse and and North American mammalian evolution. Paleobiology Supple- vicinity. In R.B. Morrison (ed.). Quaternary Nonglacial ment 26:259–288. Geology: Conterminous U.S. The Geology of North America Ashwill, M. 1983. Seven fossil floras in the rain shadow of the K2:216–228. Cascades Mountains. Oregon Geology 45:107–117. Cerling, T.E., J.M. Harris, B.J. MacFadden, M.G. Leakey, J. Bailey, M.M. 1989. Revisions to stratigraphic nomenclature of Quade, V. Eisenmann, and J.R. Ehleringer. 1997. Global vegeta- the Picture Gorge Basalt Subgroup, Columbia River Basalt. tion change through the Miocene/Pliocene boundary. Nature Pp. 67–84 in S.P Reidel and P.R. Hooper (eds.). Volcanism 389:153–158. and Tectonism in the Columbia River Flood-Basalt Province. Chaney, R.W. 1924. Quantitative studies of the Bridge Creek flora. Geological Society of America Special Paper 239. American Journal of Science 8:127–144. Bartoli, G., M. Sarnthein, M. Weinelt, H. Erlenkauser, G. Garbe- Chaney, R.W. 1948. The ancient forests of Oregon. University of Schönberg, and D.W. Lea. 2005. Final closure of Panama and Oregon, Eugene. 56 pp. onset of northern hemisphere glaciation. Earth and Planetary Chaney, R.W., and D.I. Axelrod. 1959. Miocene floras of the Science Letters 237:33–44. Columbia Plateau. Carnegie Institution of Washington Publica- Bernabo, J.L., and T. Webb. 1977. Changing patterns in the Holo- tion 617:1–237. cene pollen record from northeastern North America: a mapped Clark, R.D. 1989. The odyssey of Thomas Condon. Oregon His- summary. Quaternary Research 8:64–96. torical Society, Portland. 567 pp. Berner, R. 1997. The rise of plants and their effects on weathering Coombs, M.C., R.M. Hunt, E. Stepleton, L.B. Albright, and

and CO2. Science 276:543–546. T.J. Fremd. 2001. Stratigraphy, chronology, biogeography and Bertrand-Sarfati, J., and M.R. Walter. 1981. Stromatolite biostra- taxonomy of early Miocene chalicotheres in North America. tigraphy. Precambrian Research 9:105–166. Journal of Vertebrate Paleontology 21:607–620.

Bestland, E.A. 2000. Weathering flux and CO2 consumption deter- Courtillot, V. 2002. Evolutionary catastrophism. Cambridge Uni- mined from palaeosol sequences across the Eocene-Oligocene versity Press, Cambridge. 173 pp. transition. Palaeogeography, Palaeoclimatology, Palaeoecology DeConto, R.M., and D. Pollard. 2003. A coupled climate-ice 156:301–326. sheet modeling approach to the early Cenozoic history of the Bestland, E.A. 2002. Fossil Andisols identified with mass balance Antarctic ice sheet. Palaeogeography Palaeoclimatology Palaeoecol- geochemistry (Oligocene, John Day Formation, USA). Journal ogy 198:39–52. RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 103

DeLancey, S., C. Genetti, and N. Rude.1988. Some Sahaptian- Humphreys, E.D., K.G. Dueker, D.L. Schutt, and R.B. Smith. Klamath-Tsimshianic lexical sets. Pp. 195–204 in W. Shipley 2000. Beneath Yellowstone: evaluating plume and non-plume (ed.). In honor of Mary Haas. Mouton de Gruyter, Berlin. models using teleseismic images of the upper mantle. GSA Downs, T. 1956. The Mascall fauna from the Miocene of Oregon. Today 10(2):1–7. University of California Publications in Geological Sciences Hunt, R.M., and E. Stepleton. 2004. Geology and paleontology of 31:199–354. the upper John Day beds, John Day River, Oregon: lithostrati- Evernden, J.F., and G.T. James.1964. Potassium-argon dates and graphic and biochronologic revision in the Haystack and Kim- the Tertiary floras of North America.American Journal of Sci- berly areas (Kimberly and Mt. Misery quadrangles). American ence 262:945–974. Museum of Natural History Bulletin 282:1–90. Exon, N.F., J.P. Kennett, and M.J. Malone (eds.). 2004. The Ce- Hutchison, J.H. 1968. Fossil Talpidae (Insectivora, Mammalia) nozoic Southern Ocean: Tectonics, Sedimentation, and Climate from the late Tertiary of Oregon. Museum of Natural History Change between Australia and Antarctica. American Geophysical University of Oregon Bulletin 11:1–117. Union, Washington. 267 pp. Jacobson, A.D., and J.D. Blum. 2003. Relationship between me-

Fiebelkorn, R.B., G.W. Walker, N.S. MacLeod, E.H. McKee, and chanical erosion and atmospheric CO2 consumption of the New G.H. Smith. 1982. Index of K-Ar determinations for the state Zealand Southern Alps. Geology 31:865–868. of Oregon. Isochron West 37:1–60. Jacobson, A.D., J.D. Blum, and L.M. Walter. 2002. Reconciling Fisher, R.V. 1964. Resurrection of Oligocene hills, eastern Oregon. the elemental and Sr isotope composition of Himalayan weather- American Journal of Science 262:713–725. ing fluxes: insights from the carbonate geochemistry of stream Food and Agriculture Organization. 1974. Soil Map of the World, waters. Geochimica Cosmochimica Acta 66:3417–3429. Part 1, Legend, Paris, United Nations Educational Scientific and Janis, C.M., J. Damuth, and J.M. Theodor. 2002. The origin and Cultural Organization, Paris. 59 pp. evolution of the North American grassland biome: the story Fox, D.L. 2001. Growth increments in Gomphotherium tusks and from the hoofed mammals. Palaeogeography Palaeoclimatology implications for late Miocene climate change in North America. Palaeoecology 177:183–198. Palaeogeography Palaeoclimatology Palaeoecology 156:327–348. Jenny, H.J. 1941. Factors in soil formation. McGraw-Hill, New

Fox, D.L., and P.L. Koch. 2003. Tertiary history of C4 biomass in York. 281 pp. the Great Plains, USA. Geology 9:809–812. Jermann, T.M., J.G. Opitz, J. Stackhouse, and S.A. Benner. 1995. Fremd, T.E., E.A. Bestland, and G.J. Retallack. 1994. John Day Reconstructing the evolutionary history of the artiodactyl ribo- Basin fieldtrip guide and road log for the Society of Vertebrate nuclease family. Nature 374:57–59. Paleontology Annual Meeting. Northwest Interpretive Associa- Johnson, T.A., G.B. Binger, P.R. Hooper, and C.J. Hawkesworth. tion, Seattle. 90 pp. 1996. Implications of structure and stratigraphy in the Juntura Graham, A. 1999. Late Cretaceous and Cenozoic history of North area, east-central Oregon. Geological Society of America Abstracts American vegetation. Oxford University Press, New York. 350 pp. 28:78. Gustafson, E.P. 1978. The vertebrate fauna of the Pliocene Ringold Kasting, J.F., M.T. Howard, K. Wallmann, J. Veizer, G. Shields, Formation, south-central Washington. Museum of Natural His- and J. Jaffres. 2006. Paleoclimates, ocean depth, and the oxygen tory University of Oregon Bulletin 23:1–62. isotopic composition of seawater. Earth and Planetary Science Gustafson, E.P. 1985. Soricids (Mammalian: Insectivora) from the Letters 252:82–93.

Blufftop Local Fauna, Blancan Ringold Formation of central Kellogg, E.A. 1999. Phylogenetic aspects of the evolution of C4 Washington and correlation of the Ringold Formation. Journal photosynthesis. Pp. 411–444 in R.F. Sage and R.K. Monson of Vertebrate Paleontology 5:88–92. (eds.). Plant Biology. Academic Press, New York. Hales, T.C., D.L. Abt, E.D. Humphreys, and J.J. Roering. 2006. Kennett, J.P. 1982. Marine Geology. Prentice-Hall, Englewood A lithospheric instability origin for Columbia River flood basalts Cliffs. 813 pp. and Wallowa Mountains uplift in northeast Oregon. Nature Kent-Corson, M.L., L.S. Sherman, A. Mulch, and C.P. Cham- 438:842–845. berlain. 2006. Cenozoic topographic and climatic response Hanson, C.B. 1996. Stratigraphy and vertebrate faunas of the to changing tectonic boundary conditions in western North Bridgerian-Duchesnean Clarno Formation, north-central Or- America. Earth and Planetary Science Letters 252:453–466. egon. Pp. 206–239 in D.R. Prothero and R.J. Emry (eds.). Kohn, M.J., and T.J. Fremd. 2007. Tectonic controls on isotope The terrestrial Eocene-Oligocene transition in North America. compositions and species diversification, John Day Basin, central Cambridge University Press, New York. Oregon. PaleoBios 27:48–61. Hay, R.L. 1962. Origin and diagenetic alteration of the lower part Kohn, M.J., J.L. Miselis, and T.J. Fremd. 2002. Oxygen isotope of the John Day Formation near Mitchell, Oregon. Pp. 191–216 evidence for progressive uplift of the Cascade Range, Oregon. in A.E.L. Engel, H.L. Jones, and P.F. Leonard (eds.). Petro- Earth Planetary Sciences Letters 204:1–15. logic studies in honor of A.F. Buddington. Geological Society Leopold, E.B., and M.F. Denton. 1987. Comparative age of grass- of America, Boulder. land and steppe east and west of the northern Rocky Mountains. Huber, M., and D. Nof. 2007. The ocean circulation in the southern Missouri Botanical Garden Annals 74:841–867. hemisphere and its climatic impacts in the Eocene. Palaeogeog- Lund, D.C., J. Lynch-Stieglitz, and W.B. Curry. 2006. Gulf stream raphy Palaeoclimatology Palaeoecology 231:9–28. density structure and transport during the past millennium. 104 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

Nature 444:601–604. volcanic arc, central Oregon. Journal of Geophysical Research Lyle, M., S. Gibbs, T.C. Moore, and D.K. Rea. 2007. Late Oligo- 95:19383–19599. cene initiation of the Antarctic Circumpolar Current; evidence Prothero, D.R., E. Draus, and S.E. Foss. 2006a. Magnetic stra- from the South Pacific.Geology 35:691–694. tigraphy of the lower portion of the middle Miocene Mascall Mack, G.H., and W.C. James. 1994. Paleoclimate and global dis- Formation, central Oregon. PaleoBios 26(1):37–42. tribution of paleosols. Journal of Geology 102:360–362. Prothero, D.R., J.M. Hoffman, and S.E. Foss. 2006b. Magnetic Mack, G.H., W.C. James, and H.C. Monger. 1993. Classification of stratigraphy of the upper Miocene (Hemphillian) Rattlesnake paleosols. Geological Society of America Bulletin 105:129–136. Formation, central Oregon. PaleoBios 26(1):31–35. Manchester, S.R. 1994. Fruits and seeds of the middle Eocene Prothero, D.R., and J.M. Rensberger. 1985. Preliminary magne- Nut Beds flora, Clarno Formation, Oregon.Palaeontographica tostratigraphy of the John Day Formation, Oregon, and the Americana 58:1–205. North American Oligocene-Miocene boundary. Newsletters in Marbut, C.F. 1935. Atlas of American Agriculture. Part III Soils Stratigraphy 15:59–70. of the United States. Government Printer, Washington, DC. Raymo, M.E., and W.F. Ruddiman. 1992. Tectonic forcing of late 98 pp. Cenozoic climate. Nature 359:117–122. McBirney, A.R., J.F. Sutter, H.R. Naslund, K.G. Sutton, and C.M. Retallack, G.J. 1993. Classification of paleosols: discussion.Geologi - White. 1974. Episodic volcanism in the central Oregon Cascade cal Society of America Bulletin 105:1635–1637. Range. Geology 2:585–589. Retallack, G.J. 1994. A pedotype approach to latest Cretaceous and Merriam, J.C. 1906. Carnivora from the Tertiary formation of the earliest Tertiary paleosols in eastern Montana. Geological Society John Day region. Publications in Geological Sciences University of America Bulletin 106:1377–1397. of California 5:1–6. Retallack, G.J. 1995. Paleosols of the Siwalik Group as a 15 Ma Merriam, J.C. 1916. Mammalian remains from a Tertiary formation record of South Asian paleoclimate. In S. Wadia, R. Korisettar at Ironside, Oregon. Publications in Geological Sciences University and V.S. Kale (eds.). Quaternary Environments and Geoarchae- of California 10:129–135. ology of India: Essays in Honour of S.N. Rajaguru. Geological Merriam, J.C., and W.J. Sinclair. 1907. Tertiary faunas of the John Survey of India Memoir 32:36–51. Day region. Publications in Geological Sciences University of Retallack, G.J. 1997a. A Colour Guide to Paleosols. Wiley, Chich- California 5:171–205. ester, 175 pp. Merriam, J.C., C. Stock, and C.L. Moody. 1925. The Pliocene Retallack, G.J. 1997b. Neogene expansion of the North American Rattlesnake fauna of eastern Oregon, with notes on the geology prairie. Palaios 12:380–390. of the Rattlesnake deposits. Carnegie Institution of Washington Retallack, G.J. 1998. Fossil soils and completeness of the rock and Publications 347:43–49. fossil record. Pp. 131–162 in S.K. Donovan and C.R.C. Paul Meyer, H.W., and S.M. Manchester. 1997. Revision of the Oligo- (eds.). The Adequacy of the Fossil Record. Wiley, Chichester. cene Bridge Creek floras of Oregon. Publications in Geological Retallack, G.J. 2001a. Soils of the Past. Blackwell, Oxford. 404 pp. Sciences University of California 141:1–195. Retallack, G.J. 2001b. A 300-million-year record of atmospheric car- Mii, H.S., E.L. Grossman, and T.E. Yancey. 1997. Stable carbon bon dioxide from fossil plant cuticles. Nature 411:287–290. and oxygen isotope shifts in Permian seas of West Spitsbergen: Retallack, G.J. 2001c. Cenozoic expansion of grasslands and climatic global change or diagenetic artifact? Geology 25:227–230. cooling. Journal of Geology 109:407–426. Morgan, J.K., and N.H. Morgan. 1995. A new species of Caprom- Retallack, G.J. 2002. Carbon dioxide and climate over the past eryx (Mammalia: Artiodactyla) from the Taunton Local Fauna 300 Myr. Royal Society of London Philosophical Transactions B of Washington, and the correlation with other Blancan faunas 360:659–673. of Washington and Idaho. Journal of Vertebrate Paleontology Retallack, G.J. 2004a. Late Oligocene bunch grassland and early 15:160–170. Miocene sod grassland paleosols from central Oregon, U.S.A. Nambudiri, W.M.V., W.D. Tidwell, B.N. Smith, and N.P. Hebbert. Palaeogeography Paleoclimatology Palaeoecology 207:203–237.

1978. A C4 plant from the Pliocene. Nature 276:816–817. Retallack, G.J. 2004b. Late Miocene climate and life on land in O’Geen, A.T., and A.J. Busacca. 2002. Faunal burrows as indica- eastern Oregon within a context of Neogene global change. tors of paleovegetation in eastern Washington. Palaeogeography Palaeogeography Paleoclimatology Palaeoecology 214:97–123. Palaeoclimatology Palaeoecology 169:23–37. Retallack, G.J. 2004c. Soils and global carbon cycle change in geologi- Perkins, M.E., F.H. Brown, W.F. Nash, W. McIntosh, and S.K. cal time. Pp. 581–605 in H.D. Holland, K.K. Turekian, and J.I. Williams. 1998. Sequence, age and source of silicic fallout tuffs Drever (eds.). Treatise on Geochemistry, Volume 5: Surface and in middle to late Miocene basins of northern Basin and Range Ground Water, Weathering, and Soils. Elsevier, Amsterdam. Province. Geological Society of America Bulletin 110:344–360. Retallack, G.J. 2005. Pedogenic carbonate proxies for amount and Poag, W.C., E. Mankinen, and R.D. Norris. 2003. Late Eocene seasonality of precipitation in paleosols. Geology 33:333–336. impacts: geological record, correlation and paleoenvironmental Retallack, G.J. 2007. Cenozoic paleoclimate on land in North consequences. Pp. 495–510 in D.R. Prothero, L.C. Ivany, and E.A. America. Journal of Geology 15:271–294. Nesbitt (eds.). From Greenhouse to Icehouse: The Eocene-Oligo- Retallack, G.J., E.A. Bestland, and T.J. Fremd. 2000. Eocene and cene Marine Transition. Columbia University Press, New York. Oligocene paleosols of central Oregon. Geological Society of Priest, G.R. 1990. Volcanic and tectonic evolution of the Cascade America Special Paper 344:1–192. PRETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 105

Retallack, G.J., and A.H. Jahren 2008. Methane release from igneous Philosophical Society Transactions 53:42–69. intrusion of coal during Late Permian extinction events. Journal Smith, G.A. 1986. Simtustus Formation: paleogeographic and of Geology 116:1–20. stratigraphic significance of a newly defined Miocene unit in the Retallack, G.J., S. Tanaka, and T. Tate. 2002a. Late Miocene Deschutes Basin, central Oregon. Oregon Geology 48:63–72. advent of tall grassland paleosols in Oregon. Palaeogeography Smith, G.R., N. Morgan, and E. Gustafson. 2000. Fishes of the Palaeoclimatology Palaeoecology 183:329–354. Mio-Pliocene Ringold Formation, Washington: Pliocene capture Retallack, G.J., J.G. Wynn, B.R. Benefit, and M.L. McCrossin. of the Snake River by the Columbia River. University of Michigan 2002b. Paleosols and paleoenvironments of the middle Mio- Publications in Paleontology 32:1–47. cene, Maboko Formation, Kenya. Journal of Human Evolution Soil Survey Staff. 1993. Soil survey manual. U.S. Department of 42:659–703. Agriculture Handbook 18:1–437. Retallack, G.J., J.G. Wynn, and T.J. Fremd. 2004. Glacial-intergla- Soil Survey Staff. 1999. Keys to Soil Taxonomy. Pocahontas Press, cial-scale paleoclimatic changes without large ice sheets in the Blacksburg, Virginia. 600 pp. Oligocene of central Oregon. Geology 32:297–300. Stace, H.C.T., G.D. Hubble, R. Brewer, K.H. Northcote, J.R. Slee- Rigsby, B.J. 1965. Linguistic relations in the southern Plateau. man, M.J. Mulcahy, and E.G. Hallsworth. 1968. A Handbook Ph.D. dissertation, University of Oregon, Eugene. of Australian Soils. Rellim, Adelaide. 435 pp.

Sage, R.F., O.A. Wedin, and M. Li. 1999. Biogeography of C4 Stoeffler, D., N. Artemieva, and E. Pierazzo. 2002. Modeling the photosynthesis: pattern and controlling factors. Pp. 313–373 Ries-Steinheim impacts and the formation of the moldavite in R.F. Sage and R.K. Monson (eds.). Plant Biology. Academic strewn field.Meteoritics and Planetary Science 37:1893–1907. Press, San Diego. Streck, M.D., J.A. Johnson, and A. Grundner. 1999. Field guide to Savory, A., and J. Butterfield. 1999. Holistic Management: a New the Rattlesnake Tuff and High Lava Plains near Burns, Oregon. Framework for Decision Making. Island Press, Washington Oregon Geology 61:64–76. DC. 616 pp. Strömberg, C.A.E. 2002. The origin and spread of grass-dominated Scholl, D.W., A.J. Stevenson, M.A. Noble, and D.R. Rea. 2003. ecosystems in the late Tertiary of North America: preliminary The Meiji Drift Body and late Paleogene-Neogene paleoceanog- results concerning the evolution of hypsodonty. Palaeogeography raphy of the North Pacific and Bering Sea region. Pp. 119–123 Palaeoclimatology Palaeoecology 177:59–75. in D.R. Prothero, L.C. Ivany, and E.A. Nesbitt (eds.). From Strömberg, C.A.E. 2004. Using phytolith assemblages to recon- Greenhouse to Icehouse: the Eocene-Oligocene Marine Transi- struct the origin and spread of grass-dominated habitats in tion. Columbia University Press, New York. the Great Plains of North America during the late Eocene to Seilacher, A. 1970. Cruziana stratigraphy of “unfossiliferous” early Miocene. Palaeogeography, Palaeoclimatology, Palaeoecology Paleozoic sandstones. In T.P. Crimes and J.C. Harper (eds.). 207:239–275. Trace fossils. Geological Journal Special Issue 3:47–76. Strömberg, C.A.E. 2005. Decoupled taxonomic radiation and Sheldon, N.D. 2003. Pedogenesis and geochemical alteration of ecological expansion of open-habitat grasses in the Cenozoic of the Picture Gorge Subgroup, Columbia River Basalt. Geological North America. Proceedings of the National Academy of Sciences Society of America Bulletin 115:1377–1387. 102:11980–11984. Sheldon, N.D. 2006. Using paleosols of the Picture Gorge Basalt Strömberg, C.A.E. 2006. Evolution of hypsodonty in equids: testing to reconstruct the middle Miocene climatic optimum. PaleoBios a hypothesis of adaptation. Paleobiology 32:236–258. 26(2):27–36. Tate, T.A. 1998. Micromorphology of loessial soils and paleosols on Sheldon, N.D., and G.J. Retallack. 2001. Equation for compaction aggrading landscapes of the Columbia Plateau. M.S. thesis, De- of paleosols due to burial. Geology 29:247–250. partment of Geology, Western Washington University, Pullman. Sheldon, N.D., and G.J. Retallack. 2004. Regional paleoprecipi- Tedford, R.H., L.B. Albright, A.D. Barnosky, I. Ferrusquia-Vil- tation records from the late Eocene and Oligocene of North lafranca, R.M. Hunt, J.E. Storer, C.C. Swisher, M.R. Voorhies, America. Journal of Geology 112:487–494. S.D. Webb, and D.P. Whistler. 2004. Mammalian biochronology Sheldon, N.D., G.J. Retallack, and S. Tanaka. 2002. Geochemical of the Arikareean through Hemingfordian interval (late Oligo- climofunctions from North American soils and application to cene through early Pliocene epochs). Pp. 169–231 in M.O. paleosols across the Eocene-Oligocene boundary in Oregon. Woodburne (ed.). Late Cretaceous and Cenozoic Mammals of Journal of Geology 110:687–696. North America. Columbia University Press, New York. Sheppard, R.A., and A.J. Gude.1987. Field trip guide to the Sheaville Van Valkenburgh, B., T. Sacco, and X. Wang. 2003. Pack-hunt- and Rome zeolite deposits. Oregon Geology 49:3–10. ing in Miocene borophagine dogs: evidence from cranial and Shotwell, J.A. 1956. Hemphillian assemblages from northwestern body size data. American Museum of Natural History Bulletin Oregon. Geological Society of America Bulletin 67:717–738. 279:147–162. Shotwell, J.A. 1958. Inter-community relationships in Hemphillian Veizer, J., Y. Godderis, and L.M. Francois. 2000. Evidence for

(Mio-Pliocene) mammals. Ecology 29:271–282. decoupling of atmospheric CO2 and global climate during the Shotwell, J.A. 1963. Pliocene mammalian communities of the Juntura Phanerozoic Eon. Nature 408:698–701. Basin. American Philosophical Society Transactions 53:7–21. Wallace, P.E. 1946. A Miocene mammalian fauna from Beatty Shotwell, J.A., and D.E. Russell. 1963. Mammalian fauna of the Buttes, Oregon. Carnegie Institution of Washington Publica- upper Juntura Formation, the Black Butte local fauna. American tions 551:113–134. 106 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

Watkins, N.D., and A.K. Baksi. 1974. Magnetostratigraphy and 6:271–302. oroclinal folding of the Columbia River, Steens and Owyhee Wolfe, J.A., H.E. Schorn, C.E. Forest, and P. Molnar. 1997. Pa- basalts, Oregon, Washington and Idaho. American Journal of leobotanical evidence for high altitudes in Nevada during the Science 274:148–189. Miocene. Science 276:1672–1675.

Wheeler, E.A., and S.R. Manchester. 2002. Woods of the Eocene Wynn, J.G. 2003. Towards a physically-based model of CO2-induced Nut Beds flora, Clarno Formation, Oregon, USA.International stomatal frequency response. New Phytologist 157:391–398. Association of Wood Anatomists Journal Supplement 3:1–188. Zachos, J., M. Pagani, L. Sloan, E. Thomas, and K. Billups. 2001. Whistler, D.P., and D.W. Burbank. 1992. Miocene biostratigraphy Trends, rhythms, and aberrations in global climate, 65 Ma to and biochronology of the Dove Spring Formation, Mojave Des- present. Science 292:686–693. ert, California, and characterization of the Clarendonian mammal Zeitler, P.K., A.S. Meltzer, P.O. Koons, D. Craw, B. Hallet, S.P. age. Geological Society of America Bulletin 104:644–658. Chamberlain, W.F.S. Kidd, S.K. Park, L. Seeber, M. Bishop, Wolf, K.H., and S. Ellison. 1971. Sedimentary geology of the and J. Shroder. 2001. Erosion, Himalayan geodynamics and the zeolitic volcanic Rome Beds, Oregon. Sedimentary Geology geomorphology of metamorphism. GSA Today 11:1–9.

Appendix 1. Diagnoses and identifications of Cenozoic pedotypes of Oregon and Washington. Sahaptin meaning is after Rigsby (1965) and Delancey et al. (1988); some paleosols are described in this paper, and the others are described by Retallack et al. (2000, 2002a). RETALLACK Pedotype Sahaptin Orthography Type profile Diagnosis U.S. F.A.O. map Australian

Abiaxi Bitter root AbiáXi Bone Creek High soda clayey sandstone with siliceous Haplosalid Orthic Solonchak rhizoconcretions, and relict bedding Solonchak Acas eye Á_aš Hancock Canyon Purple, slickensided, subsurface clayey (Bt) Plinthic Ferric Acrisol Lateritic —CENOZOIC COOLING AND GRASSLAND EXPANSION—CENOZOIC COOLING INORANDWA ANDGRASSLAND (Clarno) horizon with red nodules Haplohumult Podzolic Apax skin Apáx Southern Painted Brown conglomerate, with weak subsurface Andic Dystric Earthy Sand Hills clayey (Bt) horizon Dystrochrept Cambisol Cil round Cí.lÁ Ringold Crumb textured surface (mollic) over deep Calciaquoll Orthic Wiesenboden (>50 cm) calcareous nodules Greyzem Cilpa in round Cí.l-paÁ Ringold Crumb textured surface (mollic) over shallow Calciaquoll Orthic Wiesenboden (<50 cm) calcareous nodules Greyzem Cmti new _ mtí Mascall Ranch Brown siltstone with relict bedding and Fluvent Eutric Fluvisol Alluvial Soil root traces Cmuk black _ múk below Black Spur Black lignite on gray claystone with local Hemist Eutric Histosol Humic Gley (Clarno) iron-manganese nodules Ilukas fire-wood Iluk-as Picture Gorge Thick, red (10R), with clayey subsurface Hapludalf Orthic Luvisol Brown Podzolic horizon on basaltic rubble and basalt Iscit path Íš_ít Bone Creek Crumb-structured surface (A) over siliceous Durixeralf Mollic Brown Hardpan duripan (Bq) Solonchak Soil Kalas racoon Ka.lás Mascall Ranch Crumb-structured clayey (mollic) surface Placaquand Mollic Gleysol Wiesenboden over black-spotted and veined (placic horizon) Kskus small Kskús Central Painted Thin reddish brown, rooted surface Fluvent Dystric Fluvisol Alluvial Soil Hills Kwalk long kwa.lk Picture Gorge Carbonaceous clayey (A) on gray shale Aquent Gleyic Luvisol Humic Gley and basalt Lakayx shine La.kàyX Red Hill (Clarno) Red (2.5YR-10R), clayey, thick, abundant Hapludult Ferric Acrisol Krasnozem slickensided cutans, deeply weathered Lakim soot La.k’im Central Painted Brown to olive, with root traces and black Aquandic Eutric Gleysol Humic Gley Hills iron-manganese nodules Placaquept Luca red Lu_á Whitecap Knoll Red (2.5YR-10R), thick, clayey, with Hapludalf Chromic Red Podzolic (Clarno) remnant weatherable minerals Luvisol Luquem decayed fire Luq’_m Clarno fern quarry White bedded volcanic ash with root traces Typic Udivitrand Vitric Andosol Alluvial 107 108

Appendix 1. (cont.) Diagnoses and identifications of Cenozoic pedotypes of Oregon and Washington.

Pedotype Sahaptin Orthography Type profile Diagnosis U.S. F.A.O. map Australian

Maqas yellow, orange Maqáš Carroll Rim Brown, fine blocky peds, thick subsurface Vitric Ochric Andosol Non-calcic Soil horizon Haplustand Micay root Mí_ay Clarno mammal Brown to olive clay with root traces and Aquandic Eutric Fluvisol Alluvial Soil quarry relict bedding Fluvaquent Monana under-neath Mona.na Bone Creek Thin impure lignite (O) on sandstone and Saprist Eutric Histosol Acid Peat siltstone with shallow root traces PALEOBIOS, VOL. 28,NUMBER3,JANUARY 2009 Nix good Níx Kahlotus Thick (>50 cm) crumb textured (mollic A) Haploxeroll Kastanozem Prairie Soil over deep calcareous loess Nukut flesh Nukút Brown Grotto Red slickensided clay over thick violet Lithic Orthic Acrisol Krasnozem (Painted Hills) saprolite on rhyolite flow Kanhapludult Nuqwas throat Nuq’was Picture Gorge Orange moderately weathered basaltic Dystrochrept Dystric Non-calcic rubble over basalt Cambisol Brown Soil Pasct cloud Páš_t Red Hill (Clarno) Olive gray to orange, slickensided, Sombrihumult Humic Acrisol Grey Brown subsurface clayey (Bt) horizon Podzolic Patat tree Pátat Hancock Canyon Bedded sandstone with root traces, mildly Psammentic Eutric Brown Earth (Clarno) leached and ferruginized Eutrochrept Cambisol Patu mountain Pátu Bone Creek Crumb-structured brown (2.5Y) surface (A) Calcixeroll Calcic Chernozem over shallow (<50 cm) micrite-chalcedony Kastanozem rhizoconcretions (Bk) Plas white Pláš Bone Creek White, weakly structured siltstone with Ustic Calcic Xerosol Grey brown deep (>45 cm) calcareous nodules Haplocalcid Calcareous Soil Plaspa In white Pláš-pa Bone Creek White, weakly structured siltstone with Typic Calcic Grey Brown shallow (<45 cm) calcareous nodules Haplocalcid Yermosol Calcareous Soil Pswa stone, clay Pšwá below Black Purple clayey subsurface (Bt) with Lithic Hapludalf Orthic Luvisol Brown Podzolic Spur (Clarno) corestones and gradational contact down to andesite Sak onion Šá.k southern Painted Red, clayey, thick saprolite with andesite Typic Paleudult Ferric Acrisol Brown Podzolic Hills corestones Sayayk sand Sayáykw Clarno Nut Beds Bedded siltstone with root traces Tropofluvent Eutric Fluvisol Alluvial Scat dark S_át below Clarno Thin gray claystone on andesitic Haplumbrept Humicl Alpine Humus Nut Beds conglomerate Cambisol

Appendix 1. (cont.) Diagnoses and identifications of Cenozoic pedotypes of Oregon and Washington.

Pedotype Sahaptin Orthography Type profile Diagnosis U.S. F.A.O. map Australian RETALLACK

Sitaxs liver Šit’áXš Red Hill (Clarno) Olive-purple silty claystone, with relict Placaquand Eutric Gleysol Humic Gley bedding, and iron-manganese skins and nodules Skaw scare Skaw Picture Gorge Thin, dark gray to black spotted siltstone with Mollic Eutric Gleysol Humic Gley —CENOZOIC COOLING AND GRASSLAND EXPANSION—CENOZOIC COOLING INORANDWA ANDGRASSLAND root traces over bedded tuffaceous siltstone Endoaquent Skwi-skwi brown Skw’i-skw’i central Painted Reddish brown (7.5YR-10YR) with subsurface Eutric Ochric Brown Earth Hills clayey (Bt) horizon Fulvudand Andosol Tatas basket Tátaš Mascall Ranch Crumb-structured, brown clayey silty surface Calciudoll Calcic Chernozem over deep (>50 cm) calcareous nodules and Kastanozem calcareous rhizoconcretions Ticam earth ti._ám central Painted Red (7.5YR-5YR), weak subsurface Andic Eutric Chocolate Soil Hills clayey (Bt) horizon Eutrochrept Cambisol Tiliwal blood Tilíwal Brown Grotto Vivid red (10YR-7.5YR) claystone breccia Plinthic Plinthic Krasnozem (Painted Hills) with drab-haloed root traces Kandiudox Ferralsol Tima write Tima Bone Creek Granular structure surface (A) over clayey Natric Durixeralf Mollic Solonetz subsurface (Bt) and siliceous duripan (Bq) Solonetz Tlal cicada Tlal Kahlotus White loessic with abundant shallow (<50 cm) Haplocalcid Calcic Grey Brown calcareous nodules and abundant cicada Xerosol Calcareous Soil burrows Tnan cliff tnán Mascall Ranch Reddish brown (10YR-7.5YR), clayey Mollic Calcic Brown silty, granular-crumb structure surface Haplocalcid Xerosol Hardpan Soil over shallow (<50 cm) calcareous rhizoconcretions Tuksay cup, pot Tuksáy southern Painted Red (2.5YR-10R), kaolinitic, subsurface Plinthic Plinthic Red Podzolic Hills clayey (Bt) horizon, with redeposited Paleudult Acrisol soil clasts Tutanik hair Tútanik Unity Near-mollic brown thick surface (A) Typic Haplic Brown Earth over deep calcareous and siliceous Natrixeralf Kastanozem rhizoconcretions Walasx pine gum Walá.sX Mascall Ranch Pale yellow clayey (A) with slickensided Chromudert Chromic Brown Clay clay skins Vertisol 109 110 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

Australian Prairie Soil Brown Grey Soil Calcareous Alluvial Soil Wiesen-boden Brown Grey Soil Calcareous Grey Clay Grey Humic Gley

F.A.O. map F.A.O. Vertisol Gleysol Mollic Andosol Calcic Xerosol Psamment Vitric Andosol Calcaric Gleysol Chromic Humic U.S. Chromudert Humaquept Mollic Haplustand Vitrandic Haplocalcid Calcaric Fluvisol Aquic Ustivitrand Aquic Haplocalcid Entic Histic

Diagnosis clastic dikes skins and prominent underclay on a rooted lignites peds (A, fine blocky Bw), brown, Dark deep (>50 cm) calcareous over nodules (Bk) peds (A, fine blocky Bw), brown, Dark (<50 cm) calcareous shallow over nodules (Bk) with sandstone volcaniclastic Brown traces bedding and root relict peds (A,over fine blocky Green, Bw), nodules (Bk) deep (>50 cm) calcareous peds (A,over fine blocky Green, Bw), (Bk) nodules calcareous cm) (<50 shallow Olive brown, clayey, with deformed clay clayey, brown, Olive impure silty, to clayey Thin, brown,

Type profile southern Painted southern Hills Painted southern Hills Carroll Rim Hills) (Painted Bone Creek Mascall Ranch Foree (near Dayville) Foree (near Dayville) Wawc’ak Yanwá Yápaš Yápaš-pa XauS XáXuš XáXuš-pa Orthography Sahaptin split poor weak, grease in grease root green in green (cont.) Diagnoses and identifications of Cenozoic pedotypes of Oregon and Washington. Washington. and of Oregon (cont.) Diagnoses and identifications of Cenozoic pedotypes Appendix 1. Pedotype Wawcak Yanwa Yapas Yapaspa Xaus Xaxus Xaxuspa

Appendix 2. Key to Cenozoic paleosols of central Oregon and Washington.

Parent Material Subsurface Horizon Surface Horizon Other Differentiae Pedotype RETALLACK

1. Rhyodacitic loessic 1.1. Relict bedding and root 1.1.1. Clear relict bedding 1.1.1.1. Gray, green or brown claystone Micay silty tuff traces only 1.1.1.2. Gray to brown siltstone Sayayk

1.1.1.3. Red claystone Kskus EXPANSION—CENOZOIC COOLING INORANDWA ANDGRASSLAND 1.1.1.4. Brown clayey siltstone Cmti 1.1.1.5. White volcanic ash Luquem 1.1.1.6. Olive brown clay, with deformed clay skins Wawcak and prominent clastic dikes 1.1.1.7. Yellow clay with deformed clay skins Walasx 1.1.2. Peat, lignite or coal 1.1.2.1. Black coal on claystone Cmuk 1.1.2.2. Brown clayey lignite on siltstone Yanwa 1.1.2.3. Black clayey lignite on sandstone and siltstone Monana 1.2. Large black iron-manganese 1.2.1. Gray or green claystone 1.2.1.1. Relict bedding Lakim mottles 1.3. Small dark gray to black iron 1.3.1. Platy to blocky peds Skaw manganese nodules 1.3.2. Crumb textured surface Kalas (mollic) 1.4. Clay enriched (argillic), 1.4.1. Platy to blocky peds 1.4.1.1. Purple, slickensided, subsurface clayey (Bt) Acas non-calcareous, blocky peds (non mollic) horizon with red nodules 1.4.1.2. Red (2.5YR-10R), smectitic, with remnant Luca weatherable minerals 1.4.1.3. Red (2.5YR-10R), kaolinitic, with Tuksay redeposited soil clasts 1.4.1.4. Vivid red (10R-7.5R) claystone breccia with Tiliwal drab-haloed root traces 1.4.1.5. Red (2.5YR-10R) with slickensided smectitic Lakayx clay and rare weatherable minerals 1.5. Clayey enriched (argillic) 1.5.1. Fine blocky to granular 1.5.1.1. Non-nodular Skwiskwi and granular structured structured surface (near mollic)

1.5.1.2. deep calcareous and siliceous rhizoconcretions Tutanik 111 112

Appendix 2. (cont.) Key to Cenozoic paleosols of central Oregon and Washington.

Parent Material Subsurface Horizon Surface Horizon Other Differentiae Pedotype

1.5.1.3. Siliceous duripan (Bq) at depth Tima 1.5.2. Crumb textured surface Nix (mollic) 1.6. Clay enriched, but not 1.6.1. Platy to blocky structured 1.6.1.1. Brown (2.5Y-10YR) Maqas quite argillic, noncalcareous surface (non mollic)

1.6.1.2. Red (7.5YR-5YR) Ticam PALEOBIOS, VOL. 28,NUMBER3,JANUARY 2009 1.7 Well developed calcareous 1.7.1. Massive, platy or blocky 1.7.1.1. White, tuffaceous Plas nodules deeper than 50 cm peds (non-mollic) 1.7.1.2. Green tuffaceous, Xaxus 1.7.1.3. Brown, tuffaceous Yapas 1.7.2. Crumb textured surface Cil (mollic) 1.8. Well developed calcareous 1.8.1 Massive, platy or blocky 1.8.1.1. Green tuffaceous Xaxuspa nodules shallower than 50 cm peds (non-mollic) 1.8.1.2. Brown tuffaceous Yapaspa 1.8.1.3. White loessic with abundant cicada burrows Tlal 1.1.2. Crumb textured surface Cilba (mollic) 1.9. Well developed calcareous 1.9.1. Massive, platy or blocky 1.9.1.1. White, tuffaceous, Plaspba nodules shallower than 45 cm peds (non-mollic) 1.10. Silicic rhizoconcretions 1.10.1. Crumb textured surface 1.10.1.1. Calcic horizon deeper than 50 cm Tatas and lesser carbonate at depth (mollic) 1.10.1.2. Calcic horizon shallower than 50 cm Patu 1.11. Thick siliceous duripan Iscit (Bq) at depth 2. Volcaniclastic sandstone 2.1. Clayey root traces little 2.1.1. Relict bedded sandstone 2.1.1.1. Low-soda sandstone Xaus or conglomerate weathered 2.2. Siliceous rhizoconcretions 2.2.1. Relict bedded sandstone 2.2.1.1. High soda clayey sandstone Abiaxi little weathered 2.3. Mildly leached and 2.3.1. Relict bedded sandstone 2.3.1.1. On andesitic conglomerate Patat ferruginized

Appendix 2. (cont.) Key to Cenozoic paleosols of central Oregon and Washington.

Parent Material Subsurface Horizon Surface Horizon Other Differentiae Pedotype RETALLACK

2.4. Little weathered 2.4.1. Thin gray claystone 2.4.1.1. On andesitic conglomerate Scat 2.5. Relict bedding, and iron- 2.5.1. Olive-purple silty claystone 2.5.1.1. On andesitic conglomerate Sitaxs manganese clay-skins and nodules

2.6. With weak subsurface 2.6.1. Brown pedolithic 2.6.1.1. On brown pedolithic conglomerate Apax EXPANSION—CENOZOIC COOLING INORANDWA ANDGRASSLAND clayey (Bt) horizon conglomerate 2.7. Olive gray to orange, 2.7.1. Olive gray to orange 2.7.1.1. On andesitic conglomerate Pasct slickensided, clayey (Bt) horizon claystone 3. Rhyolite flow 3.1. Red slickensided clay 3.1.1. Red slickensided clay 3.1.1.1. Thick violet saprolite Nukut 4. Basaltic flow 4.1. Thick, red (10R), clayey 4.1.1. Red (10R) platy to blocky Ilukas subsurface horizon 4.2. Gray shaley 4.2.1. Carbonaceous clayey Kwalk 4.3. Orange clayey 4.3.1. Orange clayey 4.3.1.1. Orange-weathered basaltic rubble Nuqwas 5. Andesitic flow 5.1. Red, clayey, subsurface (Bt) 5.1.1. Red claystone 5.1.1.1. Corestones and thick saprolite Sak 6. Andesitic intrusive 5.2. Purple clayey subsurface (Bt) 5.2.1. Purple platy claystone 5.2.1.1. Corestones and thick saprolite Pswa 113