University of Montana ScholarWorks at University of Montana
Graduate Student Theses, Dissertations, & Professional Papers Graduate School
1997
Paleoclimate study of Eocene fossil woods and associated paleosols from the Gallatin Petrified orF est Gallatin National Forest SW Montana
Lorin Amidon The University of Montana
Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y
Recommended Citation Amidon, Lorin, "Paleoclimate study of Eocene fossil woods and associated paleosols from the Gallatin Petrified orF est Gallatin National Forest SW Montana" (1997). Graduate Student Theses, Dissertations, & Professional Papers. 8963. https://scholarworks.umt.edu/etd/8963
This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. ■
Maureen and Mike MANSFIELD LIBRARY
The University of IVIONTANA
Permission is granted by the author to reproduce tliis material in its entirety, provided that this material is used for scholarly purposes and is properly cited in published works and reports.
** Please check "Yes*' or "No" and provide signature**
Yes, I grant permission ^ No, 1 do not grant permission _____
Author's Signature
Any copying for commercial purposes or financial gain may be undertaken only with the author's explicit consent.
PALEOCLIMATE STUDY OF EOCENE FOSSIL WOODS AND ASSOCIATED PALEOSOLS FROM THE GALLATIN PETRIFIED FOREST, GALLATIN
NATIONAL FOREST, SW MONTANA
by
Lorin Amidon
B.S., University of Washington, 1995
Presented in partial fulfillment of the requirements for the degree of
Master of Science
UNIVERSITY OF MONTANA
1997
Approved by
Committee Chair, Board of Examiners
Dean, Graduate School
S '-1 ^ ? 7 Date UMI Number: EP39764
All rights reserved
INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted.
In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion.
IMT Oia«aft«tion Publishing
UMI EP39764 Published by ProQuest LLC (2013). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code
ProOuesf
ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 -1 3 4 6 Amidon, Lorin, M S., May, 1997 Geology
Paleoclimate study of Eocene fossil woods and associated paleosols from the Gallatin Petrified Forest, Gallatin National Forest, SW Montana. (142 pages)
Committee Chair: Marc Hendrix / W i t f
Middle Eocene fossil trees located in the Cedar Creek drainage near Dome Mountain, Montana are described here for the first time. Vertical, horizontal, and inclined fossil logs were examined in the field. Tree ring sequences were analyzed in thin sections and slab sections prepared from 42 stumps and logs. Both in situ and transported woods are preserved in a 136 m volcaniclastic section dominated by coarse subaerial debris flow deposits and fluvially reworked debris flow deposits. A northwest to southeast paleocurrent direction, indicated by the orientation of horizontal trees, is similar to inferred paleocurrent directions in contemporaneous strata of Yellowstone National Park. Paleoclimate data from this study and studies of northern Yellowstone National Park flora reveals a seasonal climate, defined by the presence of growth rings in coniferous specimens. Early wood and latewood is well developed in tree ring sequences. Early wood to latewood transitions are generally gradual. This indicates a gradual change from optimal growth conditions to dormancy conditions, consistent with the highly seasonal, cool-temperate climate indicated by the fossil assemblage itself. Calculated latewood to earlywood ratios average 0.15. Mean sensitivity values average 0.31. Immature paleosols and weathering surfaces associated with fossil trees were also examined. X-ray diffraction analysis reveals a high proportion of X-ray amorphous mineraloids, reflecting the volcanic parent material. Two moderately developed paleosol horizons contain smectite, indicative of an arid to semiarid climate. ACKNOWLEDGMENTS
I would like to extend my warmest thanks to the members of my committee Marc
Hendrix, Gray Thompson, and Anna Sala for their help in editing this thesis, and for their timely encouragement.
Thanks are also extended to those who helped me with field and laboratory work.
Bob Lenegan provided enthusiastic assistance in both the field and the lab. I will never forget limping out of the field area after fracturing my leg; I would still be there if it was not for Bob. Sheri Forst, Derek Sjostrom, and Tim Kirkpatrick also provided assistance in the field. I also appreciate thought provoking discussions held with Dr. Charles Miller,
Amy Waddell, and Boyd Benson (who also sacrificed his camera for the summer).
Derek Sjostrom provided endless technical support, advice, and patience. His assistance with computer software enabled me to complete this study in a reasonable amount of time.
I would also like to thank the persormel of the Gallatin National Forest for their cooperation and advice. Those that personally aided me were Ron Gardiner, Pat Hoppe, and Tris Hoffman of the Gardiner Ranger Station. Ron and Wendy, in residence at the
OTO Ranch, generously allowed me to use their short cut, saving us 40 minutes on the daily hike.
Research was partially funded by the Geological Society of America, the Clay
Minerals Society, the American Chemical Society (Petroleum Research Fund), and The University of Montana (Geology Department), Permission to conduct this study was granted by the U.S. Department of Agriculture (special use-permit, holder No. 5389-01).
lU TABLE OF CONTENTS
Abstract...... i
Acknowledgments ...... ii
Table of Contents...... iv
List of Tables...... vi
List of Figures ...... vii
Introduction...... 1
Geologic Setting ...... 8
Sedimentology
Field methods...... 14
Sedimentology at the Cedar Creek locality ...... 17
Description and interpretation of coarse grained units ...... 17
Description and interpretation of fine grained units ...... 26
Nature of the “fossil forest” at Cedar Creek...... 28
Orientation of horizontal fossil trees...... 30
Paleodendrology
Field methods...... 40
Laboratory methods ...... 41
Dendrology analysis ...... 43
Results and interpretations...... 47
Yellowstone area paleoclimate...... 55
Relevance of this study in the context of interior US Eocene paleoclimate...... 59
IV TABLE OF CONTENTS (continued)
Paleosol Analysis ...... 63
Field methods...... 66
Laboratory methods ...... 82
Results and interpretations Stratigraphy of paleosols and weathered horizons ...... 83
Mineralogy of paleosols and weathered horizons ...... 86
Discussion...... 94
Conclusions...... 96
References cited...... 98
Appendix A ...... 113
Appendix B ...... 131
Appendix C ...... 136 LIST OF TABLES
Table 1. Tree ring data summary ...... 49
Table 2. Early wood/L ate wood ratios ...... 50
Table 3. Summary of paleodendrological data ...... 60
VI LIST OF FIGURES
Figure 1. Study site location map ...... 3
Figure 2. Dome Mountain Quadrangle, MT ...... 4
Figure 3. Absaroka volcanic belt map ...... 9
Figure 4. Generalized stratigraphie column ...... 10
Figure 5. Outcrop face map showing fossil tree distribution ...... 15
F igure 6. Photograph of massive conglomerate ...... 18
Figure 7. Photograph of massive conglomerate ...... 19
Figure 8. Photograph of debris flow deposit conglomerate ...... 20
Figure 9a. Photograph of debris flow deposits ...... 22 b. Close-up photograph of F igure 9a ...... 22
Figure 10. Photograph of cross-bedded pebble sandstone ...... 25
Figure 11. Photograph of discontinuous sandy layer ...... 27
Figure 12. Photograph of fossil leaves and twigs ...... 29
Figure 13. Photograph of fossil tree bark ...... 29
Figure 14. Photograph of tall vertical fossil tree ...... 31
Figure 15. Photograph of two boreholes ...... 32
Figure 16. Photograph of a borehole ...... 32
Figure 17. Photograph of vertical fossil tree and tree roots ...... 33
Figure 18. Rose plots of orientation of horizontal trees at Cedar Creek ...... 35
Figure 19. Photograph of preferentially oriented logs ...... 37
vu LIST OF FIGURES (continued)
Figure 20. Gallatin Petrified Forest tree orientations ...... 38
Figure 21. Photograph of compression and tension wood ...... 39
Figure 22. Fossil tree thin section illustrating growth ring characteristics ...... 45
Figure 23. Tree ring width series plots...... 51
Figure 24. Fossil tree thin section photograph ...... 56
Figure 25. Graphs illustrating relation between clay minerals and precipitation ...... 64
Figure 26-31. Explanation of paleosol photos and sketches ...... 67
Figure 26. Photo and sketch of VI5 ...... 68
Figure 27. Photos and sketch of V82 ...... 70
Figure 28. Photo and sketch of V46 ...... 73
Figure 29. Photo and sketch of V76 ...... 75
Figure 30. Photos and sketch of V49 ...... 77
Figure 31. Photos and sketch of V75 ...... 80
Figure 32. X-ray diffraction patterns from paleosol section V I5 ...... 87
Figure 33. X-ray diffraction patterns from paleosol section V15 ...... 88
Figure 34. X-ray diffraction patterns from five paleosol sections ...... 89
Figure 35a. X-ray diffraction patterns from paleosol section V 82 ...... 91
Figure 35b. X-ray diffraction patterns from paleosol section V82 ...... 92
Figure 35c. X-ray diffraction patterns from paleosol section V 82 ...... 93
Vlll Introduction
The presence of a “fossil forest” containing diverse Eocene flora has been recognized in volcaniclastic and alluvial strata of the Yellowstone region since these rocks were first reported by members of the Hayden expedition in 1870 (Lesquereus,
1872; Jones, 1874; Holmes, 1883; Knowlton, 1896,1899; Fisk, 1976). Fossil trees located throughout northern Yellowstone National Park and the Gallatin National Forest are collectively known as the Gallatin Petrified Forest. Since Hayden’s initial scientific expedition, numerous studies have focused on locating and surveying the variety of plant and fossil tree species in an effort to better understand Eocene paleoenvironment
(Knowlton, 1914; Read, 1933; Andrews, 1939; Andrews and Lenz, 1946; Sanborn,
1951; Ritland, 1968; Dorf, 1974; Simons, 1983; Mohlenbrock, 1989).
Prior to 1979, studies concentrated on trees preserved in easily accessible sites in north-central Yellowstone National Park. Fisk ( 1976) reviewed geological and paleobotanical observations made throughout the Gallatin Petrified Forest. He noted the lack of previous work in the northwest section of Yellowstone National Park and sites outside the Park’s boundaries, in the Gallatin National Forest. This paucity of work persisted until the late 1970’s despite documentation of the presence of impressive horizontal and vertical trees at these sites (Sanborn, 1951).
Studies since the 1970’s have focused on flora located within Yellowstone
National Park, (Fritz and Fisk, 1978; Ammons et al., 1987; Arct, 1991). Relative to 1 earlier work, these studies have broadened in scope, incorporating sedimentoiogicai
(Fritz, 1980b), palynological (Chadwick and Yamamoto, 1984), and dendrological techniques (Arct, 1991) in an effort to distinguish between vertical trees preserved in situ and trees transported and preserved upright. Since the initial attempt to correlate tree ring signatures using “floating” chronologies (Fritz and Fisk, 1978), dendrological techniques have been successfully applied to fossil trees in the Yellowstone region
(Arct, 1979, 1991; Ammons et al., 1980, 1987; Arct and Chadwick, 1983). Utilizing dendrochronology, researchers documented that vertical trees at certain sites were coeval and consequently reflect environmental factors which persisted during the time of their growth
The location of middle Eocene fossil trees north of the OTO Ranch in the Cedar
Creek drainage of southern Gallatin National Forest, Montana (Figures 1 and 2) was first described by a park ranger (Sanborn, 1951) Though this report documents the presence of abundant prostrate and vertical trees “eroding out of the cliffs,” the purpose of the report was to describe access to the site. Since Sanborn’s reconnaissance visit these fossil trees had only been examined by tourists and curiosity seekers and remained essentially unstudied until the present investigation (Amidon et al., 1996). The flora at
Cedar Creek is part of the Gallatin petrified forest which contains a superbly preserved series of upright trees consisting of a variety of conifers and hardwoods (Fisk, 1976). Oauatin Beartooth Range
Montana Wyoming Yellowstone Park
Gallatin “ O m
Beartooth Range Stiid\ Site
Montana Wyoming Û Yellowstone National Park Area enlarged in B /
ID WY
X ^ Field site In D Absaroka Volcanics
Figure 1 Index map showing location of field study site. Site is located in the Gallatin National Forest (U.S.G.S. Dome Mountain Quadrangle, MT, 1986, ) 14.5 Km north of Yellowstone National Park :> -T \ 7 j _L , '6T/fJ i /^ VA I ' ■
)AA
^ \ I '' ' ^ r-. V \ l - '' A / y V
. 1 - 'L y sA S i A.k''
eejrA : / u / \ / IS"'! 'T',_
: AA' O / .
"'-L.
1
\ , ^#OR^ch 1 V;: 'A.
Figure 2. Portion of Dome Mountain Quadrangle (U.S.G.S., 1986) showing study site boundaries. The objective of this study is to acquire additional data relating to climate that persisted during the growth of middle Eocene trees from the Gallatin Petrified Forest.
This study reports the results of growth ring analysis performed on trees located on a west-facing slope north of the Cedar Creek drainage (Figure 2). Sedimentology of strata encasing fossil trees is described and mineral analysis of paleosols associated with vertical in situ trees is presented.
This study is important for three principal reasons. Firstly, it is presently the only study to apply paleodendrological techniques to fossil trees in the Gallatin
Petrified Forest outside of Yellowstone National Park. A comparison and discussion of the significance of middle Eocene paleoclimate for locations in and outside of the
Yellowstone National Park is also presented.
Secondly, this study is an important contribution to the regional climate database, in that it provides a high resolution record (annual scale) of paleoclimate in the continental interior of North America (Mifflin, 1964). Analysis of Eocene floral assemblages from Yellowstone National Park indicate a range of cool-temperate to tropical climatic conditions (Ritland, 1968; Dorf, 1974; Fisk, 1976; Yamamoto and
Chadwick, 1982; 1983; 1984). This range of climatic conditions differed from the generally mild humid tropical conditions that characterized the northern Rocky
Mountain region during the middle Eocene, as suggested by the presence of Eocene tropical flora in Wyoming (Knowlton, 1922), the extensive development of widespread anoxic lakes across Wyoming and Utah (Picard, 1985), and the presence of lateritic 6 paleosols in southwest and eastern Montana (Thompson et al., 1982; Retallack, 1994).
Thus, the regionally warm, humid climate of the Eocene western interior appears not to be the only climatic signature recorded by flora in the Yellowstone Park region. Rather, the Yellowstone flora was likely responding to local microclimates which may have been modified by short-term climate fluctuations and/or variations in paleoaltitude. The addition of dendrology data from high altitude sites will further the understanding of seasonality and ranges exhibited by Eocene paleoclimate.
The third reason for conducting this work is to describe paleosols and weathered surfaces and to analyze paleosol minerals associated with these horizons. Clay minerals within tree-bearing formations elsewhere in the Gallatin Petrified Forest have yet to shown to be pedogenic. Fritz documented the stratigraphy of the Lamar River
Formation in north-central Yellowstone National Park and described in detail the relationship between preserved trees and the tree-encasing sediment (Fritz, 1980a,
1980c). Fritz ( 1980a, 1980c) described discontinuous organic rich layers (“organic zones”) commonly associated with in situ trees. Retallack (1981) examined the same strata and suggested that the layers may represent an immature soil, based on color changes. Both Fritz and Retallack acknowledged the need for paleosol characterization and clay mineral analysis to differentiate weathered horizons from organic litter deposits (Retallack, 1981). In addition to characterizing organic litter and immature paleosols, mineral analyses conducted in the present study will provide paleo- 7 precipitation data (Barshad, 1966; Singer, 1979/1980,1984; Thompson et al, 1982;
Curtis, 1990). Geologic Setting
This study site is located in the Beartooth Range located in southwest Montana
(N 49°9’30”, W 110° 4730") (Figure I). The Bearthooth Range is composed of volcaniclastic sediment, initially derived from two volcanic belts (Figure 3) (Chadwick,
1970; Fritz, 1980c; Meen, 1988). These volcanic belts were active during the Eocene and have since been deeply eroded. Deposits resulting from these volcanic belts are collectively known as the Absaroka Volcanic Supergroup (Smedes and Prostka, 1972).
Potassium/Argon dating of biotite from dacite stocks that cut both the eastern and western Absaroka belts constrain the age to 49.5 - 1.7 Ma (Smedes and Prostka, 1972;
Shaver, 1978). This correlates with Eocene dates (late Wasatchian to early Bridgerian) of floral assemblages within sedimentary units of the Absaroka Volcanic Supergroup
(Smedes and Prostka, 1972).
The Washburn Group is the lowermost member of the Absaroka Volcanic
Supergroup (Figure 4). The Lamar River Formation, Sepulcher Formation, and Hyalite
Peak Volcanics are contemporaneous with the Washburn Group (Smedes and Prostka,
1972). These formations are characterized by near-vent lava flows, breccia flows, mudflows, avalanche debris flows, and welded tuffs which grade laterally into and interfmger with well bedded, epiclastic deposits (Smedes and Prostka, 1972). Epiclastic units were likely deposited as paleovalley fill, flanking Eocene composite stratovolcanoes (Fritz, 1980a). These strata preserve an abundant and uniquely diverse
8 Symbols Map Area # Absaroka Volcanic Vents — Lamar River Drainage ^ Fossil tree locations
Cedar Creek Study Site Kilometer
Gardiner Specimen Cooke City Creek
Specimen Ridge
Canyon Village
West Yellowstone
Figure 3. Map of Yellowstone National Park showing east and west Absaroka volcanic belts and the locations of select fossil tree sites. Modified from Fritz ( 1980). 10
dnO^OHHdnS DINVDIOA V"HOHVSaV
o
â E u u
k\\\\\\\\\\X OA
II III
IIz < III m £ a o v is MVHNSHHDna NVlNin NviHHoaiHa NVIHDIVSVAV
Figure 4. Stratigraphie correlation of the Absaroka Volcanic Supergroup in Yellowstone National Park and Gallatin National Park. All units of the Washburn Group contain upright and horizontal fossil trees. Modified from Fritz (1980) and Smedes, et al. ( 1972). 11 collection of Eocene flora. “Fossil forests” within these formations have been well documented (Knowlton, 1914; Dorf, 1974), however, comprehensive studies have been limited to sites within Yellowstone National Park boundaries.
Sedimentoiogicai evidence from the Lamar River Formation in northeast
Yellowstone National Park indicated that a “complex alluvial system” resulted in the transportation of cool-temperate high altitude plant debris to tropical, lower elevations
(Fritz, 1980c). This caused a mixed assemblage of fossil flora which led early workers to conclude that Eocene flora maintained a higher climatic tolerance than observed in their modem counterparts (Dorf, 1974). Evidence supporting the transport theory includes broken and eroded roots, lack of roots penetrating strata, debarked trees, mud encased trees, and a high proportion of horizontal trees relative to vertical trees (Fritz,
1980a).
Specimen Creek and Specimen Ridge, located in the northwest and north-central parts of the Yellowstone Park, respectively, contain debris flow deposits of the
Sepulcher Formation and Lamar River Formation that preserve a high percentage of vertical fossil trees (Ritland, 1968; Ammons et al., 1987). Fritz (1985) documented the ratio of horizontal and vertical trees within distal mudflow deposits initiated by the
1980 Mt. St. Helen eruption. He observed an increasing percentage of vertical trees with increasing distance and concluded that prostrate trees were initially transported some distance, then deposited horizontally among in situ trees which were not 12 incorporated into the flow (Fritz, 1980b). Applying this interpretation to sites with a high percentage of vertical fossil trees within the Gallatin Petrified Forest, Ammons et al. (1987) concluded that these fossil forests likewise grew in low-energy valley sections, distal to a volcanic sediment source. Using a “floating chronology” (Arct and
Chadwick, 1983; Ammons et al., 1987), tree ring sequences from fossil trees at these sites were well correlated, suggesting that a number of vertical trees were contemporary, supporting Fritz’s in situ forest interpretation (Fritz, 1985; Ammons etal., 1987). To further test the idea that some trees are preserved in situ, detailed sedimentology and tree orientations were recorded at the Cedar Creek site.
Currently classified as part of the Sepulcher Formation, Cedar Creek deposits have yet to be correlated with those of Yellowstone Park (Fisk, 1976). Lack of stratigraphie continuity makes correlation between formations difficult, although studies proposed for the northern and central parts of the Absaroka Range may establish a correlation between epiclastics of the Hyalite Peak Volcanics and deposits to the south
(Schmitt, 1996, per. comm.). The sedimentoiogicai character of strata encasing the
Cedar Creek Petrified Forest is similar to that of the Hyalite Peak Volcanics
(McMannis and Chadwick, 1964; Stanley, 1972; Hiza, 1994), the Sepulcher Formation
(Smedes and Prostka, 1972), and the Lamar River Formation (Fritz, 1980c).
Reconnaissance mapping by a number of workers (Smedes and Prostka, 1972) suggests that deposits in the southern Gallatin National Forest (including the Cedar Creek site) 13 are part of the Sepulcher Formation, although there is no specific evidence to support this conclusion. Until more conclusive studies are conducted on the regional architecture of Eocene wood-bearing strata in the Yellowstone area, the Cedar Creek site remains tentatively classified as part of the Sepulcher Formation. Sedimentology
Field methods
The relative positions of fossil trees and organic litter horizons were recorded on a two-dimensional sketch of the outcrop face (Figure 5). This was done with the aid of a 300 m measuring tape, a 1.5 m Jacob staff, a Brunton compass, and modified plane table techniques (Compton, 1985). Figure 5 illustrates the relative sizes of trees and the continuity of bedding planes and organic litter horizons.
In order to document the sedimentology and stratigraphy of the tree-bearing units at Cedar Creek three stratigraphie sections, approximately 150 m apart, were also measured (Appendix A and Plate 1). All stratigraphie units are subhorizontal, and dip 1 to 6° to the southeast, probably as a result of regional tilting (Mifflin, 1964; Simons,
1983). In each section, sedimentary textures and structures were examined on a meter scale. Grain and clast size, sorting, rounding, and proportion of matrix were noted, as was to the nature of bedding contacts.
Paleocurrent direction indicators are limited to fossil tree orientations. Tree orientations were placed into two general categories, upright and prostrate. Prostrate trees lie at an incline or are horizontal. At the Cedar Creek site, there are few (13) inclined trees The plunge of the inclined horizontal trees was typically less than 30°,
14 15
Explanation
——— — — Upright trees Organic Zone Stumps with visible roots Bedding Plane
cc © Prostrate trees Coarse Sand
-€> Fossil Leaves Conglomerate or cover
* Tree studied for dendrological analysis 3m P Paleosol sample location 15m
Figure 5, Outcrop face sketch. Illustration shows position, relative size, and orientation of fossil trees relative to one another V (vertical) or H (horizontal) indicate general tree orientation; numbers 1 to 131 correspond to the order in which trees were described in the field. FL indicates sites with abundant fossil leaves. Numbers following FL indicate flora sample identification number. Growth ring analysis was performed on trees designated with an asterisk. Paleosol sample sites are indicated by "p" after the associated tree identification number. Apparent truncation of bedding planes is caused by slope cover. Much of the outcrop consists of conglomerate and slope cover, both have been omitted for clarity. Location of stratigraphie colum n 1 Location of stratigraphie colum n 2 V15‘
1114
1113
1158 VIO 119
VI»
V5 V6 ItB 1160
1187 V50 III09
11108 11127
11 1 0 2 11104 I 11?')
V II7 V1Q7 11105 6 '' V84* V112» 1196 V49' V106 11103 Vlüi 1183 11110
» 1138
V76' i m V41» V77 V75' 1147
V8<) II');
1171 1167 VI 111 M'8) nvi 1170
V73 1188 V72 n 17 with few exceptions (Appendix B). Horizontal tree orientation data were plotted on rose diagrams using Stereonet 4.9.5a (Allmendinger, 1988-1995).
Sedimentology at the Cedar Creek locality
Epiclastic deposits at Cedar Creek are predominantly massive, consisting of angular to subrounded coarse volcanic and lithic clasts. They display variable grading, grain size distribution, clast lithologies, and mode of clast support. Most of the deposits are tabular, nonerosive and continuous at the outcrop scale (Figure 6). Bed thickness varies from 5 cm to 10 m, but is commonly 1 to 5 m. Sharp contacts between deposits are generally nonerosional and planar, with few amalgamation surfaces.
Stratified layers of tuffaceous coarse grained sandstone are interbedded with coarse grained deposits throughout the section (Figure 6). These layers constitute only a small proportion of the total lithology, but preserve an abundant collection of organic material and pedogenic features. Several of the sandstone layers show small scale sedimentary structures, such as low angle trough cross-stratification.
Description and interpretation o f coarse grained mits:
Coarse grained units are dominated by massive, poorly sorted, matrix to clast supported conglomerate (Figure 7). Clasts range in size from cobble (commonly 4 cm) to boulder (up to 3 m in diameter), and are subangular to subrounded (Figure 8). Clast types include basalt, andésite, scoria, pumice, and fragments of fossil wood. In places, clast lithology is monolithic, frequently consisting of andésite or basalt. The matrix 18
Figure 6. Massive conglomerates are interbeded with coarse sandstone, and are interpreted to be debris flow deposits. 19
Figure 7. Massive poorly sorted matrix supported conglomerate. Arrow points to the non-erosive base. 20
Figure 8. Debris flow deposits with amalgamation surfaces (position shown by arrow). This unit consists of poorly sorted matrix to clast support conglomerate. Note the boulder, designated by B, at the top of photo. 21 consists of poorly sorted fine to coarse sand with variable amounts of silt and clay.
Matrix color varies from gray, tan, brick red, brown, to green. Bedding contacts are continuous and nonerosional.
These sediments are interpreted as subaerial volcaniclastic fan deposits resulting from a variety of debris flow processes (Smedes and Prostka, 1972). Poorly sorted clasts and matrix suggest that these deposits resulted from nonNewtonian, laminar flow.
The poorly sorted fabric likely resulted from cohesive freezing of sediment (Smith,
1986). Matrix supported deposits suggest the flows were cohesive and that matrix strength and buoyancy were the dominant clast support mechanisms (Lowe, 1979).
Clast supported deposits may also be the product of a cohesive debris flow, in which the ratio of clast to matrix is too high to produce a matrix supported fabric (Smith,
1986).
The nonerosional contact between bedding planes is suggestive of debris flow levees where deposits accumulated adjacent to aggrading, non-scouring channels. As debris moves downslope, clasts positioned at the front and sides of the flow were pushed aside by the advancing debris flow, leaving poorly sorted, clast supported sediment (Schmitt, 1996, per. comm ). Subsequent erosion by water and wind after deposition winnowed the fine sediment fraction, leaving a clast rich, locally clast supported deposit (Figure 9) (Blair and McPherson, 1992). 22
Figure 9a. Tabular non-erosive, poorly sorted sandstone (lens cap for scale).
Figure 9b. Closer view of prominent bedding plane shown in Figure 11. Note large clast on right side of photo protruding into overlying sandy layer. Sandy layer (designated by arrow) is interpreted to be reworked debris flow sediment. 23 24 Conglomerate beds with vertical variability are massive, poorly sorted, and clast supported at the base. Clasts are subrounded to angular and less than 10 cm in diameter. These layers are generally less than 3 m thick. Middle and upper portions of these units become increasingly matrix rich. The vertical change in matrix proportion suggest the evolution of a noncohesive debris flow to a cohesive debris flow with matrix strength (Lowe, 1979).
Conglomerates with basal matrix support are poorly sorted with fine to coarse sand and silt matrix (Figure 7). Some layers exhibit inverse to normal grading within one bed. Variability in grading likely resulted from clast segregation within the flow during deposition (Denlinger, 1984). Clasts are typically 5 to 13 cm and occasionally reach up to 0.5 m in diameter. These matrix supported layers suggest deposition by laminar cohesive debris flow processes (Lowe, 1979; Smith, 1986).
Several units contain gravel with subtle, low angle trough cross-stratification
(Figure 10). Troughs are up to 0.6 m wide. Clasts are rounded to subrounded with a maximum clast size of 9 cm, and consist of black and gray andésite, brown to black chert, and gray quartzite. The matrix consists of coarse sand with angular pebbles.
These are interpreted to be water reworked debris flow sediments. Evidence in support of this interpretation includes grain-to-grain contact and traction transport structures
(Smith, 1986). Because sedimentary structures are rare and poorly expressed in three dimensions it was difficult to collect paleocurrent data from these units. 25
Figure 10. Rare low angle trough cross-bedding in poorly sorted pebbly coarse sand. This structure suggests that sediments were deposited by traction transport mechanisms. 26 Description and interpretation of fine grained units:
Debris flow deposits are interbedded with coarse sand and laminated organic rich silt and mud layers, 1.0 cm to 4.0 m thick (Figure 11 ). Sandy units are generally massive to normally graded with medium to coarse sand, pebbles, and granules. Local erosional scours occur within some units. Deposits are poorly sorted with subangular to subrounded grairis and consist primarily of lithic volcanic fragments and volcanic glass. Some units contain rounded granule sized pumice fragments. These fine grain beds are suggestive of hyperconcentrated flow with sediment being supported by turbulence (Smith, 1986). The lack of cross-bedding and the geometry of these deposits suggests that channels were shallow and poorly confined (Blair and McPherson, 1992).
Horizontally stratified fine to coarse sand commonly contains pebbles and granules. Sand is normally graded, poorly sorted and locally contains rounded pumice or angular to subrounded andésite, basalt, and dacite clasts. These layers are thin and discontinuous, suggesting the presence of amalgamation surfaces. In addition to planar lamination, the deposits exhibit subtle low angle cross stratification in units 5 to 25 cm thick. These layers may have been deposited under normal stream flow conditions
(Smith, 1986).
Fine grained silt and clay layers are horizontally laminated or massive and become more clay rich up-section. Units are thin (generally less than 50 cm) and exhibit a variety of colors (gray, tan, to white). Many massive coarse sand layers grade 27
A
Figure 11. Discontinuous sandy layer mantling underlying conglomerate. Sandstone layer is interpreted to have formed by the reworking of debris flow deposits. 28 upward into laminated silt and mud These fine grained layers may have accumulated as a result of poorly confined channel flow or overland flow, which incorporated surficial sediment winnowed from debris flow deposits (Blair and McPherson, 1992).
The fine grained units contain abundant organic litter including twigs, needles, bark, and leaf impressions (Figures 12 and 13). The preservation and accumulation of organic debris may have resulted from sheet wash flooding and deposition. Fossil leaves and needles are best preserved in poorly lithified silty sands, which render sample extraction difficult. Studies using fossil leaves at this locality would be best conducted in the field.
Tree fragments, exhibiting both perimineralization and coalification, are preserved in both coarse and fine grained sediments. According to Yamaguchi (1995), debris flows can debark, shatter, or uproot trees as flows move downslope, incorporating bark, branches, and fragments of tree trunks, or entire trees. Thus, small tree fragments within conglomerate and sandy layers are interpreted to be transported and deposited as clasts by debris flows
Nature of the “fossil forest” at Cedar Creek
At the Cedar Creek locality, in place and transported vertical and prostrate fossil woods are well preserved and well exposed in all rock types. The largest tree is
2.5 m in diameter (specimen # V31) exposed in poorly sorted matrix supported cobble 29
Figure 12. Fossil leaves and twigs preserved in coarse grained sandstone.
Figure 13. Litter of fossil tree bark preserved in coarse grained sandstone. 30 conglomerate. The longest length of tree exposed is 2.4 m ( V28), which is encased in poorly sorted matrix to clast support cobble conglomerate (Figure 14). Few trees contain borings (trace fossils), interpreted to be beetle boreholes (Figures 15 and 16)
(Laws, 1996, per. comm ).
The Cedar Creek outcrop contains 54 vertical, 63 horizontal, and 13 inclined fossil trees (Figure 5). Roots or flared bases were noted in 16 vertical trees (Figure 17)
(Appendix B). Trees with roots can be transported and deposited both vertically and horizontally (Fritz, 1980a, 1980c). The high percentage of vertical trees (41%) at the
Cedar Creek site satisfies the proposed 10-20% vertical versus horizontal criterion described by Fritz (1985) (see Geologic Setting), to suggest at least some of the vertical trees are preserved in situ at the Cedar Creek site. Additional evidence supportive of an in situ forest includes lack of root abrasion (Fritz, 1980c), sedimentological evidence, such as successive burial of V49 (see Paleosol Analysis), and a tree trunk/root ratio >1
(Fritz, 1985).
Orientation of horizontal fossil trees
Paleocurrent direction indicators in the Cedar Creek area are limited to horizontal tree orientations (Figure 18). The long axes of the trees are principally oriented northwest-southeast. Fewer trees are oriented northeast-southwest. The dispersion in orientation may reflect differences between trees that were partially or wholly suspended in a flow. Trees carried as part of the bedload tend to roll and orient 31
Figure 14. Tall vertical fossil tree V28, 2.40 m in length and 0.90 m in diameter, is preserved in matrix supported conglomerate. 32
Figure 15. Boreholes (from tree V I7) approximately 4.0 mm in diameter.
Figure 16. Boreholes (from tree H42) approximately 3.5 mm in diameter 33
Figure 17a. Vertical tree (VlOO) 0.70 m in diameter exposed in a cave. A post Eocene rat midden covers the fossil tree on the right.
Figure 17b. Lateral roots of fossil tree VlOO penetrating strata. Length to root width ratio (trunk length/root width)is >1 indicating that this specimen was preserved in situ. 34
» 35
Equal Area Circle = 6 % N = 71 A
N 18b
Equal Area Circle = 100% N = 6
Figure 18a. Orientation of 71 horizontal trees. Figure 18b. Orientation of 6 horizontal trees. 36 perpendicular to the flow direction, whereas trees carried in suspension tend to orient parallel to flow (Hendrix, 1997, per. comm.). Figure 18 b shows the orientation of 6 horizontal trees (Figure 19) which were deposited during a single depositional event.
These trees occur on the bedding sole of coarse fluvial tuffaceous sandstone. The northwest-southeast orientation of these trees coincides with the overall paleocurrent direction for the entire outcrop.
Orientations of horizontal petrified trees at the Cedar Creek site are strikingly similar to orientations for trees at Amethyst Mountain and Mount Homaday in
Yellowstone National Park (Figure 20) (Fritz, 1985). Cedar Creek tree orientations are also similar to those found at Mount Norris (Fritz, 1985) and Specimen Creek (Coffin,
1976) (Figure 20). In addition to sharing similar paleocurrent directions, all the sites contain some percentage of trees preserved in fluvial deposits.
In summary, coarse grained units at this site are interpreted to be subaerial debris flow deposits, resulting form a variety of flow processes (Smedes and Prostka,
1972). Fine grained layers at this site were deposited by surficial winnowing, poorly confined channel flow, and overland flow (Blair and McPherson, 1992), and by normal stream flow conditions (Smith, 1986). The high percentage of vertical trees at this site indicates that a number of trees were preserved in situ. Trees showing signs of abrasion, however were likely transported by debris flow processes. Horizontal tree orientations at Cedar Creek suggest a subsidiary northwest to southeast paleocurrent direction with a northeast to southwest component. Similar paleocurrent directions were observed in 37
Figure 19. Six similarly oriented logs preserved on the bedding sole of an overlying resistant coarse grained sandstone bed. 38
Amethyst Mountain Mount Norris
j SL =39% n = 29 = 8 % n = 34 = 6% H = 51%
Mount Homaday Cache Creek
=34% . ^ L =0% = 6% n = 33 = 4% er^ r> = 6o%
Specimen Creek
Level 25 Level 23 Level 21 Plot 2 I n = 8 n = 9 n = 7 \ n = 11
Cedar Creek Cedar Creek (This study) (This study)
=41% n = 71 = 100% n = 6 = 13%
Figure 20. Rose diagrams of vertical, horizontal, and inclined fossil trees from six Gallatin Petrified Forest sites. Taken from Fritz ( 1985) and Coffin ( 1976). 39 the north-central and northwest sections of Yellowstone National Park (Fritz, 1985;
Coffin, 1975). Paleodendrology
Field methods
Before sampling, fossil stumps, logs, and branches were photographed and examined using a lOX hand lens Data regarding the physical nature of each specimen and a general description of encasing lithology were recorded. Tree orientation, diameter, exposed length, ring count, presence of roots and insect galleries, and encasing lithology are presented in Appendix B Total ring estimates, which correspond to the age of the tree, were extrapolated from ring counts on short, well exposed sections.
This was often necessary due to poor preservation of the central portions of trees, or the presence of lichen, moss, or iron staining which obscured large areas on the surface.
Because the width of the central rings is usually wider than that of the outer rings
(Carlquist, 1988) age estimates were made by counting rings from the outermost section of the tree to the center (pith) of the tree. Age estimates presented in Appendix B thus represent a minimum age. Horizontal fossil tree HI 28 records 808 years of tree growth.
The criteria for sampling fossil wood included tree accessibility, degree of tree preservation, tree age, and length of recoverable ring record. Where possible, fossil tree samples were taken from the outer perimeter of the trees along fractures to insure minimal destruction of the specimens and to capture any possible correlations in ring sequences among trees. Correlations in ring sequences between contemporaneous trees
40 41 of varying ages are most likely to be found in sections of the outermost parts of the tree
(Arct, 1991). An effort was made to avoid sampling compression and tension wood
(zones where rings are narrower and wider than the mean ring width). Figure 21 illustrates the relationship between tension wood and compression observed in fossil tree HI 29. Woods of this type reflect varying stress within a growing tree and are caused by external forces, such as prevailing wind direction (with compression wood growing in the direction of wind source) or gradient of substrate (with compression wood located in the upslope direction) (Zobel and van Buijtenen, 1989). Compression wood and tension wood were thus avoided during sampling due to their capacity to overprint climate influences.
In a few cases, conspicuous trees were inaccessible because of steep or unstable slopes. Limited information was recorded for these trees and samples were collected only when it was evident that fossil float originated from that specimen. When possible, these inaccessible trees were mapped and photographed, and general attitudes
(vertical or horizontal) were recorded. Orientation of inaccessible horizontal trees was determined by sighting trend and plunge where possible.
Laboratory methods
Because wood from the trunk of a tree provides the most reliable environmental data, samples from fossil tree trunks were chosen for detailed laboratory analysis
(Benson, 1994, per. comm.) Samples suspected to be roots or branches were not 42
Figure 21. Horizontal tree H129 is 0.25 m in diameter. The closely spaced rings on the left portion of this specimen are compression wood. Tension wood is opposite the compression wood with wider rings. 43 measured. Forty-two transverse thin sections and 6 transverse polished slabs were analyzed using magnifications up to 300X. Tree ring widths, the nature and transition of earlywood to latewood, and the presence of false rings were measured and noted.
Dendrology analysis
Growth ring analysis was initially applied to Quaternary and younger woods, and originally developed for environmental, geological, and archaeological chronology studies (Fritts, 1976; Clague, 1982; Jozsa, 1988; Détienne, 1989; Jozsa and Brix, 1989;
Benson et al., 1992; Jozsa, 1993). Paleoclimate studies on wood ranging from Miocene to Jurassic in age have established that ring analysis also allows similar interpretations of fossilized wood (Francis, 1984, 1986; Parrish and Spicer, 1988,1990a, 1990b; Poole,
1992; Prive-Gill, 1993; Kumagai et al., 1994). Unlike other fioristic paleoenvironmental indicators, such as floral or pollen assemblages, growth rings reflect yearly environmental changes.
Wood forms as the result of growth activity in the vascular cambium
(Nadakavukaren and McCracken, 1985). Cell layers within the cambium grow in an inward direction translating xylem outward (Sala, 1997, per. comm ). The number and size of tree cells determine the width of a ring. Growth activity begins at the onset of favorable growing conditions such as temperate weather and adequate water or sunlight supply (Creber and Chaloner, 1984a). Wood cells produced during the growing season have a greater radial diameter and thinner cell walls due to rapid growth (Creber and 44 Chaloner, 1984a). These cells are termed earlywood (Figure 22). With the onset of unfavorable conditions, such as cooler weather or reduced sunlight or moisture, cambia activity slows, producing thicker cell walls with smaller radii (Fritts, 1976; Creber and
Chaloner, 1984a). These smaller growth cells are termed latewood (Figure 22).
Together, earlywood and latewood record annual tree growth. The size of a growth ring can also be affected by factors such as age of the tree (as a tree ages, ring widths become progressively narrower) or competition for resources (such as water, sunlight, or minerals) which limit tree growth (Jozsa, 1988).
A ring boundary, in ring-porous wood, is a sharp contact between the last layer of latewood and the first layer of earlywood (Figure 22) ( Sala, 1997, per. comm ). Ring widths are determined by measuring the distance between ring boundaries . Successive ring measurements are customarily measured from the center outward (Phipps, 1985).
False rings, which resemble ring boundaries, are a narrow band of small, dense cells within a tree ring (Figure 22) (Panshin and De Zeeuw, 1970). False rings reflect a temporary cessation in growth due to environmental stress during the growing season, such as fluctuations in water supply, frost, pest infestations, or fire (Fritts, 1976). A false ring is distinguished by a progressive increase in cell size within a few cell layers, unlike ring boundaries which have an abrupt increase in cell size (Panshin and De
Zeeuw, 1970).
Mean ring width and mean annual sensitivity are the statistical parameters of a ring width sequence most commonly used in growth ring analysis (Fritts, 1976; Creber 45
I Latewood
Earlywood False rings
Ring boundaiy 1.45 mm Ring boundary
Figure 22. Thin section of fossil tree V56 illustrating growth ring characteristics. Ring boundaries are defined by an abrupt difference in cell size. The direction of growth, in this sample, is from bottom to top. 46 and Chaloner, 1984a; Schweingruber, 1988; Yadav and Bhattacharyya, 1994). Both parameters reflect the response of tree growth to environment. Ring width indicates length of the growing season and growth rate. Mean ring width is the average of ring widths in a tree ring sequence, and is expressed as:
t=n = 1/n X Xt 1
Where t is the total number of tree rings in a sequence, n is the ring number, and Xt is tree ring width (Fritts, 1976; Schweingruber, 1988).
Mean sensitivity calculations measure the average annual variations in a tree’s response to its environment. It is expressed as:
t=n-l MS = 1/n-l % 2|(xt-n-xt)|/(xt+i+Xt) t=i
Where t is the total number of tree rings in a sequence, n is the ring number, Xt is the width of a tree ring, and Xt+i is the width of the adjacent ring (Fritts, 1976; Creber and
Chaloner, 1984a; Schweingruber, 1988; Arct, 1991; Yadav and Bhattacharyya, 1994;
Keller, 1995). The term 2j(xt+i-X()|/( Xt+i+ Xt) describes annual sensitivity (Fritts, 1976).
Wood with mean sensitivities less than 0.3 are termed “complacent,” indicating growth under favorable and uniform conditions. Wood with mean sensitivities greater than 0.3 are termed “sensitive,” indicating growth under variable conditions. Variations in the 47 annual growth width are associated with the circumference of the ring, the development of the crown, and the amount of competition with neighboring trees (Fritts, 1976).
Latewood to earlywood ratios are calculated by measuring the widths of earlywood and latewood. Ratios are expressed as:
Latewood to earlywood ratio = L / E where L= width of latewood and E= width of earlywood (Creber and Chaloner, 1984a).
The proportion of latewood in a tree’s growth ring is affected by length of the growing season and water supply (Creber and Chaloner, 1984a).
Results and Interpretations
Rings width measurements and nature of earlywood to latewood transitions were examined in all 42 fossil tree thin sections. Of the 42 thin sections, only 15 were suitable for dendrological analysis. These samples consisted of coniferous wood with and without resin ducts (Panshin and De Zeeuw, 1970; Core et al., 1979). Identification of wood genera and taxon is tentative due to the lack of tangential and radial cross sections. Thin sections reveal a large amount of fracturing, and irregular ring boundaries.
Sequences of fewer than 14 rings were not included in the analysis. For statistical purposes, thin section data were calculated separately from the 5 polished slabs because of their shorter ring sequences and smaller ring width means. 4 8 The results of the growth ring analysis are summarized in Tables 1 and 2. The total number of rings measured, mean width of ring, earlywood, and latewood, and standard deviations are listed along with mean sensitivities and averages.
Individual ring widths range from 0.3 mm to 6.5 mm (Appendix C). Mean ring widths range from 0.6 mm (VlOO) to 3.1 mm (H90) and average 1.4 mm for thin sectioned samples. Figure 23 illustrates plots for 12 select ring width series, demonstrating moderate to high seasonal variability. Modem conifers growing in a limiting envrionment with persistent arid conditions have a mean ring width range of 0.6
- 1.5 mm (Fritts, 1976). The relatively large ring width increments observed in Cedar
Creek samples suggest moderate growth rates and/or a fairly long growth season. Mean ring width for the 5 polished slabs is 2.2 mm. The difference in ring width means may be a result of artificial bias during sampling, because thin sections were taken from samples with a high occurrence of rings in a short length, in order to increase the tree ring sequence sample size. Polished slab measurements were performed on samples with a large number of tree rings regardless of the length interval.
Mean sensitivity values range from 0.17 (V23) to 0.48 (V41). The average mean sensitivity for thin sections is 0.32 and 0.28 for polished slabs. This difference is not statistically significant, and the average sensitivities are nearly equal. Mean sensitivity of all sections examined average 0.31.
Earlywood and latewood are well developed in ring sequences. The nature of the transition from earlywood to latewood varied between samples, though transitions 49
Table 1 Tree ring measurements from thin sections and slab sections of 21 fossil trees.
Specimen Total Rings Ring Width (mm) Annual Sensitivity Number Measured Mean Standard Mean Standard Deviation Deviation
Thin sections
VI 29 1.00 0.45 0.43 0.36 H16 21 1.51 0.39 0 29 0,24 V23 15 2.54 1,36 0.17 0.10 V28-1 18 1.14 0.41 034 0.25 V28-2 23 1.48 0.97 0.43 0.01 V31 30 1.39 0 31 0.20 0.14 H39 30 1.36 0,59 0.36 0 30 V41 21 2.23 0.92 0,48 0.37 V52 22 0.85 0.29 0,25 0.20 V56 21 1.51 0.49 0,35 0.20 H65 40 0.77 0.44 0,25 0,30 V82 48 0.62 0.20 0,37 0.26 V84 61 0.66 0.26 0,34 0.24 H90 14 3.13 1.08 0,30 0.30 VlOO 49 0.62 0.22 0,26 0.24 V I07 23 0.88 0.36 0.30 0.20 V1I2 19 1.42 0.65 0.29 0.20 AVERAGE (Thin sections) 28 1.36 0.55 0.32 0.23
Slabs
H128 65 1.98 0.69 0,30 0,26 H129 46 2.05 0.64 0.20 0,20 V130 35 3.06 1.35 0,29 0.20 V132 24 1.35 0.75 0.34 0.20 H40 54 2.65 1.21 0.28 0.19 AVERAGE (Slab): 45 2.22 0.93 0,28 0.21
COMBINED AVERAGE: 31 1.55 0.64 0.31 0,23 50
Table 2. Summary of latewood and earlywood measurements for 16 fossil trees. LW/EW = Latewood/Earlywood Ratio
Earlywood Latewood LW/EW Specimen Total Rings Mean width Standard Mean width Standard Ratio - Number Mesured (mm) Deviation (mm) Deviation Specimen Average VI 8 2.73 0.73 0.29 0.34 0.12 VIS 6 4.85 1,00 0.25 0.05 0.05 V17 9 2.80 1.42 0.22 0.22 0.08 H22 14 1.91 1.02 0.54 0.18 0.28 V23 13 2.31 1.18 0.31 0.11 0.13 V31 31 1.13 0.30 0.15 0.50 0.13 H39 23 1.20 0.52 0.27 0.13 0.23 V41 12 1.93 0,56 0.21 0.08 0.11 H42 10 4.08 1.13 1.13 0.19 0.28 V51 12 2.64 1 35 0.35 0.24 0.13 V52 21 0.63 0.16 0.10 0.09 0.16 V56 22 1.30 0.37 0.14 0.05 0.11 V82 15 1.20 0.41 0.09 0.02 0.08 V84 33 0.58 0.23 0.07 0.03 0.12 H90 14 2.53 0.82 0.50 0.29 0.20 V107 22 0.61 0.25 0.15 O il 0,25
Average ratio: 0.15 Standard Deviation: 0.07 51
. 4 0 0
2 2 00
000-
Ring Num ber
4,00- H 3 9
£ 3.00
2 200
000-
Ring Number
400 V 31
£ 3 00
2 2.00-
Ring Number
Figure 23. Twelve ring series plots illustrating the variation in ring widths. Specimens VI, H39, and V31 are shown on this page 52
400 H16
S 2.00
0 00-
Ring Number
400 V 2 8
Ê 3,00-
2 2.00
000- Ring Number
4.001 V 41
Ê 3.00-
2 2.00
0.00-
Ring Number
Figure 23 continued. Ring series plot for specimens H16, V28, V41 53
400 V 5 2
0.00
Ring Number
4001 H 6 5
S 200
ir 1.00
0.00
Ring Num ber
4.00- V 8 4
6 3.00
P 200
0.00
Ring Number
Figure 23 continued. Ring series plot for specimens V52, H65, V84. 54
400 V 5 6
S 200
0.00'
Ring Number
4,00 V 8 2
S 300 Ê c S 200 ? % 1.00
0.00 I I I 0 5 10 15 20 25 30 35 40 45 50 55 60 65 Ring Number
4.00 V 1 0 0
s 200
ooo Ring Number
Figure 23 continued. Ring series plot for specimens V56, V82, H 100. 55 were more commonly gradual (Figures 22 and 24). Earlywood and latewood measurements and ratios are presented in Table 2. Ratios range from 0.05 to 0.28, with an average of 0.15.
False rings, examined only in thin sectioned samples, are common and occur irregularly throughout ring series (Figure 22). One false ring in a single growth ring is most common.
Yellowstone area paleoclimate
Comprehensive studies using paleodendrology on fossil trees of the Gallatin
Forest were conducted by Ammons, et al (1987) at Specimen Ridge and Arct (Arct,
1991) at Specimen Creek. These studies were originally conducted to determine whether the vertical fossil trees were in situ or allochthonous. In addition, Arct (1991) presented and interpreted paleoclimate evidence based on his dendrology data.
Ammons et al. (1987) presented dendrological data without providing paleoclimate interpretations. These studies, along with data from the present study, form the basis for the paleoclimate and paleoenvironmental interpretation of the Gallatin Petrified
Forest presented below.
At all three Gallatin Petrified Forest sites (Figure 3) fossil trees record seasonality. Annual growth rings were found in all species examined at Cedar Creek and at Specimen Creek (Arct, 1991). Distinct growth rings were also observed at Specimen
Ridge and were used to develop a floating chronology (Ammons et al., 1987). This 56
1.45 mm
Figure 24, Photograph of a thin section from fossil tree V82 showing wide earlywood and narrow latewood with an abrupt transition. 57 seasonality was likely driven by changes in the length of the photoperiod (Kozlowshi,
1971; Fritts, 1976; Creber and Chaloner, 1984b; Arct, 1991) and possibly by annual changes in temperature.
At Cedar Creek, growth ring widths are relatively large, with maximum ring widths of 6.5 mm (Appendix C). At Specimen Ridge, growth ring widths are also large, approximately 8.0 mm (Ammons et al., 1987). This suggests a moderate growth rate and/or a slightly long season of growth for these trees. Maximum ring widths were nearly twice as large (14.0 mm) at the Specimen Creek site as those found at other sites
(Arct, 1991).
Average mean sensitivity values for all three sites range from 0.28 to 0.44 (Table
2). At the Cedar Creek site mean sensitivity of 0.31 compares well with an average of
0.28 calculated from Specimen Creek trees. Mean sensitivity values were relatively high in fossil trees examined at Specimen Ridge (Ammons et al., 1987). Ammons et al.
( 1987) reported mean sensitivities which average 0.44 (Ammons et al., 1987). This result suggests that these trees were ‘‘sensitive” and responding to a high amount of climate variability. The range observed between sites may be due to differing tree assemblages. However, Arct (1991) determined that trees shared cross identifiable features, regardless of species. On this basis, he concluded that all specimens “were exposed to a strong environmental signal” and responded similarly (Arct, 1991)
Alternatively, the range in average mean sensitivity may be due to environmental variations, not yet resolved, between the forests. These variations may include 58 differences in substrate topography (steep slope or flat-lying area), tree position within its forest (margin or interior), and/or slope aspect (i.e. position on a south or north facing slope which exerts a control on the amount of water and sunlight available).
Increasing the sample number at all three sites and the addition of data from new sites may resolve this variation in annual sensitivity across the northern Yellowstone area.
Growth rings from Cedar Creek exhibit a characteristic gradual transitions from earlywood to latewood. A gradual transition was also observed in Specimen Creek tree thin sections. This suggests that trees in the Yellowstone area were subjected to a slow transition from the growing season to dormancy. Width of latewood was not examined at the Specimen Ridge site. From photos presented in Ammons et al. ( 1987) trees appear to exhibit both gradual and abrupt transitions. Latewood to earlywood ratios are relatively high (0.15 at Cedar Creek; values were not provided for Specimen Creek but were described as “a large percentage of latewood”) (Arct, 1991). This indicates that the majority of tree growth took place under optimal conditions.
Insect activity was noted at both Cedar Creek and Specimen Creek.
Macroscopic borings were observed in a few specimen from Cedar Creek, but were not examined morphologically and remain unidentified. At Specimen Creek, the presence of microscopic insect galleries was observed in 50% of the Pinus specimen examined in thin section. Arct (1991) identified insect gallery morphologies and attributed their formation to wood boring beetles, Buprestid and Cerambycid larva. These beetles typically infest repressed and dead trees and are not considered likely to have affected 59 tree growth. Thus these beetle borings probably did not interfere with climate data recorded in tree rings (Arct, 1991).
In summary. Eocene paleoclimate in the Yellowstone area (perhaps a microclimate) was seasonal with a possible moderate to long warm, summer season.
Transition from this warm season to a cool season was gradual, causing a progressive change from optimal tree growth conditions to dormancy. Dormancy in tree growth, indicated by ring boundaries, suggests that winter months were cold. Tree dormancy may additionally reflect seasonal changes in the photoperiod. The range in mean sensitivity values between sites may reflect differences between separate forests.
Insects, which infested trees at two sites, apparently did not affect tree ring width distributions reported from the Specimen Creek site Table 3 provides a summary of paleodendrological data from these three sites in the Gallatin Petrified Forest.
Relevance of this study in the context of interior US Eocene paleoclimate
Early Eocene paleoclimate in the continental interior of North America was warm and equable in basinal areas, as suggested by the presence of rhythmically stratified organic rich lacustrine deposits (Picard, 1985; Baer, 1987), abundant tropical floral remains (Knowlton, 1922; Axelrod, 1966; MacGinitie, 1969, 1974; Hickey, 1977;
Sloan, 1994), and lateritic paleosols (Thompson et al., 1982; Fastovsky and
McSweeney, 1991; Retallack, 1994). During this time, circulation of oceanic waters was a major mechanism for the transfer of heat from equatorial regions to the poles 60
Table 3. Summary of Gallatin Petrified Forest paleodendrology data from three ’’fossil forest" sites. Information was taken from Arct ( 1990) and Ammons, et al. (1987).
Dendrology data Cedar Creek Specimen Creek Specimen Ridge
Seasonality Distinct growth "clearly defined Distinct growth rings present annual growth rings rings present in all species"
Maximum ring width up to 6.5 mm up to 14.0 mm ~ 8.0 mm
Mean thin sections: .28 sensitivity slab sections: .32 0.28 .44* average: .31
Latewood to Photos show both Latewood/ Latewood to earlywood transitions gradual and abrupt E a rly w o o d earlywood transitions are gradual; latewood to ratio are gradual; LW:EW ratio: earlywood transitions LW:EW ratio: 0.15 "large percentage of LW:EW ratio: latewood" not examined
False rings Present Present Present
Insect activity Macroscopic Microscopic not examined boreholes beetle larva galleries
* value calculated from data presented in Ammons (1987) 61 (Barron, 1989). Atmospheric circulation maintained a low latitudinal temperature gradient, resulting in a weak circulation which caused seasonal contrasts, as suggested by high altitude flora (Shackleton and Boersma, 1981 ; Rea, 1985; Crowley et al., 1986;
Barron, 1989). The absence of permanent polar ice during the Eocene has been attributed to high summer polar temperatures, despite colder winter temperatures
(Crowley et al., 1986). Models simulating Tertiary geographic and orographic effects on atmospheric circulation reveal a direct response between topographic highs and climate (namely moisture and temperature), similar to orographic processes ongoing today (Manabe and Broccoli, 1990). Related studies and the present study show that climate was not warm and equable in all areas within the continent.
Continental paleoclimate indicators typically include fossil flora assemblages
(Chadwick and Yamamoto, 1984), pollen (Batten, 1984; Farley, 1989), isotope data
(Stuiver and Burk, 1985), and paleosols (Singer, 1984; Bird et al., 1990; Curtis, 1990;
Fastovsky and McSweeney, 1991). However, climate modeling has yet to include
Eocene climate data from high altitude sites (Barron and Washington, 1984; Crowley et al., 1986). Climate data from high altitudes can be easily collected through paleodendrology and leaf margin analysis (e.g. Wolfe, 1971,1994; Spicer and Parrish,
1990a; Gregory and Chase, 1992; Meyer, 1992; Gregory and McIntosh, 1996).
Tertiary climate models using paleoclimate data inferred from common climate indicators do not systematically predict data. Wing (1991) was unable to correlate patterns of Eocene continental temperature, determined from terrestrial flora ,with the 62 marineO record. The discrepancy was attributed to possible “sampling problems in the terrestrial flora, regional climatic evolution in western interior North America, or a global phenomenon” (Wing et al, 1991). Additionally, Eocene continental climate models have failed to estimate minimum temperature data (Barron and Washington,
1982,1984; Barron, 1985; Sloan, 1990; Sloan and Barron, 1990, 1992, 1994). This was attributed to “limitations of available data,” typically derived from methods that do not provide detailed information regarding mean temperature, range in temperature, and nature of seasonality (Sloan, 1994).
Paleodendrology and leaf margin analysis together provide insight regarding seasonality and paleotemperature. Calculations based on leaf margin analysis quantitatively describes the mean and range of temperature and precipitation, while paleodendrology provides information regarding seasonality. The combination of these techniques can potentially provide high resolution climate data which can facilitate a more accurate paleoclimate model. This study, in addition to other Gallatin flora studies have been limited to the use of paleodendrology. Future Gallatin floral studies should include both paleodendrology and leaf margin analysis. Combining these methods could potentially furnish mean temperature and precipitation data for cold and warm months in addition to providing mean and range data (Gregory and McIntosh,
1996). Paleosol Analysis
The chemical and physical properties of a paleosol are the result of the interactions between parent material, topography, organisms, climate, and time (Jenny,
1941; Birkeland, 1984; Singer, 1984; Curtis, 1990; Fastovsky and McSweeney, 1991;
Mack, 1992). Clay minerals formed in paleosols are the direct and indirect result of decomposition of primary aluminosilicates (McBride, 1994). Rate of decomposition is affected by amount of rainfall, temperature, soil biota activity, evaportranspiration, and the rate of vertical water movement (leaching) through the medium (Curtis, 1990).
Paleoclimatic interpretations based on the analysis of paleosols require that clay minerals be pedogenic (Singer, 1979/1980; Retallack and German-Heins, 1994)
Pedogenic features and structures (both macroscopic and microscopic) allow for the differentiation between detrital clay and clay formed in situ (Mack, 1992). These features include color, horizonation, and the presence of root casts and peds. The degree of weathering or stage of soil profile development observed in a paleosol reflects the duration of interaction between parent material and climate. A mature soil profile may develop over a considerable amount of time and indicates a state of chemical and physical stability between climate and the substrate (Singer, 1979/1980).
Several studies have shown the relationship between clay mineral formation and local precipitation in modem soils (Barshad, 1966; Singer, 1966; Birkeland, 1984).
Smectite-rich soils tend to form in arid climates (Figure 25a) (Barshad, 1966; Singer,
63 s o 100 64 (ë 80
O 60 .ë G 0 40 1 i G 20 o
30 40 5060 70 80 Annual Rainfall (cm) Figure 25a. Curve illustrates the proportion of smectite with increasing precipitation (annual rainfall) in the weathering environment. Taken from Singer (1966).
80 smectite I Kaolinite/halloysite I 60 U 1 40 illite vermiculite
S' 20 0 gibbsite
50 100 150 200 250 Annual Rainfall (cm)
Figure 25b. Curve illustrates the relationship between annual precipitation and mineral composition of residual soils weathered from acid igneous rocks. Taken from Barshad, (1966). 6 5 1984). In addition to persistent arid or semiarid conditions, low leaching rates will also lead to incomplete decomposition of primary minerals. The resulting products are high in Si, Mg, Na, Ca and K and lead to crystallization of smectite. Kaolinite-rich soils form in wet climates and are indicative of extensive leaching. Figure 25b illustrates the relationship between proportion and variety of clay types to intensities of precipitation. Leaching in warm, humid climates removes many of the soluble cations from soil, leaving a higher proportion of Al, Fe, and Si (Curtis, 1990; McBride, 1994).
Silicon and aluminum then combine to form the kaolinite group of 1:1 clays. Other clay minerals, such as illite, chlorite, vermiculite, and mixed layered clays may occur under a range of precipitation regimes (Figure 25b) (Mack, 1992).
Clay mineral composition of paleosols as a paleoclimate indicator has been successfully adapted to paleosols and saprolites (weathering horizons) as old as
Palaeozoic in age and has been applied to a number of studies worldwide (Singer, 1984).
These studies include early Pleistocene paleosols in central Yukon Territory (Foscolos et al., 1977), Quaternary paleosols east of Verdi in Sierra Nevada Great Basin
(Birkeland and Janda, 1971), Miocene to early Pleistocene paleosols forming on a basalt in northern Israel (Singer, 1970), Tertiary paleosols in Montana and Idaho (Thompson et al., 1982), early Tertiary submarine laterites on the Iceland-Faeroe Ridge, North
Atlantic region (Nilsen, 1978; Nilsen and Kerr, 1978), early Cretaceous paleosols intercalated with yellow argillaceous sand of the Paris Basin, western Europe (Meyer, 66 1976), and middle Pennsylvanian paleosols from an ancient rain forest in Missouri
(Retallack and German-Heins, 1994).
Field methods
Six short stratigraphie sequences of suspected paleosols were measured in detail to document relevant lithologie and pedogenic evidence (Figures 26 to 31). Evidence suggesting the presence of paleosols included petrified roots penetrating strata, breccias, root casts, and organic litter horizons (Mack, 1992). Sedimentary textures and structures were noted and colors were assigned with a Munsell soil color chart
(Macbeth, 1992). The length of measured sections was commonly determined by accessibility or cover. In some cases measured sections were lengthened by removing talus and trenching alluvium and poorly lithified rock.
For this study, paleosol sampling was limited to sites adjacent to /w vertical trees with roots visibly penetrating strata or with trunk length to root base v^dth ratios
>1 (Fritz, 1985). Figures 26-31 illustrate the relationship between trees, their roots and underlying strata. Sampling intervals were chosen based on color changes and/or lithologie changes. In the absent of color or lithologie changes samples were taken at 15 cm intervals. A total of 59 samples, including field duplicates, were collected from strata adjacent to sample sites. Recognizable paleosol horizons were designated with subordinate descriptions defined by Mack (1992). 67 Explanation
Pebble conglomerate Silt and clay
Tuffaceous sandstone- Coarse sand conglomerate
Fine to medium sand Bedding contact
^ Organic debris: needles, . Fine sand with clay lenses twigs, leaves, or bark
Coarse to fine sandstone Organic rich layers with pumice clasts Modem plants
Explanation of Figures 26 - 31. Each figure includes a photo of one in situ vertical tree accompanied by a sketch of tree and detail stratigraphie section. 68
»
' / W 7
Figure 26a. Photograph of fossil tree VI5. Root base width is 2.00 m. 69
1
Sample PI Massive siltstone. [5Y 5/2, olive gray]
Sample P2 and F3 Well sorted coarse grained sandstone. [5Y 5/2, olive gray] Bt Sample P4 P2 Moderately sorted fine to medium P3 grained sandstone. [5GY 6/1, greenish gray]
Sample PS Moderately sorted fine to medium grained sandstone. D O P6 [lOYR 8/2, very pale brown] Sample P6 B q O Û. O Q P7 D Poorly sorted angular clasts in a O D ? O F8 crystalline matrix. [5Y 7/2, light gray]
Sample P7 and P8 Poorly sorted subangular to angular clasts in a cry stalline matrix. [5Y 7/2, light gray] W É Ê Ê § Ê M : 20 cm I 40 cm Figure 26b. Sketch of fossil tree V I5 and associated strata showing location of sampling for clay mineral analysis. 70
Figure 27a. Vertical tree V82 with tap roots penetrating strata (lower center of photo). Rock hammer rests of igneous clast which is surrounded by roots.
Figure 27b. Close-up photograph of root from V82 penetrating strata. 71
m
ï m
î î 72
. \j/N/
Sample 111, PI, 112, and P2 pj Moderately sorted fine grained sandstone. [2.5Y 5/3, light brownish **2 gray] m P3 Sample P3 and P4 Well indurated siltstone and crystalline quartz. [2.5 YR 5/3, reddish brown]
Sample P5, P6, and 113 Fine grained sandstone with subangular to subrounded pumice clasts. [2.5Y 6/2, light brownish gray]
Sample 114 Moderately sorted fine grained sandstone with subangular to subrounded pumice clasts. Some bark present. [2.5Y 6/2, light brownish
20 cm O' o 40 cm Figure 27c. Sketch of fossil tree V82 and associated strata showing location of sampling for clay mineral analysis. Tree roots grow around a large clast shown in lower center of tree. 73
^ . .
\i> y . î L,:- '-•* *.
Figure 28a. Photograph of fossil tree V46. Buttress roots extend to the left 0.82 m beyond the tree stump. ?
Sample III Poorly sorted matrix sryported pebble conglomerate. Subangular to subrounded clasts. |2.SY 6/4, light yellowish brown] Sample 112 \!oderately sorted coarse grained sandstone with few organic debris. [2.5Y 7/3, pale yellow] Sample U3 N/oderately sorted coarse grained sandstone with organic debris including bark, few 1 mm rounded clasts. ( 2 .5Y 7/3, pale yellow] Sam pie 114 %ell sorted fine grained silty sandstone with few organics. 5 Y 8/2. pale yellow] Sample P8 h/assive well sorted fine silty sand. [5Y 7/3, pale yellow] Sam pie PI and P9 V assive well sorted line silty sand. Few coarser sand grains. [5Y 7/2, light gray] Sample F2 and PiO h/assive well sorted fine silty sand. (5Y 8/3. pale yellow] Sample P3 and P ll K/oderately sorted medium to fine grained silty sandstone. [SY 7/2, light gray] Sample P12 %ell sorted fine grained sandstone with silty clay laminca. [5Y 7/2, light gray]
Sample P4 N/assive moderately sorted fine silty sandstone. [5Y 6 3, pale yellow] Sample PS V assive fairly well sorted fine silty sandstone, f 5Y 6/3. pale olive] Sample P6 Subltly laminated fairly well sorted medium sandstone with fine silty sandstone. [5Y 7/4, pale yellow] 10 cm Figure 28b. Sketch of fossil tree V46 and associated strata showing location of sampling V.assive siltstone. (5Y 8/1, white] for clay mineral analysis. 30 cm 75
Figure 29a. Photograph of fossil tree V76. Ferrari cutan vughs are in the lower right section of this photo. 76
Sample HI Very fine grained well sorted sandstone. Few subrounded coarse pumice clasts. [5Y 7/3, pale yellow]
Sample 112 Poorly sorted coarse grained sandstone with subangular clasts. Organic rich I I 2 horizon at lower contact. [2.5Y 7/3, pale yellow]
Sample 113 Moderately sorted medium grained sandstone with subrounded clasts. Organic rich horizon below upper contact. [2.5Y 6/2, light brownish
Sample 114 Well sorted medium to fine grained sandstone with few coarse grained clasts. 1 cm thick organic horizon at lower contact. [7.5YR 6/3, light brown]
Sample IIS and PI Well sorted medium to fine grained sandstone with few coarse grained clasts. [2.5YR • a s 6/2,
P2 Sample H6, P2, and P3 Poorly sorted coarse grained sandstone n 6 with subangular clasts. [7.5YR 7/1,light gray]
4 cm 4 / -
10 cm
Figure 29b. Sketch of fossil tree V76 and associated strata showing location of sampling for clay mineral analysis. 77
Figure 30a. Vertical fossil tree V49, with length to root width ratio >1, was preserved by successive burial.
Figure 30b. Close-up photograph of organic litter and strata adjacent to fossil tree V49 (lens cap for scale). 78 79 & f n O ^
Sample 1 Organic rich fine silty sand. 1 [lOYR 7/2, light gray]
Sample 2 Poorly sorted normally graded 2 lithic rich coarse grained sandstone with some rounded pumice clasts. Organic rich at the lower boundary. [lOYR 7/2, light gray]
Sample 3 and 4 Upper contact is normally gradded with subtle low-angle cross stratification. Conglomerate is ^ matrix supported with abundant pebbles. Clasts are sub-angular to sub-rounded. [lOYR 7/2, light gray]
10 cm
2 0 cm FigureMi 30c. Sketch of fossil tree V49 and associated strata showing location of sampling for clay mineral analysis. 80
\ f» ^ V I
JL
Figure 31a. Photograph of fossil tree V75. (Lens cap for scale. ) 81
\l/ /J / Sample ni Fairly well sorted fine grained sandstone I with few subrounded lithic grains. - [2.5YR5/3, reddish brown]
Sample 112, PI, and P2 Moderately sorted subrounded coarse grained sandstone. Some silt and few PI organics including bark. [5Y 7/3, pale yellow] Sample 113 P2 Moderately sorted medium grained sandstone. Lithics are subrounded. [5Y O H3 7/1, light gray] Q . Q q : ■ ■••.o'; :■ Sample 114 jj^ Moderately sorted medium grained O o sandstone. Few subrounded .5 cm diameter clasts and bark. [5Y 7/1, light gray] O O Sample P3 and 115 6 ns Moderately sorted medium grained sandstone. Lithic grains are subrounded. [5Y 7/1, light gray]
# g ë # # 10 cm 20 cm
Figure 31b. Sketch of fossil tree V75 and associated strata showing location of sampling for clay mineral analysis. Object protruding from center of strata is interpreted to be an exposed root associated with V75. 82 Laboratory treatment
Clay minerals from suspected paleosols were analyzed by standard X-ray diffraction techniques (Moore and Reynolds, 1997). Oriented <2p, <.5p, and < 2 p size fractions were prepared from each sample. Random powder < 2p size fraction were prepared from a select number of samples to aid in mineral identification. Before mounting, samples were washed with deionized water to remove modem organics and weathering products. Samples were gently crushed into a fine powder using an iron mortar and pestle. Approximately 1 to 2g of sample were suspended in deionized water. Sodium-hexametaphosphate was added to prevent clay flocculation. The mixture was then ultrasonically disaggregated to disperse the clay minerals. All <2p,
<.5p, and < 2p equivalent spherical diameter size fractions were separated by timed centrifugation and were then air-dried on glass microscope slides. Once air-dried, duplicate samples were saturated in ethylene glycol vapor for no less than 24 hours.
After preliminary analysis, selected samples were heat treated at 600° C for 2 hours to dehydrate the samples to verify the presence of smectite.
X-ray diffraction patterns were produced by a Philips Norelco flat-specimen goniometer with CuK alpha radiation at 30 kV and 20 mA and a graphite crystal monochrometer. The X-ray diffractometer was calibrated by analyzing blank glass slides, randomly oriented quartz powder, and by duplicating oriented paleosol sample patterns. All samples were run at a 2 0 range of 0-65°. Digital data were gathered using 83
a Radix Instruments, Inc. Databox stepscanner, operating at s = 800 and 10 seconds per increment counts with a step size of .2°. X-ray data were plotted and diffraction peaks were labeled using Plotdata (Reynolds, 1976).
Results and Interpretation
Stratigraphy of paleosols and weathered horizons
Fossil tree V I5 and associated paleosol (Figure 26a) are located approximately
80 m stratigraphically above other units examined in detail. VI5 consists predominantly of an extensive root system penetrating a moderately well differentiated paleosol (Figure 26b). The uppermost exposed layer is an olive gray Bt horizon (B horizon with clay accumulate) consisting of massive, well indurated siltstone. The Bt horizon is underlain by a Bq horizon (B horizon with quartz accumulate) consisting of a greenish gray blocky siltstone encased in a crystalline matrix which grades to a brown, granular fine sandstone. The lowermost C horizon exposed in this section is composed of slightly modified parent material. Strata associated with VI5 are interpreted to be paleosol formed in situ as a result of prolonged weathering.
Strata located at V82 (Figure 27a- c) is slightly differentiated, with a vitric texture throughout. The uppermost layer consists of a light-brownish-gray moderately sorted sandstone underlain by a reddish brown well indurated siltstone (Bt horizon)
(Figure 27a-c). At the base of this section is a fine grained sandstone which becomes 84 rich in organic debris with depth, grading into poorly sorted conglomerate. Strata associated with V82 are interpreted to be an in situ paleosol.
Organic litter, composed of indistinguishable blanched woody organic detritus is present throughout the field site as thin, 1-3 mm thick, discontinuous lamina These layers are generally confined to bedding planes of silty sand or silty clay units. In places, organic litter drapes clasts of underlying units.
Of the six fossil trees examined for the presence of a paleosol, three had an organic litter layer adjacent to their roots The accumulations of litter associated with trees V46 (Figure 28a and b) and V76 (Figure 29a and b) were designated the O horizon of a thin A horizon (Mack, 1992). Immediately beneath the A horizon of these trees is a layer of clay accumulate, designated Bt horizon. The Bt horizon of V76 contains visible ferran vugh cutans (iron rich soil plasma filling disconnected voids (Mack, 1992)
(Figure 29a). V46 is located in a cave, while V76 is located in a recess between an overhang and the more resistant ground surface, preventing an incomplete view of these paleosol sections below the Bt horizon.
Two layers of organic litter at and below the root mass of V49 are separated and underlain by a poorly sorted coarse sand (Figure 30a-c), which lack any evidence of horizonation or other pedogenic features. In the absence of pedogenic features, these surfaces are designated as a weathered surface. The >1 trunk length to root base
(trunk/root) ratio of this tree suggests that it was preserved in place (Fritz, 1985).
Additionally, thin bedding separated by organic debris suggests that this specimen was 85 buried by successive deposition of sediment by debris flows (Figure 30a). Separate sedimentation events likely truncated and obscured soil horizonation.
Strata of V75 (Figure 31a and b) lacks differentiation and an associated organic litter horizon. Blanched woody fragments protrude throughout the section and are interpreted to be petrified roots associated with the overlying fossil tree (Figure 31a).
The absence of vertic features and lack of well developed horizonation for paleosols adjacent to trees V46, V75, and V76 suggest a moderate amount of bioturbation or rhyzoturbation, though no recognizable trace fossils within these units were observed. Bedding planes associated with these trees are interpreted to be weathered surfaces, representing immature soil development.
Strata with pedogenic features occurs throughout the field site, though in this study paleosols were not analyzed unless they were associate with an in situ tree. At one locality near stratigraphie section 1 (Figure 5 and Appendix A), root casts preserve the only evidence of a paleosol. Organic rich layers not association with in situ trees occurred throughout the field site. The absence of in situ trees, distinguishable soil horizons, pedogenic features, and well preserved flora suggest that many of the organic rich horizons were allochthonous accumulates and not part of an O horizon. Fluvial deposition possibly associated with reworked debris flow deposits explains the ubiquitous nature of these organic rich layers. Clay mineralogy o f paleosols and weathered horizons 8 6
From the six paleosol sections, 52 samples plus 7 field duplicates were collected and examined by X-ray diffraction. Samples examined in the <2, <5, and <2p size fraction gave similar diffraction patterns. Field and laboratory duplicate samples reliably duplicated X-ray diffraction data.
A small proportion of smectite, mica, and degraded or vermiculitized mica occurs throughout paleosol section VI5. Varying amounts of quartz and X-ray amorphous mineraloids are present all through this section. Ethylene glycol saturated mounts from samples V15-P2, V15-P3, V15-P5, V15-P6, and V15-P7 display smectite peaks ranging from 16.71 to 16.07Â (Figures 32 and 33). Dehydration of these samples at 600°C collapsed these peaks to 10Â (Figures 32 and 33). Sample V15-P5 was partially dehydrated by evaporating an ethylene glycol saturated sample at room temperature. This caused the 16.70Â peak to collapse to a 12.82Â reflection (Figure
33).
Samples V15-P2 through P4 also show (001) mica reflections with 10.16Â (001 ) and 4.95Â (002) (Figure 32), 10.02Â (001) and 5.02Â (002) (Figure 32), and 10.16Â
(001) and 5.09Â (002) respectively. Samples V15-P1 contain a 10Â (001) with an absent (002) reflection (Figure 34), indicating a trioctahedral mineral such as biotite. In this sample the 10Â peak is broad and asymmetrical, skewed toward a low 2 0 angle, an indication that the mica is vermiculitized (Thompson, 1997, per. comm ). 87 1<5.70A V I 5-P>2 sm ectite (OO 1 ) EOS
ica c o o l)
ica (0 0 2 ) V 1 5 - E 2 <.5|a JrdT
3 .3 5 A
n ica (0 0 2 )
V I 5-E3 ______EGS
16.71 A smectite (001)
3 .3 5 À
V 15-E 3 i - l T
10.02A m ica (OO 1 )
i c a (0 0 2 )
12 1 7 22 2 7 32
2®-tlieta
Figure 32. X-ray difïraction patterns of oriented ethylene glycol saturated and heat treated paleosol samples from fossil tree VI 5. HT = heat treated samples, EGS = Ethylene glycol saturated sample, Pvl = machine peak. le .v lÀ 88 ectîte (OO 1 )
V15-F»5 < .5 |x W T
V 1 5 - P 5 12.8 1 <.5^t D ehydrated >Vix*-clrieci sm ectite (OO 1 >
V 1 5 -P 6 < - 5 E G S 1 6-O V À smectite (OOl)
\ / l 5 -E 6 C .5 JrdT
r T 12 1 7 22 2 7 32
2^-thêta
Figure 33. X-ray diffraction patterns of oriented ethylene glycol saturated, heat treated, and air-dried paleosol samples from fossil tree V^IS. HT = heat treated samples, EGS = Ethylene glycol saturated sample, Ivl = machine peak. 89
<-5|j. EOS
ica COOl )
1 < 5 ^ 1 E C 3 S
V 75-F *2 < 5 ^ 1 E G S
EOS
3.31A
3.03 A < - 5 | a E G S
T T T I 12 1 7 22 2 7 32
2°-the ta
Figure 34. X-ray diffraction patterns of oriented ethylene glycol saturated paleosol samples from fossil tree V^IS, V'46, V"75, V'76, and V'49. EGS = Ethylene glycol saturated sample, Kf = machine peak. Rock sample V46-P1 from fossil tree V46 section contains a skewed ^ asymmetrical 10Â (001) reflection identical to that observed in V15-P1 (Figures 34).
This reflection is likewise interpreted to represent degraded or vermiculitized mica
Diffraction patterns from the remainder of this section produced reflections indicating abundant X-ray amorphous mineraloids.
Samples examined from sections V75, V76, and V49 contain large proportions of
X-ray amorphous mineraloids (Figure 34). Quartz was detected throughout section
V75 in the <2p size fraction. In addition to amorphous mineraloids, sample V49-P1 produced a number of distinct reflections including an unidentified 6.66Â peak. No identifiable clay minerals were observed in any patterns from oriented, randomly oriented, or heat treated samples (Figure 34). The lack of abundant clay minerals in sections V46, V49, V75, and V76 together with lithologie evidence suggest that preservation of these horizons may have occurred at an early stage of soil development, before development of well crystallized minerals.
The paleosol section at fossil tree V82 contains a large portion of X-ray amorphous mineraloids throughout the section. Samples V82-P1 through P3 are comprised exclusively of X-ray amorphous mineraloids. Smectite was detected in samples V82-P4 through V82-P6, and V82-IIP2 through V82-IIP4. Ethylene glycol saturated samples show 15.59 to 16.71 A (001) reflections. These samples showed no diffraction peaks after heat treatment (Figure 35a and b). An air-dried sample of V82-
11P4 showed a peak at 12.09Â (Figure 35c). This reflection transition is similar to that 1 5 - 5 Q Â
sm ectite COO I ) 91
< -5 n t l T
16-V O A sm ectite COO 1 )
V^82-f*5 EGS
3 .3 5 A
1 -T —I— 2 7 12 17 22 2 7 32
2°-theta
Figure 3 5a. X-ray diffraction patterns of oriented ethylene glycol saturated and heat treated paleosol samples from fossil tree V82. EGS == Ethylene glycol saturated sample, HX = heat treated samples, IVI = machine peak. 1<3.3 l À sm ectite (OO I ) 92 V^82-F*«5 EGS
V 8 2 - E 6 < . 5 m H T
3 .3 T A
N /82-113 smectite (OOl ) < 5(Lt EGS
V^82-H3 < .5 |a H T
r- — I— —'—'—I— ’—r~ 2 T 12 1 V 22 27 32
2°-theta
Figure 35t>. X-ray difïraction patterns of oriented ethylene glycol saturated and heat treated paleosol samples from fossil tree V82. EGS = Ethylene glycol saturated sample, HX = heat treated samples, fvi = machine peak. 93
smectite (OO 1
V^82-114- < . 5 | j . E G S
\/82-114 C.SjLt D ehydrated yVir-<±r ie ci smectite (O01 )
1 —r —T- — T— 2 7 12 1 7 22 2 7 3 2
2°-tlieta
Figure 35c. X-ray ciifïraction patterns of oriented ethylene glycol saturated and air-dried paleosol samples from fossil tree V82. EGS = Ethylene glycol saturated sample, Js/l = machine peak. observed in V15-P5 (Figure 33) and indicates the presence of smectite (Thompson, ^
1997, per. comm ).
Discussion
At Cedar Creek, two short stratigraphie sections, VI5 and V82, preserve paleosols with moderately differentiated horizons, interpreted to be the result of immature soil development. The paucity of well developed soil in these units is likely related to the high rate of sedimentation driven by local volcanism. Debris flow sedimentation truncated soil sections and shortened the time these units were exposed to weathering processes. The occurrence of root traces, O, A, Bt, and Bq horizons, vertic features and weathering surfaces indicate an immature soil (i.e. developed in a period of less than 1,000 years) (Mack, 1992).
The high proportion of amorphous mineraloids observed in X-ray diffraction patterns may reflect a parent material rich in volcanic glass. The presence of smectite is limited to sections with moderate soil development (VI5 and V82). The presence of smectite in these paleosol samples is indicative of low leaching rates and/or climate with low precipitation (Barshad, 1966; Singer, 1984; Mack, 1992). This suggests that weathering occurred under arid or semiarid conditions, consistent with the presence of cool-temperate flora found throughout the Yellowstone area (Fisk, 1976; Ammons et al, 1987; Arct, 1991) 95 The presence of paleosols in the Yellowstone area warrants further investigation. Pétrographie, bulk chemical, and stable isotope analysis combined with methods described here could be employed in the area to better understand of the evolution of these weathered surfaces. Conclusions
Several conclusions may be made regarding Eocene paleoclimate and paleoenvironment in the Yellowstone area. 1) The Gallatin fossil forest at Cedar Creek was largely preserved in situ by burial resulting from subaerial debris flows. Debris flow deposits are interstratified with braided fluvial deposits. These deposits are lithologically and architecturally similar to Eocene units described throughout the Absarokas. 2) The orientation of horizontal fossil trees suggests a northwest to southeast paleocurrent direction. This orientation is similar to the orientation of fossil trees at other sites in northern Yellowstone National Park. 3) All fossil tree specimens examined at Cedar
Creek have distinct growth rings which record seasonal variability in climate. An average mean sensitivity of 0.31 was determined by growth ring analysis. 4) Latewood and early wood transitions are generally gradual, indicative of a gradual transition from optimal growing conditions to dormancy Latewood to early wood ratios average 0.15, this indicates that a large percent of tree growth took place during the growing season.
5) False rings observed in a number of fossil tree thin section samples may be the result of unfavorable climate conditions such as unseasonable frost or drought. 6) The presence of discontinuous organic litter horizons was documented throughout the field site.
Weathered horizons and paleosols are weakly developed, and reflect immature soil development and/or bioturbation or rhyzoturbation which obscured horizonation
Evidence supporting these mechanisms include truncation surfaces, trace fossils
96 97 (boreholes in petrified wood), and root casts. 7) The presence of smectite in the moderately developed paleosols is indicative of low annual rainfall. This indicates that
Cedar Creek paleosols and fossil trees formed under arid to semiarid conditions.
Paleoclimate data from northern Yellowstone National Park combined with this study indicate that the area was seasonal with a moderate to long growing season. A range of mean sensitivities calculated from the Gallatin flora suggests a local variation in annual climate changes across the Yellowstone area, but more study is needed to resolve the apparent variation in climatic conditions. References cited
Allmendinger, R., 1988-1995, Stereonet, Absoft Corporation.
Amidon, L. J., Hendrix, M., and Lenegan, R , 1996, Dendroclimatologic analyses of the Gallatin Petrified Forest (Middle Eocene), southwest Montana: A record of altitude-related microclimate in the Yellowstone region?: The Geological Society of America Abstracts with Programs, v. 28, p. A-294.
Ammons, R , Ammons, A., and Ammons, R. B., 1980, Evidence from petrified wood for stability of growth and solar cycles since the Tertiary, in Proceedings of Montana Academy of Sciences, p. 98.
Ammons, R , Fritz, W. J., Ammons, R B., and Ammons, A., 1987, Cross-identification of ring signatures in Eocene Trees {Sequoia magnifica) from the specimen ridge locality of the Yellowstone Fossil Forests: Palaeogeography, Palaeociimatology, Palaeoecology, v. 60, p. 97-108.
Andrews, H. N., 1939, Notes on the fossil flora of Yellowstone National Park with particular reference to the Gallatin region: American Midland Nature, v 21, p. 454-460.
Andrews, H. N., and Lenz, L. W., 1946, The Gallatin Fossil Forest Yellowstone national Park, Wyoming: Missouri Botanical Garden, Annual, v. 33, no. 3, p. 309-313.
Arct, M., and Chadwick, A. V., 1983, Dendrochronology in the Yellowstone Forests, in Rocky Mountain Section, 36th annual meeting; Cordilleran Section, 79th annual meeting, p. 408.
Arct, M. J., 1979, Dendrochronology in the Yellowstone fossil forests [Masters Thesis]: Loma Linda University, 65 p.
98 99 Arct, M. J., 1991, Dendroecology in the fossil forests of the Specimen Creek area, Yellowstone National Park [Dissertation]; Loma Linda University, 92 p.
Axelrod, D. I., 1966, The Eocene copper Basin Flora of northeastern Nevada: University of California Publications in Geological Sciences, v 59, p. 1-125.
Baer, J. L , 1987, Green River formation (Eocene), central Utah: A classic example of fluvial-lacustrine environments, in Bues, S. S., ed.. Centennial Field Guide: Rocky Mountain Section: Boulder, CO, Geological society of America, p. 247- 250.
Barron, E. J., 1985, Explanation of the Tertiary global cooling trend: Palaeogeography, Palaeociimatology, Palaeoecology, v. 50, p. 45-61.
Barron, E. J., 1989, Pre-Pleistocene climates: data and models, in Berger, A., Schneider, S., and Duplessy, J. C., eds.. Climate and Geo.-Sciences: Dordrecht, Kluwer Academic Publishers, p. 3-19.
Barron, E. J., and Washington, W. M., 1982, Cretaceous climate: A comparison of atmospheric simulations with the geologic record: Palaeogeography, Palaeociimatology, Palaeoecology, v. 40, p. 103-133.
Barron, E J., and Washington, W. M., 1984, The role of geographic variables in explaining paleoclimates: Results from Cretaceous climate model sensitivity studies: Palaeogeography, Palaeociimatology, Palaeoecology, v. 40, p. 1267- 1279.
Barshad, L , 1966, The effect of a variation in precipitation on the nature of clay mineral formation in soils from acid and basic igneous rocks, in Proceedings of the International Clay Conference, Jerusalem, p. 167-172. 1 0 0 Batten, D. J., 1984, Palynology, climate and the development of Late Cretaceous floral provinces in the Northern Hemisphere; a review, in Brenchley, P., ed.. Fossils and climate; Chichester, J. Wiley and Sons.
Benson, B. E , Amidon, L. J., Atwater, B. F., and Yamaguchi, D. K., 1992, Limiting tree ring ages for plate boundary seismicity in southern coastal Washington [Abstract], in Eos, Transactions of the American Geophysical Union, San Francisco, p. 398.
Bird, M. I., Fyfe, B. I, Chivas, A., and Longstaffe, F., 1990, Deep weathering at extra- tropical latitudes: A response to increased atmospheric CO], in Bouwman, A. F., ed.. Soils and the Greenhouse effect: London, J. Wiley, p. 383-389.
Birkeland, P. W., 1984, Soils and geomorphology: New York, New York, Oxford University Press, 281 p.
Birkeland, P. W., and Janda, R. J., 1971, Clay mineralogy of soils developed from Quaternary deposits of the eastern Sierra Nevada, California: Geological Society of America Bulletin, v. 82, p. 2495-2514.
Blair, T., and McPherson, J. G., 1992, The Trollheim alluvial fan and facies model revisited: Geological Society of America Bulletin, v. 104, p. 762-769.
Carlquist, S., 1988, Comparative wood anatomy, systematic aspects of Dicotyledon wood. Springer series in wood science: Berlin, Springer Verlig,
Chadwick, A., and Yamamoto, T. A., 1984, A palaeoecological analysis of the petrified trees in the Specimen Creek area of the Yellowstone National Park, Montana, USA: Palaeogeography, Palaeociimatology, Palaeoecology, V. 45, p. 39-48. 101 Chadwick, R. A., 1970, Belts of eruptive centers in the Absaroka-Gallatin volcanic province, Wyoming-Montana: Geological Society of America Bulletin, v. 81, p. 267-273.
Clague, J., 1982, Dendrochronological dating of Glacier-dammed lakes; An example from Yukon Territory, Canada: Arctic and Alpine Research, v. 14, no 4, p. 301- 310.
Coffin, H. G., 1976, Orientation of trees in the Yellowstone Petrified Forests: The Society of Economic Paleontologists and Mineralogists, v. 50, no. 3, p. 539-543.
Compton, R. R., 1985, Geology in the Field: New York, John L. Wiley & Sons, 398 p.
Core, H. A., Cote, W. A., and Day, A. C., 1979, Wood structure and identification, Syracuse wood science series: Syracuse, Syracuse University Press, 182 p.
Creber, G. T., and Chaloner, W G , 1984a, Climatic indications from growth rings in fossil wood, in Brenchley, P. J., ed.. Fossils and Climate: New York, John Wiley and Sons LTD, p. 49-74.
Creber, G. T., and Chaloner, W. G , 1984b, Influence of Environmental Factors on the Wood Structure of Living and Fossil Trees: The Botanical Review, v. 50, no. 4, p. 357-448.
Crowley, T. J., Short, 1. A., Mengel, J. G , and North, G. R., 1986, Role of seasonality in the evolution of climate during the last 100 million years: Science, v. 231, p. 579-584.
Curtis, C. D., 1990, Aspects of climatic influence on the clay mineralogy and geochemistry of soils, paleosols and clastic sedimentary rocks: Journal of the Geological Society, London, v. 147, p. 351-357. 102 Denlinger, R. P., Scott, K., and Pierson, T., 1984, Granular resorting and its effects on resistance to flow in grain-supported lahars [Abstract ], m EOS, American Geophysical Union Transactions, p. 1142.
Détienne, P., 1989, Appearance and periodicity of growth rings in some tropical woods: lAWA Bulletin n.s., v. 10, no. 2, p. 123-132.
Dorf, E., 1974, Early Tertiary fossil forests of Yellowstone Park, Rock mechanics, the American Northwest: International Congress on Rock Mechanics, Expedition Guide: Third, University Park, Pennsylvania State University, p. 108-111
Farley, M. B., 1989, Vegetation response to climate change in the early Eocene of Wyoming [Abstract]: Geological Society of America, v. 21, no. 6, p. A147.
Fastovsky, D. E., and McSweeney, K., 1991, Paleocene paleosols of the petrified forests of Theodore Roosevelt National Park, North Dakota: A natural experiment in compound pedogenesis: Society for Sedimentary Geology, v. 6, p. 67-80.
Fisk, L. H., 1976, The Gallatin “Petrified Forest”: a review. The Tobacco Root Geological Society 1976 Field Conference Guidebook, Montana College of Mineral Science and Technology, Butte, Montana, in Montana Bureau of Mines and Geology Special Publication, p. 53-72.
Foscolos, A. E., Rutter, N. W , and Hughes, O. L., 1977, The use of pedological studies in interpreting the Quaternary history of central Yukon Territory: Geological Survey of Canada, Energy of Mines Resource Bulletin, v. 271, p. 48.
Francis, J. E., 1984, The seasonal environment of the Purbeck (Upper Jurassic) fossil forests: Palaeogeography, Palaeociimatology, Palaeoecology, v. 48, p. 285-301 103 Francis, J. E., 1986, Growth rings in Cretaceous and Tertiary wood from Antarctica and their palaeoclimatic implications: Palaeontology, v. 29, p. 665-684.
Fritts, H. C , 1976, Tree Rings and Climate: London, Academic Press, 567 p.
Fritz, W. J., 1980a, Depositional Environment of the Eocene Lamar River Formation in Yellowstone National Park [Dissertation]: University of Montana, 113 p.
Fritz, W. J., 1980b, Reinterpretation of the depositional environment of the Yellowstone “fossil forest”: Geology, v. 8, no. 7, p. 309-313.
Fritz, W. J., 1980c, Stratigraphie framework of the Lamar River Formation in Yellowstone National Park: Northwest Geology, v. 9, no. 1-18.
Fritz, W J., and Harrison, S., 1985, Transported trees from the 1980 Mount St. Helens sediment flows: Their use as paleocurrent indicators: Sedimentary Geology, v. 42, p. 49-64.
Fritz, W. J , and Fisk, L. H , 1978, Eocene Petrified woods from one unit of the Amethyst Mountain “Fossil Forest”: Northwest Geology, v. 7, p. 10-19.
Gregory, K. M., and Chase, C. G., 1992, Tectonic significance of paleobotanically estimated climate and altitude of the late Eocene erosion surface, Colorado: Geology, v. 20, p. 581-585.
Gregory, K. M., and McIntosh, W. C., 1996, Paleoclimate and paleoelevation of the Oligocene Pitch-Pinnacle flora. Sa watch Range: Geological Society of America Bulletin, v. 108, no. 5, p. 545-561. 104 Hickey, L. J., 1977, Stratigraphy and paleobotany of the Golden Valley Formation (early Tertiary) of western North Dakota; Geological Society of America Memoir, v. 150, p. 183.
Hiza, M. M., 1994, Process of alluvial sedimentation in the Eocene Hyalite Peak Volcanics, Absaroka-Gallatin Volcanic Province [Masters thesis]: Montana State University, 167 p.
Holmes, W. H., 1883, Report on the geology of the Yellowstone National Park: US Geological Geography Survey Territory (Hayden) Annual Report, v. 12, no. 2, p. 1-57.
Jenny, H., 1941, Factors of soil formation: New York, McGraw-Hill, 281 p.
Jones, W. A., 1874, Report upon the reconnaissance of northwestern Wyoming including Yellowstone National Park, made in the summer of 1873: US 43rd Congressional Session, Hayden Expedition, no. Document 285, p. 210.
Jozsa, L. A., 1988, Dendroclimatic research at Forintek Canada Corp., Climate Change and Forestry in B.C.: British Columbia, University of British Columbia.
Jozsa, L. A., 1993, Dendrochronology : What can it do for you: Forintek Canada Corporation.
Jozsa, L. A., and Brix, H., 1989, The effects of fertilization and thiiming on wood quality of a 24-year-old Douglas-fir stand: Canadian Journal of Forestry Resources, V. 19, p. 1137-1145.
Keller, A. M. D , 1995, Paleoclimatologic analysis of an upper Jurassic petrified forest, southeastern Mongolia, [Masters thesis]: Stanford University, 55 p. 105 Knowlton, F. H., 1896, Description of a supposed new species of fossil wood from Montana; Torrey Botany Club Bulletin, v. 23, p. 250-252.
Knowlton, F. H , 1899, Fossil flora (of Yellowstone National Park): US Geological Survey Monolith, v. 32, pt. II, p. 651-882.
Knowlton, F. H., 1914, A forest of stone (Gallatin Mountains, Montana): American Forestry, v. 20, p. 709-718.
Knowlton, F. H., 1922, The Laramie Flora of the Denver Basin: U.S. geological Survey Professional Paper, V. 130, p. 175.
Kozlowshi, T. T., 1971, Growth and development of trees: New York, Academic Press, 514 p.
Kumagai, H., Sweda, T., Hayashi, K., Kojima, S., Basinger, J. F., Shibuya, M., and Fukaoa, Y., 1994, Growth-ring analysis of Early Tertiary conifer woods from the Canadian High Arctic and its paleoclimatic interpretation: Palaeogeography, Palaeociimatology, Palaeoecology, v 116, p. 247-262.
Lesquereus, L., 1872, An enumeration with descriptions of some Tertiary fossil plants from specimens procured in the explorations of Dr. F V. Hayden in 1870. US Geological Geography Survey Territory (Hayden) Annual Report, v. 5, Supplementary, p. 283-318.
Lowe, D. R., 1979, Sediment gravity flow: their classification and some problems of application to natural flows and deposits: Society of Economic Paleontologists and Mineralogists, v. 27, Special Publication, p. 75-82.
Macbeth, 1992, Munsell soil color charts: Division of Kollmorgen Instruments Corp. 106 MacGinitie, H. D., 1969, The Eocene Green River flora of northwestern Colorado and northeastern Utah: University of California Publications in Geological Sciences, V. 83, p . 1-203.
MacGinitie, H. D., Leopold, E. B., and Rohrer, W. L., 1974, An early middle Eocene Flora from the Yellowstone-Absaroka volcanic province, northwestern Wind River Basin, Wyoming: University of California Publications in Geological Sciences, V. 108, p. 1-103.
Mack, G. H., and Calvin, J.W., 1992, Paleosols for sedimentologists, /«Geological Society of America Short Course Manual, Cincinnati, Ohio, p. 127.
Manabe, S., and Broccoli, A.J., 1990, Mountains and arid climates of middle latitudes: Science, v. 247, p. 192-194
McBride, M. B , 1994, Environmental chemistry of soils: New York, Oxford, 406 p.
McMannis, W. J , and Chadwick, R A., 1964, Geology of the Garnet Mountain quadrangle, Gallatin county, Montana: Montana Bureau of Mines and Geology Bulletin, v. 43, p. 47.
Meen, J. K., 1988, Petrological and chemical variations in the Independence volcanic complex, Absaroka Mountains, Montana: Northwest Geology, v. 17, p. 21-41
Meyer, H. W , 1992, Lapse rates and other variables applied to estimating paleoaltitudes from fossil floras: Palaeogeography, Palaeociimatology, Palaeoecology, v. 99, p. 71-99.
Meyer, R , 1976, Continental sedimentation, soil genesis and marine transgression in the basal beds of the Cretaceous in the East of the Paris Basin: Sedimentology, v. 23, p. 235-253. 107 Mifflin, M. D., 1964, Geology of a part of the southern margin of the Gallatin Valley, Southwest Montana [Abstract]: Geological Society of America Special paper, V. 76, p 284.
Mohlenbrock, R. H., 1989, Tom Miner Basin, Montana: Natural History, v. 12, p. 14- 16.
Moore, D. M., and Reynolds, R. C., Jr., 1997, X-ray diffraction and the identification and analysis of clay minerals, Oxford University Press, Inc., 378 p.
Nadakavukaren, M., and McCracken, D., 1985, Botany, An introduction to plant biology: Saint Paul, West Publishing Company.
Nilsen, T. H., 1978, Lower Tertiary laterite on the Iceland-Faeroe and the Thulean Land Ridge: Nature, v. 274, p. 786-788.
Nilsen, T. H , and Kerr, D. R , 1978, Paleoclimate and paleogeographic implications of a lower Tertiary laterite (latosol) on the Iceland-Faeroe Ridge, North Atlantic region: Geology Magazine, v. 115, p. 153-182.
Panshin, A. J., and De Zeeuw, C., 1970, Textbook of wood technology, McGraw-Hill Series in Forest Resources: New York, McGraw-Hill Book Company, 705 p.
Parrish, J. T., and Spicer, R. A., 1988, Middle Cretaceous wood from the Nanushuk Group, central North Slope, Alaska: Palaeontology, v. 31, p. 19-34.
Phipps, R L., 1985, Collecting, preparing, cross-dating, and measuring tree increment cores. Water Resources Investigations Report, v. 45, no 4148, p. 48. 108 Picard, M. D., 1985, Hypothesis of oil shale genesis. Green River Formation, Northeast Utah, Northwest Colorado, and southwest Wyoming, m Picard, M. D., ed.. Geology and energy resources, Uinta Basin of Utah: Utah Geological Association Publication, p. 193-210.
Poole, L, 1992, Pyritized twigs from the London Clay, Eocene, of Great Britain: Tertiary Research, v. 13, no. 2-4, p. 71-85.
Prive-Gill, C ., Azanza, B., Morales, J., Gill, B.A., and Lemoine, M , 1993, Early Miocene silicified wood and associated fauna from the Curenca Province, Spain Genistoxylon dorycnioides n.sp. (Leguminosae-Papilionaceae): Review of Palaeobotany and Palynology, v. 78, p. 395-402.
Rea, D. K., 1985, Early to mid Cenozoic continental climate and atmospheric circulation as determined from pacific ocean eolian sediments [Abstract]: Geological Society of America, v. 17, no. 7, p. 696.
Read, C. B., 1933, Coniferous woods of Lamar River flora. Fossil floras of Yellowstone National Park: Carnegie Institute of Washington, contribution to Paleoecology, V. 416(1), p . 1-19.
Retallack, G., 1981, Comment and reply on “Reinterpretation of the depositional environment of the Yellowstone fossil forest": Geology, v. 3, p. 52-54.
Retallack, G. J., 1994, A pedotype approach to latest Cretaceous and earliest tertiary paleosols in eastern Montana: Geological Society of America Bulletin, v. 106, p. 1377-1397.
Retallack, G. J., and German-Heins, J., 1994, Evidence from Paleosols for the Geological Antiquity of Rain Forest: Science, v. 265, p. 499-502.
Reynolds, R. C , Jr., 1976, Plotdata. 109 Ritland, J. H., 1968, Fossil forests of the Specimen Creek area, Yellowstone National Park, Montana [Masters thesis]: Andrews University, 62 p.
Sanborn, W. B., 1951, Groves of stone: Fossil forests of the Yellowstone region: Pacific Discovery, May - June, 1951, p. 18-25.
Schweingruber, 1988, Tree rings; Basics and applications of dendrochronology: Dordrecht, Kluwer Academic Publishers, 276 p.
Shackleton, N. J., and Boersma, A., 1981, The climate of the Eocene ocean: Journal of the Geological Society of London, v. 138, p. 153-157.
Shaver, K. C , 1978, Chronology of Dacite intrusion in the northwest end of the Absaroka-Gallatin Volcanic Province, Montana: Northwest Geology, v. 7, p. 20-26.
Simons, F. S., 1983, Mineral resource potential of the Gallatin Divide roadless area, Gallatin and Park counties, Montana: Miscellaneous Field Studies: U.S. Geological Survey.
Singer, A., 1966, The mineralogy of the clay fractions from basaltic soils in the Galilee (Israel): Journal of Soil Science, v. 17, p. 136-147.
Singer, A., 1970, Edaphois and paleosols of basaltic origin in the Galilee (Israel): Journal of Soil Science, v. 21, p. 136-296.
Singer, A., 1979/1980, The Paleoclimatic Interpretation of Clay Minerals in Soils and Weathering Profiles: Earth Science Reviews, v. 15, p. 303-326.
Singer, A., 1984, The Paleoclimatic Interpretation of Clay Minerals in Sediments - a Review: Earth Science Reviews, v 21, p 251-293. 110 Sloan, L., Cirbus, and Barron, E. J., 1992, A comparison of Eocene climate model results to quantified paleoclimatic interpretations; Palaeogeography, Palaeociimatology, Palaeoecology, v. 93, p. 183-202.
Sloan, L. C., 1994, Equable climates during the early Eocene: Significance of regional paleogeography for North American climate: Geology, v. 22, p. 881-884.
Sloan, L. C , and Barron, E. J., 1990, Quantitative analyses of early Eocene paleoclimatic interpretations: comparison of model results to proxy climate data [Abstract]: EOS Transactions, American Geophysical Union, v. 71, no. 43, p. 1384.
Smedes, H. W., and Prostka, H. J., 1972, Stratigraphie framework of the Absaroka Volcanic Supergroup in the Yellowstone National Park region: U.S. Geological Survey Professional Paper, v. 729-C, p. 33.
Smith, G. A., 1986, Coarse-grained nonmarine volcaniclastic sediment: Terminology and depositional process: Geological Society of America Bulletin, v. 97, p. 1-10.
Spicer, R. A., and Parrish, J. T., 1990a, Late Cretaceous-early Tertiary palaeoclimates of northern high latitudes: a quantitative view: Journal of the Geological Society of London, v. 147, p. 329-341.
Spicer, R. A., and Parrish, J. T., 1990b, Latest Cretaceous woods of the central North Slope, Alaska. Palaeontology, v. 33, p. 225-242.
Stanley, T. G., 1972, Bedrock geology of the southern part of Tom Miner Basin, Park and Gallatin Counties, Montana: Northwest Geology, v. 1, p. 38-41.
Stuiver, M., and Burk, R. L., 1985, Appendix: Paleoclimatic studies using isotopes in trees, in Hech, A. D., ed., Paleoclimate analysis and modeling: Washington, DC, A Wiley-Interscience Publications, p. 151-161. n i Survey, U. S. G., 1986, Dome Mountain, Montana: U.S. Geological Survey, scale 1:24
000 .
Thompson, G T., Fields, R. W , and Alt, D., 1982, Land-based evidence of Tertiary climatic variations, northern Rockies: Geology, v. 10, p. 413-417.
Wing, S. L., Bown, T., M., and Obradovich, J. D., 1991, Early Eocene biotic and climatic change in interior western North America: Geology, v. 19, p. 1189- 1192.
Wolfe, J. A., 1971, Tertiary climatic fluctuations and methods of analysis of Tertiary floras: Palaeogeography, Palaeociimatology, Palaeoecology, v. 9, p. 27-57.
Wolfe, J. A., 1994, Tertiary climatic changes at middle latitudes of western North America: Palaeogeography, Palaeociimatology, Palaeoecology, v. 108, p. 195- 205.
Yadav, R. R , and Bhattacharyya, A., 1994, Growth ring features in Sahnioxylon from Rajmahal Hills and their climatic implications: Current Science, v. 67, no. 9 & 10, 10 &25, p. 739-740.
Yamaguchi, D. K., and Hoblitt, Richard P., 1995, Tree-ring dating of pre-1980 volcanic flowage deposits at Mount St. Helens, Washington: Geological Society of America Bulletin, v 107, no. 9, p. 1077-1093.
Yamamoto, T., and Chadwick, A. V., 1982, Identification of fossil wood from the Specimen Creek area of the Gallatin Petrified Forest, Yellowstone National Park, Part I Gynmosperms, J. San-iku Gakuin J. C., 25-42 p.
Yamamoto, T., and Chadwick, A. V., 1983, Identification of fossil wood from the Specimen Creek area of the Gallatin Petrified Forest, Yellowstone National Park, Part II Angiosperms, J. San-iku Gakuin J. C , 49-66 p. 112 Zobel, B. J., and van Buijtenen, J. P., 1989, Wood Variation; It's causes and control. Springer Series in Wood Science: Berlin, Springer-Verlig, 366 p. Explanation
Organic Zone Coarse Sand
A Upright trees Conglomerate Stumps with visible roots i Bedded Sand
Coarse to fine sandstone QZ. @ Prostrate trees with silt and Clay Fossil leaves Low angle cross stratified sand Stratigraphie location of paleosol samples Finely laminated silt and clay Petrified tree associated with paleosol sample site
Lithology scale describes bed's largest grain size. F= Fine sand, M = medium sand, C = Coarse sand, Peb = pebble conglomerate. Cob = cobble conglomerate.
Explanation of Appendix A. Three detail stratigraphie sections 1, 2, and 3 totalling 245 m of measured section from the Cedar Creek site. Location of measured sections is shown in Figure 5. Sections include stratigraphie position of fossil flora and paleosols. Sample numbers shown in sections represent field number given to each fossil tree; V = vertical, H = horizontal. 113 Appendix A - Stratigraphie Section 1 114
H39, H43, H45, V46*,H47 1 5m —
O o . H37, H39, H40, V44, H42, V41. V48,Hlll,H114,H115
, i3 ca cr:? '
H113 IVIarker horizon te ' V116 1 Om — H129
H128
5m —
la t f S - â ? | î ^ « î
Om I I I I I I Clay& F 1VÏ C Peb Cob Silt Appendix A - Stratigraphie Section 1 (continued) 115
H108,H109 30m
25m —
V112, V112, V127 20m -o' ###
V49*
HllO ,m0 - m
C la y F TS/T C P e b C o b & S ilt Appendix A - Stratigraphie Section 1 (continued) 116
45m —
V50
o Q ^ rTL.
- o : ..
. d ■ , ^ o ® .
; : .ez' ::
40m — . o o : < c
■ o.' ■ H103, H105, V107
HlOO, V101,H102,H104 3 , 0 : g . ..■-... ■' 6CD- ■ • ■ o V106 ■Û ; >=^ C7 35m — •• •à.*-o.- - •, ■ :.:0
■ ■ O Obv..::: :/
o : .
Clay p IVI C Peb Cob & S ilt Appendix A - Stratigraphie Section 1 (continued) 117
o.
O’ O
60m —
■O r, o -
4 .: : ■Vo : A Ô ; •■
:1 a # : ; # ■.O '- a # " a •• CT3 55m —
50m —
LU C la y p IVf C P e b C o b & S ilt 118 Appendix A - Stratigraphie Section 1 (continued)
• c6 > o . 0 9 O . . o . • ■ o -® . •..».• P . O o ' .. . a - • '.i O '. O. ■ . c ? . . .-' . . . • o J FL 11, H2, H3
O . VIO 75m H8, H9, H61, H62, H63, H65
VI
6. 9 - 0 '.
V7
%■. O ■ - " a V % 6< •O' 'o ;Ci-. D V4, V5, V6, V56 70m — H57, H58, H59
>■ .t>
O O Or>QD O O H54, H55
OCjOO\z> 3 : H54, H55, V51, V52 - . O . O ■ o' . ^ O Ô '.; : ■ ■to «■.■ ■'»■'■'■.«’«■■ ■■ H53 H60, V118
65m — ■ .o. 9 Cb. • .c?’ ■ O
. . r ' C ) . . .
C^y F VI C Peb Cob Silt Appendix A - Stratigraphie Section 1 (continued) 119
95m : 0
D. .
90m
■ Q . f ^ î
85m —
______H14
- o c , - r 4 .
80m —
P 1 V 1 C P e b C o b S ilt 120 Appendix A - Stratigraphie Section 1 (continued)
g " Vo :'Cd^ 1 1 Om — ##o o c. d
10 5 m — $#b ': s s i i »
V15 o.' ■ O' -p '^ 'P O '.i ■■■.-■. «.
1 OOm —
.' o ■O -,
O
o o.
C ^ y F N4 C P e b C o b Silt Appendix A - Stratigraphie Section 1 (continued) 121
125m —\ -C>. m # c s la' m i i : :
7 m m
■ '• ■ y-mp- ■? !• ■ " C
V119
1 1 5 m
Soo
C^y F IVl C Peb Cob Silt Appendix A - Stratigraphie Section 1 (continued) 122
Top of'stratigraphie section 1
— --CS
1 35m —
m m m
130m
ml:o m :
C& la y F ÎV1 C P e b C o b S ilt Appendix A - Stratigraphie Section 2 123
H80, H8K H83, H94, L 1495, 1496, 1497, 1498, 15m — 1499, V 79
V 76*. V 78
Tvfarker horizon V75*, V77, V82*
1 Om —
V 130 V131
C^:; .O;:'
5m — 1469, 1470, 1471
FL 74
P 0 , ^ o 1 V66, H68, H67, V72,
- wri -ÇS: :
Om
C U y F Tvr C P e b C o b S ilt 124 Appendix A - Stratigraphie Section 2 (continued)
30m —
##
O .'-' Q . 25m — m a a ? CP,
0< C D a . a '■■'O' ^ a . ; ' Q i û
20m — ##V 84
■o
Clay& p IS/I O Peb Cob S ilt 125 Appendix A - Stratigraphie Section 2 (continued)
45m —
f S
/T> . a. C I - b ■ •■ .
40m —I ####,
o>
i i & s 35m —
r è > m o i
C l a y F IV T C P e b C o b S û t 126 Appendix A - Stratigraphie Section 2 (continued)
60m
55m
50m
C^y F VI C Peb Cob Silt 127 Appendix A - Stratigraphie Section 2 (continued)
Top of stratigraphie section 2
H 121
V 120 65m — o.
C ^ y F M C P e b C o b S ilt 128 Appendix A - Stratigraphie Section
15m —
V93
H22, H27 1 Om —
HI8, H19, H20, V21
VI7, V89, H92 ------Marker horizon H90, V91 o . c ? Q- Q- o. 5m — : . ' ■ a . ■o. ■ ■ ' _Q$ V23, H24, H25, V26
■ O Q
- , :.ô 9 .' : O." -O'-
o
Om
CUy F TVl C Peb Cob S ilt Appendix A - Stratigraphie Section 3 (continued) 129
H87
V126 30m — C3- O'
H85
- g » 'O D 3 5 :
25m ^■O: 0 CZ>:o-. o - O o .- : Q ■ p. H20, H32, H33, H34, H35, H36 V28, V31 20m — V125 Qi.o^D o- C^y F TV4 C Peb Cob S l i t Appendix A - Stratigraphie Section 3 (continued) 130 Top of stratigraphie section 3 40m — H122, V123, V124 o ; ■ -o' ' : O " o 35m — Cf'.VO-' c ) 9 : O. ' H86 I I I I I I CUy F IVf C Peb Cob Silt Appendix B - Fossil Tree Field Data Identification Orientation Diameter Length Ring Number (degrees) (m) (m) Roots Count Lithology VI 0 ,9 0 0.90 0.65 flared based 112 peb cong H2 105,0 0.20 0.80 no - coarse ss H3 7 5,0 0.40 0,00 no 220 coarse ss V4 0 ,9 0 0.25 1.00 yes 50 cob cong V5 0 ,9 0 0.75 0.35 yes 33 cob cong V6 0, 90 0.80 0.00 yes 320 cob cong V7 0, 90 0.95 0.23 no 427 coarse ss H8 151,0 0.45 0.00 no 112 coarse ss H9 156,0 0.60 0.00 no 330 peb ss VIO 0 ,9 0 0.12 0.00 no 30 peb cong H12 142,0 0.28 0.00 no 8 coarse ss H13 130,0 0.15 0.00 no 23 cob cong H14 6 0 ,0 0.09 0.70 no 15 coarse ss V15** 0,90 2.00 1.10 yes 300 coarse ss H16 111,0 0.35 0.85 no 61 coarse ss Explanation of appendix B: * Trees examined in thin section. ** Trees with associated paleosol samples analyzed. Identification number: Numbers applied to fossil trees correspond to the order in which trees were sampled and described in the field. Numbers were also assigned to leaf impression samples causing gaps in the tree sequence presented here. Orientation: Measurements were made using an azimuth (0-360*^ ) Brunton compass Vertical trees are oriented 0®, 90®. Trend and plunge is given for thirteen inclined non-vertical trees and for all flat lying prostrate trees, with plunge equaling zero. Diameter: Measurements were taken on exposed trunk cross-sections. Trees V6, V46, and V77 have poorly exposed or missing trunks. Their measurements reflect the root base diameter. Largest measurements are given for trees with irregular shapes. Length exposed: Measurements represent tree lengths exposed at the outcrop. Many trees encased in rock reveal only a central portion of trunk or one end. Ring count: Estimate of number of rings for trees is based on field counts. Counts were; not performed on poorly preserved or lichen covered trees. : Lithology: A general description is given for grain size encasing each tree. Peb cong =j pebble conglomerate; cob cong = cobble conglomerate; coarse ss — coars^ sandstone; peb ss = pebble sandstone 131 Appendix B (continued) 132 Identification Orientation Diameter Length exposed Ring Number (degrees) (m) (m) Roots Count Lithology V17 0 ,90 0.10 0.07 no 35 coarse ss H18 210,0 0 0 9 0.15 no 8 coarse ss H19 210,0 0.02 0.17 no - coarse ss H20 240,0 0.12 - no - coarse ss V21 0,90 0.05 0.00 no 15 coarse ss H22 215, 19N 0.17 0.12 no 51 cob cong V23 0,90 0.30 0.17 no 45 cob cong H24 140, 9W 0.25 0.19 no 50 cob cong H25 235,0 0.26 0.00 no - cob cong V26 0,9 0 0.20 0.14 no 30 cob cong H27 160, 9N 0.11 1.75 no 7 cob cong V28 0,90 0.90 2.40 no 225 cob cong H29 230,0 0.20 0.00 no - cob cong V30 0, 90 0.60 0.60 no 300 cob cong V31 0,90 2.48 1.85 no 575 cob cong H32 233,0 0.22 0.00 no - cob cong H33 300, 15W 0.13 0.00 no 37 cob cong H34 304,0 0.15 0.17 no 12 pebss H35 305,0 0.15 0.68 no - peb ss H36 200,0 0.22 1.30 no 444 peb ss H37 140,0 0.15 0.05 no 30 peb ss H38 50,0 0.07 0.16 no - cob cong H39 1,0 0.75 0.00 no 75 coarse ss H40 174,0 0.30 3.60 no - silty sand V41 0 ,90 0.60 0.50 yes - silty sand H42 150,0 0.25 0.85 no 37 coarse ss H43 100,0 0.05 0.19 no - coarse ss V44 0, 90 0.11 0.00 no - silty sand V45 0, 90 - 1.30 no - cob cong V46** 0, 90 0.70 0.80 yes 30 cob cong H47 30,0 0.90 0.50 no 52 cob cong 133 Appendix B (continued) Identification Orientation Diameter Length exposed Ring Number (degrees) (m) (m) Roots Count Lithology V48 0, 90 0.10 0.10 no - cob cong V49** 0,90 - 1.60 flared base - cob cong V50 0,90 0.15 0.90 no - peb ss V51 0, 90 0.50 0.15 flared base - peb ss V52 0,90 0.60 0.25 no - peb ss H53 8 ,0 0.25 0.50 no - coarse ss H54 70,0 0.20 0.13 no - peb cong H55 90,0 0.19 0.03 no - peb cong V56 0, 90 0.40 0.90 no - cob cong H57 65,5 S 0.17 0.20 no - peb cong H58 185, 23 SW 0.07 1.00 no - peb cong H59 34,0 0.65 1.50 no - peb cong H60 125, l o w 0.30 0.03 no - coarse ss H61 40,0 0.20 0.40 no - peb cong H62 150,0 0.13 0.20 no - peb cong H63 135,0 0.25 0.00 no - peb cong H64 174,0 0.20 0.55 no - cob cong H64.5 horizontal 0.40 0.00 no - cob cong H65 40,0 0.20 0.40 no - peb cong V66 0, 90 0.40 0.10 no - cob cong H67 44,0 0.09 0.09 no - cob cong H68 110,0 0.06 0.02 no - coarse ss H69 155,0 0.20 0.15 no - peb cong H70 126,0 0.22 0.27 no - cob cong H71 110,0 0.20 0.06 no - cob cong V72 0, 90 0.08 0.30 no - cob cong V73 0, 90 0.30 0.45 no 45 cob cong V75** 0, 90 0.80 0.65 yes 320 coarse ss 134 Appendix B (continued) Identification Orientation Diameter Length exposed Ring Number (degrees) (m) (m) Roots Count Lithology V76** 0 ,9 0 0.17 0.37 yes - coarse ss V77 0 ,9 0 2.20 0.30 yes - coarse ss V78 0, 90 0.15 0.13 no 120 coarse ss V79 0, 90 0.20 0.60 no 20 cob cong H80 3 0 ,0 0.20 1.00 no - coarse ss H81 140,0 0.07 0.03 no - coarse ss V82** 0, 90 2.20 2.20 yes 660 coarse ss H83 130,0 0.12 0.08 no 30 coarse ss V84 0 ,9 0 1.45 1.30 no 507 cob cong H85 2 5 ,0 0.34 0.40 no 68 cob cong H86 7 5 ,0 0.22 0.22 yes n o cob cong H87 1,0 0.43 0.90 no 237 cob cong H88 153,0 O il 0.19 no - cob cong V89 0, 90 0.15 0.29 no 148 coarse ss H90 106,0 0.11 0.13 no 16 cob cong V91 0, 90 0.17 0.35 no - cob cong H92 159,0 0.45 0.07 no 135 silty sand V93 0, 90 0.23 0.11 flared base - coarse ss H94 150,0 0.30 0.00 no - coarse ss H95 132,0 0.14 0.10 no 42 coarse ss H96 174,0 0.04 0.02 no - coarse ss H97 170,0 0.11 0.11 no - coarse ss H98 ? 0.13 0.70 no 26 coarse ss H99 9 5 ,0 0.18 0.08 no - coarse ss VlOO 3 9 ,0 0.70 0.60 yes 315 cob cong VlOl 0, 90 0.19 2.10 no 48 coarse ss H102 --- no - cob cong Appendix B (continued) 135 Identification Orientation Diameter Length exposed Ring Number (degrees) (m) (m) Roots Count Lithology H103 7 ,0 - - no - coarse ss H I04 130, 6 E 0.31 0.36 no 17 peb cong H105 125,5 E 0.13 0.15 no 8 coarse ss V106 0, 90 0.80 0.80 no 320 cob cong V107 0, 90 1.00 0.60 no 275 coarse ss H108 75,11 E 0.20 0.01 no - coarse ss H109 123,0 0.43 0.01 no - coarse ss H llO 14,0 0.20 0.12 no 40 peb cong H i l l 32, 30$ 0.06 0.15 no 12 coarse ss V112 0, 90 0,27 2.10 yes 72 peb cong H113 160,0 0.13 0.70 no - peb cong HIM 8 1 ,2 5 W 0.10 0.06 no 32 coarse ss H115 67, 5E 0.13 0.00 no 10 coarse ss V116 0, 90 0.50 0.80 no 40 peb cong V117 0, 90 0.09 0.54 no - cob cong V118 0,90 0.20 0.23 no 72 coarse ss V119 0, 90 0.80 0.45 no 370 cob cong V120 0, 90 0.70 0.40 no 360 cob cong H121 3 0 ,0 - 0.40 no 280 cob cong H122 165, 57 W 0.13 0.29 no 39 cob cong V123 0, 90 0.30 0.26 no 60 cob cong V124 0, 90 0.50 0.20 no 150 cob cong V125 0, 90 0.22 0.33 no 22 cob cong V126 0, 90 0.07 0.19 no 14 cob cong V127 0, 90 1.00 0.20 no 200 cob cong H128 3 0 ,0 1.70 1.50 no 808 cob cong H129 115,0 0.25 0.35 no 125 cob cong V130 0, 90 0.20 0.33 no 60 cob cong V131 0, 90 0.32 0.24 no - coarse ss Appendix C - Ring width data (mm) Ring Number VI H16 H22 V23 V28-1 V28b-2 m m i H H H H H H I H HBHH BBBB 1 0.55 1.25 5 11 6.47 1.95 1.72 2 0.98 1.64 4.21 4.21 1.33 1.95 3 1.01 1.40 2.26 3.04 1.01 1 56 4 1.25 2.11 1.29 3.16 2.38 1.17 5 0.39 1.87 1.72 2.89 0.70 1.79 6 0,86 1.17 2.07 2.93 1.05 1.01 7 1.01 1.48 2.46 2.54 1.33 3.82 8 0.78 1.25 2.50 2.42 0.78 3.67 9 0.59 0.94 1 91 2.18 0.78 2.50 10 1.09 1.95 2 18 1.56 1.09 2.34 11 2.26 1.25 1.87 1.56 0.82 1.95 12 1.48 1.25 1.79 1.72 1.17 2.26 13 0.39 1.48 2.42 1.25 0.86 1.09 14 0.86 1.56 1.44 0.98 1.01 0.94 15 0.78 1.56 1.21 1.25 0.94 0.62 16 0.62 1.17 0.98 1.99 17 0.94 0.70 1.33 043 18 0.86 2.03 1.09 0.39 19 1.17 1.64 0.70 20 1.48 2.11 0.55 21 1.48 1.99 0.86 22 1.48 0.35 23 1.79 0.39 24 0.62 25 0.43 26 1.40 27 1.17 28 0.78 29 0.39 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 136 Appendix C (continued) - Ring width data (mm) 137 Ring U V31 H39 H40 V41 V52 V56 1 1.09 2.22 2.40 2.65 0.70 2.26 2 1.25 1 91 2.50 2.93 0.62 1.56 3 1.40 1.29 2.30 3.67 0.55 0.82 4 1.01 1.83 2.00 0.70 0.47 1.40 5 1.29 1.17 2.20 1.79 0.62 2.07 6 0.94 1.52 1.70 2.42 0.66 1.95 7 1.25 1.05 1.30 1.56 0.70 1.72 8 1.40 0.98 1.70 4.17 0.94 2.03 9 1.40 1.95 1.50 1.64 0.66 1.83 10 1.37 1.40 1.70 2.11 0.98 1.17 11 1.25 0.47 2.00 2.73 1.05 1.05 12 1.56 0.78 1.70 2.81 1.56 0.82 13 1.68 0.78 1.50 2.18 0.59 1.48 14 1.76 1.64 1.00 0.74 0.62 0.86 15 1.76 1.25 1.60 1.33 0.59 1.91 16 1.64 2.07 1.30 0.94 0.70 1.56 17 1.40 1.40 1.10 3.67 1.05 2.57 18 2.18 1.40 1.00 2.73 1.25 1.37 19 1.25 2.18 1.70 2 15 0.78 1.05 20 1.79 2.61 1.20 1.87 1.33 0.94 21 1.95 2.26 1.10 2.03 1,17 1.25 22 1.52 1.83 2.00 1.05 23 1.09 1.44 1.30 24 1.64 0.47 1.90 25 1.40 0.86 1.20 26 0.78 0.62 3.50 27 0.98 0.62 2.60 28 1.09 0.55 3.00 29 1.29 0.94 2.30 30 1.33 1.17 3.90 31 3.10 32 5.00 33 2.90 34 2.00 35 2.40 36 3.00 37 2.80 38 3.00 39 3.40 40 4.10 41 5.00 42 3.10 43 5.40 44 2.40 45 3.20 Appendix C (continued) - Ring width data (mm) 138 Ring # V31 V39 H 4 0 (co n t) V41 V52 V56 46 3.80 47 3.30 48 3.00 49 4.20 50 4.10 51 5.20 52 3.70 53 5.00 54 4.00 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 Appendix C (continued) - Ring width data (mm) 139 Ring # H65 V82 V84 H90 VlOO V107 1 0.47 0.90 0.90 4.41 0.59 0.82 2 0.39 0.86 1.40 4.10 0 6 2 1.17 3 0.39 0.62 0.94 2.26 0 7 0 0.62 4 031 1.01 0.51 0.86 0.59 0.62 5 0.59 0.31 0.47 1.21 0.51 1.17 6 0.51 0.78 0.31 3.24 0.43 1.25 7 0.47 0.59 0.43 3.04 0.39 0.47 8 0.27 0.39 0.31 4.10 0.43 0.47 9 0.27 0.47 0.39 3.59 0.43 0.47 10 0.31 0.70 0.39 4.17 0.43 0.59 11 0.62 0.78 0.31 4.37 0.39 0.47 12 0.62 0.39 0 3 9 2.89 0.43 0.55 13 0.59 0.31 0.78 2.85 0.43 0.82 14 0.39 0.62 0.39 2.73 0.43 1.83 15 0.47 0 7 8 1.09 0.43 1.48 16 0.39 0.74 0.39 0.55 1.37 17 0.39 0.98 0.78 0.47 0.94 18 0.70 0.70 0.62 0.39 0.62 19 0.35 0.70 0.55 0.66 0.90 20 0.39 0.78 0.78 0.55 0.94 21 0.39 0.70 0.59 0.27 1.09 22 0.39 0.55 0.78 0.55 0.78 23 0.78 0.70 0.62 043 0.86 24 0.78 0.94 0.74 0.62 25 0.43 0.86 0.78 0.55 26 1.01 0.55 0.51 0.86 27 1.48 0.31 0.35 0 9 4 28 1.17 0.70 0.51 0.70 29 1.17 0.55 0.74 0.47 30 1.17 0.39 0.78 0.31 31 1.37 0.59 0.78 1.09 32 1.33 0.82 0.66 0.47 33 1.64 0.82 0.86 0.78 34 1.64 0.31 0.62 0.62 35 0.90 0.51 1.68 0.62 36 1.17 0.31 1.01 0.66 37 1.09 0.78 0.51 0.55 38 1.52 0.43 0.78 1.09 39 1.64 0.82 0.47 1.09 40 0.70 0.62 0.51 0.98 41 0.31 0.70 0.70 42 0.43 0.47 1.05 43 0.39 0.70 0.98 44 0.43 0.78 0.70 45 0.39 0.78 0.39 Appendix C (continued) - Ring width data (mm) 140 Ring # _H65 V82 (cont ) V84 (cent ) H90 VlOO (cent ) VI07 46 0,78 0.70 0.51 47 0.59 0.55 0.78 48 0.70 0.59 49 0.62 0.66 50 1.09 51 0.62 52 0.39 53 0.43 54 0.43 55 0.47 56 0.78 57 0.39 58 0.62 59 0.47 60 0.74 61 0.74 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 Appendix C (continued) - Ring width data (mm) 141 Ring # V I12 H128 H 1 2 9 V130 V132 1 3.47 2.00 1.70 6.00 1.00 2 1.33 2.50 1.10 6.50 3.00 3 1.95 1.90 2.00 4.50 3.10 4 2.18 1.00 2.00 5.50 2.50 5 2.18 1.30 1.90 2.50 1.00 6 1.76 2.70 2.00 2.50 1.70 7 1.48 2.20 2.00 2.50 4.00 8 1.13 3.00 2.10 2.00 3.50 9 1.01 3.30 2.00 2.20 2.50 10 0.86 1.80 2.10 2.70 3.00 11 1.17 3.00 3.00 2.70 2.50 12 1.29 2.30 2.70 3.40 3.00 13 1.64 2.00 3.00 3.00 3.20 14 1.01 1.30 2.60 2.50 2.00 15 0.62 2.50 2.30 3.40 2.00 16 1.21 2.50 2.10 2.50 2.00 17 0.86 2.00 2.50 4.00 2.50 18 0.82 3.50 1.50 3.50 2.50 19 1.05 1.50 1.60 2.50 2.00 20 1.50 1.80 3.00 2.50 21 1.50 1.00 1.10 1.00 22 1.30 2.00 2.10 2.00 23 1.20 1.60 1.00 3.00 24 1.30 1.20 1.00 2.50 25 2.00 1.60 1.50 26 2.00 1.60 2.00 27 2.00 1.60 2.60 28 2.50 1.80 4.00 29 2.30 2.00 3.00 30 3.00 2.00 3.40 31 1.07 2.00 3.70 32 1.70 2.00 2.00 33 1.90 1.80 2.40 34 1.70 1.50 4.00 35 1.00 1.00 6.00 36 1.50 0.90 pith 37 2.70 1.90 38 1.00 3.00 39 0.70 2.00 40 1.20 3.00 41 1.50 3.40 42 1.80 3.20 1.80 4.00 1.80 2.00 45 1.80 2.00 Appendix C (continued) - Ring width data (mm) 142 Ring # V112 HI28 (cont ) H129 V130 VI32 46 1.80 2.00 47 2.00 48 1.80 49 2.30 50 2.00 51 3.30 52 2.00 53 1.00 54 2.50 55 2.90 56 3.10 57 3.50 58 3.00 59 2.50 60 1.30 61 1.70 62 1.00 63 1.00 64 2.00 65 2.00 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90