PaleoBios 28(3):89–113, January 22, 2009© 2009 University of California Museum of Paleontology

Cenozoic cooling and grassland expansion in Oregon and Washington

GREGORY J. RETALLACKDepartment of Geological Sciences, University of Oregon, Eugene, OR 97403; gregr@darkwing.uoregon.edu

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

INTRODUCTION

Oregon’s Painted Hills of red-streaked badlands are the best known of colorful badlands scattered throughout the high desert of eastern Oregon and Washington (Figs. 1, 2B). In the Painted Hills, the prominent red bands are clayey subsurface (Bt) horizons of forest soils (Alfisols) representing successive humid-climate ecosystems that colonized tuffa-ceous alluvial terraces over periods of tens of thousands of years (Retallack et al. 2000). Evidence for this interpretation comes from studies of root traces (drab-haloed claystone),

soil structures (angular blocky peds and sesqui-argillans), soil microfabrics (porphyroskelic skelmasepic), grain-size distri-bution (subsurface clay enrichment) and chemical composi-tion (alkali depletion and iron oxidation). The Painted Hills includes at least ten paleosols of this Luca pedotype, as well as 14 other kinds of paleosols that are among 435 paleosols in a composite stratigraphic section (430 m thick) of the lower John Day Formation. The abundance and diversity of paleosols in the Painted Hills is not unusual (Retallack et al. 2002a, Bestland and Forbes 2003, Sheldon 2003, Retallack 2004a, b, Retallack et al. 2004, Sheldon 2006), and calls for a systematic approach to classifying, naming, and interpret-ing the thousands of paleosols known from the Cenozoic of the Pacific Northwest. This paper reviews the long record of paleosols in Oregon and Washington, comparing different approaches of: (1) their field classification (2) their interpreta-tion within modern soil taxonomies; and (3) the application of transfer functions derived from study of modern soils. Such varied approaches to paleosol archives have implications for understanding long-term changes in climate and vegeta-tion, both locally and globally (Retallack 2007). This paper emphasizes the paleosol record and different approaches to its interpretation.

COMMON PALEOSOLS OF THE PACIFIC NORTHWEST

Cenozoic fossils of Oregon have been famous since Thomas Condon’s discovery in 1865 of fossil leaves and mammal bones in what is now known as the Painted Hills Unit of the John Day Fossil Beds National Monument (Clark 1989). University of California paleontologists John Merriam (1906, 1916, Merriam and Sinclair 1907), Ralph Chaney and Dan Axelrod (Chaney, 1924, 1948, Chaney and Axelrod 1959) subsequently collected rich fossil floras and faunas from Eocene, Oligocene, and Miocene rocks nearby, and geologists Hay (1962) and Fisher (1964) were the first

Figure 1. Localities of paleosols examined in Oregon and Wash-ington.

90 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

to note paleosols in these rocks. The temporal resolution and completeness of this paleosol record recently became apparent when the geochronology of these strata was refined by magnetostratigraphy (Prothero and Rensberger 1985, Prothero et al. 2006a, b) and by radiometric dating of nu-merous interbedded volcanic tuffs and lava flows (Fremd et al. 1994, Streck et al. 1999). With these new data has come an appreciation of the abundance and diversity of paleosols, outlined below.

Clarno Formation

The Hancock Field Station near Clarno has a sequence of at least 76 successive paleosols of 11 different types de-veloped within volcaniclastic conglomerates and tuffaceous red beds of the Clarno Formation that accumulated on the margins of a large andesitic stratovolcano (Retallack et al. 2000). The Nut Beds Member of the Clarno Formation has yielded a middle Eocene flora of 173 species of fossil fruits and seeds from tropical forest plants, including magnolia, palms, and vines (Manchester 1994). Fossils from near Clarno also include permineralized wood (Wheeler and Manchester 2002) and middle Eocene (Bridgerian) mammals, as well as a later Eocene (Duchesnean) bone bed yielding titanotheres, creodonts, and other mammals (Hanson 1996). Radiometric dating of andesitic and basaltic flows and rhyodacitic tuffs at the Clarno Nut Beds locality allows age determination by linear interpolation from the following tie points: 43.8 ± 0.5 Ma basalt at 38 m, 43.0 ± 3.5 Ma tuff at 52 m, 42.7 ± 0.3 Ma tuff at 90 m, 39.2 ± 0.03 Ma tuff at 128 m (Bestland et al. 1999, Retallack et al. 2000).

John Day Formation

The Painted Hills Unit of the John Day Fossil Beds Na-tional Monument exposes the lower John Day Formation, with hundreds of paleosols ranging from deeply weathered, red claystones, to little-weathered volcanic siltstones (Figs. 1A–B). Only calcareous volcanic soils and associated sedi-ments have yielded Oligocene (early Arikareean) mammals (Retallack et al. 2000). Bridge Creek near the Painted Hills has lent its name to fossil floras of temperate paleoclimatic affinities, dominated by dawn redwood, alder and oak (Meyer and Manchester 1997). High quality 40Ar/39Ar single-crystal laser radiometric dates of tuffs in the Painted Hills range from 40–29 Ma (late Eocene to middle Oligocene): 39.7 ± 0.03 Ma at 0 m, 32.99 ± 0.11 Ma at 98 m, 32.66 ± 0.03 Ma at 137 m, 29.75 ± 0.02 Ma at 329 m, 29.70 ± 0.06 Ma at 381 m, and 28.65 ± 0.05 Ma at 427 m (Retallack et al. 2000). There are hundreds more unstudied paleosols in the upper John Day Formation in this area, which continues from Bridge Creek north into the canyons south of Sutton Mountain.

Paleosols and mammal fossils of the upper John Day Formation are best known from the Sheep Rock and Blue Basin units of the John Day Fossil Beds north to Longview Ranch, Johnson Canyon, Kimberly and Spray (Retallack 2004a). These paleosols contain calcareous nodules and

preserve abundant mammal bones and teeth (Retallack 1998). Orellan(?), Arikareean, and Hemingfordian mammals (Coombs et al. 2001, Hunt and Stepleton 2004), radiometric dates of tuffs (Fremd et al. 1994), and magnetostratigraphy (Prothero and Rensberger 1985) indicate that this sequence ranges in age from 29–17 Ma (middle Oligocene to early Miocene). Beginning at top of tuff H on Longview Ranch, recent 40Ar/39Ar single-crystal laser dates include 28.7 ± 0.07 Ma at 0 m, 27.89 ± 0.57 Ma at 67 m, 27.18 ± 9,13 Ma at 106 m, 25.9 ± 0.31 Ma at 177.5 m, and 19.6 ± 0.13 Ma at 497 m (Fremd et al. 1994, Retallack 2004a, Tedford et al., 2004).

Columbia River Basalt

The Middle Miocene (16 Ma) Columbia River Basalt Group includes numerous paleosols between the flood ba-salts. These have been studied extensively in Picture Gorge (Sheldon 2003, 2006). Although these red paleosols have been regarded as baked zones from the heat of overlying flows, the vitrinite reflectance of peaty interbasaltic paleosols and the degree of ceramicization of red clayey inter basaltic paleosols both indicate that only the top few centimeters of the meter-thick paleosols have been thermally altered (Sheldon 2003). Vaporization of vegetation thoroughly vesiculated and zeolitized the flows, rather than altering underlying paleosols. Tie points for ages within the section beginning 300 m north of Picture Gorge include a 16.01 Ma magnetic reversal at 50 m, and the 15.77 ± 0.04 Ma Mascall tuff at 280 m (Watkins and Baksi 1974, Bailey, 1989, Tedford et al., 2004).

Mascall Formation

The middle Miocene Mascall Formation near Dayville is well known for a fossil flora of oak and bald cypress within diatomaceous lake beds (Chaney and Axelrod 1959). Paleo-sol-rich overbank deposits of the Mascall Formation yield Barstovian mammal assemblages in the type section near Day-ville, through Rock Creek and Antone, and west to Paulina (Downs 1956). Bones and teeth are rare because paleosols of the Mascall Formation are clayey and non-calcareous, more like those of the lower than upper John Day Forma-tion (Bestland and Forbes 2003). Chronostratigraphic ages of paleosols for the lower part of the formation in the type area include a 16.2 ± 1.4 Ma ash at 35 m, 15.77 ± 0.04 Ma ash at 119 m, 15.2 Ma magnetic reversal at 120 m, 15.0 Ma reversal at 129 m, 14.9 Ma reversal at 165 m, and 14.8 Ma reversal at 190 m (Tedford et al., 2004, Prothero et al. 2006a, Prothero et al. 2006b). Other Barstovian (middle Miocene) paleosols are known from fossil mammal sites near Gateway (Downs 1956, Ashwill 1983, Smith 1986) and Beatty Buttes (Wallace 1946, Hutchison 1968).

Ironside and Juntura Formations

Late Miocene plant, bird, and mammal fossils of the Clarendonian land mammal age have been reported from the Unity, Ironside, and Juntura formations (Bowen et al. 1963, Shotwell 1963, Shotwell and Russell 1963, Retallack,

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 91

2004b). A sequence of tuffs in the Ironside Formation of upper Windlass Gulch, north of Unity have been correlated with tuffs radiometrically dated as 11.8 Ma at 49.5 m, 11.8 Ma at 60.0 m, 11.7 Ma at 73.6 m, 11.7 Ma at 83.3 m, 11.6 Ma at 100.5 m, 11.6 Ma at 110 m, 11.5 Ma at 115.5 m, and 11.3 Ma at 173 m (Perkins et al. 1998, Retallack 2004b). Radiometrically dated rocks in the Juntura Formation west of Juntura include a 12.4 ± 0.5 Ma basalt at 0 m, 11.5 ± 0.6 Ma tuff at 230 m, and 9.7 ± 0.22 Ma ash-flow tuff at 259 m (Bowen et al. 1963, Evernden and James 1964, Fiebelkorn et al. 1982, Johnson et al. 1996, Retallack 2004b, Tedford et al., 2004). Unity, Ironside, and Juntura paleosols are weakly calcareous and siliceous like soils found in the summer dry grassy woodlands of northern California today (Retallack 2004b).

Rattlesnake, Deschutes, Shutler, and Drewsey Formations

The latest Miocene Rattlesnake Formation near Dayville yields Hemphillian mammals, including large grazing horses (Merriam et al. 1925), and chronostratigraphic ages that include a 7.14 Ma magnetic reversal at 25 m, a 7.05 ± 0.01 Ma tuff at 77 m, and a 7.0 Ma reversal at 101 m (Streck et al. 1999, Prothero et al. 2006b). Paleosols of the Rattlesnake Formation reveal a transition from woodland through tall grassland to sagebrush steppe (Retallack et al. 2002a). The Rattlesnake Ash-Flow Tuff is widespread beyond the type area near Dayville, and overlies paleosols at Logan Butte and in Spanish Gulch (Retallack 2007). Paleosol sequences of the Deschutes Formation near Prineville have the 7.05 ± 0.01 Ma ash-flow tuff at 0 m, and a 3.3 ± 0.2 Ma basalt rimrock at 103 m (Bishop and Smith 1990, Streck et al. 1999).

Other Hemphillian mammals found near Rome are corre-lated with the section at Juntura, for which radiometric dates are 9.7 ± 0.22 Ma at the base of the Drewsey Formation and 8.08 ± 0.56 Ma for a basalt at 100 m (Wolf and Ellison 1971, Fiebelkorn et al. 1982, Sheppard and Gude 1987). The Shut-ler Formation at McKay Reservoir yields a late Hemphillian mammal assemblage (Shotwell 1956, 1958).

Ringold Formation

The Miocene-Pliocene Ringold Formation yields fragmen-tary Blancan fossil mammals, and is well exposed in White Cliffs along the Columbia River near Richland, and in road and railway cuts near Taunton, Washington (Gustafson 1978, Smith et al. 2000). The White Cliffs section records the fol-lowing paleomagnetic reversals: 5.23 Ma at 2.81 m, 4.98 Ma at 32 m, 4.89 Ma at 40 m, 4.8 Ma at 44 m, 4.62 Ma at 63.1 m, 4.48 Ma at 61.1 m, and 4.29 Ma at 142 m (Gustafson 1985). Near Taunton, the formation records the Pliocene paleomagnetic reversal at 3.040–3.110 Ma between 0–9.9 m in a local section above a railway siding (Morgan and Morgan 1995, Smith et al. 2000). Plio-Pleistocene paleosols are pres-ent in the 2-Ma Huckleberry Tuff exposed on high terraces south of Sutton Mountain (Perkins et al. 1998). Paleosols at

White Cliffs, Taunton, and Sutton Mountain include crumb-structured soils like those of grasslands, as well as calcareous nodular soils like those of sagebrush steppe.

Palouse Loess

The Palouse Loess is an eolian deposit of redeposited rhyodacitic ash and quartzofeldspathic fluvial silt . It forms a thick and agriculturally fertile veneer on the Columbia River Basalts throughout much of the Columbia River basin in eastern Oregon and Washington. Dating by magnetostratig-raphy, tephrochronology, and thermoluminescence of the road cut west of Helix, Oregon, includes ages of 0.0636 Ma at 4 m and 0.158 Ma at 6 m from the top (Tate 1998). An outcrop near Washtucna, Washington yielded a paleomagnetic age of 0.788 Ma at 12 m and a radiometric age 0.055 Ma for an ash layer at 3 m from the top (Busacca 1989, 1991). The best known sections near Helix and Washtucna show Milankovich cyclicity (41–100 ka) alternating between two distinct pedotypes: (1) crumb-textured paleosols with abun-dant earthworm microfabrics like those in grassland soils, and (2) massive calcareous paleosols riddled with cicada burrows like those of sagebrush steppe soils (Tate 1998, O’Geen and Busacca 2002, Blinnikov et al. 2002).

CLASSIFICATION OF PALEOSOLS

Paleosols can be classified by field pedotypes or taxonomic orders. Pedotypes are different kinds of paleosols based on specified type sections, and recognizable from field charac-teristics. In contrast, taxonomic orders are categories of clas-sification based on modern soils, which can only be applied to paleosols after consideration of laboratory data obtained as proxies for taxonomic criteria (Retallack 1997a).

Pedotypes

The general paleosol type, or pedotype, is a non-genetic field mapping designation (Retallack 1994), comparable with “series” of soil maps (Soil Survey Staff 1993). Each pedotype is based on a specified type profile (Retallack et al. 2000, 2002a, Retallack 2004a, b). Cenozoic pedotypes in Oregon and Washington have been named using simple descriptive terms from the Sahaptin Native American language (Figs. 2–3), which was widely spoken throughout the southern Co-lumbia River basin (Rigsby 1965, De Lancey et al. 1988).

The purpose of pedotype naming and description is to facilitate precise description and characterization of paleo-sols as natural objects in their own right. Conventions of naming and definition, such as nomination of type sections, are needed to facilitate the growth of descriptive databases through the efforts of successive investigators. These conven-tions follow standard procedures of soil survey (Soil Survey Staff 1993). Differences between pedotypes need to be documented (Fig. 3) before their environmental significance is interpreted. Although interpretations of paleoclimate, fossil flora and fauna, paleotopographic position, parent material, and time for formation differ between pedotypes, they can

92 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

be generalized to different individual paleosols of the same pedotype (Retallack et al. 2000).

Pedotype interpretation

Each pedotype represents a particular combination of soil-forming influences; i.e., a particular ecosystem formed in a particular climate, on a particular parent material, in a particular landscape setting, and over a particular period of time. As with paleontological data, pedotypes have lo-cal stratigraphic ranges and can be useful in stratigraphic correlation and paleoenvironmental reconstruction (Fig. 4). As with trace fossils (Seilacher 1970) and stromatolites (Bertrand-Sarfati and Walter 1981), pedotypes do not need temporal and genetic continuity to be useful in stratigraphy and paleoecology. There is a general progression of differ-ent pedotypes in the Cenozoic of Oregon (Fig. 4), aside from a few repetitions, such as the return of green (Xaxus) pedotypes after brown (Plas) pedotypes in the Haystack Valley Member of the upper John Day Formation, and the return of brown clayey (Skwiskwi) pedotypes from the Big Basin Member of the John Day Formation in the Mascall and Rattlesnake Formations. Each formation has a unique sequence of pedotypes that reflects temporal changes in soil-

forming conditions.Diversity, overturn, appearances, and disappearances of

pedotypes through time can be estimated (Fig. 5) in the same way as evolutionary metrics of mammal fossils (Alroy et al. 2000, Janis et al. 2002). Unlike biological species, which persist from evolution to extinction, ecosystems and their soils can be dispersed and reconstituted as conditions allow (Bernabo and Webb 1977). Thus, Skwiskwi paleosols in the upper Big Basin Member (30 Ma) and the Mascall (15 Ma) and Rattlesnake formations (7 Ma) all represent subhumid woodland communi-ties, even though their taxonomic compositions were probably quite different. With these few exceptions, stratigraphic ranges defined by the first and last occurrences of pedotypes are comparable in duration with stratigraphic ranges of associated mammals (Alroy et al. 2000, Janis et al. 2002). In addition, both pedotype and mammalian diversity and turnover were generally greater during the warm-wet late Eocene (34–45 Ma) and middle Miocene (19–12 Ma) than during the cold-dry late Oligocene and late Miocene-Pleistocene (Alroy et al. 2000, Janis et al. 2000; Fig. 5).

Each pedotype also represents a particular kind of vegetation, geomorphic setting, parent material, and time for formation (see Retallack et al. 2000, 2002a, Retallack 2004a, b). The relative

Figure 2. Field photographs of selected paleosols: A. Ultisols and Alfisols above the Nut Beds near Clarno. B. Alfisols and Gleyed Incep-tisols in the central Painted Hills. C. Aridisols and Andisols at Foree north of Kimberly. D. Caprock Aridisols south of Kimberly.

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 93

Figure 3. Chemical and petrographic data on selected Oregon paleosols. A. Xaxus and Xaxuspa paleosols (revised section) from Foree. B. Luca paleosol from Whitecap Knoll near Clarno. C. Lakayx and Scat paleosols above Nut Beds near Clarno (data from Re-tallack et al. 2000).

94 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

importance of these paleoenvironmental factors through time can be assessed from the relative abundance of pedotypes for two million year bins centered on each million-year increment (Fig. 6). Forest pedotypes were common in the Eocene (35–45 Ma), woodland pedotypes in early Oligocene (30–35 Ma) and the middle Miocene (19–12 Ma), and desert shrubland (prob-ably sagebrush) pedotypes at other times. Forest and woodland paleosols have large root traces and differ in the degree of chemical and mineral weathering of the clayey subsurface (Bt) horizons (Retallack et al. 2000), whereas shrubland paleosols

Figure 4. Stratigraphic range of named pedotypes of paleosols from Oregon and Washington.

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

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 95

have shallow calcareous nodules (Bk) and common cicada bur-rows (Retallack 2004a). There has also been a steady increase in bunch grasslands with granular-ped paleosols since the early Oligocene (30 Ma), and sod grasslands with crumb-ped pa-leosols since the early Miocene (19 Ma: Fig. 6A). Streamside habitats with very weakly developed pedotypes were most com-mon during the warm-wet Eocene-early Oligocene (>30 Ma) and middle Miocene (19–12 Ma), whereas chemically oxidized paleosols of well-drained floodplains were common at other times (Fig. 6B). Although coarse-grained fluvial sediments and volcanic lahars are common in the Eocene-early Oligocene and middle Miocene, most of the paleosol record was formed on claystones weathered from redeposited rhyodacitic airfall tuffs (Fig. 6C; Bestland 2000, Retallack et al. 2000).

Some quantifiable aspects of paleosols reflect vegetation and the activities of soil-dwelling animals. Modern soils of eastern Washington have large (1–2 cm in diameter) burrows of cica-das in sagebrush soils, abundant small (0.5 mm in diameter) earthworm pellets in grasslands, and medium to coarse (1–5 cm) blocky peds in forests (O’Geen and Busacca 2002). The fine crumb structure of sod grassland soils, granular structure of bunch grassland soils, and blocky structure of woodland soils can also be recognized in paleosols (Retallack 2004a,b). The decline in minimum size of peds in paleosol surface horizons over the past 45 Ma in Oregon (lower envelope to Fig. 7A) produces a corresponding increase in internal surface area of paleosols (upper envelope of Fig. 7B). Internal surface area was calculated from the number of approximating cubes to the average ped size in the thickness of A horizons, added to a comparable calculation for Bt or Bw horizons when present. These measurements support an early Oligocene (30 Ma) advent of bunch grassland, early Miocene (19 Ma) appearance of sod grassland, and late Miocene (7 Ma) appearance of tall sod grassland in Oregon from pedotypes (Fig. 6A). Despite these innovations, both average ped size and internal surface area have changed little over the past 45 Ma.

Soil Taxonomy

There are 12 orders in the soil taxonomy of the US Soil Conservation Service (Soil Survey Staff 1999). Identification of soils and paleosols in this classification system requires laboratory analyses (Fig. 2). For paleosols, there are petro-graphic and chemical proxies that accommodate alterations to soil during burial (Retallack 1997a, 2001a). Comparable laboratory data also is needed for identification of paleosols in other soil classifications, such as map units of the United Nations Educational Scientific and Cultural Organization’s soil maps of the world (Food and Agriculture Organiza-tion 1974), and traditional soil names (Stace et al. 1968). A simplified field classification (Mack et al. 1993) is useful for labelling paleosols, but not for paleoenvironmental in-terpretation (Retallack 1993, Mack and James 1994), which is emphasized in the present study.

Details of soil taxonomic determinations are published elsewhere (Retallack et al. 2000, 2002a, Retallack 2004a,b),

but a guide to key criteria is presented here. Many paleosols dominated by volcanic shards (Fig. 3A) have non-crystalline colloids that have been partly recrystallized to clinoptilolite and celadonite (Retallack et al. 2000, 2002a, Bestland 2002), as in Andisols (suffix “-and” of Soil Survey Staff 1999) and Andosols (Food and Agriculture Organization 1974). Some paleosols have the crumb texture, thin root traces, and thick-ness of this fine soil fabric to qualify as Mollisols (suffix “-oll” of Soil Survey Staff 1999) and Kastanozems (of Food and Agriculture Organization 1974). Other paleosols have high soda/potash ratios, and shallow nodules and concretions of calcite and chalcedony, which are characteristic of Aridisols (suffix “-id” of Soil Survey Staff 1999) and Xerosols, Solon-chak, and Solonetz (of Food and Agriculture Organization 1974). Paleosols that are weakly developed with bedding

Figure 6. Variation in soil forming factors of vegetation (A), geo-morphic setting (B), parent material (C) and degree of develop-ment (D) through time of pedotypes of paleosols from Oregon and Washington. Bin size and data source are same as for Figure 5.

96 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

planes of sedimentary parent material little disrupted by root traces are classified as Entisols (suffix “-ent” of Soil Survey Staff 1999) and Fluvisols (Food and Agriculture Organization 1974). These can be contrasted with moderately developed paleosols in which all traces of sedimentary organization have been obliterated by the activity of worms and roots, and which have a subsurface horizon that has been enriched (by at least 8%) in clay washed down into the profiles, as in Alfisols (Fig. 3B; suffix “-alf” of Soil Survey Staff 1999) and Luvisols (Food and Agriculture Organization 1974). All of the paleosols noted above are rich in cationic nutrients (Ca2+, Mg2+, Na+, K+); however, the paleosols were significantly less fertile if the molar sum of these bases divided by molar alumina is less than 0.5 (Sheldon et al. 2002). Such base-depleted paleosols with a subsurface clay-enriched horizon can be regarded as Ultisols (Fig. 3A; suffix “-ult” of Soil Survey Staff 1999) and Acrisols (Food and Agriculture Organization 1974). Strongly base-depleted, uniformly clayey, and often ferruginous and bauxitic paleosols can be identified as Oxisols (suffix “-ox” of Soil Survey Staff 1999), Ferralsols, and Nitosols (Food and Agriculture Organization 1974, Bestland et al. 1996).

Taxonomic interpretationThe primary purpose for identifying paleosols within modern

soil taxonomies is to find modern soils analogous to paleosols. Fossil soils, like other fossils, have lost much of their original form and function during burial and other alterations (Retallack 1997a). In the same way that behavior and ecology of fossil snails and mammals can be inferred from their nearest living relatives, much can be learned by comparison of paleosols with comparable soils. Soil classification is a simple way of navigat-

ing the vast array of modern soil descriptions in county and regional soil surveys. The Food and Agriculture Organization (1974) soil maps of the world are especially useful in this regard because they are global in coverage. It is primarily taxonomic considerations that enable comparison of the suite of paleo-sols from the middle Eocene Clarno Nut Beds (Figs. 2A, 3A) with soils now forming under the tropical forest (“selva of Lauraceae”) on Volcán San Martin, Mexico, and the suite of paleosols from the middle Oligocene Turtle Cove Member of the John Day Formation (Figs. 2C, 3C) with soils now form-ing under deciduous grassy woodland near Tehuacán, Mexico (Retallack et al. 2000).

Also informative is the relative abundance through time of soil orders (Fig. 5F) and Marbut’s (1935) simpler classification of calcareous soils (pedocals) versus non-calcareous soils (pe-dalfers: Fig. 5E). The onset of pedocals in the early Oligocene (30 Ma) is striking, as is their rarity in the middle Miocene (19–12 Ma). Pedocals reflect dry and seasonal climates with insufficient moisture to leach carbonate from soils. Forest soils (Oxisols, Ultisols, Alfisols) are common in the Eocene and early Oligocene (30–45 Ma), and Alfisols reappear during the middle Miocene (19–12 Ma) when woodland and highly sea-sonal soils (Andisols and Vertisols) are common. Desert soils (Aridisols) have been common at other times, with a fluctuating but increasing abundance of grassland soils (Mollisols) since the early Miocene (19 Ma).

TRANSFER FUNCTIONS

Paleoenvironmental interpretations can be quantified for paleosols by applying the experimental designs of Jenny (1941). His space-for-climate approach to quantifying soil formation uses a collection of modern soils from different climates, but that are comparable in other soil-forming factors, including vegetation, parent material, topographic setting, and time for formation. From this set of soils (a climosequence) can be extracted mathematical relationships (climofunctions) between soil variables (such as base deple-tion) and climatic variables (such as mean annual precipita-tion). Similarly, biofunctions for vegetation or other biotic effects can be extracted from biosequences, topofunctions for geomorphic changes from toposequences, lithofunc-tions for parent material effects from lithosequences, and chronofunctions for time of soil development from chrono-sequences (Retallack 2005). Generally applicable biofunc-tions, topofunctions, lithofunctions and chronofunctions for paleosols have yet to be devised, and for those aspects of paleoenvironmental interpretation, pedotype and taxonomic approaches are most useful (Fig. 6).

In contrast, there are several climofunctions from which to choose (Sheldon et al. 2002, Retallack 2005). Several features of modern soils show significant relationships with mean an-nual precipitation (P in mm) and mean annual temperature (T in oC): (1) depth to calcareous nodules (D in cm) in the soil profiles (Retallack 2005); (2) chemical index of alteration without potash (C, which is the molar ratio of alumina over

Figure 7. Variability in (A) ped size (cm) within surface horizons and (B) in calculated internal surface area versus land surface area (mm2/mm2) in paleosols of Oregon and Washington through time. Each plotted point represents one paleosol.

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 97

alumina plus lime, magnesia, and soda times 100) of paleosol subsurface (Bt or Bw) horizons (Sheldon et al. 2002), and (3) alkalies index (S which is molar potash plus soda over alumina) of paleosol subsurface (Bt or Bw) horizons (Sheldon et al. 2002) , according to the equations:

P = 139.6 + 6.39D + 0.013D2 , where S.E. = ± 141 mm; R2 = 0.62

P = 221.12e0.0197C, where S.E. = ± 182 mm; R2 = 0.72T = -18.52S + 17.3, where S.E. = ± 4.4oC; R2 = 0.37

Depth to calcareous nodules can be corrected for burial compaction (using Inceptisol physical constants of Sheldon and Retallack 2001), but atmospheric CO2 levels and erosion of the paleosols before burial were not considered sufficiently significant to require correction (Retallack et al. 2000, Retal-lack 2004a,b).

Climofunction application

When applied to calcic and chemical data from Oregon paleosols, each paleoclimatic transfer function indicates long term oscillations between arid-cool and humid-warm paleoclimate. The covariance of paleotemperature and paleo-precipitation is striking from chemical climofunctions (Fig. 8A). Paleoprecipitation estimated from depth to carbonate (Fig. 8B) is comparable with that estimated from chemical composition. There are limitations to carbonate data, because carbonate-bearing paleosols appeared in Oregon only after 30 Ma, and such paleosols cannot record high precipitation, which creates non-calcareous soils (Retallack 2005).

Some parts of Oregon’s fossil soil record show exceptional temporal resolution. During the late Oligocene (28.6–23.4 Ma) accumulation of the upper Turtle Cove Member on Longview Ranch near Kimberly there are 105 climatic fluctua-tions recorded by depth to carbonate in 358 paleosols, as well as by the oxygen and carbon isotopic composition of their pedogenic carbonate (Fig. 9). These variations principally record paleoclimatic cycles paced with changes in obliquity (41 k.yr) of the Earth’s orbit, a temporal resolution generally associated with Quaternary paleoclimatic records (Retallack et al. 2004).

Paleosol-based paleoclimatic curves are comparable with long-term variation in oxygen and carbon isotopic compo-sition of benthic marine foraminifera (Fig. 8D), and with variation in atmospheric CO2 estimated from stomatal index of Ginkgo leaves (Fig. 8E). Also comparable are time series of North American mammalian diversity, origination and extinction (Alroy et al. 2000, Janis et al. 2002), and diversity and floristic affinities of broadleaf forest vegetation in the lacustrine deposits of Oregon and Washington (Graham 1999). Paleosol data confirm Meyer and Manchester’s (1994) estimate of a mean annual precipitation of 1000-1500 mm and mean annual temperature of 3–9oC for the early Oligocene (32 Ma) Bridge Creek floras of central Oregon, and Chaney and Axelrod’s (1959) estimate of a mean annual precipitation of about 1270 mm and mean annual temperature of about 17oC for the middle Miocene (15 Ma) Mascall flora. Unlike

floral estimates, which require large collections and are scat-tered in time, paleosol data are easier to obtain and much more abundant through time.

An unexpected result, also found in comparable studies in Montana and Nebraska (Retallack 2007), is that paleoclimatic drying encouraged the spread of desert shrubland rather than grasslands (Fig. 6A). Grasslands appear for the first time and then spread at times of warm-wet climate (Figs. 6, 8) and high soilscape diversity (Fig. 5) in the early (30 Ma) Oligo-cene and early (19 Ma) and late (7 Ma) Miocene. Ancient grasslands are here inferred from paleosol data (Figs. 6, 7, 10), although there is a record of grass pollen (Leopold and

Figure 8. Cenozoic variation in mean annual precipitation (A) and mean annual temperature (B) inferred from paleosol chem-istry (A, B) and depth to calcic horizons (B), compared with oxygen and carbon isotopic composition of marine foraminifera (C–D), and CO2 levels inferred from stomatal index (E). Data of A and B from Retallack (2004a,b) and Retallack et al. (2000), with flanking curves one standard error from the transfer func-tion; data of C and D from Zachos et al. (2001); data of E from Retallack (2001b, 2002) with flanking curves one standard devia-tion of the stomatal index measurement, using transfer function of Wynn (2003).

98 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

Denton 1987), phytoliths (Strömberg 2002, 2004, 2005, Blinnikov et al. 2002) and a few megafossils (Graham 1999, Retallack 2004b). Most of the fossil record of plants comes from swampy lowland deposits, whereas grasslands were mainly a phenomenon of dry, well drained soils (Retallack 1998). The evolution of grasslands can be inferred from root traces and aggregate size in paleosols. Soil aggregates (peds) are small in grassland soils because defined by a net-work of fine roots, and because produced as fecal pellets by earthworms, both characteristic of grassland soils (Retallack 1997a, 2001c). These highly coevolved ecosystems did not simply fill in arid inland regions, which were occupied then, as now, by desert shrublands.

Surprisingly, the uplifting of the Cascade, Klamath, and Olympic mountain ranges does not appear to correspond to the spread of rain-shadows, as traditionally inferred from fossil floras (Chaney 1948, Ashwill 1983), and more recently from declining isotopic values of oxygen in tooth enamel and pedogenic carbon (Kohn et al. 2002, Kohn and Fremd 2007). Growth of the Oregon Cascades inferred from radio-metrically dated eruptions (McBirney et al. 1974, Priest 1990) shows peaks of volcanic activity at 35, 25, 16, 10 and 4 Ma, but these are all times of warm-humid rather than cold-dry paleoclimate (Fig. 8A–B). Re-evaluation of the physiog-nomy of fossil floras from the northern Great Basin indicate high altitudes since at least the early Miocene, for example 2100 m for the middle Miocene (16 Ma) 49 Camp flora of northwestern Nevada (Wolfe et al. 1997), again at a time of warm-humid paleoclimate (Fig. 8A–B) and high atmospheric CO2 (Retallack 2001b, 2002). Eastern Oregon was broadly elevated during middle Miocene (16 Ma) initial eruptions of the Yellowstone hot spot, then subsided subsequently (Hum-phreys et al. 2000), with the exception of remarkably focused uplift of the Wallowa Mountains (Hales et al. 2006). Cascades and Klamath Mountain rain shadows have been important in creating generally dry long-term climate in eastern Oregon, with loessial sediments and calcareous paleosols starting during the Oligocene (30 Ma: Retallack et al. 2000). Rocky Mountain barriers also promoted summer-dry climate due to a cool nearby ocean by isolation of eastern Oregon from Gulf Coast cyclonic circulation starting during the early Miocene (19 Ma: Retallack 2004a). Orographic rain shadows were thus long-term boundary conditions to circulation since at least 50 Ma (Kent-Corson et al. 2006), but do not explain observed short-term paleoclimatic variation such as middle Miocene warm-wet spikes (Retallack 2007).

Also surprising are mismatches between broadly compa-rable paleoclimatic records of Oregon paleosols and oxygen and carbon isotopic composition of deep marine benthic foraminifera (Fig. 8C–D). Abrupt terminal Eocene, late Oligocene and Pleistocene change in oxygen isotopic data contrast with ramps in paleosol data (Sheldon et al. 2002, Sheldon and Retallack 2004), and the general trend of oxygen isotope records is sloping whereas paleosol records are level with deviations (Fig. 8C). Abrupt terminal Eocene, late Oli-

gocene and Pleistocene shifts in oxygen isotope values in the deep ocean are due to growth and decay of the Antarctic and Arctic ice caps, which abstracted large volumes of isotopically light oxygen from the ocean-atmosphere system (Zachos et al. 2001). Long term drift of marine oxygen isotopic values to lower values also is well known, and is attributed to crustal recycling (Veizer et al. 2000, Kasting et al. 2006) or burial diagenesis (Mii et al. 1997). Other theoretically plausible, but quantitatively unlikely reasons for mismatches of oceanic oxygen and Oregon paleosol records include evolution of C4 photosynthetic pathways in grasses which select CO2 heavy for either carbon or oxygen, and Rayleigh distillation to lower oxygen isotope values on land increasingly elevated and isolated from the sea by mountains (Retallack 2007). Less surprising is the carbon isotope value of the same deep marine foraminifera, which matches Oregon paleoclimatic records well (Fig. 8D), apart from Plio-Pleistocene deviation attributable to the rise of C4 vegetation on land (Cerling et al. 1997).

IMPLICATIONS FOR CENOZOIC GLOBAL CHANGE

The Cenozoic Oregon paleosol record is unusually long and detailed. Oregon’s back-arc paleotopography, rate of basinal subsidence, and rhyolitic parent materials changed little over the past 45 Ma, but Oregon’s changing climate and vegetation reflects a global paleoclimate signal for several reasons. Annual variation in oxygen isotopic composition of growth bands within Miocene mammalian tooth enamel reflect planetary revolutions (Fox 2001, Kohn et al. 2002). Also, temporal variations in depth to carbonate and its stable isotopic composition (Fig. 9) have the same periodicity (41-100 ka) as orbital variations in obliquity and eccentricity (Retallack et al. 2004). Late Eocene and middle Miocene peaks in temperature and precipitation in Oregon paleosols (Fig. 8A–C) correspond to highs in global atmospheric CO2 revealed by stomatal index of fossil Ginkgo (Fig. 8E) and peaks in deep ocean temperature inferred from marine oxygen isotopic values (Fig. 8D). Cenozoic global cooling from late Eocene (35 Ma) and middle Miocene (16 Ma) peaks of warmth has been explained by mountain uplift (Raymo and Ruddiman 1992), changing oceanic currents (Kennett 1982, Broecker 1989) and grassland coevolution (Retallack 2001c), and the Oregon paleosol record is relevant to each of these hypotheses.

Mountain uplift

Raymo and Ruddiman (1992) proposed that Himalayan and other mountain uplift promoted deep weathering by carbonic acid and was thus a sink for atmospheric carbon dioxide promoting Cenozoic climatic cooling after about 40 Ma. Their argument was based largely on the temporal in-crease of 87Sr/86Sr ratios, now attributed largely to carbonate weathering, which does not appreciably affect atmospheric redox, unlike silicate weathering (Jacobson et al. 2002, Ja-cobson and Blum 2003). There are additional fundamental

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 99

problems with Raymo and Ruddiman’s (1992) hypothesis be-cause metamorphic and volcanic emissions of carbon dioxide together with reduced chemical weathering at high altitude make mountain uplift a force not for global cooling, but for global warming (Zeitler et al. 2001). Himalayan and other mountain uplift promotes physical weathering, especially by means of glaciation, but not carbon-consuming chemical weathering of silicates (Jacobson and Blum 2003). Warm-wet spikes at 35 and 16 Ma in climate records of Oregon (Fig. 8) and elsewhere around the world (Retallack 2007) coincide with peaks in volcanic activity in the western US (McBirney et al. 1974, Priest 1990), and in globally significant eruptions of Ethiopia-Yemen and Columbia River flood basalts (Courtillot 2002). Some of these eruptions may have intruded coal (such as Oregon’s Herren Formation) and released to the atmo-sphere large amounts of thermogenic methane, which then oxidized to atmospheric CO2, as has been argued for other global warming events (Retallack and Jahren 2008). These warm-wet spikes also coincide with the Chesapeake impact crater at 35 Ma (Poag et al. 2003), and Ries and Steinheim craters at 16 Ma (Stoeffler et al. 2002), which would induce initial cooling from particulate ejecta in the atmosphere fol-

lowed by warming effects of carbon dioxide from destroyed soils and biomass (Poag et al. 2003).

In the Oregon paleosol record, which includes the Colum-bia River basalts (Sheldon 2003, 2006), the most chemically weathered paleosols are those least disturbed by volcanism, uplift and sedimentation (Bestland et al. 1996, Retallack et al. 2000). These paleosols would have consumed significant amounts of carbon dioxide by hydrolysis, especially at times of high atmospheric carbon dioxide and warm-wet weath-ering (Fig. 8). Thus, times of volcano-tectonic quiescence promote cooling, by consuming atmospheric carbon dioxide during hydrolytic weathering and fertilizing the ocean with bicarbonate and nutrients for deep oceanic storage of reduced carbon largely from phytoplankton (Retallack 2001c). In contrast, perturbations of mountain uplift, volcanism, and bolide impact are forces for planetary warming.

Ocean gateways

Ocean current reorganization as a result of continental drift has also been proposed as a force for Cenozoic global cooling. Kennett (1982) argued that cooling across the Eo-cene-Oligocene transition was caused by continental drift of

Figure 9. Milankovitch-scale fluctuations in mean annual paleoprecipitation inferred from depth to calcic (Bk) horizon within paleo-sols of the upper John Day Formation on Longview Ranch, near Kimberly.

100 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

Australia and South America away from Antarctica, so that the ice continent was then thermally isolated by the Circum-Antarctic current. Broecker (1989) argued that Panamanian isthmus closure created a warm salty Caribbean and stimu-lated thermohaline circulation into North Atlantic bottom water formation to bring on the Pleistocene ice age. Problems with timing and mechanism have emerged for both ideas. The Circum-Antarctic current was initiated at 37 Ma rather than the 33.9 Ma Eocene-Oligocene boundary (Exon et al. 2004) and completed by 25 Ma (Lyle et al. 2007) when Oregon and other isotopic data indicate warming and deglaciation in a reversal of the proposed effect (Zachos et al. 2001). Pana-manian isthmus closure was at 2.8–3.1 Ma rather than the 1.8 Ma Plio-Pleistocene boundary (Bartoli et al. 2005), also a time of warming. More problematic is modeling indicating warming rather than cooling by diminution of the Humboldt Current as Chile drifted north (DeConto and Pollard 2003), and by Gulf Stream redistribution into the North Atlantic of warmth from an enclosed Caribbean Sea (Lund et al. 2006). Thermal transport modeling now suggests a more important role for global carbon dioxide than southern ocean currents in Cenozoic cooling (Huber and Nof 2007).

Southern and central American oceanic gateways are re-mote from Oregon records (Fig. 8A–B) which show general similarity with oceanic isotopic records (Fig. 8C–D) domi-nated by cores from the Southern Ocean (Zachos et al. 2001). Eocene-Oligocene cooling in the northern Pacific Ocean was synchronous with that in the southern hemisphere, yet not accompanied by changes in northern oceanic basin configura-tion (Scholl et al. 2003), lending support to climate-change mechanisms of global reach such as the greenhouse effect of atmospheric carbon dioxide.

Grassland coevolution

A third suggested cause of Cenozoic climatic cooling is stepwise coevolution of grassland grasses and grazers into novel ecosystems (sod grasslands) and soils (Mollisols) over the past 35 Ma (Retallack 2001a). Evidence for this view is well documented in Oregon (Fig. 10), where it has a long pedigree back to Thomas Huxley’s insights on horse evolu-tion from his 1876 examination of the collection of Oregon fossils O.C. Marsh at Yale obtained from Thomas Condon (Clark 1989). The coeval appearance of hypsodont horses and Mollisols in Oregon reflects grass-grazer coevolution that is also evident in Montana, Nebraska, Pakistan, and Kenya (Retallack 1995, 1997b, 2007, Retallack et al. 2002b). The appearance of open-country grass phytoliths 4 Ma.earlier than hypsodont horses in the Great Plains (Strömberg 2006) does not contradict this conclusion because the open country grass phytoliths come from desert and rangeland soils (Aridisols and Inceptisols) comparable with those now supporting sagebrush and bunch grassland (Retallack 2007). Other phy-toliths in these paleosols are considered by Strömberg (2004, 2006) as forest indicators, but they are indistinguishable from phytoliths of modern desert shrubs (Artemisia tridentata)

and small trees (Juniperus occidentalis) (see Blinnikov et al. 2002) and may also be from arid shrubland communities indicated by paleosols.

Considering the combined evidence from paleosols and phytoliths, grasslands did not merely adapt to climate change, but were a biological force for global change. Compared with preexisting woodland soils, grasses created soils richer in re-duced carbon and finer in structure deeper within the profile (Figs. 7, 10), thus promoting carbon sequestration in soils and derived sediments, as well as carbon dioxide consumption by hydrolytic weathering. Woodlands create moist air and dry soils by active transpiration, but grasslands create moist soil and dry air, which is cooler without greenhouse-inducing water vapor. Finally albedo of grasses is higher than that of woodlands, reflecting much solar warmth back into space (Retallack 2001c). Thus, grasslands and their soils (Molli-sols) became a force for planetary glaciation comparable with Late Devonian to Carboniferous (300-390 Ma) evolution of trees (Berner 1997) and soils of forests (Alfisols) and swamps (Histosols: Retallack 2001a, 2004c).

Unlike ocean gateways or mountain uplift, this mecha-nism of global cooling is biological not physicochemical. In the long term, weedy reproduction and abrasive phytoliths of grasses withstood the onslaught of increasingly large, hypsodont and hard-hooved mammals more effectively than pre-existing woody plants, but key stages in the process are evident in Oregon (Fig. 10). An early stage appearing by 35 Ma in Nebraska and 30 Ma in Oregon is marked by abundant opal phytoliths of grasses, cursorial and lophodont mixed browser-grazer rhinos and horses, and granular-structured calcareous paleosols (Retallack 1983, Retallack et al. 2000, Janis et al 2002, Strömberg 2002, 2004) A likely biological adaptation triggering the appearance of these fossils and paleosols is the origin of rumination (cud chewing) dated to 34–35 Ma by molecular clock techniques on digestive ribonucleases of ruminants (Jermann et al. 2001). Another coevolutionary advance at a time of warm-wet climate was appearance of hypsodont horses, abundant open country phytoliths and crumb-structured paleosols (Mollisols) of short sod grasslands in Oregon, Montana and Nebraska at about 19 Ma (early Miocene: Retallack 2007). The seminal evolutionary innovation for these communities may have been pack-hunting, indicated by the prorean gyrus in brain casts of fossil carnivores (Van Valkenburgh et al. 2003), which in turn promoted herding, intensive “cell grazing” and sod development (Savory and Butterfield 1999). A final coevolutionary advance, again at a time of warm-wet climate at about 7 Ma, was the appearance of large horses, along with deep-calcic, crumb structured paleosols (Mollisols) of subhumid climates and tall-grasslands (Retallack et al. 2002a). The seminal evolutionary adaptations in this case may have been monodactyl hard hooves and highly hypso-dont teeth, harder on seedlings of trees than grasses, so that the grassland-woodland ecotone rolled outward into more humid regions (Retallack 1997b). The 7 Ma coevolutionary

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 101

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

advances marked the onset of the C4 photosynthetic pathway as a global carbon isotopic perturbation (Cerling et al. 1997), although the pathway itself may be older; an origin of 40 Ma is estimated from paleosol carbon isotopic studies (Fox and Koch 2003), 25 Ma from phylogenetic analyses (Kellogg 1999), and 12.5 Ma from isotopic and anatomical studies of fossil grasses (Nambudiri et al. 1978, see Whistler and Bur-bank 1992, for revised age). There is as yet no evidence of C4 grasses in Oregon before their agricultural introduction, and such summer-dry climates have mainly C3 grasses today (Sage et al.1999). Cooling coevolutionary advances in carbon

consumption and sequestration, water vapor reduction and albedo increases of grasslands arrested tectono-volcanic and extraterrestrial warmings at 35, 16 and 7 Ma to create the bumpy ride of Oregon and global climate over the past 45 million years (Fig. 8).

CONCLUSIONS

The multifaceted Cenozoic paleosol record of Oregon and Washington undoubtedly has more to reveal about global change beyond the interpretations of changing vegetation and climate reviewed here. Especially promising is the role of

102 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

past weathering in atmospheric carbon dioxide consumption (Bestland 2000) and mammalian community dynamics of different pedotypes (Retallack et al. 2004). New approaches to research can be expected beyond those of pedotypes, taxonomy, and transfer functions outlined here. Oregon and Washington’s Cenozoic paleosol record is continuous back to at least 45 Ma, and some parts of it are comparable in temporal resolution with deep-sea cores (Retallack et al. 2004). Comparable paleosol records are developing for Montana, Nebraska (Retallack 2007), and elsewhere (Retal-lack 2001a). Paleoenvironmental information from paleosols now supports evidence from fossil phytoliths and bones in paleosols at many localities, and provides new evidence for theories of global change.

ACKNOWLEDGMENTS

I thank Ted Fremd, Scott Foss, and Mary Oman for funding, research clearance, and curatorial assistance. Erick Bestland, Evelyn Krull, Jonathan Wynn, Megan Smith, Russell Hunt, and Nathan Sheldon helped with fieldwork and fossil collection. Ken Finger and Randall Irmis greatly improved the manuscript by diligent editing. Work was funded by National Park Service Contracts CX-9000-1-1009, 144-PX9345-99-005, and P1325010503, Bureau of Land Management cooperative agreement 8/21/01, and National Science Foundation grant EAR-0000953.

LITERATURE CITED

Alroy, J., P.L. Koch, and J.C. Zachos. 2000. Global climate change and North American mammalian evolution. Paleobiology Supple-ment 26:259–288.

Ashwill, M. 1983. Seven fossil floras in the rain shadow of the Cascades Mountains. Oregon Geology 45:107–117.

Bailey, M.M. 1989. Revisions to stratigraphic nomenclature of the Picture Gorge Basalt Subgroup, Columbia River Basalt. Pp. 67–84 in S.P Reidel and P.R. Hooper (eds.). Volcanism and Tectonism in the Columbia River Flood-Basalt Province. Geological Society of America Special Paper 239.

Bartoli, G., M. Sarnthein, M. Weinelt, H. Erlenkauser, G. Garbe-Schönberg, and D.W. Lea. 2005. Final closure of Panama and onset of northern hemisphere glaciation. Earth and Planetary Science Letters 237:33–44.

Bernabo, J.L., and T. Webb. 1977. Changing patterns in the Holo-cene pollen record from northeastern North America: a mapped summary. Quaternary Research 8:64–96.

Berner, R. 1997. The rise of plants and their effects on weathering and CO2. Science 276:543–546.

Bertrand-Sarfati, J., and M.R. Walter. 1981. Stromatolite biostra-tigraphy. Precambrian Research 9:105–166.

Bestland, E.A. 2000. Weathering flux and CO2 consumption deter-mined from palaeosol sequences across the Eocene-Oligocene transition. Palaeogeography, Palaeoclimatology, Palaeoecology 156:301–326.

Bestland, E.A. 2002. Fossil Andisols identified with mass balance geochemistry (Oligocene, John Day Formation, USA). Journal

of Sedimentary Research A72:673–686.Bestland, E.A., and M.S. Forbes. 2003. Stratigraphy and geochem-

istry of the mid-Miocene Mascall Formation (upper part) in its type areas. Unpublished Report John Day Fossil Beds National Monument, Kimberly. 50 pp.

Bestland, E.A., P.E. Hammond, D.L.S. Blackwell, M.A. Kays, G.J. Retallack, and J. Stimac. 1999. Geologic framework of the Clarno Unit, John Day Fossil Beds National Monument, central Oregon. Oregon Geology 61:3–19.

Bestland, E.A., G.J. Retallack, E.A. Rice, and A. Mindszenty. 1996. Late Eocene detrital laterites in central Oregon: mass balance geochemistry, depositional setting, and landscape evolution. Geological Society of America Bulletin 108:285–302.

Bishop, E.M., and G.A. Smith. 1990. A field guide to the geology of Cove Palisades State Park and the Deschutes Basin in central Oregon. Oregon Geology 52:3–12.

Blinnikov, M., A. Busacca, and C. Whitlock. 2002. Reconstruction of the late Pleistocene grassland of the Columbia Basin, Washing-ton, USA, based on phytolith records in loess. Palaeogeography Palaeoclimatology Palaeoecology 177:77–101.

Bowen, R.G., W.L. Gray, and D.C. Gregory. 1963. General geology of the northern Juntura Basin. American Philosophical Society Transactions 53:22–34.

Broecker, W.S. 1989. The salinity contrast between the Atlan-tic and Pacific Ocean during glacial time. Paleoceanography 4:207–212.

Busacca, A.J. 1989. Long Quaternary record in eastern Washington, USA, interpreted from multiple paleosols in loess. Geoderma 45:105–122.

Busacca, A.J. 1991. Loess deposits and soils of the Palouse and vicinity. In R.B. Morrison (ed.). Quaternary Nonglacial Geology: Conterminous U.S. The Geology of North America K2:216–228.

Cerling, T.E., J.M. Harris, B.J. MacFadden, M.G. Leakey, J. Quade, V. Eisenmann, and J.R. Ehleringer. 1997. Global vegeta-tion change through the Miocene/Pliocene boundary. Nature 389:153–158.

Chaney, R.W. 1924. Quantitative studies of the Bridge Creek flora. American Journal of Science 8:127–144.

Chaney, R.W. 1948. The ancient forests of Oregon. University of Oregon, Eugene. 56 pp.

Chaney, R.W., and D.I. Axelrod. 1959. Miocene floras of the Columbia Plateau. Carnegie Institution of Washington Publica-tion 617:1–237.

Clark, R.D. 1989. The odyssey of Thomas Condon. Oregon His-torical Society, Portland. 567 pp.

Coombs, M.C., R.M. Hunt, E. Stepleton, L.B. Albright, and T.J. Fremd. 2001. Stratigraphy, chronology, biogeography and taxonomy of early Miocene chalicotheres in North America. Journal of Vertebrate Paleontology 21:607–620.

Courtillot, V. 2002. Evolutionary catastrophism. Cambridge Uni-versity Press, Cambridge. 173 pp.

DeConto, R.M., and D. Pollard. 2003. A coupled climate-ice sheet modeling approach to the early Cenozoic history of the Antarctic ice sheet. Palaeogeography Palaeoclimatology Palaeoecol-ogy 198:39–52.

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 103

DeLancey, S., C. Genetti, and N. Rude.1988. Some Sahaptian-Klamath-Tsimshianic lexical sets. Pp. 195–204 in W. Shipley (ed.). In honor of Mary Haas. Mouton de Gruyter, Berlin.

Downs, T. 1956. The Mascall fauna from the Miocene of Oregon. University of California Publications in Geological Sciences 31:199–354.

Evernden, J.F., and G.T. James.1964. Potassium-argon dates and the Tertiary floras of North America. American Journal of Sci-ence 262:945–974.

Exon, N.F., J.P. Kennett, and M.J. Malone (eds.). 2004. The Ce-nozoic Southern Ocean: Tectonics, Sedimentation, and Climate Change between Australia and Antarctica. American Geophysical Union, Washington. 267 pp.

Fiebelkorn, R.B., G.W. Walker, N.S. MacLeod, E.H. McKee, and G.H. Smith. 1982. Index of K-Ar determinations for the state of Oregon. Isochron West 37:1–60.

Fisher, R.V. 1964. Resurrection of Oligocene hills, eastern Oregon. American Journal of Science 262:713–725.

Food and Agriculture Organization. 1974. Soil Map of the World, Part 1, Legend, Paris, United Nations Educational Scientific and Cultural Organization, Paris. 59 pp.

Fox, D.L. 2001. Growth increments in Gomphotherium tusks and implications for late Miocene climate change in North America. Palaeogeography Palaeoclimatology Palaeoecology 156:327–348.

Fox, D.L., and P.L. Koch. 2003. Tertiary history of C4 biomass in the Great Plains, USA. Geology 9:809–812.

Fremd, T.E., E.A. Bestland, and G.J. Retallack. 1994. John Day Basin fieldtrip guide and road log for the Society of Vertebrate Paleontology Annual Meeting. Northwest Interpretive Associa-tion, Seattle. 90 pp.

Graham, A. 1999. Late Cretaceous and Cenozoic history of North American vegetation. Oxford University Press, New York. 350 pp.

Gustafson, E.P. 1978. The vertebrate fauna of the Pliocene Ringold Formation, south-central Washington. Museum of Natural His-tory University of Oregon Bulletin 23:1–62.

Gustafson, E.P. 1985. Soricids (Mammalian: Insectivora) from the Blufftop Local Fauna, Blancan Ringold Formation of central Washington and correlation of the Ringold Formation. Journal of Vertebrate Paleontology 5:88–92.

Hales, T.C., D.L. Abt, E.D. Humphreys, and J.J. Roering. 2006. A lithospheric instability origin for Columbia River flood basalts and Wallowa Mountains uplift in northeast Oregon. Nature 438:842–845.

Hanson, C.B. 1996. Stratigraphy and vertebrate faunas of the Bridgerian-Duchesnean Clarno Formation, north-central Or-egon. Pp. 206–239 in D.R. Prothero and R.J. Emry (eds.). The terrestrial Eocene-Oligocene transition in North America. Cambridge University Press, New York.

Hay, R.L. 1962. Origin and diagenetic alteration of the lower part of the John Day Formation near Mitchell, Oregon. Pp. 191–216 in A.E.L. Engel, H.L. Jones, and P.F. Leonard (eds.). Petro-logic studies in honor of A.F. Buddington. Geological Society of America, Boulder.

Huber, M., and D. Nof. 2007. The ocean circulation in the southern hemisphere and its climatic impacts in the Eocene. Palaeogeog-raphy Palaeoclimatology Palaeoecology 231:9–28.

Humphreys, E.D., K.G. Dueker, D.L. Schutt, and R.B. Smith. 2000. Beneath Yellowstone: evaluating plume and non-plume models using teleseismic images of the upper mantle. GSA Today 10(2):1–7.

Hunt, R.M., and E. Stepleton. 2004. Geology and paleontology of the upper John Day beds, John Day River, Oregon: lithostrati-graphic and biochronologic revision in the Haystack and Kim-berly areas (Kimberly and Mt. Misery quadrangles). American Museum of Natural History Bulletin 282:1–90.

Hutchison, J.H. 1968. Fossil Talpidae (Insectivora, Mammalia) from the late Tertiary of Oregon. Museum of Natural History University of Oregon Bulletin 11:1–117.

Jacobson, A.D., and J.D. Blum. 2003. Relationship between me-chanical erosion and atmospheric CO2 consumption of the New Zealand Southern Alps. Geology 31:865–868.

Jacobson, A.D., J.D. Blum, and L.M. Walter. 2002. Reconciling the elemental and Sr isotope composition of Himalayan weather-ing fluxes: insights from the carbonate geochemistry of stream waters. Geochimica Cosmochimica Acta 66:3417–3429.

Janis, C.M., J. Damuth, and J.M. Theodor. 2002. The origin and evolution of the North American grassland biome: the story from the hoofed mammals. Palaeogeography Palaeoclimatology Palaeoecology 177:183–198.

Jenny, H.J. 1941. Factors in soil formation. McGraw-Hill, New York. 281 pp.

Jermann, T.M., J.G. Opitz, J. Stackhouse, and S.A. Benner. 1995. Reconstructing the evolutionary history of the artiodactyl ribo-nuclease family. Nature 374:57–59.

Johnson, T.A., G.B. Binger, P.R. Hooper, and C.J. Hawkesworth. 1996. Implications of structure and stratigraphy in the Juntura area, east-central Oregon. Geological Society of America Abstracts 28:78.

Kasting, J.F., M.T. Howard, K. Wallmann, J. Veizer, G. Shields, and J. Jaffres. 2006. Paleoclimates, ocean depth, and the oxygen isotopic composition of seawater. Earth and Planetary Science Letters 252:82–93.

Kellogg, E.A. 1999. Phylogenetic aspects of the evolution of C4 photosynthesis. Pp. 411–444 in R.F. Sage and R.K. Monson (eds.). Plant Biology. Academic Press, New York.

Kennett, J.P. 1982. Marine Geology. Prentice-Hall, Englewood Cliffs. 813 pp.

Kent-Corson, M.L., L.S. Sherman, A. Mulch, and C.P. Cham-berlain. 2006. Cenozoic topographic and climatic response to changing tectonic boundary conditions in western North America. Earth and Planetary Science Letters 252:453–466.

Kohn, M.J., and T.J. Fremd. 2007. Tectonic controls on isotope compositions and species diversification, John Day Basin, central Oregon. PaleoBios 27:48–61.

Kohn, M.J., J.L. Miselis, and T.J. Fremd. 2002. Oxygen isotope evidence for progressive uplift of the Cascade Range, Oregon. Earth Planetary Sciences Letters 204:1–15.

Leopold, E.B., and M.F. Denton. 1987. Comparative age of grass-land and steppe east and west of the northern Rocky Mountains. Missouri Botanical Garden Annals 74:841–867.

Lund, D.C., J. Lynch-Stieglitz, and W.B. Curry. 2006. Gulf stream density structure and transport during the past millennium.

104 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

Nature 444:601–604.Lyle, M., S. Gibbs, T.C. Moore, and D.K. Rea. 2007. Late Oligo-

cene initiation of the Antarctic Circumpolar Current; evidence from the South Pacific. Geology 35:691–694.

Mack, G.H., and W.C. James. 1994. Paleoclimate and global dis-tribution of paleosols. Journal of Geology 102:360–362.

Mack, G.H., W.C. James, and H.C. Monger. 1993. Classification of paleosols. Geological Society of America Bulletin 105:129–136.

Manchester, S.R. 1994. Fruits and seeds of the middle Eocene Nut Beds flora, Clarno Formation, Oregon. Palaeontographica Americana 58:1–205.

Marbut, C.F. 1935. Atlas of American Agriculture. Part III Soils of the United States. Government Printer, Washington, DC. 98 pp.

McBirney, A.R., J.F. Sutter, H.R. Naslund, K.G. Sutton, and C.M. White. 1974. Episodic volcanism in the central Oregon Cascade Range. Geology 2:585–589.

Merriam, J.C. 1906. Carnivora from the Tertiary formation of the John Day region. Publications in Geological Sciences University of California 5:1–6.

Merriam, J.C. 1916. Mammalian remains from a Tertiary formation at Ironside, Oregon. Publications in Geological Sciences University of California 10:129–135.

Merriam, J.C., and W.J. Sinclair. 1907. Tertiary faunas of the John Day region. Publications in Geological Sciences University of California 5:171–205.

Merriam, J.C., C. Stock, and C.L. Moody. 1925. The Pliocene Rattlesnake fauna of eastern Oregon, with notes on the geology of the Rattlesnake deposits. Carnegie Institution of Washington Publications 347:43–49.

Meyer, H.W., and S.M. Manchester. 1997. Revision of the Oligo-cene Bridge Creek floras of Oregon. Publications in Geological Sciences University of California 141:1–195.

Mii, H.S., E.L. Grossman, and T.E. Yancey. 1997. Stable carbon and oxygen isotope shifts in Permian seas of West Spitsbergen: global change or diagenetic artifact? Geology 25:227–230.

Morgan, J.K., and N.H. Morgan. 1995. A new species of Caprom-eryx (Mammalia: Artiodactyla) from the Taunton Local Fauna of Washington, and the correlation with other Blancan faunas of Washington and Idaho. Journal of Vertebrate Paleontology 15:160–170.

Nambudiri, W.M.V., W.D. Tidwell, B.N. Smith, and N.P. Hebbert. 1978. A C4 plant from the Pliocene. Nature 276:816–817.

O’Geen, A.T., and A.J. Busacca. 2002. Faunal burrows as indica-tors of paleovegetation in eastern Washington. Palaeogeography Palaeoclimatology Palaeoecology 169:23–37.

Perkins, M.E., F.H. Brown, W.F. Nash, W. McIntosh, and S.K. Williams. 1998. Sequence, age and source of silicic fallout tuffs in middle to late Miocene basins of northern Basin and Range Province. Geological Society of America Bulletin 110:344–360.

Poag, W.C., E. Mankinen, and R.D. Norris. 2003. Late Eocene impacts: geological record, correlation and paleoenvironmental consequences. Pp. 495–510 in D.R. Prothero, L.C. Ivany, and E.A. Nesbitt (eds.). From Greenhouse to Icehouse: The Eocene-Oligo-cene Marine Transition. Columbia University Press, New York.

Priest, G.R. 1990. Volcanic and tectonic evolution of the Cascade

volcanic arc, central Oregon. Journal of Geophysical Research 95:19383–19599.

Prothero, D.R., E. Draus, and S.E. Foss. 2006a. Magnetic stra-tigraphy of the lower portion of the middle Miocene Mascall Formation, central Oregon. PaleoBios 26(1):37–42.

Prothero, D.R., J.M. Hoffman, and S.E. Foss. 2006b. Magnetic stratigraphy of the upper Miocene (Hemphillian) Rattlesnake Formation, central Oregon. PaleoBios 26(1):31–35.

Prothero, D.R., and J.M. Rensberger. 1985. Preliminary magne-tostratigraphy of the John Day Formation, Oregon, and the North American Oligocene-Miocene boundary. Newsletters in Stratigraphy 15:59–70.

Raymo, M.E., and W.F. Ruddiman. 1992. Tectonic forcing of late Cenozoic climate. Nature 359:117–122.

Retallack, G.J. 1993. Classification of paleosols: discussion. Geologi-cal Society of America Bulletin 105:1635–1637.

Retallack, G.J. 1994. A pedotype approach to latest Cretaceous and earliest Tertiary paleosols in eastern Montana. Geological Society of America Bulletin 106:1377–1397.

Retallack, G.J. 1995. Paleosols of the Siwalik Group as a 15 Ma record of South Asian paleoclimate. In S. Wadia, R. Korisettar and V.S. Kale (eds.). Quaternary Environments and Geoarchae-ology of India: Essays in Honour of S.N. Rajaguru. Geological Survey of India Memoir 32:36–51.

Retallack, G.J. 1997a. A Colour Guide to Paleosols. Wiley, Chich-ester, 175 pp.

Retallack, G.J. 1997b. Neogene expansion of the North American prairie. Palaios 12:380–390.

Retallack, G.J. 1998. Fossil soils and completeness of the rock and fossil record. Pp. 131–162 in S.K. Donovan and C.R.C. Paul (eds.). The Adequacy of the Fossil Record. Wiley, Chichester.

Retallack, G.J. 2001a. Soils of the Past. Blackwell, Oxford. 404 pp.Retallack, G.J. 2001b. A 300-million-year record of atmospheric car-

bon dioxide from fossil plant cuticles. Nature 411:287–290.Retallack, G.J. 2001c. Cenozoic expansion of grasslands and climatic

cooling. Journal of Geology 109:407–426.Retallack, G.J. 2002. Carbon dioxide and climate over the past

300 Myr. Royal Society of London Philosophical Transactions B 360:659–673.

Retallack, G.J. 2004a. Late Oligocene bunch grassland and early Miocene sod grassland paleosols from central Oregon, U.S.A. Palaeogeography Paleoclimatology Palaeoecology 207:203–237.

Retallack, G.J. 2004b. Late Miocene climate and life on land in eastern Oregon within a context of Neogene global change. Palaeogeography Paleoclimatology Palaeoecology 214:97–123.

Retallack, G.J. 2004c. Soils and global carbon cycle change in geologi-cal time. Pp. 581–605 in H.D. Holland, K.K. Turekian, and J.I. Drever (eds.). Treatise on Geochemistry, Volume 5: Surface and Ground Water, Weathering, and Soils. Elsevier, Amsterdam.

Retallack, G.J. 2005. Pedogenic carbonate proxies for amount and seasonality of precipitation in paleosols. Geology 33:333–336.

Retallack, G.J. 2007. Cenozoic paleoclimate on land in North America. Journal of Geology 15:271–294.

Retallack, G.J., E.A. Bestland, and T.J. Fremd. 2000. Eocene and Oligocene paleosols of central Oregon. Geological Society of America Special Paper 344:1–192.

PRETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 105

Retallack, G.J., and A.H. Jahren 2008. Methane release from igneous intrusion of coal during Late Permian extinction events. Journal of Geology 116:1–20.

Retallack, G.J., S. Tanaka, and T. Tate. 2002a. Late Miocene advent of tall grassland paleosols in Oregon. Palaeogeography Palaeoclimatology Palaeoecology 183:329–354.

Retallack, G.J., J.G. Wynn, B.R. Benefit, and M.L. McCrossin. 2002b. Paleosols and paleoenvironments of the middle Mio-cene, Maboko Formation, Kenya. Journal of Human Evolution 42:659–703.

Retallack, G.J., J.G. Wynn, and T.J. Fremd. 2004. Glacial-intergla-cial-scale paleoclimatic changes without large ice sheets in the Oligocene of central Oregon. Geology 32:297–300.

Rigsby, B.J. 1965. Linguistic relations in the southern Plateau. Ph.D. dissertation, University of Oregon, Eugene.

Sage, R.F., O.A. Wedin, and M. Li. 1999. Biogeography of C4 photosynthesis: pattern and controlling factors. Pp. 313–373 in R.F. Sage and R.K. Monson (eds.). Plant Biology. Academic Press, San Diego.

Savory, A., and J. Butterfield. 1999. Holistic Management: a New Framework for Decision Making. Island Press, Washington DC. 616 pp.

Scholl, D.W., A.J. Stevenson, M.A. Noble, and D.R. Rea. 2003. The Meiji Drift Body and late Paleogene-Neogene paleoceanog-raphy of the North Pacific and Bering Sea region. Pp. 119–123 in D.R. Prothero, L.C. Ivany, and E.A. Nesbitt (eds.). From Greenhouse to Icehouse: the Eocene-Oligocene Marine Transi-tion. Columbia University Press, New York.

Seilacher, A. 1970. Cruziana stratigraphy of “unfossiliferous” Paleozoic sandstones. In T.P. Crimes and J.C. Harper (eds.). Trace fossils. Geological Journal Special Issue 3:47–76.

Sheldon, N.D. 2003. Pedogenesis and geochemical alteration of the Picture Gorge Subgroup, Columbia River Basalt. Geological Society of America Bulletin 115:1377–1387.

Sheldon, N.D. 2006. Using paleosols of the Picture Gorge Basalt to reconstruct the middle Miocene climatic optimum. PaleoBios 26(2):27–36.

Sheldon, N.D., and G.J. Retallack. 2001. Equation for compaction of paleosols due to burial. Geology 29:247–250.

Sheldon, N.D., and G.J. Retallack. 2004. Regional paleoprecipi-tation records from the late Eocene and Oligocene of North America. Journal of Geology 112:487–494.

Sheldon, N.D., G.J. Retallack, and S. Tanaka. 2002. Geochemical climofunctions from North American soils and application to paleosols across the Eocene-Oligocene boundary in Oregon. Journal of Geology 110:687–696.

Sheppard, R.A., and A.J. Gude.1987. Field trip guide to the Sheaville and Rome zeolite deposits. Oregon Geology 49:3–10.

Shotwell, J.A. 1956. Hemphillian assemblages from northwestern Oregon. Geological Society of America Bulletin 67:717–738.

Shotwell, J.A. 1958. Inter-community relationships in Hemphillian (Mio-Pliocene) mammals. Ecology 29:271–282.

Shotwell, J.A. 1963. Pliocene mammalian communities of the Juntura Basin. American Philosophical Society Transactions 53:7–21.

Shotwell, J.A., and D.E. Russell. 1963. Mammalian fauna of the upper Juntura Formation, the Black Butte local fauna. American

Philosophical Society Transactions 53:42–69.Smith, G.A. 1986. Simtustus Formation: paleogeographic and

stratigraphic significance of a newly defined Miocene unit in the Deschutes Basin, central Oregon. Oregon Geology 48:63–72.

Smith, G.R., N. Morgan, and E. Gustafson. 2000. Fishes of the Mio-Pliocene Ringold Formation, Washington: Pliocene capture of the Snake River by the Columbia River. University of Michigan Publications in Paleontology 32:1–47.

Soil Survey Staff. 1993. Soil survey manual. U.S. Department of Agriculture Handbook 18:1–437.

Soil Survey Staff. 1999. Keys to Soil Taxonomy. Pocahontas Press, Blacksburg, Virginia. 600 pp.

Stace, H.C.T., G.D. Hubble, R. Brewer, K.H. Northcote, J.R. Slee-man, M.J. Mulcahy, and E.G. Hallsworth. 1968. A Handbook of Australian Soils. Rellim, Adelaide. 435 pp.

Stoeffler, D., N. Artemieva, and E. Pierazzo. 2002. Modeling the Ries-Steinheim impacts and the formation of the moldavite strewn field. Meteoritics and Planetary Science 37:1893–1907.

Streck, M.D., J.A. Johnson, and A. Grundner. 1999. Field guide to the Rattlesnake Tuff and High Lava Plains near Burns, Oregon. Oregon Geology 61:64–76.

Strömberg, C.A.E. 2002. The origin and spread of grass-dominated ecosystems in the late Tertiary of North America: preliminary results concerning the evolution of hypsodonty. Palaeogeography Palaeoclimatology Palaeoecology 177:59–75.

Strömberg, C.A.E. 2004. Using phytolith assemblages to recon-struct the origin and spread of grass-dominated habitats in the Great Plains of North America during the late Eocene to early Miocene. Palaeogeography, Palaeoclimatology, Palaeoecology 207:239–275.

Strömberg, C.A.E. 2005. Decoupled taxonomic radiation and ecological expansion of open-habitat grasses in the Cenozoic of North America. Proceedings of the National Academy of Sciences 102:11980–11984.

Strömberg, C.A.E. 2006. Evolution of hypsodonty in equids: testing a hypothesis of adaptation. Paleobiology 32:236–258.

Tate, T.A. 1998. Micromorphology of loessial soils and paleosols on aggrading landscapes of the Columbia Plateau. M.S. thesis, De-partment of Geology, Western Washington University, Pullman.

Tedford, R.H., L.B. Albright, A.D. Barnosky, I. Ferrusquia-Vil-lafranca, R.M. Hunt, J.E. Storer, C.C. Swisher, M.R. Voorhies, S.D. Webb, and D.P. Whistler. 2004. Mammalian biochronology of the Arikareean through Hemingfordian interval (late Oligo-cene through early Pliocene epochs). Pp. 169–231 in M.O. Woodburne (ed.). Late Cretaceous and Cenozoic Mammals of North America. Columbia University Press, New York.

Van Valkenburgh, B., T. Sacco, and X. Wang. 2003. Pack-hunt-ing in Miocene borophagine dogs: evidence from cranial and body size data. American Museum of Natural History Bulletin 279:147–162.

Veizer, J., Y. Godderis, and L.M. Francois. 2000. Evidence for decoupling of atmospheric CO2 and global climate during the Phanerozoic Eon. Nature 408:698–701.

Wallace, P.E. 1946. A Miocene mammalian fauna from Beatty Buttes, Oregon. Carnegie Institution of Washington Publica-tions 551:113–134.

106 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

Watkins, N.D., and A.K. Baksi. 1974. Magnetostratigraphy and oroclinal folding of the Columbia River, Steens and Owyhee basalts, Oregon, Washington and Idaho. American Journal of Science 274:148–189.

Wheeler, E.A., and S.R. Manchester. 2002. Woods of the Eocene Nut Beds flora, Clarno Formation, Oregon, USA. International Association of Wood Anatomists Journal Supplement 3:1–188.

Whistler, D.P., and D.W. Burbank. 1992. Miocene biostratigraphy and biochronology of the Dove Spring Formation, Mojave Des-ert, California, and characterization of the Clarendonian mammal age. Geological Society of America Bulletin 104:644–658.

Wolf, K.H., and S. Ellison. 1971. Sedimentary geology of the zeolitic volcanic Rome Beds, Oregon. Sedimentary Geology

6:271–302.Wolfe, J.A., H.E. Schorn, C.E. Forest, and P. Molnar. 1997. Pa-

leobotanical evidence for high altitudes in Nevada during the Miocene. Science 276:1672–1675.

Wynn, J.G. 2003. Towards a physically-based model of CO2-induced stomatal frequency response. New Phytologist 157:391–398.

Zachos, J., M. Pagani, L. Sloan, E. Thomas, and K. Billups. 2001. Trends, rhythms, and aberrations in global climate, 65 Ma to present. Science 292:686–693.

Zeitler, P.K., A.S. Meltzer, P.O. Koons, D. Craw, B. Hallet, S.P. Chamberlain, W.F.S. Kidd, S.K. Park, L. Seeber, M. Bishop, and J. Shroder. 2001. Erosion, Himalayan geodynamics and the geomorphology of metamorphism. GSA Today 11:1–9.

App

endi

x 1.

Dia

gnos

es a

nd id

entifi

catio

ns o

f C

enoz

oic

pedo

type

s of

Ore

gon

and

Was

hing

ton.

Sah

aptin

mea

ning

is a

fter

Rig

sby

(196

5) a

nd D

elan

cey

et a

l. (1

988)

; so

me

pale

osol

s ar

e de

scri

bed

in t

his

pape

r, a

nd t

he o

ther

s ar

e de

scri

bed

by R

etal

lack

et

al. (2

000,

200

2a).

Ped

otyp

e Sa

hapt

in

Ort

hogr

aphy

T

ype

profi

le

Dia

gnos

is

U.S

. F.

A.O

. m

ap

Aus

tral

ian

Abi

axi

Bitt

er r

oot

Abi

áXi

Bon

e C

reek

H

igh

soda

cla

yey

sand

ston

e w

ith

silic

eous

H

aplo

salid

O

rthi

c So

lonc

hak

rhiz

ocon

cret

ions

, an

d re

lict

bedd

ing

So

lonc

hak

Aca

s ey

e Á

_aš

Han

cock

Can

yon

Pur

ple,

slic

kens

ided

, su

bsur

face

cla

yey

(Bt)

Plin

thic

Fe

rric

Acr

isol

L

ater

itic

(C

larn

o)

hori

zon

wit

h re

d no

dule

s H

aplo

hum

ult

Po

dzol

ic

Apa

x sk

in

Apá

x So

uthe

rn P

aint

ed

Bro

wn

cong

lom

erat

e, w

ith

wea

k su

bsur

face

A

ndic

D

ystr

ic

Ear

thy

Sand

Hill

s cl

ayey

(B

t) h

oriz

on

Dys

troc

hrep

t C

ambi

sol

Cil

roun

d C

í.l

Rin

gold

C

rum

b te

xtur

ed s

urfa

ce (

mol

lic)

over

dee

p C

alci

aquo

ll O

rthi

c W

iese

nbod

en

(>50

cm

) ca

lcar

eous

nod

ules

Gre

yzem

Cilp

a in

rou

nd

Cí.l

-pa

Rin

gold

C

rum

b te

xtur

ed s

urfa

ce (

mol

lic)

over

sha

llow

C

alci

aquo

ll O

rthi

c W

iese

nbod

en

(<50

cm

) ca

lcar

eous

nod

ules

Gre

yzem

Cm

ti ne

w

_m

tí M

asca

ll R

anch

B

row

n si

ltsto

ne w

ith

relic

t be

ddin

g an

d Fl

uven

t E

utri

c Fl

uvis

ol

Allu

vial

Soi

l

ro

ot t

race

s

Cm

uk

blac

k _

múk

be

low

Bla

ck S

pur

Bla

ck li

gnite

on

gray

cla

ysto

ne w

ith

loca

l H

emis

t E

utri

c H

isto

sol

Hum

ic G

ley

(C

larn

o)

iron-

man

gane

se n

odul

es

Iluk

as

fire-

woo

d Il

uk-a

s Pic

ture

Gor

ge

Thi

ck, re

d (1

0R),

wit

h cl

ayey

sub

surf

ace

Hap

luda

lf O

rthi

c L

uvis

ol

Bro

wn

Podz

olic

ho

rizo

n on

bas

altic

rub

ble

and

basa

lt

Isci

t pa

th

Íš_í

t B

one

Cre

ek

Cru

mb-

stru

ctur

ed s

urfa

ce (

A)

over

sili

ceou

s D

urix

eral

f M

ollic

B

row

n H

ardp

an

duri

pan

(Bq)

So

lonc

hak

So

il

Kal

as

raco

on

Ka.

lás

Mas

call

Ran

ch

Cru

mb-

stru

ctur

ed c

laye

y (m

ollic

) su

rfac

e Pla

caqu

and

Mol

lic G

leys

ol

Wie

senb

oden

ov

er b

lack

-spo

tted

and

vei

ned

(pla

cic

horizo

n)

Ksk

us

smal

l K

skús

C

entr

al P

aint

ed

Thi

n re

ddis

h br

own,

roo

ted

surf

ace

Fluv

ent

Dys

tric

Flu

viso

l A

lluvi

al S

oil

H

ills

Kw

alk

long

kw

a.lk

Pic

ture

Gor

ge

Car

bona

ceou

s cl

ayey

(A

) on

gra

y sh

ale

Aqu

ent

Gle

yic

Luv

isol

H

umic

Gle

y

an

d ba

salt

Lak

ayx

shin

e L

a.kà

yX

Red

Hill

(C

larn

o)

Red

(2.

5YR

-10R

), c

laye

y, t

hick

, ab

unda

nt

Hap

ludu

lt Fe

rric

Acr

isol

K

rasn

ozem

sl

icke

nsid

ed c

utan

s, d

eepl

y w

eath

ered

Lak

im

soot

L

a.k’

im

Cen

tral

Pai

nted

B

row

n to

oliv

e, w

ith

root

tra

ces

and

blac

k A

quan

dic

Eut

ric

Gle

ysol

H

umic

Gle

y

Hill

s iro

n-m

anga

nese

nod

ules

Pla

caqu

ept

Luc

a re

d L

u_á

Whi

teca

p K

noll

Red

(2.

5YR

-10R

), t

hick

, cl

ayey

, w

ith

Hap

luda

lf C

hrom

ic

Red

Pod

zolic

(Cla

rno)

re

mna

nt w

eath

erab

le m

iner

als

L

uvis

ol

Luq

uem

de

caye

d fir

e L

uq’_

m

Cla

rno

fern

qua

rry

Whi

te b

edde

d vo

lcan

ic a

sh w

ith

root

tra

ces

Typ

ic U

divi

tran

d V

itric

And

osol

A

lluvi

al

ÁÁ

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 107

App

endi

x 1.

(co

nt.)

Dia

gnos

es a

nd id

entifi

catio

ns o

f C

enoz

oic

pedo

type

s of

Ore

gon

and

Was

hing

ton.

Ped

otyp

e Sa

hapt

in

Ort

hogr

aphy

T

ype

profi

le

Dia

gnos

is

U.S

. F.

A.O

. m

ap

Aus

tral

ian

Maq

as

yello

w, or

ange

M

aqáš

C

arro

ll R

im

Bro

wn,

fine

blo

cky

peds

, th

ick

subs

urfa

ce

Vitr

ic

Och

ric

And

osol

N

on-c

alci

c So

il

ho

rizo

n H

aplu

stan

d

Mic

ay

root

M

í_ay

C

larn

o m

amm

al

Bro

wn

to o

live

clay

wit

h ro

ot t

race

s an

d A

quan

dic

Eut

ric

Fluv

isol

A

lluvi

al S

oil

qu

arry

re

lict

bedd

ing

Fluv

aque

nt

Mon

ana

unde

r-ne

ath

Mon

a.na

B

one

Cre

ek

Thi

n im

pure

lign

ite (

O)

on s

ands

tone

and

Sa

pris

t E

utri

c H

isto

sol

Aci

d Pe

at

silts

tone

wit

h sh

allo

w r

oot

trac

es

Nix

go

od

Níx

K

ahlo

tus

Thi

ck (

>50

cm)

crum

b te

xtur

ed (

mol

lic A

) H

aplo

xero

ll K

asta

noze

m

Pra

irie

Soi

l

ov

er d

eep

calc

areo

us lo

ess

Nuk

ut

flesh

N

ukút

B

row

n G

rott

o R

ed s

licke

nsid

ed c

lay

over

thi

ck v

iole

t L

ithi

c O

rthi

c A

cris

ol

Kra

snoz

em

(P

aint

ed H

ills)

sa

prol

ite o

n rh

yolit

e flo

w

Kan

hapl

udul

t

Nuq

was

th

roat

N

uq’w

as

Pic

ture

Gor

ge

Ora

nge

mod

erat

ely

wea

ther

ed b

asal

tic

Dys

troc

hrep

t D

ystr

ic

Non

-cal

cic

rubb

le o

ver

basa

lt

Cam

biso

l B

row

n So

il

Pasc

t cl

oud

Páš_

t R

ed H

ill (

Cla

rno)

O

live

gray

to

oran

ge, sl

icke

nsid

ed,

Som

brih

umul

t H

umic

Acr

isol

G

rey

Bro

wn

subs

urfa

ce c

laye

y (B

t) h

oriz

on

Podz

olic

Pata

t tr

ee

Páta

t H

anco

ck C

anyo

n B

edde

d sa

ndst

one

wit

h ro

ot t

race

s, m

ildly

Psa

mm

entic

E

utri

c B

row

n E

arth

(Cla

rno)

le

ache

d an

d fe

rrug

iniz

ed

Eut

roch

rept

C

ambi

sol

Patu

m

ount

ain

Pátu

B

one

Cre

ek

Cru

mb-

stru

ctur

ed b

row

n (2

.5Y)

sur

face

(A

) C

alci

xero

ll C

alci

c C

hern

ozem

ov

er s

hallo

w (

<50

cm)

mic

rite

-cha

lced

ony

K

asta

noze

m

rhiz

ocon

cret

ions

(B

k)

Pla

s w

hite

Plá

š B

one

Cre

ek

Whi

te, w

eakl

y st

ruct

ured

silt

ston

e w

ith

Ust

ic

Cal

cic

Xer

osol

G

rey

brow

n

de

ep (

>45

cm)

calc

areo

us n

odul

es

Hap

loca

lcid

Cal

care

ous

Soil

Pla

spa

In w

hite

Plá

š-pa

B

one

Cre

ek

Whi

te, w

eakl

y st

ruct

ured

silt

ston

e w

ith

Typ

ic

Cal

cic

Gre

y B

row

n

sh

allo

w (

<45

cm)

calc

areo

us n

odul

es

Hap

loca

lcid

Ye

rmos

ol

Cal

care

ous

Soil

Psw

a st

one,

cla

y Pšw

á be

low

Bla

ck

Pur

ple

clay

ey s

ubsu

rfac

e (B

t) w

ith

Lit

hic

Hap

luda

lf O

rthi

c L

uvis

ol

Bro

wn

Podz

olic

Spur

(C

larn

o)

core

ston

es a

nd g

rada

tiona

l con

tact

dow

n to

an

desi

te

Sak

onio

n Šá

.k

sout

hern

Pai

nted

R

ed, cl

ayey

, th

ick

sapr

olite

wit

h an

desi

te

Typ

ic P

aleu

dult

Ferr

ic A

cris

ol

Bro

wn

Podz

olic

Hill

s co

rest

ones

Saya

yk

sand

Sa

yáyk

w

Cla

rno

Nut

Bed

s B

edde

d si

ltsto

ne w

ith

root

tra

ces

Tro

poflu

vent

E

utri

c Fl

uvis

ol

Allu

vial

Scat

da

rk

S_át

be

low

Cla

rno

Thi

n gr

ay c

lays

tone

on

ande

sitic

H

aplu

mbr

ept

Hum

icl

Alp

ine

Hum

us

N

ut B

eds

cong

lom

erat

e

Cam

biso

l

108 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

App

endi

x 1.

(co

nt.)

Dia

gnos

es a

nd id

entifi

catio

ns o

f C

enoz

oic

pedo

type

s of

Ore

gon

and

Was

hing

ton.

Ped

otyp

e Sa

hapt

in

Ort

hogr

aphy

T

ype

profi

le

Dia

gnos

is

U.S

. F.

A.O

. m

ap

Aus

tral

ian

Sita

xs

liver

Ši

t’áX

š R

ed H

ill (

Cla

rno)

O

live-

purp

le s

ilty

clay

ston

e, w

ith

relic

t Pla

caqu

and

Eut

ric

Gle

ysol

H

umic

Gle

y

be

ddin

g, a

nd ir

on-m

anga

nese

ski

ns a

nd

nodu

les

Skaw

sc

are

Skaw

Pic

ture

Gor

ge

Thi

n, d

ark

gray

to

blac

k sp

otte

d silts

tone

with

M

ollic

E

utri

c G

leys

ol

Hum

ic G

ley

root

tra

ces

over

bed

ded

tuff

aceo

us s

iltst

one

End

oaqu

ent

Skw

i-sk

wi

brow

n Sk

w’i-

skw

’i ce

ntra

l Pai

nted

R

eddi

sh b

row

n (7

.5YR

-10Y

R)

with

sub

surf

ace

Eut

ric

Och

ric

Bro

wn

Ear

th

H

ills

clay

ey (

Bt)

hor

izon

Fu

lvud

and

And

osol

Tat

as

bask

et

Tát

aš

Mas

call

Ran

ch

Cru

mb-

stru

ctur

ed, br

own

clay

ey s

ilty

surf

ace

Cal

ciud

oll

Cal

cic

Che

rnoz

em

over

dee

p (>

50 c

m)

calc

areo

us n

odul

es a

nd

Kas

tano

zem

ca

lcar

eous

rhi

zoco

ncre

tions

Tic

am

eart

h ti.

_ám

ce

ntra

l Pai

nted

R

ed (

7.5Y

R-5

YR),

wea

k su

bsur

face

A

ndic

E

utri

c C

hoco

late

Soi

l

Hill

s cl

ayey

(B

t) h

oriz

on

Eut

roch

rept

C

ambi

sol

Tili

wal

bl

ood

Tilí

wal

B

row

n G

rott

o V

ivid

red

(10

YR-7

.5YR

) cl

ayst

one

brec

cia

Plin

thic

Plin

thic

K

rasn

ozem

(Pai

nted

Hill

s)

wit

h dr

ab-h

aloe

d ro

ot t

race

s K

andi

udox

Fe

rral

sol

Tim

a w

rite

T

ima

Bon

e C

reek

G

ranu

lar

stru

ctur

e su

rfac

e (A

) ov

er c

laye

y N

atri

c D

urix

eral

f M

ollic

So

lone

tz

subs

urfa

ce (

Bt)

and

sili

ceou

s du

ripa

n (B

q)

So

lone

tz

Tla

l ci

cada

T

lal

Kah

lotu

s W

hite

loes

sic

with

abu

ndan

t sh

allo

w (

<50

cm)

Hap

loca

lcid

C

alci

c G

rey

Bro

wn

calc

areo

us n

odul

es a

nd a

bund

ant

cica

da

X

eros

ol

Cal

care

ous

Soil

burr

ows

Tna

n cl

iff

tnán

M

asca

ll R

anch

R

eddi

sh b

row

n (1

0YR

-7.5

YR),

cla

yey

Mol

lic

Cal

cic

Bro

wn

silty

, gr

anul

ar-c

rum

b st

ruct

ure

surf

ace

Hap

loca

lcid

X

eros

ol

Har

dpan

Soi

l

ov

er s

hallo

w (

<50

cm)

calc

areo

us

rhiz

ocon

cret

ions

Tuk

say

cup,

pot

T

uksá

y so

uthe

rn P

aint

ed

Red

(2.

5YR

-10R

), k

aolin

itic,

sub

surf

ace

Plin

thic

Plin

thic

R

ed P

odzo

lic

H

ills

clay

ey (

Bt)

hor

izon

, w

ith

rede

posi

ted

Pale

udul

t A

cris

ol

soil

clas

ts

Tut

anik

ha

ir

Tút

anik

U

nity

N

ear-

mol

lic b

row

n th

ick

surf

ace

(A)

Typ

ic

Hap

lic

Bro

wn

Ear

th

over

dee

p ca

lcar

eous

and

sili

ceou

s N

atri

xera

lf K

asta

noze

m

rhiz

ocon

cret

ions

Wal

asx

pine

gum

W

alá.

sX

Mas

call

Ran

ch

Pale

yel

low

cla

yey

(A)

wit

h sl

icke

nsid

ed

Chr

omud

ert

Chr

omic

B

row

n C

lay

clay

ski

ns

V

ertis

ol

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 109

110 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

App

endi

x 1.

(co

nt.)

Dia

gnos

es a

nd id

entifi

catio

ns o

f C

enoz

oic

pedo

type

s of

Ore

gon

and

Was

hing

ton.

Ped

otyp

e Sa

hapt

in

Ort

hogr

aphy

T

ype

profi

le

Dia

gnos

is

U.S

. F.

A.O

. m

ap

Aus

tral

ian

Waw

cak

split

W

awc’

ak

sout

hern

Pai

nted

O

live

brow

n, c

laye

y, w

ith

defo

rmed

cla

y E

ntic

C

hrom

ic

Gre

y C

lay

H

ills

skin

s an

d pr

omin

ent

clas

tic d

ikes

C

hrom

uder

t V

ertis

ol

Yanw

a w

eak,

poo

r Ya

nwá

sout

hern

Pai

nted

T

hin,

bro

wn,

cla

yey

to s

ilty,

impu

re

His

tic

Hum

ic

Hum

ic G

ley

H

ills

ligni

tes

on a

roo

ted

unde

rcla

y H

umaq

uept

G

leys

ol

Yapa

s gr

ease

Yá

paš

Car

roll

Rim

D

ark

brow

n, fi

ne b

lock

y pe

ds (

A, B

w),

M

ollic

M

ollic

Pra

irie

Soi

l

(Pai

nted

Hill

s)

over

dee

p (>

50 c

m)

calc

areo

us

Hap

lust

and

And

osol

no

dule

s (B

k)

Yapa

spa

in g

reas

e Yá

paš-

pa

Bon

e C

reek

D

ark

brow

n, fi

ne b

lock

y pe

ds (

A, B

w),

V

itran

dic

Cal

cic

Gre

y B

row

n

ov

er s

hallo

w (

<50

cm)

calc

areo

us

Hap

loca

lcid

X

eros

ol

Cal

care

ous

Soil

nodu

les

(Bk)

Xau

s ro

ot

Xau

S M

asca

ll R

anch

B

row

n vo

lcan

icla

stic

san

dsto

ne w

ith

Cal

cari

c Psa

mm

ent

Allu

vial

Soi

l

re

lict

bedd

ing

and

root

tra

ces

Fluv

isol

Xax

us

gree

n X

áXuš

Fo

ree

Gre

en, fin

e bl

ocky

ped

s (A

, B

w),

ove

r A

quic

V

itric

W

iese

n-bo

den

(n

ear

Day

ville

) de

ep (

>50

cm)

calc

areo

us n

odul

es (

Bk)

U

stiv

itran

d A

ndos

ol

Xax

uspa

in

gre

en

XáX

uš-p

a Fo

ree

Gre

en, fin

e bl

ocky

ped

s (A

, B

w),

ove

r A

quic

C

alca

ric

Gre

y B

row

n

(nea

r D

ayvi

lle)

shal

low

(<5

0 cm

) ca

lcar

eous

nod

ules

(B

k)

Hap

loca

lcid

G

leys

ol

Cal

care

ous

Soil

App

endi

x 2.

Key

to

Cen

ozoi

c pa

leos

ols

of c

entr

al O

rego

n an

d W

ashi

ngto

n.

P

aren

t M

ater

ial

Subs

urfa

ce H

oriz

on

Surf

ace

Hor

izon

O

ther

Dif

fere

ntia

e Ped

otyp

e

1. R

hyod

aciti

c lo

essi

c 1.

1. R

elic

t be

ddin

g an

d ro

ot

1.1.

1. C

lear

rel

ict

bedd

ing

1.1.

1.1.

Gra

y, g

reen

or

brow

n cl

ayst

one

Mic

ay

silty

tuf

f tr

aces

onl

y

1.

1.1.

2. G

ray

to b

row

n si

ltsto

ne

Saya

yk

1.

1.1.

3. R

ed c

lays

tone

K

skus

1.

1.1.

4. B

row

n cl

ayey

silt

ston

e C

mti

1.

1.1.

5. W

hite

vol

cani

c as

h L

uque

m

1.

1.1.

6. O

live

brow

n cl

ay, w

ith

defo

rmed

cla

y sk

ins

Waw

cak

an

d pr

omin

ent

clas

tic d

ikes

1.

1.1.

7. Y

ello

w c

lay

wit

h de

form

ed c

lay

skin

s W

alas

x

1.1.

2. P

eat,

lign

ite o

r co

al

1.1.

2.1.

Bla

ck c

oal o

n cl

ayst

one

Cm

uk

1.

1.2.

2. B

row

n cl

ayey

lign

ite o

n si

ltsto

ne

Yanw

a

1.

1.2.

3. B

lack

cla

yey

ligni

te o

n sa

ndst

one

and

silts

tone

M

onan

a

1.

2. L

arge

bla

ck ir

on-m

anga

nese

1.

2.1.

Gra

y or

gre

en c

lays

tone

1.

2.1.

1. R

elic

t be

ddin

g L

akim

mot

tles

1.

3. S

mal

l dar

k gr

ay to

blac

k iro

n 1.

3.1.

Pla

ty t

o bl

ocky

ped

s

Skaw

man

gane

se n

odul

es

1.3.

2. C

rum

b te

xtur

ed s

urfa

ce

K

alas

(m

ollic

)

1.

4. C

lay

enri

ched

(ar

gilli

c),

1.4.

1. P

laty

to

bloc

ky p

eds

1.4.

1.1.

Pur

ple,

slic

kens

ided

, su

bsur

face

cla

yey

(Bt)

A

cas

no

n-ca

lcar

eous

, bl

ocky

ped

s (n

on m

ollic

) ho

rizo

n w

ith

red

nodu

les

1.

4.1.

2. R

ed (

2.5Y

R-1

0R),

sm

ectit

ic, w

ith

rem

nant

L

uca

w

eath

erab

le m

iner

als

1.

4.1.

3. R

ed (

2.5Y

R-1

0R),

kao

liniti

c, w

ith

Tuk

say

re

depo

site

d so

il cl

asts

1.

4.1.

4. V

ivid

red

(10

R-7

.5R

) cl

ayst

one

brec

cia

wit

h T

iliw

al

dr

ab-h

aloe

d ro

ot t

race

s

1.

4.1.

5. R

ed (

2.5Y

R-1

0R)

wit

h sl

icke

nsid

ed s

mec

titic

L

akay

x

clay

and

rar

e w

eath

erab

le m

iner

als

1.

5. C

laye

y en

rich

ed (

argi

llic)

1.

5.1.

Fin

e bl

ocky

to

gran

ular

1.

5.1.

1. N

on-n

odul

ar

Skw

iskw

i

and

gran

ular

str

uctu

red

stru

ctur

ed s

urfa

ce (

near

mol

lic)

1.

5.1.

2. d

eep

calc

areo

us a

nd s

ilice

ous

rhiz

ocon

cret

ions

T

utan

ik

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 111

App

endi

x 2.

(co

nt.)

Key

to

Cen

ozoi

c pa

leos

ols

of c

entr

al O

rego

n an

d W

ashi

ngto

n.

P

aren

t M

ater

ial

Subs

urfa

ce H

oriz

on

Surf

ace

Hor

izon

O

ther

Dif

fere

ntia

e Ped

otyp

e

1.

5.1.

3. S

ilice

ous

duri

pan

(Bq)

at

dept

h T

ima

1.5.

2. C

rum

b te

xtur

ed s

urfa

ce

N

ix

(mol

lic)

1.

6. C

lay

enri

ched

, bu

t no

t 1.

6.1.

Pla

ty t

o bl

ocky

str

uctu

red

1.6.

1.1.

Bro

wn

(2.5

Y-10

YR)

Maq

as

qu

ite a

rgill

ic, no

ncal

care

ous

surf

ace

(non

mol

lic)

1.

6.1.

2. R

ed (

7.5Y

R-5

YR)

Tic

am

1.

7 W

ell d

evel

oped

cal

care

ous

1.7.

1. M

assi

ve, pl

aty

or b

lock

y 1.

7.1.

1. W

hite

, tu

ffac

eous

Pla

s

nodu

les

deep

er t

han

50 c

m

peds

(no

n-m

ollic

)

1.

7.1.

2. G

reen

tuf

face

ous,

X

axus

1.

7.1.

3. B

row

n, t

uffa

ceou

s Ya

pas

1.7.

2. C

rum

b te

xtur

ed s

urfa

ce

C

il

(m

ollic

)

1.

8. W

ell d

evel

oped

cal

care

ous

1.8.

1 M

assi

ve, pl

aty

or b

lock

y 1.

8.1.

1. G

reen

tuf

face

ous

X

axus

pa

no

dule

s sh

allo

wer

tha

n 50

cm

pe

ds (

non-

mol

lic)

1.

8.1.

2. B

row

n tu

ffac

eous

Ya

pasp

a

1.

8.1.

3. W

hite

loes

sic

wit

h ab

unda

nt c

icad

a bu

rrow

s T

lal

1.1.

2. C

rum

b te

xtur

ed s

urfa

ce

C

ilba

(mol

lic)

1.

9. W

ell d

evel

oped

cal

care

ous

1.9.

1. M

assi

ve, pl

aty

or b

lock

y 1.

9.1.

1. W

hite

, tu

ffac

eous

,

Pla

spba

nodu

les

shal

low

er t

han

45 c

m

peds

(no

n-m

ollic

)

1.

10. Si

licic

rhi

zoco

ncre

tions

1.

10.1

. C

rum

b te

xtur

ed s

urfa

ce

1.10

.1.1

. C

alci

c ho

rizo

n de

eper

tha

n 50

cm

T

atas

and

less

er c

arbo

nate

at

dept

h (m

ollic

)

1.

10.1

.2. C

alci

c ho

rizo

n sh

allo

wer

tha

n 50

cm

Pa

tu

1.

11. T

hick

sili

ceou

s du

ripa

n

Is

cit

(B

q) a

t de

pth

2. V

olca

nicl

astic

san

dsto

ne

2.1.

Cla

yey

root

tra

ces

little

2.

1.1.

Rel

ict

bedd

ed s

ands

tone

2.

1.1.

1. L

ow-s

oda

sand

ston

e X

aus

or c

ongl

omer

ate

wea

ther

ed

2.

2. S

ilice

ous

rhiz

ocon

cret

ions

2.

2.1.

Rel

ict

bedd

ed s

ands

tone

2.

2.1.

1. H

igh

soda

cla

yey

sand

ston

e A

biax

i

little

wea

ther

ed

2.

3. M

ildly

leac

hed

and

2.3.

1. R

elic

t be

dded

san

dsto

ne

2.3.

1.1.

On

ande

sitic

con

glom

erat

e Pa

tat

fe

rrug

iniz

ed

112 PALEOBIOS, VOL. 28, NUMBER 3, JANUARY 2009

App

endi

x 2.

(co

nt.)

Key

to

Cen

ozoi

c pa

leos

ols

of c

entr

al O

rego

n an

d W

ashi

ngto

n.

P

aren

t M

ater

ial

Subs

urfa

ce H

oriz

on

Surf

ace

Hor

izon

O

ther

Dif

fere

ntia

e Ped

otyp

e

2.

4. L

ittle

wea

ther

ed

2.4.

1. T

hin

gray

cla

ysto

ne

2.4.

1.1.

On

ande

sitic

con

glom

erat

e Sc

at

2.

5. R

elic

t be

ddin

g, a

nd ir

on-

2.5.

1. O

live-

purp

le s

ilty

clay

ston

e 2.

5.1.

1. O

n an

desi

tic c

ongl

omer

ate

Sita

xs

m

anga

nese

cla

y-sk

ins

and

nodu

les

2.

6. W

ith

wea

k su

bsur

face

2.

6.1.

Bro

wn

pedo

lithi

c 2.

6.1.

1. O

n br

own

pedo

lithi

c co

nglo

mer

ate

Apa

x

clay

ey (

Bt)

hor

izon

co

nglo

mer

ate

2.

7. O

live

gray

to

oran

ge,

2.7.

1. O

live

gray

to

oran

ge

2.7.

1.1.

On

ande

sitic

con

glom

erat

e Pa

sct

slic

kens

ided

, cla

yey

(Bt)

hor

izon

cl

ayst

one

3. R

hyol

ite fl

ow

3.1.

Red

slic

kens

ided

cla

y 3.

1.1.

Red

slic

kens

ided

cla

y 3.

1.1.

1. T

hick

vio

let

sapr

olite

N

ukut

4. B

asal

tic fl

ow

4.1.

Thi

ck, re

d (1

0R),

cla

yey

4.1.

1. R

ed (

10R

) pl

aty

to b

lock

y

Iluk

as

su

bsur

face

hor

izon

4.

2. G

ray

shal

ey

4.2.

1. C

arbo

nace

ous

clay

ey

K

wal

k

4.

3. O

rang

e cl

ayey

4.

3.1.

Ora

nge

clay

ey

4.3.

1.1.

Ora

nge-

wea

ther

ed b

asal

tic r

ubbl

e N

uqw

as

5. A

ndes

itic

flow

5.

1. R

ed, c

laye

y, s

ubsu

rfac

e (B

t)

5.1.

1. R

ed c

lays

tone

5.

1.1.

1. C

ores

tone

s an

d th

ick

sapr

olite

Sa

k

6. A

ndes

itic

intr

usiv

e 5.

2. P

urpl

e cl

ayey

sub

surf

ace

(Bt)

5.

2.1.

Pur

ple

plat

y cl

ayst

one

5.2.

1.1.

Cor

esto

nes

and

thic

k sa

prol

ite

Psw

a

RETALLACK—CENOZOIC COOLING AND GRASSLAND EXPANSION IN OR AND WA 113