STRATIGRAPHY AND CORRELATION OF GLACIAL DEPOSITS OF THE ROCKY MOUNTAINS, THE COLORADO PLATEAU AND THE RANGES OF THE GREAT BASIN

Gerald M. Richmond u.s. Geological Survey, Box 25046, Federal Center, MS 913, Denver, Colorado 80225, U.S.A.

INTRODUCTION glaciations (Charts lA, 1B) see Fullerton and Rich- mond, Comparison of the marine oxygen isotope The Rocky Mountains, Colorado Plateau, and Basin record, the eustatic sea level record, and the chronology and Range Provinces (Fig. 1) together occupy much of of glaciation in the United States of America (this the western interior United States. These regions volume). include approximately 140 mountain ranges that were glaciated during the Pleistocene. Most of the glaciers Historical Perspective were valley glaciers, but ice caps formed on uplands Following early recognition of deposits of two alpine locally. Discussion of the deposits of all of these ranges glaciations (Gilbert, 1890; Ball, 1908; Capps, 1909; would require monographic analysis. To avoid this, Atwood, 1909), deposits of three glaciations gradually representative ranges in each province are reviewed. became widely recognized (Alden, 1912, 1932, 1953; Atwood and Mather, 1912, 1932; Alden and Stebinger, Purpose and Scope 1913; Blackwelder, 1915; Atwood, 1915; Fryxell, 1930; This report summarizes the evidence for correlation Bradley, 1936). Subsequently drift of the intermediate of the Quaternary glacial deposits in 26 broadly glaciation was shown to represent two glacial advances distributed mountain ranges selected on the basis of (Fryxell, 1930; Horberg, 1938; Richmond, 1948, 1962a; availability of detailed information and length of glacial Moss, 1951a; Nelson, 1954; Holmes and Moss, 1955), record. and the older drift was shown to include deposits of Because the glacial deposits rarely are traceable from three glaciations (Richmond, 1957, 1962a, 1964a). one range to another, time-parallel criteria such as Deposits of two glacial advances during the last reliable radiometric ages, identifiable tephra, and glaciation were recognized initially (Ives, 1938; Sharp, paleomagnetic reversals are most useful for correlation. 1938; Moss, 1951a; Horberg, 1954; Holmes and Moss, However, such criteria presently are not available in 1955; Eschman, 1955). Then three were delineated most ranges, and therefore many correlations are based (Singewald, 1950; Nelson, 1954; Richmond, 1960, on relative age criteria. A great variety of relative age 1962a, 1964a, 1965a) and subsequently four were criteria currently are being explored and tested. They differentiated (Kiver, 1968, 1972; Graf, 1971). Many of are referred to here without evaluation. For some the publications cited above include regional corre- ranges I suggest correlations on the basis of chronologie lations based on stratigraphic, morphologic, pedologic, controls from other ranges, as shown on Charts 1A and and weathering criteria. The names of glaciations in the lB. Wind River Mountains (Washakie Point (oldest), The text is intended as an expanded explanation of Cedar Ridge, Sacagawea Ridge, Bull lake, and Pine- the stratigraphic columns shown in Charts 1A and lB. dale) were applied as a standard throughout the Rocky The bases for the time divisions and the time scale are Mountains in order to reduce the complexity of discussed in Introduction to Quaternary Glaciations of nomenclature (Richmond, 1965). Currently these units the United States ofAmerica (Richmond and Fullerton, are undergoing revision and subdivision (Charts lA, this volume). The glacial deposits in each range are 1B). treated individually to emphasize, from range to range, Until the advent of radiometric dating, the ages differences in the character of the deposits, the number assigned to glaciations in the western mountains were of glaciations or glacial advances recognized, and the conjectural. Few workers attempted correlation with criteria for correlation utilized by different investi- the continental glaciations. The Wisconsin 'stage' was gators. The columns for Yellowstone National Park considered to be no older than 25 ka, and the term and for the Sierra Nevada are included for purposes of early Wisconsin was applied to the earliest 'substage' of chronologie correlation. For discussions of those areas the Wisconsin 'stage' (Horberg, 1954). In this sense, see Richmond, Yellowstone National Park, and Fuller- the Bull Lake glaciation in the Rocky Mountains was ton, Sierra Nevada, this volume. For discussion of the considered to be early Wisconsin (or 'Iowan') in age correlation of marine oxygen isotope stages with and the Pinedale glaciation was considered to be late 99 100 Quaternar y Sc ience Reviews

. \ '":.. - -. -

100 laO III(ILO ME TEA S

FI G . 1. Inde x map o f th e western interior U nited States showing A , Northe rn R ock y M ountainssouthof th e limit o f Co rdille ra n ice sheetglaciation;B,MiddleRockyMou nta ins ; C , Sou thern R ocky Mountains ; D , Colo rado Pl ateau; E, Ranges in th e Great Basin. Numbered dotsrepresent a reas of al pine glaciation d iscu ssed in text a nd shown o n C ha rts lA and lB.

Area s of alpine glaciation on Figure 1 1: Glacier National Park , Montana. 15a: Front Range . Co lorado - east. 2: Elkh orn Mount ains, Montana. 15b: Front Range, Colorado - west. 3: North Bould er Mountains. Mont ana. 16a: Sawatch Range. Colorado - east. 4: Bull Mountain , Mont ana. 16b: Sawatch Range , Colora do - west. 5: Bitterroot Range, Montana. 17: San Juan Mount ains, Colorado. 6: Pioneer Mount ains, Montan a. 18: Sangre de Cristo Range , Colo rado- New Mexico. 7: Lemhi Rang e, Idaho. 19: Sierra Blanca, New Mexico. 8: Southwestern, Salmon River Mountains, Idaho. 20: Grand Mesa. Colorado. 9a: Wind River Range , Wyoming - east. 21: La Sal Mountains, Utah . 9b: Wind River Range , Wyoming - west. 22: Aquarius Plateau. Utah . 10: Bighorn Mountains, Wyomi ng. 23: San Francisco Peaks. Arizona. II : Northern Medic ine Bow Range , Wyoming . 24: White Mountains, Arizona. 12: Southern Medicine Bow Range , Colorado . 25: Ruby-East Humbolt Range . Nevada . 13: Uinta Mountains, Utah- Wyoming . 26: Wallowa Mount ains, O regon. 14: Wasatch Range , Utah . Quaternary Glaciations in the Northern Hemisphere IIII

Wisconsin in age (Blackwelder, 1915, 1931; Alden, Colorado Front Range. Henry Schwarcz, McMasters 1932; Atwood and Mather, 1932; Bradley, 1936; Sharp, University, and Barney Szabo, U.S. Geological 1938; Horberg, 1954). Bryan and Ray (1940), in a Survey, determined a number of 234U/23oTh ages, and pioneering attempt to correlate glaciations with vari- Meyer Rubin provided a 14C age from the Wind River ations in the earth's insolation proposed by Milan- Range. John N. Rosholt, Jr., determined a uranium- kovitch (1930), suggested that a succession of moraines trend age from the Glacier National Park area. Helpful in Colorado, which they assigned to 'substages' of the discussions of specific areas with Richard F. Madole, Wisconsin, might be 122-111 ka, 78-67 ka, 29.5-19.5 Ralph R. Shroba, Kenneth L. Pierce, Glenn R. Scott, ka and 10 ka old, but they pointed out the lack of David W. Moore, Paul E. Carrara, Chester A. substantive evidence for those age assignments. The Wallace, Bruce H. Bryant, Edward T. Ruppel, William characteristics of the two oldest moraines of the M. Weber, and William C. Mahaney are gratefully succession are those that typify moraines of the Bull acknowledged. I am indebted to Richard F. Madole Lake glaciation (Richmond, 1962b). and David S. Fullerton for comment and suggestions Documentation of a post-Sangamon glacial advance for improvement of the manuscript. earlier than the Wisconsin 'stage' in the midcontinent region, based on 'greater-than' 14C ages (Flint and Rubin, 1955), was followed by assignment of its NORTHERN ROCKY MOUNTAINS deposits to an early Wisconsin 'substage' (Dreimanis, 1960a, b) or to an Altonian 'substage' (Frye and The Northern Rocky Mountains, south of the Willman, 1960) of a redefined 'Wisconsinan stage' southern limit of Cordilleran ice sheet glaciation, (Frye et al., 1968). The youngest Bull Lake Till in the include approximately 58 ranges in which alpine Rocky Mountains was correlated with till of the glaciers developed during the Pleistocene. Most were Altonian 'substage' (Richmond, 1965a, Table 2), from valley glaciers, but ice caps or coalescent glacier which 14C ages from about 35,000 BP to about 38,000 complexes formed on the uplands of at least four BP had been obtained (Frye et al., 1968). Morrison and ranges. The largest ice cap was in the unnamed broad Frye (1965) estimated that the Bull Lake glaciation mountainous area along the Continental Divide south occurred between about 72,000 and 32,000 BP. Later of Glacier National Park (Fig. 1, area 1). The glacial correlations of glacial deposits in the western U.S.A. deposits of most of the ranges have received very little (Birkeland et al., 1971; Porter, 1971; Flint, 1971) study. Those of eight are discussed here. utilized the sparsely available radiometric ages, dated tephra, and paleomagnetic reversals. Subsequently, till Glacier National Park, Montana in the Yellowstone Park area, correlated with the Bull Glacier National Park, in the Lewis Range, Mon- Lake Till in the Wind River Range, has been shown to tana, (Fig. 1, area 1), extends southward from the be lllinoian in age (Pierce et al., 1976; Richmond, International Boundary with Canada on both sides of Yellowstone Park, this volume). Two extensive post- the Continental Divide. The area is significant because Sangamon, pre-Wisconsin glacial advances of 'Eowis- the relationships of alpine glacial deposits to deposits of consin' age have been identified (Richmond, Yellow- both Laurentide ice sheet glaciation to the east (see stone Park, this volume) and an early Wisconsin Fullerton and Colton, Montana Plains, this volume) advance has been postulated (Pierce et al., 1976; and Cordilleran ice sheet glaciation to the west (see Richmond, Yellowstone Park, this volume). Thus, at Richmond, Cordilleran ice sheet, this volume) are least two, and probably three, glacial advances inter- demonstrable. vened between the Bull Lake and the Pinedale glaci- Deposits of seven alpine glaciations and two Lauren- ations in Yellowstone Park (Chart lA). A recent tide glaciations are recognized (Chart lA). Source review of late Wisconsin alpine glaciation (Porter et al., rocks for the alpine tills are quartzite, argillite, lime- 1983) emphasizes chronology and the timing of devel- stone, dolomite, and diorite. The matrix is calcareous opment and wasting of the glaciers. A concurrent silty sand in the mountains and sandy clay on the review of Holocene alpine glaciation (Burke and piedmont. Pre-Wisconsin till was first recognized by Birkeland, 1983) summarizes stratigraphic and Alden (1912) and Alden and Stebinger (1913). Later, chronometric evidence for Holocene glacial advances Alden (1932) demonstrated its equivalence to the and the problems of correlating them. Kennedy Gravel of Willis (1902) as well as to part of the 'quartzite gravels' of Calhoun (1906), and he Acknowledgements renamed it the Kennedy Drift. The drift is deeply I sincerely thank Lon D. Drake, University of Iowa, leached and weathered (Horberg, 1956). It includes and Steven P. Esling, Southern Illinois University, for three superposed bouldery tills that are separated by permission to use information from their unpublished and overlain by thick weathered zones (Richmond, manuscript on the Quaternary geology of the Bighorn 1957). Together with their associated outwash gravel Mountains, referred to herein as 'written communi- and related deposits, these tills are designated the cation, 1984'. I am also grateful to P. Thompson Davis, lower, middle and upper tills of the Kennedy For- Mount Holyoke College, for permission to use an mation (Chart lA). The outwash gravel deposits cap unpublished 14C date for a near-cirque moraine in the three separate terraces, the highest being the 'No.1' 102 Quaternary Science Reviews bench of Alden (1932). A silt lens in the gravel on that recognize either alpine or continental 'early Wisconsin bench has normal magnetic polarity. Steeply tilted, or Illinoian' till in the area. However, gently sloping interlayered sand, silt, and till that unconformably end moraines of 'early Wisconsin mountain drift' were underlies gravel on the 'No. l' bench at the mountain mapped by Horberg (1956) in the headwaters of Lee front have reversed magnetic polarity. (Magnetic Creek, northwest of Saint Mary River (Fig. 2), and polarity measurements by Jeff Cary in the U.S. subsequently both alpine and continental drifts of Bull Geological Survey Laboratory at Denver from samples Lake age were recognized east of the river (Richmond, collected with the author.) The till, here informally 1965a; Richmond et al., 1965). The deposits now are termed till of Two Medicine Ridge, thus documents a considered Illinoian in age. Two similar large alpine fourth glaciation, which is older than the Matuyama- end moraines (Richmond et al., 1965), assigned to the Brunhes paleomagnetic reversal. Based on depth of lower and upper tills of the Saint Mary Ridge For- leaching and weathering, the four tills are assigned a mation (Chart 1A), extend eastward around Duck pre-Illinoian age. A uranium-trend age of 440 ± 120 ka Lake (Fig. 2, mtl and mtu) to Hall Coulee. At Hall (DLM-3) has been obtained from the youngest, or Coulee, the inner moraine (mtu) transgresses the outer upper till of the Kennedy Formation (John N. Rosholt, and merges eastward with continental till characterized written commun., 1985). by boulders of crystalline rock types from Canadian Late in pre-Illinoian time, the Saint Mary River sources. The continental till, here designated the extended its course southward from Canada, thereby Emigrant Gap Till, extends northeast along the pirating former east-flowing streams and east-trending northern escarpment of the 'No. l' bench (Fig. 2) and a paths of glacial flow (Alden and Stebinger, 1913; thin layer of it overlaps weathered gravel of the lower Alden, 1932; Richmond, 1957). Alden (1932) did not till of the Kennedy Formation on the bench.

GLACIER

NATIONAL

_____...... KILOMET£l"S /

FIG. 2. Distribution of alpine and continental moraines east of Glacier National Park, Montana.

A lpine tills Continental tills Cutbank Creek Formation Upper till - ctu Middle till - ctm Boundary Creek Till - bt Lower till - ctl St. Mary Ridge Formation Upper till - mtu Emigrant Gap Till - et Lower till - mtl Kennedy Formation Upper till - ktu Middle till - ktm DLM-3 Location of uranium-trend age. D Delta of Glacial Lake St. Mary. Quaternary Glaciations in the Northern Hemisphere 103

The lower and upper tills of the Saint Mary Ridge them and moraines in the cirques. On that basis, they Formation are correlated with the lower and upper tills probably represent the last readvance preceding wast- of the Bull Lake glaciation (Illinoian age) in the Wind ing of the ice to the cirques.Icorrelate the advance River Mountains, Wyoming, (Chart IB) (Richmond, with the Lamar Valley ad vance in Yellowstone Park 1965a, Richmond et al. , 1965a) on the basis of their (Chart lA) which occurred between about 13,140 and broad smooth form, the wide breaching of their end about 11,600 BP (Richmond, Yellowstone Park, this moraines, and the mature zonal soil formed on them. volume). The soil is preserved only very locally , owing to No radiometric ages are available from the Cutbank subsequent extensive mass wasting. Locally, where Creek Formation. Both the alp ine and continental tills developed on outwash gravel associated with the outer are characterized by youthful morphologic features, Saint Mary Ridge moraine, the soil is overlain by immature soils and a nonintegrated secondary drain- outwash gravel associated with the inner moraine. This age . The continental till especially is characterized by suggests that the lower and upper tills of the Saint Mary abundant kettles, ponds, ice-disintegration rings and Ridge Formation probably are early and late Illinoian ridges (Parizek, 1969), eskers, kame terraces, and in age respectively (Chart lA). other ice-contact features. Others have concluded that Till assigned to the Cutbank Creek Formation (Chart the 'outer continental moraine' of Horberg (1954) , lA) is the 'mountain drift of the Wisconsin stage' of composed of Boundary Creek Till , is pre-late Wiscon- Alden (1932) and the 'late Wisconsin mountain drift' of sin in age (Stalker, 1977, 1980; Stalker and Harrison, Horberg (1954) . Its stratigraphic relation to successive 1977; Rutter, 1980; Karlstrom, 1982, 1984). However. outwash deposits indicates that it includes tills of its youthful constructional topography and weakly multiple advances. Three of these advance limits are developed soil suggest a late Wisconsin age . I infer th at shown in Fig. 2. Together with their stratigraphically it was deposited about 18,000 BP (Chart lA). Th e related outwash and other deposits , the tills are problem is further discussed by Fullerton and Colton designated the lower, middle, and upper tills of the (Montana Plains, thi s volume). The presence of the Cutbank Creek Formation. Glacier Peak tephra in Saint Mary River Valley West of Saint Mary River, but not shown on Fig. 2, southwest of Duck Lake (Fig . 2) indicates that that are a two lateral moraines of the lower till (ctl) trend north was deglaciated before 11,200 BP (Paul E. Carrara . into Canada. East of the river, two similar moraines pers. commun., 1984). trend northeast along a north-facing escarpment as far Three cirque moraines are present. Till of the outer as Hall Coulee where they are overlapped by conti- moraine here is designated the Blackfoot Mountain Till nental till containing erratics of crystalline rocks from and till of the inner two moraines is designated the Canada (Fig. 2, bt). In the Saint Mary River valley, the Mount Jackson Till , based on moraines in the area of alpine till is present beneath the continental till for at those mountains (Chart 1A). The Mazama '0' tephra least 18 km northeast of the International Boundary [age 6,845 ± 50 BP (Bacon, 1983)] is locally present on (Horberg, 1954), or 46 km from the point where Saint moraines of Blackfoot Mountain Till (Carrara and Mary River issues from the mountain front. Wilcox, 1984; Osborn, 1985) indicating that they are at Calhoun (1906) and Alden (1932) showed that the least early Holocene in age. The two Mount Jackson Laurentide ice sheet did not extend into the region until moraines are considered very late neoglacial in age after the alpine glaciers had begun to recede, a (Carrara and McGimsey, 1981). However, the extent conclusion further documented by Horberg (1954). Till of development of vegetation and the stability of blocks of the Laurentide advance here is designated the on the outer of the two moraines in some cirques Boundary Creek Till , based on a locality along Bound- suggests that some of them may be earlier late ary Creek near its confluence with Saint Mary River neoglacial in age. (Fig . 2) , where the till overlies alpine till of the lower till of the Cutbank Creek Formation. At its maximum Elkhorn Mountains, Northern Boulder Mountains, and extent, the Laurentide ice sheet blocked the Saint Mary Bull Mountain, Montana River Valley, impounding Glacial Lake Saint Mary Early work in these mountains (Fig. 1, areas 2, 3, 4) (Horberg, 1954) (Fig. 2). The head of the lake lapped is summarized by Ruppel (1962) who recognized against a readvancing alpine glacier that deposited deposits of three Pleistocene glaciations and one lateral moraines of the middle till of the Cutbank Creek Holocene cirque glaciation in the region. Source rocks Formation (Fig. 2, ctm). Two sets of these moraines are are chiefly quartz monzonite and fine-grained andesite, present. The surfaces of deltas (Fig. 2, D) marginal to the former deeply weathered before extrusion of the the lake represent its high stand. The lake drained ice- andesite. The oldest deposits of a possible 'first marginally northeast to Hall Coulee and then into the glaciation' (Chart lA) are formless masses of boulders North Fork of the Milk River. on Bull Mountain that are deeply weathered and A later readvance of the glaciers is indicated by end include erratic rock types. Deposits of the second moraines and other ice-limiting deposits in the indivi- glaciation gave been mostly stripped by mass wasting, dual mountain valleys (Fig. 2, ctu). These deposits are but smooth, rounded, dissected moraines remain on grouped in the upper till of the Cutbank Creek ridges and in the lower valleys. Weathering rinds on Formation.Ihave found no younger moraines between boulders of quartz monzonite are as much as 30 em 104 Quaternary Science Reviews thick; andesite clasts are not noticeably weathered. The The Lost Horse Drift underlies a sequence of 'second glaciation' was the most extensive, and ice caps irregular moraines characterized by steep slopes and an developed in the Elkhorn and northern Boulder abundance of boulders. An immature zonal soil about Mountains (Ruppel, 1962). Moraines of the 'third 60 em thick is developed on the till and in places the till glaciation' are bouldery and steeply sloping. Kettles overlies the soil developed on Charlos Drift. Granite and ponds are abundant in the ground moraine. weathering ratios range from 32-68-0 on the outer- Boulders are little weathered. Deposits of this glaci- most moraine to 76-24-0 on the innermost. Nine end ation are lacking in the northern Boulder Mountains moraines of Lost Horse Drift have been identified. (Ruppel, 1962) . The 'fourth glaciation' is represented Some are more pronounced than others. The outer five by fresh cirque moraines. are somewhat more dissected and more widely Based on degree of preservation of morainal form, breached than the inner four. They are assigned to the extent of dissection, and extent of weathering, Ruppel lower member of the Lost Horse Drift. The less (1962) considered the oldest glaciation to be early dissected inner four moraines are assigned to the Pleistocene in age, the second to correlate with the Bull middle member. Moraines of the upper member are Lake glaciation (Illinoian) in the Wind River Moun- present in or near the cirques. tains, Wyoming, and the third to be late Wisconsin in The extent to which end moraines of the lower age (Chart lA). Moraines in the cirques probably are member are breached relative to end moraines of the Holocene in age. Ruppel (1962) pointed out that middle member suggested to Weber (1972) that a summits in all three areas are at about the same significant time interval separated deposition of the two altitude; that all four glaciations occurred in the sets of moraines. I suggest correlation of that time Elkhorn Mountains, that only the first and third interval with a brief but warm interstadial about 17,000 occurred at Bull Mountain, and only the second BP that is documented by 14C dates and pollen in occurred in the northern Boulder Mountains. He Yellowstone National Park (Richmond, this volume). suggested that this distribution may be due to 'recur- Evidence of forest conditions along the Columbia River rent differential uplift of the individual mountain in Canada, near the International Boundary, about masses in Pleistocene time'. 17,000 BP also is documented (Chart lA) (Richmond, Cordilleran ice sheet, this volume). Bitteroot Range, Montana The youngest glacial deposits in the Bitteroot Range Alden (1953) recognized deposits of three glaciations are small moraines in and near the cirques. They have in the Bitteroot Range (Fig. 1, area 5). Subsequently a not been studied, but probably they are latest Pleisto- detailed study by Weber (1972) has stratigraphically cene and Holocene in age. defined and named the deposits and has determined Weber (1972) found wedges of well sorted sand of that lake sand representing high stands of Glacial Lake Glacial Lake Missoula, 3 to 25 m thick, interfingering Missoula interfingers with end moraines of the last with till of the outermost, the fourth, and the fifth end glaciation. Glacial Lake Missoula was a large lake moraines of the lower member of the Lost Horse Drift, dammed intermittently in the drainage of the Clark and with the second end moraine of the middle member Fork (river) by a glacier in the basin of Lake Pend (Chart lA). Some moraines of both members also are Oreille, Idaho, in late Wisconsin time (see Richmond, overlapped by sand initially attributed to Glacial Lake Cordilleran ice sheet, this volume). Missoula. However, Weber (pers . commun., 1985) According to Weber (1972) , the tills in the Bitteroot indicates that much of the sand that overlaps the Range consist of boulders and smaller clasts of massive moraines may have been winnowed from them by and gneissic crystalline rocks in an arkosic sandy colluvial or alluvial processes. The sand wedges that matrix. The Judd Drift (oldest) (Chart lA) commonly interfinger with the tills occur at the same range in retains no morainal form but locally underlies broad altitude as established high stands of Glacial Lake smooth ridges on the piedmont beyond end moraines of Missoula, and indicate that the lake existed at those the next younger glaciation. Boulders of gneiss in the levels at times during deposition of the outermost drift are much more weathered than those of massive moraine, and at least two other moraines of the lower granite or granodiorite. The soil on stratigraphically member of the Lost Horse Drift. These relationships related outwash gravel is about 1.3 m thick. demonstrate that alpine glaciers extended into Glacial The Charlos Drift underlies two sets of low, Lake Missoula early in late Wisconsin time, probably smoothly sloping moraines beyond the canyon mouths. between about 22,000 and 18,000 BP, and several A zonal soil about 80 em thick is developed on it and thousand years before the 15,000 BP maximum ad- the till overlaps the soil developed on Judd Drift. vance of the Cordilleran ice sheet (Richmond, Cordil- Granite weathering ratios are 16-86-4 to 22-76-2. * leran ice sheet, this volume). They also imply that End moraines are broadly breached. Glacial Lake Missoula was dammed by a glacier in the basin of Lake Pend Oreille, Idaho, early in late • Granite-weathering ratio is a comparison of the number of Wisconsin time and that the glacier was of local alpine surface boulders of massive granite or granodiorite that are: (a) origin. almost unweathered, (b) notably decayed on the surface but still solid , (c) greatly weathered, cavernous, or rotted (Blackwelder, The highest shorelines of Glacial Lake Missoula are 1931). not stratigraphically associated with moraines. Weber Quaternary Glaciations in the Northern Hemisphere 105

(1972) suggests that they may be Charlos (late Illi- thickness of carbonate coatings on clasts. The lower noian) in age. two tills are separated from the upper till by the carbonate horizon of a mature soil. They were corre- Pioneer Mountains, Idaho lated by Butler et al. with the 'early' and 'late' Bull Three glaciations are recognized in the Pioneer Lake moraines in the Wind River Mountains, Wyo- Mountains of Idaho (Fig. 1, area 6), the younger two of ming (Chart lA). The upper till is much less weathered which initially were correlated with 'substages' of the and has surficial characteristics common to till of the 'Wisconsin glacial stage' (Umpleby et al., 1930), and last glaciation. with the 'Wisconsin' and 'Illinoian or Iowan glacial Knoll (1977) attempted to distinguish deposits of stages' by Alden (1953). The deposits recently have separate advances during the last glaciation by detailed been reclassified (Evenson et al., 1982) (Chart 1A) on mapping of moraine segments. Subsequent application the basis of the degree of preservation of morainal of the same approach, in conjunction with a compara- form, extent of erosion and breaching by streams, tive study of a number of surface characteristics, broad differences in soil characteristics, relative dis- resulted in distinction of five glacial readvances of late tance of terminal moraines from cirque heads, and Wisconsin age and three of Holocene age (Butler et al., relationships of moraines to outwash terraces. Local 1983, 1984) (Chart 1A). Discovery of a Glacier Peak names also have been assigned to them. tephra, dated 11,200 BP (Mehringer et al., 1984), in Deposits attributed to the Pioneer glaciation (oldest) sediments retained by the third oldest of these mor- consist of thin patches of gravel on interfluves high aines (Chart 1A, moraine p) indicated that at least above present streams. Younger subdued end moraines three, and probably all five, advances are older than of two glacial advances associated with two successively 11,200 BP. A subsequent advance, the outer limits of lower outwash terraces are assigned to the Potholes which are designated by moraine segments e.' to i' glaciation. Still younger steeply sloping, sharp-crested, (Chart lA) is considered to be early Holocene in age, bouldery end moraines characterized by surface based on comparison of surface characteristics. How- irregularities, undrained depressions, ice-disintegration ever, the limit of that advance is unusually distant from features, and abundant boulders, are assigned to the the cirque headwall compared to the extent of early Copper Basin glaciation. Four such end moraines mark Holocene advances elsewhere. I suggest correlation of the extents of its maximum advance and of three that moraine with the Lamar Valley moraines, dated recessional readvances. All four moraines are graded to between about 13,100 and 11,600 BP, in Yellowstone the same outwash terrace and no buried soils have been National Park (Chart lA), and correlation of moraines observed in the deposits. Each of the three drainages of the preceding advance (moraine segments v, w, x, studied by Evenson et al. (1982) is underlain by and y on Chart lA), with the Deckard Flats moraines different rock types, thus providing a basis for deter- dated about 15,000 BP in Yellowstone National Park. mining provenance relationships. Rock glaciers, but no Butler et al. (1984) estimated that moraine j' (Chart moraines, are present in the cirques. lA) corresponds in age to that of periglacial ice wedge casts in sediments retained by moraine p. The wedge Lemhi Range, Idaho casts are dated between 10,130 ± 500 BP (Beta-3659) The glacial deposits of the Lemhi Range (Fig. 1, area and 7,560 ± 310 BP (Beya-3658). This suggests 7) in central Idaho have been subdivided into four units correlation of moraine j' with early Holocene moraines representing four episodes of glaciation (Ruppel, 1968, elsewhere. Moraine k', a cirque moraine, is considered 1980; Ruppel and Lopez, 1981) (Chart lA). The oldest to be early neoglacial in age on the basis of its distal deposits are sparse remnants of till that lack morainal slope angle, weak soil development, and the degree of form and consist of angular boulders of slightly implantation of surface boulders. weathered quartzite and rounded boulders and cobbles of siltite and deeply weathered quartzite that lie above and also beyond the outer limit of deposits of younger Southwestern Salmon River Mountains, Idaho glaciations. The intermediate deposits underlie Deposits of four glaciations were recognized in the smoothly sloping, well rounded moraines that are drainage of the North Fork of the Payette River near broadly breached and dissected. Clasts include quartz- the town of McCall (Fig. 1, locality 8) by Schmidt and ite, siltite, limestone, dolomite, andesite and granitic Mackin (1970). Till clasts are chiefly basalt and granitic rock types. Clasts at the surface of the intermediate rock types and the matrix is silty sand. Deeply moraines are more weathered and leached than are weathered, formless till-like diamictons, probably of clasts on the youngest moraines. The youngest mor- different ages (Schmidt and Mackin, 1970), extend far aines are sharp, irregular, bouldery, little dissected and beyond younger end moraines. The diamictons and little weathered. Several of them are nested upstream overlying fluvial and lacustrine beds containing pollen from the intermediate moraines. Small moraines in the indicative of a cool climate are tectonically (?) tilted cirques are essentially unmodified. locally as much as 20°. A younger undeformed till A study by Butler et al. (1983) disclosed three forms a broad, smooth end moraine. Granite boulders superposed tills, the lower two of which are distin- in the till are completely disintegrated and quartzite guished by differences in texture, weathering, and boulders have oxidized weathering rinds 15 ern or more 106 Quaternary Science Reviews in thickness. Schmidt and Mackin assigned a pre-Bull Yellowstone National Park (Chart lA and Richmond, Lak e age (here pre-Illinoian) to both units (Chart 1A). Yellowstone National Park, this volume). Moraines of the next younger glaciation are charac- terized by broad smooth slopes, filled or drained MIDDLE ROCKY MOUNTAINS depression s and well integrated drainage. Schmidt and Mackin considered them to be Bull Lake in age (here The Middle Rocky Mountainscomprise22ranges, late Illinoian). Moraines of the last glaciation are most of which are broad high arches separated by rough, little modified, bouldery, and have closed extensive basins. Valley glaciers de veloped in most of depressions; they were assigned to the Pinedale glaci- the ranges. Commonly they extended to the mouths of ation (here late Wisconsin) . Cirque moraines and rock the canyons, but in some cases they formed piedmont glaciers were assigned a neogl acial age. I infer that they lobes at the mountain fronts. Ice caps formed on the may include early Holocene deposits. uplands of at least three ranges. Each of the glaciated Recently, Colman and Pierce (1981, 1983, 1986) ranges has been investigated, some intensively. The remapped and analyzed the deposits using a variety of deposits in six of them are discussed here. relative age criteria, in particular,soildevelopment and thickness of weathering rinds on basalt clasts. They Wind River Range, Wyoming measured and statistically analyzed rinds on basalt Piedmont deposits of three glaciations: Buffalo drift, clasts in th e weathered zone on the Bull Lake and Bull Lake drift, and Pinedale dri ft (Blackwelder, 1915), Pinedale moraines of Schmidt and Mackin (1970), and initially were distinguished in the Wind River Range also on a ' pre-Bull Lake till beneath a Bull Lake (Fig. 1, area 9a and b) on the basis of differences in moraine. They assigned informal local names to the preservation of morainal form , breaching of terminal deposits (Chart 1A): moraines, dissection of lateral moraines, integration of

Schmidt and Mackin (1970) Coleman and Pierce (/986)

Pinedale morainal deposits Pilgrim Cove deposits McCall deposits

Some Pinedale and some Bull Lake deposits Williams Creek deposits

Bull Lake mor ainal deposits Timber Ridge deposits inner mora ine intermediate moraine outer moraine

Pre-Timber Ridge deposits

Pre-Bull Lake morainal ridge

Pre-Bull Lake till, fluvial and lacustrine deposits Map unit Otd of Schmidt and Mackin

Colm an and Pierce (1983, 1986) correlated the drainage, steepness of moraine slopes, surface boulder Timber Ridge deposits with till of a Bull Lake moraine frequency, extent of clast weathering, loess cover, and near West Yellowstone, Montana, which has been relation to outwash terraces. Currently, piedmont or estimated to be about 140,000 years old on the basis of lower canyon deposits of seven Pleistocene glaciations, the obsidian-hydration dating technique controlled by and upper canyon and cirque deposits of five advances the K-Ar ages of an older and ayoungerrhyolite flow of latest Pleistocene, early Holocene, and neoglacial (Pierce et a/., 1976). They compared weathering rind ages are recognized. thickn ess data from basalt clasts in soils on moraines in On the north and east flanks of the range, source Idaho with that from basalt clasts in soil on the Bull rocks are chiefly graniteandgranodiorite, quartzite, Lake moraine near West Yellowstone and made limestone, dolomite, sandstone and mudstone; on the 'reasonable guesses' for the ages of the succession of south and west flanks they are almost all Precambrian tills in Idaho as follows: Pilgrim Cove deposits-14 ka ; crystalline rock types. Most clasts in the tills are derived McCall deposits - 20 ka ; Williams Creek deposits - from bedrock, but some are derived from a Tertiary 50 ka, but more likely 60 ka; Timber Ridge deposits - regolith and others from boulder deposits of Tertiary 140 to 150 ka. In a buried soil on a pre-Timber Ridge age . The type deposit of the Buffalo drift has been deposit, basalt rinds are nearly as thick as those from an shown to be Pinedale in age (Richmond, 1976), and overlying Timber Ridge deposit; an age of about 260 ka both the 'Buffalo till' and the 'early' and 'late' Bull therefore was suggested for the pre-Timber Ridge Lake tills of Holmes and Mos s (1955) , along Big Sandy deposit. Ages shown on Chart 1A are modified slightly River in the southern part of th e range, are boulder to conform with K-Ar age controls for glaciations in deposits of Tertiary age (Richmond, 1983). The Wash- Quaternary Glaciations in the Northern Hemisphere 107 akie Point (oldest), Cedar Ridge, and Sacagawea Ridge area 9b), the outer Bull Lake end moraine has a Tills (Richmond, 1957, 1962, 1964) (Chart 1A) in uranium-trend age of 160 ± 50 ka (Rosholt et al ., 1985) places are superposed, are lithologically distinct and and therefore is late Illinoian in age. As at Bull Lake, are separated by paleosols. The Washakie Point Till is four inner moraines are nested within the outer known only where buried by younger till. The surface moraine (Richmond, 1986). In neither area are these of Cedar Ridge Till has no morainal form and the till is younger moraines dated, but it is possible that one or thoroughly oxidized, leached, and grussified. Its associ- more of them may be 'Eowisconsin' or early Wisconsin ation with two distinct outwash gravel terraces suggests in age (alternate interpretations, Chart 1B). Bull Lake that Cedar Ridge Till represents two glacial advances. moraines commonly are gently sloping, broadly Sacagawea Ridge Till underlies massive, smooth, breached, and less bouldery than Pinedale moraines. gently rounded moraines that have relatively few Locally they are mantled with loess. Detailed data on surface boulders. Locally the till is oxidized to depths of their surface weathering phenomena and soils are as much as 4 m. Many boulders, particularly those rich reported by Shroba (1977) and Mahaney (1978), in biotite, are grussified. End moraines of two Saca- though neither recognized the extent of removal of the gawea Ridge glacial advances, associated with two post-Bull Lake soil by mass wasting. distinct outwash gravel terraces, are recognized. The Pinedale Till was defined from the piedmont mor- Pearlette '0' volcanic ash bed (K-Ar age 610 ka) is aines that enclose large lakes in the vicinity of Pinedale present locally in the lower part of the older gravel near (Blackwelder, 1915). Seven end moraines enclose, or Dinwoodie Lake on the east side of the range and on terminate in, each lake (Richmond, 1986, unpublished the scarp of an outwash terrace of Cedar Ridge age maps). The moraines are fresh, steep, narrow-crested, above two adjacent outwash terraces of Sacagawea irregular, hummocky, and very bouldery. Clasts are Ridge age south of Boulder Lake on the west side. little weathered. Zones of disintegration rings (Parizek, Outwash terraces of Sacagawea Ridge age on the east 1969) are common immediately within the outermost side are capped with travertine in places. 230UP34Th moraine. Drainage is poorly integrated; depressions dates from a travertine dome on the younger outwash contain water; end moraines are narrowly breached. are >350 ka (79DUB12) near the base and ka Thin loess is mixed with the soil locally. Two outwash (WR-78-8) at the top (Schwarcz and Gascoyne, 1984). terraces are distinguished (Holmes and Moss, 1955). Sacagawea Ridge deposits thus represent two glacial The higher is related to the outer end moraine and the advances during an interval that is younger than 610 ka lower to the second and third end moraines. The small and older than 350 ka (Chart lA). amount of outwash from younger moraines commonly Bull Lake Till, at its stratotype locality at Bull Lake is present as ice contact deposits a short distance on the east side of the range (Fig. 1, area 9a) downstream from those moraines. (Richmond, 1964a; Murphy and Richmond, 1965; 230UP34Th dates as young as 24-30 ka (Henry Richmond and Murphy, 1965), includes three super- Schwarcz, written cornrnun., 1981) have been obtained posed tills (Chart lA). The lowest till rests on a from travertine on Bull Lake outwash terraces that are paleosol developed in colluvium and varved lake entrenched by Pinedale outwash terraces (Chart 1A). sediments overlying Sacagawea Ridge Till, and has a Dates of 20,800 ± 1200 BP (W-998; Ives et al., 1964) paleosol developed on it. The overlying till (Chart 1B, and 18,700 ± 600 BP (W-1303; Levin et al., 1965) were lower member, upper till) lacks a paleosol. It is obtained, respectively, from the base and above the overlain disconformably by the third till (Chart 1B, base of sediments in a small lake on Pinedale Till. The upper member, upper till) that bears a paleosol very sediments were collected and analyzed for pollen by similar to that on the lower till. Further study of the Robert C. Bright (lves et al., 1964). The lake is well area near the type locality has shown that at least two of upvalley from the outer two Pinedale end moraines in five nested Bull Lake end moraines are composed of the Green River Valley. No dates are available from the upper till. Soils on the moraines, examined with the younger Pinedale moraines. The youngest of these C.J. Sorenson, indicate that the post-Bull Lake soil has is present in the upper canyons in the southern part of been extensively stripped from moraine crests and that the range but occurs at or beyond the canyon mouths in slopes are mantled with till-derived colluvium and the northern part. Commonly it comprises two closely colluviated loess containing carbonate-coated clasts spaced ridges. The moraine enclosing Green River and scattered fragments of carbonate coatings derived Lakes is typical, and from it the glacial advance is from a pre-existing soil upslope. A partly preserved Bt designated the Green River Lakes advance. The horizon underlain by a Cca horizon, both involuted, moraine is correlated with the Deckard Flats moraines, was observed at one locality. The same conditions dated about 15,000 BP, in Yellowstone National Park prevail on the west side of the range (Richmond, 1986), (Chart 1A). where mapping of the Bull Lake and Pinedale moraines Cessation of outwash deposition along major drain- (Richmond, 1973) and of the soil types on them ages is indicated approximately by 23oUP34Th dates of (Sorenson, 1984) supports a conclusion that the post- 12.2 ± 0.7 ka (79DUB17; Schwarcz and Gascoyne, Bull Lake soil has been extensively removed by mass 1984), and 10.0 ± 2.0 (R83-4; Barney Szabo, written wasting. cornrnun., 1984), from the base and above the base At Pinedale, on the west side of the range (Fig. 1, respectively of travertine overlying the lowest Pinedale 108 Quaternary Science Reviews gravel terrace. A date of 11,100 ± 300 BP (W-1386; on valley slopes and divides, to which they assign a pre- Levin et al., 1965) was obtained from organic matter in Bull Lake (pre-late Illinoian) age (Chart 1A). travertine overlying the terrace. Moraines of the second glaciation are massive, Relatively small moraines of a previously unrecog- rounded, as much as 100 m high, and broadly breached. nized readvance are present well below the cirques Drainage is well integrated and depressions are either along upland drainages in the central and southern dissected or filled. Soils are zonal and, where fully parts of the range, and marginal to a former icecap on preserved, are characterized by a horizon of clay the plateau west of the central divide in the northern enrichment that grades down into an oxidized horizon part of the range. Their average altitude is about 3100 as much as 2 m thick (Nelson, 1977). The deposits are m (Richmond, 1984). The advance is named the attributed to the Bull Lake glaciation. Barnhardt Donald Creek advance on the basis of a type end (1979) recognized two Bull Lake moraines that he moraine in the drainage of Donald Creek west of the attributed to glacial advances of different ages on the central divide in the southern part of the range. A basis of weathering characteristics. Drake and Esling minimal age of 9,040 ± 300 BP (W-5607) has been (written commun., 1984) suggested that the moraines obtained from the base of peat overlying outwash fan represent readvances during a single glaciation. They gravel or silt of a small lake retained between the type also noted that moraines upvalley from the terminal are end moraine and the adjacent slope. The moraine is generally similar, but have more narrow crests and are estimated to be about 12,000 years old and is correlated somewhat less weathered. Their possible 'Eowisconsin' with the Lamar Valley moraines in Yellowstone or early Wisconsin age remains to be investigated. In National Park which are between about 13,100 and Tensleep Canyon, an end moraine with characteristics 11,200 years old (Chart 1A). similar to Bull Lake end moraines overlies alluvial and End moraines of four younger advances are present colluvial silts that contain a volcanic ash bed (Porter et just beyond and in the cirques. The oldest is the al., 1983). The ash bed has chemical characteristics Temple Lake moraine (Hack, 1943; Moss, 1951b) similar to a volcanic ash bed in Yellowstone National (Chart 1A). Others are the Indian Basin (early Park (Izett, 1981) that is K-Ar dated 155 ka (Rich- neoglacial), Audubon (late neoglacial) and Gannett mond, Yellowstone Park, this volume). That ash bed Peak (latest neoglacial) moraines. The deposits are occurs in lake silt that overlies older till attributed to distinguished on the basis of lichen size, surface Bull Lake glaciation. I suggest that the overlying till boulder weathering characteristics, and soil and loess probably is late Illinoian in age (Chart 1A), but it may thickness (Miller and Birkeland, 1974; Currey, 1974; be 'Eowisconsin' or early Wisconsin in age (Richmond, Mahaney, 1984; Mahaney et al., 1984). Currey (1974) Yellowstone Park, this volume). obtained a minimal age of 6,500 ± 230 BP (GX-3166D) The third glaciation in the Bighorn Mountains is for the type Temple Lake moraine. Subsequently, an represented by end moraines that are steep, high and older minimal age of 7,940 ± 190 BP (GaK-8216) was bouldery. The ground moraine is irregular and locally obtained from a moraine correlated with the Temple there are undrained depressions and ponds. Drake and Lake but referred to as 'late Pinedale' (Mahaney et al., Esling (written commun., 1984) assigned the deposits to 1984; Mahaney, 1984). Minimal dates for a correlative the Pinedale glaciation (late Wisconsin); the terminal moraine in a similar fourfold sequence in the Teton moraine and end moraines of three recessional re- Range (Mahaney and Spence, 1984) are 7,390 ± 100 advances upcanyon are designated Pinedale I, Pinedale BP (BGS-931) and 7,880 ± 100 BP (BGS-930) II, Pinedale III and Pinedale IV, respectively (Chart (Mahaney, written commun., 1985). I estimate the 1A). The basal organic sediment in a lake on a Pinedale actual age to be slightly less than 10 ka BP. A minimal III end moraine yielded a minimal age of 12,910 ± 400 age for the Indian Basin moraines is 3,050 ± 120 BP BP (DIC-189; Burkart, 1976). A minimal age of 8,195 (GaK-6024) (Mahaney et al., 1984). The Audubon ± 75 BP (ISGS-513) was obtained from the basal peat moraines have not been dated. Gannett Peak moraines of a bog retained by a Pinedale IV? end moraine were deposited during the late 19th century and (Loomis Lake moraine of Barnhardt, 1979). Two presently are at or near the outer margins of modern small, blocky, sharp-crested end moraines in the glaciers. cirques were assigned a neoglacial age by Drake and Esling. Bighorn Mountains, Wyoming Two glaciations were recognized in the Bighorn Medicine Bow Range, Wyoming and Colorado Mountains (Fig. 1, area 10) by Blackwelder and Bastin The high northern and southern parts of the (in Salisbury, 1905). Three are distinguished at present Medicine Bow Range (Fig. 1 areas 11 and 12) are (Drake and Esling, written commun., 1984) (see separate glaciated areas. The tills are derived chiefly Acknowledgements). Source rocks are mostly quartz from crystalline rocks, although in some areas in the diorite, granite, and gneiss, but in canyons on the northern part they contain abundant quartzite clasts. In western slope they include quartzite, limestone, dolo- the northern part, pre-Bull Lake deposits (McCallum, mite, and sandstone. According to Drake and Esling, 1962) (Chart 1A) are present as isolated patches of the oldest deposits of possible glacial origin are very formless drift that commonly are greatly weathered. weathered, bedded, sandy gravel and unsorted rubble End moraines initially considered pre-Wisconsin in age Qu aternary Glaciat ions in the Northern Hemisphere 10 9

(A twood, 1937) and later designated Wisconsin I (WI) .(Chart lA) are the oldest. Br adl ey described them as (Ray, 1940) are assigned to the 'late stade' (upper till) massive terminal mor aines on remnants of a preglacial of the Bull Lake glaciation in the Wind River Range pediment surface and considered them to be pre-Bull (McCallum , 1962) on the ba sis that the moraines are Lake in age . The dep osits are known from onl y a few more gently sloping and less bouldery, and the till is localities on the north side of the mountains; some in more weathered than are moraines and till of the last the Bald R ange area have be en shown to be landslide glaciation upvalley. In the southern part of the range deposits (A nthony A . Gibbon s, written comm un .. the pre-Home (WI) and Home (WIl ) moraines of Ray 1985). Moraines of the BlacksFork stage of Bradl ey (1940) have been assigned to the 'early' and 'late' (1936) are on a high terrace below the preglacial stades of Bull Lake glaciation (Richmond, 1962b). Two pediment. Theyarethe mor aines of the 'earlier similar moraines in the upper valley of the Laramie glaciation' of Atwood (1909) and were considered to be River also have been assigned to the Bull Lake Bull Lake in age by Bradley . The moraines are mor e glaciation (Kiver, 1972). smoothly sloping, have fewer surface boulders, and are In the northern part of the range, end moraines much more weathered than are moraines of the last assigned a Wisconsin age by Atwood (1937) were glaciation. My brief studies in the area indicate the designated as WIl, WIll, and WIV by Ray (1940) . presence of two such morain es associated with sep arate McCallum (1962) described them as steeply sloped, outwash terraces, which suggests th at the Blacks Fo rk little modified, hummocky, and very bouldery. De- stage probably includes two glaciations (Chart 1A). pressions contain water and drainages are poorly Moraines of the last Ple istocene glaciation, the integrated. He assigned them to the Pinedale glaciation Smiths Fork stage of Bradley (1936) , were considered and recognized four end moraines, on e at and one near by him to be Pined ale in age . They are fresh and the maximum extent (early Pinedale), one somewhat hummocky, narrowly breached, and little mod ified by upvalley ('intermediate' Pinedale) , and one near the erosion . Soils are thin and azon al. I have found three source area (late Pinedale). In a detailed study of latest low e nd moraines upvalley from the terminal mor aine Wisconsin and Holocene moraines in the northern part of the maximum advan ce and Atwoo d (1909) reported of the range, Oviatt (1977) differentiated two tills a small hummockyendmoraine in the upper valleys, (French Creek Till and Lak e Marie Till) (Chart 1A) about 2.5 km from the cirque headwalls. This morain e within the younger part of McCallum's 'intermediate' may correlate with the Lam ar Valley morain es in till. In the cirques, he distinguished two younger closel y Yellowstone National Park and with the Donald Cree k spaced moraines (Lookout Lake Till) that are associ- moraines in the Wind Riv er Range (Cha rt 1A) . ated with blocky protalus deposits and two closely Small end moraines of at least two Holocen e glacial spaced ridges of blocky debris (Disaster Peak Till) that advances, and also rock glaciers, occur in the cirques also are associated with protalus deposits. The dis- (Bruce H. Bryant, oral comm un. , 1985). tinctions were based on relative differences in lichen diameters, weathering data, and soil characteristics. In the southern part of the range, Kiver (1972) Wasatch Range, Utah differentiated a parallel sequence of end moraines: Tills of four glaciations are recognized in the Pinedale 1 at the maximum extent, Pinedale 2 nested Wasatch Range (Fig. 1, area 14) (Chart lA). Source within the Pinedale 1 moraine, Pinedale 3 in the middle rocks are chiefly quartzite, quartz monzonite, granite, part of the valleys, Pinedale 4 in the upper valleys, and gneiss, amphibolite, diorite, and Precambrian tillite. three cirque moraines: Temple Lake 1, Temple Lake 2, The oldest deposits include weathered erratic boulders, and Gannett Peak (Chart 1A). His criteria included intensely weathered till, and local deposits of bouldery relative geographic position, frontal moraine slope gravel that contain striated stones beyond or above angle, relation to outwash terraces, weight percentage deposits of subsequent glaciations (Marsell, 1946; Ives, of silt and clay in the soils, and granite weathering rind 1950; Crittenden et al., 1952; Hunt et al., 1953; Eardley density ratios. He noted that the greatest inter-terrace et al. , 1957; Richmond, 1964b). The deposits may erosion was between the Pinedale 2 and Pinedale 3 represent two glaciations (Crittenden et al., 1952; adv ances. Richmond, 1964b). Two large end moraines at the canyon mouths were distinguished as deposits of two glaciations by Atwood Uinta Mountains, Utah-Wyoming (1909) , but disagreement concerning their age and The glacial deposits of the Uinta Mountains (Fig. 1, correlation existed for many years. On the basis of area 13) have not been studied in detail. Tills of three differences in weathering, and stratigraphic relations to glaciations were recognized on the north flank of the adjacent deposits of Lake Bonneville, some authors range by Bradley (1936). Five groups of end moraines, concluded that the moraines represented the last representing four glaciations, were recognized on the glaciation and an earlier glaciation (Atwood, 1909; south flank by Nelson (1982). On the north flank, Marsell, 1946; Ives, 1950; Eardley et al., 1953). Eardley source rocks are chiefly quartzite. On the south flank et al. correlated them with the Pinedale and Bull Lake they are quartzite, limestone, dolomite, and sandstone. moraines in the Wind River Range. Others (Black- Deposits of the Little Dry stage of Bradley (1936) welder, 1931; Richmond, 1964b) concluded, on the 110 Quaternary Science Reviews basis of preservation of morainal form , extent of post- Front Range, Colorado morainal breaching, the presence of deposits of Lake Tills of four and possibly five Pleistocene glaciations Bonneville in the breach, and interpretation of the are recognized in the Front Range (Fig. 1, areas 15a weathering of the older till as interstadial in character, and b). Source rocks are chiefly massive and gneissic that the moraines represented two advances of Bull granite, quartz monzonite, metamorphic mafic rocks , Lake glaciation. An age of BP (GX-4737) and local rhyolite and rhyolite tuff. Correlation of the has been obtained from organic carbon in the Bt nomenclature applied to the deposits in reports prior to horizon of a buried soil between the two tills (Madsen 1970 with that in this report (Chart IB) is shown in and Currey, 1979), thus substantiating a late Wisconsin Table 1. age for the upper till. Madsen and Currey informally On the east side of the range (Chart IB , area 15a) applied the term Dry Creek till to the older till and pre-Bull Lake till is present as patches and sheet-like Bells Canyon till to the younger till. The term Bells deposits that lack morainal form and are preserved in Canyon previously had been applied to the older positions above or beyond younger end moraines moraine and the term Little Cottonwood A had been (Richmond, 1960). Locally, only scattered erratics assigned to the younger moraine (Ives, 1950). Two remain. The till contains abundant gruss, and com- reces sional moraines in the middle part of Little monly is oxidized throughout. Silt in an ice-marginal Cottonwood Canyon (Ives, 1950) were shown to be deposit associated with the pre-Bull Lake till has deposits of the same advance, one from the canyon normal magnetic polarity (Madole and Shroba, 1979). head and one from a tributary (Richmond, 1964b; End moraines of Bull Lake Till (Chart 18) are Madsen and Currey, 1979). Moraines of two younger subdued, gently sloping, and broad crested. They lack advances were identified both in the canyon and in its undrained depressions and have fewer and more tributaries by Richmond (1964b) . Madsen and Currey weathered surface boulders; soils are thicker and more grouped all of these deposits as the Hogum Fork till fully developed than are soils on younger moraines (Chart lA). Peat from a bog 1.5 km upstream from a (Richmond, 1960; Madole, 1969, 1976; Madole and moraine of Hogum Fork till (Gad Valley moraine of Shroba, 1979). Commonly, only a single end moraine is Ives , 1950), in the upper part of Little Cottonwood present, but in places two similar end moraines are Canyon, yielded an age of 12,300 ± 300 BP (GX-3481; graded to two outwash terraces (Richmond, 1960). A Madsen and Currey, 1979), thu s providing an upper uranium-trend age of 130 ± 40 ka , obtained from a limit for the age of the Hogum Fork till (Chart lA). lateral moraine segment of Bull Lake Till (Shroba et Wood from near the base of a bog higher in the valley al., 1983; Madole et al. , 1984) , indicates that at least yielded ages of 9,560 ± 240 BP (RL-695)and 9,430 ± one of the end moraines is late Illinoian in age (Chart 260 BP (GX-4736), and organic matter in colluvium IB). The other end moraine may be either late Illinoian nested within moraines at the head of Little Cotton- or early Illinoian in age (Chart IB). wood Canyon [the Albion Basin moraines of Ives End moraines of Pinedale Till, especially the outer- (1950), or Devils Castle till of Madsen and Currey most, tend to have steep distal slopes, narrow crests, (1979)], yielded an age of 7,515 ± 180 BP (GX-6466; abundant undrained depressions, abundant little- Madsen and Currey, 1979). The latter date supports weathered surface boulders, and shallow oxidized soils correlation of the moraines of Devils Castle till with the that display little evidence of clay illuviation (Madole Temple Lake moraine in the Wind River Range, and Shroba, 1979). Wyoming. Madsen and Currey implied that late Wis- Multiple Pinedale end moraines have long been consin glaciation included only two advances, rep- recognized (Table 1). A large outer end moraine or resented by the terminal moraines of the Bells Canyon morainal complex commonly includes at least two and Hogum Fork tills. However, end moraines of at ridges. Smaller moraines upvalley are described as least two younger late Pleistocene advances (Maybird varying greatly in number and continuity from valley to Gulch moraine and Red Pine Lake moraine) (Chart valley (Madole, 1976). Three are mapped in some lA) are present below Holocene rock glaciers at the drainages (Gable and Madole, 1976). In Rocky Moun- heads of Little Cottonwood Canyon and Bells Canyon tain National Park, I have observed that the large outer (Richmond, 1964b) . moraine locally overlapsapaleosol on Bull Lake Till, that two inner ridges either breach or are nested within the outer moraine, that two smaller end moraines are SOUTHERN ROCKY MOUNTAINS present a few kilometers upstream, and that a single end moraine, or, locally , two closely spaced ridges , is The Southern Rocky Mountains include approxi- present in the upper valleys a few kilometers from the mately 30 ranges in which alpine glaciers existed during cirques (Richmond, unpublished map). the Pleistocene. Most were valley glaciers, but local ice The upper valley moraine occupies a position in the caps developed on the uplands of the San Juan valleys that is similar to the Monarch moraine of Ives Mountains and on the White River Plateau. Several (1938) (Table 1) and the late Pinedale moraine of areas have been intensively investigated; many have Richmond (1960) and Madole (1969). Because of been studied only in reconnaissance. Deposits of seven priority, the term Monarch is applied here to all of are discussed here. these moraines (Chart IB). Upstream from the Mon- TABL E 1. Correlation of nomenclature fro m 1969 and ea rlier literatu re for moraines in the Front Range , Colorado, with that of Chart IB , area 15a,

Ivcs, Ray, Ivcs, Richmond, Benedict, 1938 1940 1953 1960 , 1962b , 1965a 1968 Cha rt 1b. area 15a

,- -- .-- ._ ------_.. _ - 0 ------_. c: Gann ett Peak b Gannett Peak Arapaho Peak ::r: ;:; Cirque Recent Ga nnett Peak a Arikaree Aud ubon 0 ".., ()0" ::l moraines Sprague W5 moraines Temple Lake a, b Temple Lake Tri ple Lakes' ".., locally Ptarmigan "::l '< " 0 0;- n Temp le Lake a, b, Temp le Lake Satanta Peak and §' ...... locally _- type Triple Lakes 0' r ::l Madole, 1969 "s V> -,- -- -_._..'---- _.- ..- s Monarch Long Draw W4 Upper Valley Late 'stadc' Late 'stade ' Monarch :J:' 5- "e n (1 mora ine) (2 moraines) Middle 'stade' "e Middle 'stadc' "e Three middle _,0 " s ::l ::l Z s ..,0 Ar apah o (multiple moraines) "0. "0. valley moraines 0." -,C/O Albion II Two outer moraines " ::l 5- "0- "0- 0- .., River Co rral Creek W3 (2 moraines) Ea rly 'stadc' Early 'stade' J. "::l :r: Hom e W2 Late 'stadc ' Late 'stade' Inn er moraine 3" tll tll tll ..... :J:' Stillwater Albion I e c: "'0 ==-:c: - :r (1 moraine) =r =r roe ".., Twin Lak es WI Ea rly 'stade' Early 'stadc' ...,. Ou ter moraine " -, :>I'"'" " :>1'" " " (pre-Home) 0 " " ::l

..... "e Prett y Meadow Pre-Bu ll Lake Pre-Bull Lake Pre-Bull Lak e till 112 Quaternary Science Reviews arch moraines, till is present only as discontinuous than 10,000 BP). If deposition of the Satanta Peak patches between areas of glacially smoothed, polished, moraines was separated in time by as much as 2,000 or striated bedrock on which abundant erratic boulders years, the outer moraine may correlate with the Lamar are scattered (Ives, 1938; Benedict, 1985). One or two Valley and Donald Creek moraines, and the inner may closely spaced bouldery end moraines, the Satanta correlate with the Temple Lake moraine (Charts lA, Peak moraines of Benedict (1973, 1981, 1985), dis- B) . cussed below, are present outside the cirques beyond Blocky end moraines of four younger Holocene the Holocene cirque moraines. The weathering charac- glacial advances are recognized in some cirques (Bene- teristics of Satanta Peak moraines are similar to those dict 1968, 1973, 1981, 1985) (Chart 1B). The climate of adjacent older Pinedale Till. As in the Wind River and environment during the Satanta Peak-Ptarmigan Range, Wyoming (Chart 1B), these youngest Pinedale- interval was similar to or milder than today (Benedict, like moraines are not included in the definition of 1985). Ptarmigan moraine marks an advance that Pinedale Till (Blackwelder, 1915; Benedict, 1973; occurred after 7,250 BP, based on weathering rind Madole, 1986; Richmond, 1986). However, the data, and before 6,380 ± 95 BP, the weighted average sequence of Pinedale end moraines both here and in of two 14C ages (Benedict, 1981) (Chart lB). The other ranges demonstrates the existence of more than advance has not been recognized elsewhere. the initially recognized two or three readvances of The type Triple Lakes moraines were initially Pinedale glaciers. described by Benedict (1973) as difficult to distinguish The outermost Pinedale end moraine is dated from Satanta Peak end moraines, and no Satanta Peak approximately by an age of BP (DIC-870) moraines were identified downvalley from them. from organic matter near the base of silt of glacial Lake Recently, an age of 9,915 ± 380 BP (GX-ll ,365) has Devlin, dammed in a side valley by the oldest Pinedale been obtained from organic matter ,near the base of lateral moraine 2.3 km upstream from the outer limit of sediments of a small pond on the outer moraine (P .T. the Pinedale glacial advance (Madole and Shroba, Davis , written commun., 1985). The type Triple Lakes 1979; Madole, 1980a, 1986; Rosenbaum and Larson, moraines therefore probably are equivalent in age to 1983) (Chart IB). Younger Pinedale end moraines are the Satanta Peak moraines. However, other moraines not dated, but Monarch moraines are known to be mapped as Triple Lakes (Benedict, 1985) are present older than a minimal age of 11,800 ± 450 BP (GX- headward of Satanta Peak and Ptarmigan moraines and 7723) (Nichols et al. , 1984). A succession of 14C ages downvalley from Audubon moraines in some cirques, (Chart 1B) from the sediments of glacial Lake Devlin for example west of Caribou Lake (Chart 1B). A new indicates that the lake existed until shortly after 12,910 name and type locally for these moraines is desirable. ± 270 BP (DIC-2271), when the moraine dam was Their age may differ only slightly from the earlier breached (Madole, 1986). Triple Lakes age assignment that now is considered I infer correlation of the Monarch end moraines with inadequate by Benedict (1985). the Green River Lakes end moraines in the Wind River Audubon moraines representing two glacial puls- Range (Chart IB), and with the Deckard Flats end ations are estimated to have formed between 2,400 and moraines, dated about 15,000 BP, in Yellowstone 900 BP, on the basis of 14C ages from layers of clastic National Park (Chart lA). In each area, the moraine sediments in moraine-related bogs (Benedict, 1973). represents the last readvance of Pinedale glaciation Arapaho Peak moraines, locally three nested ridges, prior to wasting of the ice to high mountain uplands or are estimated to have formed between 350 and 100 BP to the cirques. (Benedict, 1981). In the Front Range, deglaciation of the canyons is On the west side of the Front Range (Fig. 1, area estimated to have been completed between 15,000 BP 15b) in the Fraser River valley, two pre-Wisconsin, one and 12,000 BP (Madole, 1986). The disappearance of post-Illinoian-pre-late Wisconsin, and four late Wis- an ice cap from the southern summit upland of the Park consin glacial advances are recorded (Nelson et al., Range, immediately west of the Front Range, about 1979). The older Hideaway Park advance (Chart IB) is 14,000 BP is indicated by an age of 13,680 ± 110 BP represented by outwash gravel on which a paleosol that (W-5028) from the basal sediment of a bog on the has a Bt horizon as much as 50 ern thick is developed. glaciated upland (Madole, 1980b, 1986). In the Front Locally, the paleosol is overlain by till of the younger Range, cirques above Satanta Peak moraines became Hideway Park advance, demonstrating that the two deglaciated at the end of Satanta Peak time. The outer advances were separated by an interglacial interval. Satanta Peak moraine is older than 9,915 BP (Benedict, The till of the younger advance forms several moraines 1981, 1985) (Chart B). The younger moraine is older that have smooth slopes, broad crests, scattered surface than 9,215 BP. These ages are minimal. Ifdeposition of boulders, and relatively few unweathered clasts in the the Satanta Peak moraines was closely spaced in time, B horizon of the soils (Madole et al., 1972; Nelson et both may correlate with either the Lamar Valley al ., 1979). The soils are otherwise similar to soils on moraines in Yellowstone Park (age between 13,100 and moraines of the Winter Park advance (Chart lB). End 11,600 BP) and the Donald Creek moraines in the moraines of the Winter Park advance are characterized Wind River Range, or with the Temple Lake moraine by steep distal slopes, narrow crests, abundant surface in the Wind River Range (estimated age a little less boulders, and many unweathered clasts in the soils. Quaternary Glaciations in the Northern Hemisphere 113

Moraines of the Jim Creek advance (Chart 1B) have drainage of the Arkansas River on the east side of the steeper distal slopes and more unweathered clasts than Sawatch Range (Fig. 1, area 16a). Source rocks are end moraines of the Winter Park advance. They also chiefly granite, gneiss, quartz monzonite, quartzite, cross-cut Winter Park end moraines. limestone, andesite, and rhyolite. Correlation of the Nelson et at. (1979) did not attempt correlation or stratigraphy and nomenclature applied to the deposits age assignment of the Hideaway Park deposits, but in reports prior to 1977 with that in this report (Chart correlation of the end moraines with end moraines of IB) is shown in Table 3. the Bull Lake glaciation has been inferred on the basis The oldest glaciation is represented by deeply of relative geomorphic and soil characteristics (Madole oxidized and grussified, erratic-bearing bouldery out- et al., 1972). Here, the post-paleosol moraines are wash and alluvial fan gravel, termed Gravell by Van assigned a late I1linoian age and the pre-paleosol Alstine (1969) and 'lower Pleistocene gravel' by Tweto outwash is assigned an early Illinoian age (Chart 1B). (1961). The deposit caps a terrace and pediment The age of the Winter Park advance is inferred from 90-210 m above the Arkansas River (Scott, 1975). It 14C ages obtained from a sequence of tills and inter- overlies beds of known Pliocene age (Dry Union vening lake sediments temporarily exposed in an Formation) and may correlate with Till No.1 of Tweto excavation at a nearby ski area. Till? A (Chart 1B) at (Tweto, 1961; Tweto and Case, 1972) (Table 3), which the base is overlain by oxidized outwash gravel that is overlies Pliocene beds in the northern part of the correlated with the Hideaway Park advance. Till C, valley. Till No.1 also is deeply oxidized and grussified, disconformably above the outwash, in turn is overlain and has a thick reddish-brown clayey soil developed on by organic lake sediment from which dates of 30,050 ± it (Tweto, 1961). However, other facts, discussed 1200 BP (SI-2912) and BP (DIC-482) were below, suggest that Till No.1 of Tweto may be early obtained. Pollen analysis of the lake sediment indicated middle Pleistocene in age. a vegetation change upward from subalpine (same as Gravell of Van Alstine is entrenched by a terrace, present) to tundra to subalpine. Initially, till C was 73 to 85 m above the Arkansas River, on which is a inferred to represent a first advance of Pinedale second deeply oxidized and calichified gravel, termed glaciation prior to 30,000 BP (Nelson et al., 1979; Gravel 2 by Van Alstine (1969) (Table 2). Gravel 2 Porter, et al., 1983). Subsequently, Madole (1986) has locally is overlain by fine-grained alluvium containing suggested that the organic lake sediment overlying till the Bishop volcanic ash bed (Van Alstine, 1969; Scott, C was deposited during oxygen isotope stage 3 on the 1975; Izett et al., 1970) (K-Ar age, 738 ka). Both basis that its pollen content is similar to that at the Gravell and Gravel 2 therefore are early Pleistocene in locality today (Madole, 1986). I concur with a middle age (Chart IB). Neither is stratigraphically associated Wisconsin age assignment and suggest that till C may with till. have been deposited in early Wisconsin time. Gravel 2 is entrenched by a terrace, 48 to 61 m above Tills E, G, and I (Chart 1B) are considered Winter the Arkansas River, on which till, lacking morainal Park advances (Nelson et al., 1979). I estimate their form, merges with outwash gravel (Scott, 1975). The ages to be about 23,000-22,000 BP, 20,000 BP, and outwash gravel is overlain locally by alluvium contain- 19,000 to 18,000 BP, respectively. No pollen analyses ing the Pearlette '0' volcanic ash bed (K-Ar age, 610 of the intervening lake sediments are available. The ka) (Van Alstine, 1969; Scott, 1975) (Chart IB). Jim Creek advance did not reach the excavation site. Therefore the till is early middle Pleistocene in age. It is Nelson et al, (1979) inferred that it occurred during intensely weathered and oxidized, and clasts in the Cca deposition of the lake silt that overlies till I. The lake horizon of the soil are thickly encrusted with carbonate. silt is overlain by peat dated 13,740 ± 160 BP (DIC- The early middle Pleistocene till and outwash in turn 671). I suggest that the Jim Creek moraines may date are entrenched by an outwash gravel terrace, about 50 from about 15,000 BP and that they may correlate with m above the local drainage, that heads in low, broad, the Monarch moraines of Ives (1938) (Table 1), the late massive moraines mapped as pre-BUll Lake by Scott et Pinedale moraines of Richmond (1960) and Madole at. (1975). The weathering, oxidation, and carbonate (1969), and the Deckard Flats moraines in Yellowstone encrustation of clasts in the upper part of the till are National Park (Chart lA). The differences in weather- only slightly less pronounced than those in the early ing characteristics of the Winter Park and Jim Creek middle Pleistocene till. In the northern part of the moraines may be the product of the warm interval Arkansas Valley, similar massive moraines (till No. 2 of documented by pollen and dated at about 17,000 BP in Tweto, 1961) and associated thick outwash gravel Yellowstone National Park (Richmond, Yellowstone (Malta Gravel) that overlie till No.1 of Tweto (Tweto, Park, this volume). Pollen analysis and 14C dating of 1961; Tweto and Case, 1972) (Table 2) probably also the peat overlying the lake silt above Till I indicates are middle middle Pleistocene in age. Although till No. that peat formation and climatic amelioration began in 1 was assigned an early Pleistocene age by Tweto the area of the end moraines by at least 13,740 ± 160 (1961), he believed that it represented the glaciation BP (DlC-671) (Nelson et ai., 1979). next older than that represented by the massive moraines of his till No.2 (Table 2). Thus, if till No.2 is Sawatch Range, Colorado, East Side middle middle Pleistocene in age (Chart IB), till No.1 Deposits of seven glaciations are recognized in the probably is early middle Pleistocene in age......

TABLE 2. Correlation of nomenclature from 1977 and earlier literature for moraines and outwash gravel deposits on the east slope of the Sawatch Range and in the Arkansas Valley, Colorado, with that of Chart 1B, area 16a.

Richmond, 1953; Tweto, 1961; Scott, 1975 Westgate, Powers, Richmond and Van Alstine, Tweto and Scott, Van Alstine Chart 18 1905 1935 Ray, 1940 Tweto, 1965 1969 Case, 1972 and Sharp, 1971 Shroba, 1977 Area 16a

:r: Gannett Peak Till No. 9 Not 0 Early neoglacial Early neoglacial 0-n Wisconsin V Temple Lake Till No.8 in Temple Lake Temple Lake moraine :l" Upper " Wisconsin IV Late stade Gravel 9 Till No.7 mapped valley moraines _0"c .."r recessional "0" .-co Middle Upper Twin Wisconsin III .- stade Gravel 8 Till No.6 area Pinedale Lake moraine 0 "c" " " c:: .-e, .0;," recessional Early Lower Twin Lake (;' "0 -1 0 .., .... M3 Wisconsin II stade Till No.5 Till moraine complex :I OIl :l "C :l Gravel 7 Pinedale Till of maximum '" 0 later Late Till No. 4 Till advance nVJ >- -'""c 0 moraine stade Gravel 6 Younger Bull Younger Bull 0:1 n' ....l" .-co Bull c :I Wisconsin I -.- Lake Till Lake Lake moraine =- o -:l " Till r:; " earlier M2 (Twin Lakes) Early Gravel 5 Till No.3 Older Bull Older Bull '" :l ::0 <: moraine stade Lake Till Lake moraine "n'

V> Pre-Bull Lake Pre-Bull Lake .::: Ml Gravel 4 Till No. 2 till (Illinoian?) moraines '1:: "0 .... Pearlette '0' Pearlette '0' Pearlette '0' "0" volcanic ash volcanic ash bed volcanic ash bed 6 -e earlier Wisconsin I Pre-Bull Lake Pre-Bull Lake Middle Pleistocene .... drift (Twin Lakes) till Gravel 3 Till No. 1 till (Kansan?) till S' Bishop Bishop volcanic Bishop volcanic 0 0;' volcanic ash ash bed ash bed :l Gravel Qna Lower Pleistocene Gravel 2 (Nebraskan?) gravel 2 Gravel On Lower Pleistocene Gravell (Nebraskan") gravel I Quaternary Glaciations in the Northern Hemisphere 115

The older and younger Bull Lake moraines (Chart segments remain. These extend to an outwash terrace lB) locally are two high, smoothly sloping, broad- below that associated with the Lime Creek deposits and crested laterals that are widely breached by axial above that associated with the next younger Bigelow streams. However, commonly the older moraine is moraines. Surface boulder frequency on Thomasville 2 lower and more subdued than the younger, and is moraines averages 50 per 1,000 m ; soils are about 75 segmented by erosion. The two moraines extend to cm thick; the granite weathering ratio is 28-68-4,and separate outwash terraces. Partly weathered boulders end moraines are breached about 250 m. A low are scattered on their slopes. Soils are 1.5-2 m thick recessional moraine commonly is nested within th e and zonal. Detailed pedologic analyses are given by terminal moraine. Shroba (1977) and Nelson and Shroba (1984). Bigelow moraines are large, smoothly sloping and Pinedale end moraines commonly are nested within have broad crests. They extend to an outwash terrace the younger Bull Lake end moraine. Locally, however, below that associated to the Thomasville moraines; they breach the younger Bull Lake moraine and in they are breached about 200 m by the stream, and they places they overlap it (Westgate, 1905; Shroba, 1977). are considerably less dissected than the Thomasville Pinedale end moraines are steep, hummocky and moraines. The surface boulder frequency on Bigelow 2 littered with fresh to slightly weathered boulders. Soils moraines is about 124 per 1,000 m ; soils are about 65 are 0.5-1 m thick and exhibit little or no clay em thick; the granite weathering ratio is 40-60-0. enrichment. Detailed pedologic analyses are given by According to Nelson (1954), 31 discrete small reo Shroba (1977) and Nelson and Shroba (1984). An inner cessional moraines are present along the Frying Pan end moraine and two subsidiary anastomosing ridges River valley within about 3 km of the terminal moraine. are nested within the terminal. In one drainage (Twin The Ivanhoe moraines are 1.6 to 9.6 km upvalley Lakes) , cores taken on the inner moraine penetrated from the Bigelow moraines. They are youthful, steeply the till of the moraine, underlying outwash interstrati- sloping, continuous, little dissected, and extend to an fied with lake sediments, a highl y contorted and thrust- outwash terrace below that associated with the Bigelow faulted lower till, a lower outwash, and older lake moraines. End moraines are breached about 50-75 m. sediments (Ostenaa et al., 1981). I infer that the lower The surface boulder frequency is about 395 per 1,000 2 till was deposited during the advance of the Pinedale m ; soils are about 30 cm thick; the granite weathering glacier to its maximum position and that deformation of ratio is 88-12-0. Immediately upstream from the outer the till occurred during a readvance of the ice to the end moraine is a complex of truncating recessional and position of the inner moraine. In a nearby core , the related lateral ridges. lake sediments beneath the lower till are 70 m thick and The Hellgate moraines comprise a terminal zone of contain dispersed volcanic ash. They are inferred to 3-5 ridges and another single end moraine 0.8-1.6 km have been deposited in a lake retained by the younger upvalley. They are similar to the Ivanhoe moraines, but Bull Lake moraine (Tweto, 1978). The ash may have more bouldery, less dissected, and less weathered. The washed into the lake from exhumed exposures of granite weathering ratio is 96-4-0. They are breached Pearlette '0' volcanic ash, currently exposed at one about 25 m. locality along the present lake shore (Tweto, 1978). A single Chapman Gulch end moraine (Chart 1B) is One or two moraines of subsequent readvances of present in a sheltered valley head 0.8-1.2 km from the Pinedale glaciers are midway upvalley in most below a cirque headwall. It is very bouldery, but has a drainages, and a small Pinedale end moraine is present thin soil and a vegetation cover. The deposit is only in the upper valleys a few kilometers below the cirques. slightly dissected and all of the clasts are comparatively Small end moraines inferred by Shroba (1977) to be unweathered. early Holocene (Temple Lake) and early neoglacial in Nelson considered the Lime Creek deposits to be age are present below a few sheltered cirque headwalls. pre-Bull Lake in age. He correlated the Thomasville and Bigelow moraines with the outer and inner Bull Sa watch Range, West Side Lake moraines, the Ivanhoe and Hellgate moraines Deposits of four Pleistocene glaciations, the last of with the Pinedale I and Pinedale II moraines of Moss et which includes two significant subdivisions, are re- al. (1951) , and the Chapman Gulch moraine with the corded in the drainage ofthe Frying Pan River (Nelson, Temple Lake moraine of Hack (1943) and Moss 1954) (Fig . 1, area 16b) on the west side of the Sawatch (1951b) in the Wind River Range, Wyoming. Range. The Lime Creek deposits (Chart IB) are In the next drainage to the north, Miller (1979) formless masses of till, outwash and erratic boulders differentiated a similar sequence on the basis of a beyond the limit of younger moraines. Soils are 1-1.5 statistical computer analysis of relative age data. The m thick; the granite weathering ratio is 8-52-40, sequence included deposits of two pre-Bull Lake surface-boulder frequency averages 19 per 1,000 m2 * glaciations, early and late Bull Lake moraines, and and the deposits are breached about 650 m by the river early Pinedale and middle or late Pinedale moraines at the position of former end moraines. (Chart 1B). The oldest Pinedale end moraine is Upstream, the Thomasville moraines (Chart 1B) are approximately dated by an age BP(DIC- so extensively eroded that only short terminal moraine 1170), from organic matter near the base of silt • Con verted from measured frequency per acre. deposited in a lake dammed by the associated lateral 116 Quaternary Science Reviews moraine in a tributary valley during maximum glaci- relative weathering, they are estimated to be early ation (Rosenbaum and Larsen, 1983; Madole, 1986). Pleistocene in age. However, their glacial origin, The lake area, known as Triangle Park, was about 1.4 though possible, has not been proven. km upvalley from the terminus of the glacier. The 14C A succession of younger moraines occurs in the age is compatible with that from sediments of the canyons. The sequence along Animas River has re- similarly moraine-dammed lake in the Front Range, ceived the most study. The Durango Till (Chart lB) Colorado, discussed above, within the statistical errors (Atwood, 1915; Atwood and Mather, 1932) forms two of the dating controls. Two younger 14C dates from the large, smoothly sloping, broadly breached moraines lake deposits indicate that until about 18,000 BP, the that are mantled with as much as 2 m of loess. Soils on lake histories were essentially parallel. the till are very well developed, but partially eroded. A single cirque moraine was correlated by Miller Detailed soil data are given by Gillam et al. (1984). (1973) with the Temple Lake moraine in the Wind Outwash terraces related to the moraines are about 95 River Range (Chart 1B). and 105 m above the river. I suggest that the Thomasville and Bigelow moraines Nested within and below the Durango moraines are and the early and late Bull Lake moraines of Miller two smaller, smoothly sloping moraines that were first (1979) are, respectively, early and late Illinoian in age distinguished as Bull Lake moraines (Richmond, on the basis of their relative weathering and erosional 1965b) and more recently have been named the Spring characteristics. On the basis of 14C dating, relative Creek moraines (Gillam et al., 1984) (Chart 1B). They weathering characteristics, and relationships to separ- are poorly preserved and segmented. Both are thinly ate outwash terraces, the Ivanhoe moraines and the mantled with loess. They are related to separate early(?) Pinedale moraines of Miller (1979) are early outwash terraces about 50 m and 37 m above the river. late Wisconsin in age, i.e., about 23,000-22,000 14C Soils on the moraines are similar to but less well years old. The Hellgate moraines and the middle(?) or developed than soils on Durango moraines (Gillam et late(?) Pinedale moraines of Miller (1979) are younger al., 1984). late Wisconsin in age, i.e., about 19,000-18,000 14C Nested within and below the Spring Creek moraines years old. The single upvalley Hellgate moraine may are three bouldery, hummocky moraines. The outer correlate with the Monarch moraines in the Front consists of a single segment that was mapped as Bull Range and with the Deckard Flats moraines in Yellow- Lake by Richmond (1965b), but was considered to be stone National Park, which are about 15,000 14C years middle or early Wisconsin in age by Gillam et al. (1984) old (Chart 1A and B). The Chapman Gulch moraine on the basis of relative weathering criteria. The inner probably is equivalent to the Satanta Peak moraines in two moraines, termed Wisconsin by Atwood (1915) the Front Range on the basis of its location below the and early and middle Pinedale by Richmond (1965b), cirques. The cirque moraine of Miller (1979) probably have been named Animas City moraines by Gillam et is Temple Lake in age, but may be Satanta Peak (Front al. (1984). They are narrowly breached but otherwise Range) or Donald Creek (Wind River Range) in age continuous till ridges that have relatively weakly (Charts 1A and B). developed soils and are related to separate outwash terraces (Gillam et al., 1984). A similar moraine, San Juan Mountains, Colorado previously considered late Pinedale in age (Richmond, The San Juan Mountains (Fig. 1, area 17) were the 1965b) and here referred to as the Baker's Bridge site of a succession of ice cap and valley glacier moraine, is present 21 km upvalley, although still far complexes that, in late Wisconsin time, covered an area below the cirques. of about 5,000 km", Five, and possibly six, tills are The correlation of the moraines shown in Chart 1B, recognized, and a sequence of older terrace gravel column 17a is based on their relative morphology, soil deposits of probable fluvioglacial origin may represent development, clast weathering, loess cover, and five additional glaciations. Source rocks include gran- dissection; and it may be essentially correct. However, ite, gneiss, felsic and mafic intrusive rocks, basalt, an alternate interpretation is suggested by a chrono- andesite and rhyolite flows and tuffs, quartzite, slate, logie control in the succession of terrace gravels A phyllite, sandstone, limestone, and shale. through K (Chart 1B, column 17b), of probable Deeply weathered, bouldery deposits on narrow fluvioglacial origin (Scott and Moore, 1981; Moore and divides 100-300 m above the local drainage were Scott, 1981; Gillam et al., 1984). A colluvium on considered till by Howe and Cross (1906) and were terrace gravel J contains the Pearlette '0' volcanic ash named the Cerro Till (Atwood, 1915; Atwood and bed, which has a K-Ar age of 610 ka. Terrace gravels J Mather, 1932). Subsequently, many such deposits, and K, therefore, may represent the two pre-Illinoian including the type deposit were shown to be landslide glaciations older than 610 ka (Chart 1), and terrace deposits (Dickinson, 1965a, b). The name Cerro Till gravels I and H may represent two younger pre- therefore was abandoned, but without implication that Illinoian glaciations. According to Gillam et al. (1984), all deposits formerly mapped as Cerro Till are landslide terrace G is a surface cut in terrace gravel H, and deposits (Dickinson, 1965a). Some deposits believed to terrace gravel F has characteristics common to terrace be till in situ, have been named informally the 'Horsefly gravels E and D that are related, respectively, to the Peak' till (Sinnock, 1981). Based on clast lithology and outer and inner Durango moraines. In the light of the Quaternary Glaciations in the Northern Hemisphere 117 regional correlations shown on Charts lA and 1B, I Sangre de Cristo Range, Colorado-New Mexico suggest that terrace gravel F is early Illinoian in age and Tills of three, and possibly four glaciations are that the large outer and inner Durango moraines are recorded in the Sangre de Cristo Range (Fig. 1, area late Illinoian in age. The two smaller, poorly preserved, 18). Ray (1940) differentiated moraines of five sub- Spring Creek moraines may be 'Eowisconsin' in age divisions of the Wisconsin, not all of which occurred in and may correlate with deposits of the early and late anyone valley. In the northern part of the range in 'Eowisconsin' advances in Yellowstone National Park Colorado, a pre-Bull Lake till, two broad subdued (Chart 1A) (see Richmond, Yellowstone Park, this moraines of Bull Lake Till, and a sequence of bouldery, volume). These suggested correlations are conjectural, hummocky moraines of Pinedale Till are distinguished and require confirmation. (Scott and Taylor, 1974; Taylor et al., 1975; McAlpin, Terrace gravels J and K together comprise the 1982; Lindsey et al., 1985a, 1985b) (Chart 1B). Small Florida Gravel (Atwood and Mather, 1932; Richmond, early Holocene moraines (Morris, 1981) or early 1965b). Successively higher gravel deposits are the neoglacial moraines (McAlpin, 1982) are reported in a gravel on Mesa Mountains (Richmond, 1965b), which few northwest- to northeast-facing cirques. may represent more than one depositional unit (Gillam Deeply weathered pre-Bull Lake till (Scott and et al., 1984), and the Bridgetimber Gravel (Atwood Taylor, 1974) forms broad moraines with few boulders and Mather, 1932), which is restricted to a single at the surface that commonly are overlapped by alluvial deposit (Richmond, 1965b) 395-495 m above its source fans of Bull Lake age. The fans also locally overlap still drainage. The reversed polarity of at least a part of the older alluvium that contains discontinuous lenses of the gravel on Mesa Mountains (J.D. Strobell, written Bishop volcanic ash (age 610 ka) (McAlpin, 1982). commun., in Gillam et al., 1984) indicates that it is, at Differences in weathering-rind thickness, areal least in part, older than 788 ka and early Pleistocene in distribution, and relation to separate outwash terraces age. The Bridgetimber Gravel (not shown on Chart IB) suggest that the two Bull Lake moraines are Illinoian in has been considered Pliocene (Blancan) in age (Scott age and that they may represent separate glaciations. and Moore, 1981; Moore and Scott, 1981; Gillam etal., However, positive evidence of an intervening inter- 1984), but it may represent one or more early Pleisto- glacial is lacking. cene glaciations. McAlpin (1982) recognized two groups of Pinedale The Bakers Bridge moraine, upstream from the moraines on the basis of 14 relative age parameters -a Animas City moraines, probably is equivalent to the single large outer moraine, that he termed 'early middle-valley Pinedale moraines in the Sawatch and Pinedale', which is more broadly breached and more Front Ranges. I estimate it to be about 18,000 years weathered than a group of as many as four small old. An age of 15,450 ± 220 BP (Y-1147) from deposits moraines nested behind it, and a single moraine farther of Molas Lake (Maher, 1972), on an upland near the upvalley, that he termed 'mid-late' Pinedale (Chart head of the largest late Wisconsin glacier in the IB). McAlpin assigned both groups a late Wisconsin mountains and ages of 14,940 ± 140 BP (W-4525), age. Although the outer moraine might be considered 14,900 ± 250 BP (W-4209), and 14,130 ± 150 BP (W- early Wisconsin in age, I suggest on the basis of its 4289) from deposits of Lake Emma (Chart IB), in a weak soil that it represents an early late Wisconsin south-facing cirque central to the glacier complex, glacial advance and that the younger moraines rep- indicate that the mountains had been extensively resent readvances following a mid-late Wisconsin warm deglaciated by 15,000 BP (Carrara et al., 1984). Yankee interval documented by pollen data in Yellowstone Boy moraines (Chart IB), present in some north-facing National Park and dated about 17,000 BP (Richmond, cirques, are older than 9,620 ± 400 BP (St-3909). Yellowstone Park, this volume). Although initially correlated with the Satanta Peak In the southern part of the range, in New Mexico, moraines in the Front Range (Carrara and Andrews, terminal moraines of one pre-Bull Lake glaciation, two 1975), they are currently estimated to be about 15,000 advances of Bull Lake glaciation, and three advances of 14C years old. I suggest their correlation with the Pinedale glaciation were distinguished (Richmond, Deckard Flats moraines, dated about 15,000 BP in 1963) on the basis of relative topographic position, Yellowstone National Park. The Grenadier moraines preservation of morainal form, abundance of surface (Chart IB) and the Yankee Boy moraines have not boulders, and soil development. Subsequently, Shroba been identified in the same cirques (Carrara and (1977) suggested that the pre-Bull Lake terminal Andrews, 1975). The Grenadier moraines are not moraine is Bull Lake in age and that the Bull Lake dated, but are believed to have been deposited by terminal moraines are Pinedale in age, on the basis of remnant glaciers soon after deposition of the Yankee soil characteristics. Both studies were of a recon- Boy moraines (Carrara et al., 1984). I suggest their naissance nature. correlation with the Satanta Peak moraines in the Front Range, and with the Lamar Valley moraines dated between 13,000 BP and 11,200 BP in Yellowstone Sierra Blanca, New Mexico National Park. Though rock glaciers of Holocene age The Sierra Blanca (Fig. 1, area 19) is the most are abundant. No Holocene end moraines are recog- southerly glaciated range in the United States (Smith nized at present in the San Juan Mountains (Carrara et and Ray, 1941). Source rocks are syenite quartz al., 1984). porphyry and pegmatite. A sequence of moraines 2-3 118 Quaternary Science Reviews km down-valley from the single, northeast-facing glacially weathered basalt. Locally, remnants of a cirque on Sierra Blanca Peak were inferred on the basis paleosol are preserved on the till beneath the overlying of their overall freshness to be Wisconsin in age. Later, till of the last glaciation. the outer two moraines were assigned to the Bull Lake Till of the Lands End Formation locally extends glaciation on the basis of their broad crests, smooth beyond the limits of the last glaciation to the edge of slopes, broadly scattered surface boulders and strongly the mesa, across which the ice apparently flowed. Two developed soils (Richmond, 1963). Inner ridges were broad, gently sloping end moraines mark glacial assigned to the Pinedale glaciation on the basis of their readvances during the overall recession. Yeend irregular form, abundant surface boulders and shallow assigned a Bull Lake age to the till on the basis of its soils. Subsequently, Shroba (1977) suggested, on the weathering characteristics. basis of differences in surface form and boulder The Grand Mesa Formation (Chart IB) includes frequency, that a part of the inner Bull Lake moraine of deposits of the last glaciation (Yeend, 1969). Till Richmond is Pinedale in age. However, two Bull Lake surfaces are hummocky, bouldery, and poorly drained. moraines and at least two Pinedale moraines are The till is light gray and much less clayey than till of the present. No younger moraines have been observed. Lands End Formation. Striated stones are common. The Pinedale moraines probably are correlative with Yeend distinguished a lower till that extends to the the outer moraines of late Wisconsin age that are outer limit of the last glaciation, and an upper till that is present in many areas of the Southern Rocky Moun- present in the upper canyons and valleys of the plateau. tains (Chart IB). A long, narrow, blocky deposit along He assigned both to the Pinedale glaciation. The upper the valley bottom is characterized by multiple trans- till is characterized by a more hummocky surface, more verse ridges and a loessial matrix. It was mapped as a associated ice contact deposits and a more weakly Pinedale rock glacier by Shroba (1977). The deposit developed soil than the lower till. End moraines are extends through the Pinedale moraines and part way associated with either till only locally. Those in the through the Bull Lake moraines. It may have formed middle sectors of the canyons may represent an during recessional episodes of the Pinedale glaciation. intermediate glacial readvance. An age of 19,730 ± 500 A small early Holocene rock glacier is present at the BP (W-2143) was obtained from organic matter in an cirque headwall. alluvial fan deposit overlying outwash correlated with the lower till. The tills of the Lands End and Grand THE COLORADO PLATEAU Mesa Formations have been correlated with tills of the Bull Lake and Pinedale glaciations in Yellowstone The Colorado Plateau includes eight separate glaci- National Park on the basis of the relative thickness of ated upland areas. Plateau ice caps existed in five. weathering rinds on basalt clasts (Colman and Pierce, Valley glaciers flowed from laccolithic mountains in 1981). one area and from high volcanic peaks in another. A No glacial deposits of Holocene age have been single cirque in one area possibly may have been identified in the Grand Mesa area. associated with upland ice. La Sal Mountains, Utah Grand Mesa, Colorado Tills of six Pleistocene glaciations are recognized in Grand Mesa (Fig. 1, area 20) is a basalt-capped the La Sal Mountains (Fig. 1, area 21) (Richmond, plateau at an elevation of about 3,200 m, on which an 1962b), and some evidence exists for a seventh. Source ice cap developed at least three times during the rocks are diorite, sandstone, and shale. Gravel of Pleistocene (Yeend, 1969). Clasts in the tills are chiefly Pliocene or early Pleistocene age (Hunt, 1958) is basalt, but at lower elevations they include siltstone, overlain by the Harpole Mesa Formation. The Harpole sandstone, and limestone. The till on Chalk Mountain Mesa Formation was initially defined as including three (Chart IB) is a bouldery silty sand that is locally members, each containing a stony till (Chart lB). indurated, includes sand lenses, and is as much as 75 m Locally the three members are superposed and separ- thick. Similar thick and thin deposits occur on isolated ated by thick paleosols. More commonly, they occur uplands. No weathered zone has been observed in them separately on successive terraces or pediments 50 to 150 and all are overlain by younger till. Yeend (1969) m vertically apart. In one area, silt in gravel of the assigned them a pre-BUll Lake(?) age and indicated lower member has reversed magnetic polarity (Harden that they may represent several glaciations. et al., 1982, 1985); in another area, thick alluvial silt is The Lands End Formation (Chart IB) includes till of normally magnetized in its upper part, reversely the penultimate glaciation. It forms a thin layer magnetized in its middle part and normally magnetized beneath till of the last glaciation over much of Grand in its lower part (Colman, 1983). The uppermost part of Mesa. All clasts are basalt; most are fresh, but many the alluvium contains a volcanic ash (Richmond, are 'moderately weathered' and some are 'very' 1962b) identified as the Bishop volcanic ash bed (Izett weathered (Yeend, 1969). The matrix is dark reddish- et al., 1970) (K-Ar age 738 ka). The magnetic reversal brown to yellowish-brown gravelly sandy clay contain- at depth in the alluvium therefore probably is the ing abundant quartz grains of possible eolian origin. Matuyama-Brunhes paleomagnetic reversal. Locally, The clay may be derived from older till and from pre- the alluvium of the lower member is tilted and overlain Quaternary Glaciations in the Northern Hemisphere 119

.unconformably by alluvium of the middle member Formation may have been deposited about 15,000 BP. (Chart IB). The latter contains a volcanic ash bed However, the large valley-to-valley difference in dis- (Richmond, 1962b), identified as a Pearlette family tance between the moraines suggests that other un- volcanic ash (H.A. Powers in Richmond, 1962b), recognized moraines may be present and that more specifically the Pearlette '0' volcanic ash bed (Izett et than two advances may have taken place. al., 1970) (K-Ar age 610 ka). The alluvium of the End moraines of both the lower member and the middle member has normal magnetic polarity (S.R. upper member of the Gold Basin Formation are Colman, personal commun., 1983). present in only one cirque (Richmond, 1962b). Mor- The till of the lower member of the Harpole Mesa aines of the lower member also are present in eight Formation grades laterally into undifferentiated out- other cirques. The deposits are stony, have a weak soil wash and alluvial deposits (Richmond, 1962b) in which except where mantled with loess, and bear vegetation no volcanic ash has been observed. However, the only locally. I estimate that they are early Holocene in hiatus represented by the tilting and erosion of the age. The single moraine of the upper member is blocky lower member before deposition of the middle member and supports only a sparse pioneer vegetation. I suggests that the till of the lower member probably is estimate that it may be early neoglacial in age. older than the Bishop volcanic ash bed and is early Pleistocene in age. It may be correlative with the Aquarius Plateau, Utah Sherwin Till in the Sierra Nevada, California (Chart The Aquarius Plateau (Fig. 1, area 22) at an altitude IB). of about 3,500 m, supported an ice cap during Till of the middle member of the Harpole Mesa Quaternary glaciations. Deposits of three glaciations, Formation lacks morainal form where it overlies till of differentiated on the basis of relative extent, weather- the lower member at Harpole Mesa, but the type ing characteristics, and degree of erosion, are recog- deposit is a large bouldery end moraine that overlies nized in canyons that descend from the plateau (Flint thick gravel on a high pediment surface (Richmond, and Denny, 1958). No stratigraphy is exposed. Clasts 1962b). The two deposits are not directly related and are mostly andesitic volcanic flows and tuffs, but locally may represent separate glaciations (Chart IB). some are sandstone, limestone, siltstone, and clay- Till of the upper member commonly forms moraines stone. Northeast of the plateau, a few patches of deeply on terraces that are deeply entrenched below deposits weathered pre-Carcass Creek drift (Chart IB) may be of the middle and lower members, but the till overlaps of pre-IIIinoian age. Carcass Creek Drift forms gently those deposits in a few places. The till is more bouldery sloping moraines characterized by depressions that are than the older tills and it retains morainal topography. partly filled with colluvium. Boulders are deeply Like the older tills, it has a very strongly developed soil exfoliated and disintegrated to a fine grained gruss. No which suggests that it is pre-Illinoian and middle middle distinct criteria for subdivision of the Carcass Creek Pleistocene in age. Drift have been recognized. The drift probably is Tills of the lower and upper members of the Placer IIIinoian in age and correlative with the Placer Creek Creek Formation (Chart IB) form two broad smoothly Till in the La Sal Mountains. sloping end moraines, the younger about 3 km upvalley The Donkey Creek Drift (Chart IB) is only about from the older. Two outwash terraces, the younger half as extensive beyond the plateau margin as the entrenched within the older, commonly extend down- Carcass Creek Drift; and the Blind Lake Drift is only 1/3 valley from the moraines. However in places, the to lf4 as extensive as the Donkey Creek Drift. The younger outwash overlaps a zonal paleosol developed deposits of both advances are steeply sloping, on the older outwash. Together, the depth of inter- bouldery, and characterized by many depressions, terrace erosion and the paleosol indicate that depo- some retaining water. Volcanic boulders on Donkey sition of the two members was separated by an Creek Drift are moderately exfoliated; those on Blind interglacial interval (Chart IB). The tills are inferred to Lake Drift are little exfoliated. Two recessional mor- be early and late IIIinoian in age respectively on the aines of Blind Lake Drift are recognized headward of basis of their morphologic expression, relative soil the outer end moraine. development, and relations to outwash terraces. Both the Donkey Creek and Blind Lake Drifts were Tills of the lower and upper members of the Beaver considered to be late Wisconsin in age (Flint and Basin Formation (Chart IB) form two end moraines Denny, 1958). The marked recession between them is upvalley from those of the Placer Creek Formation. characteristic of late Wisconsin deposits in many They are steep, bouldery, hummocky, and locally sharp glaciated areas of the Colorado Plateau and Basin crested, which suggests that both moraines are late Ranges (Chart IB). No glacial deposits of Holocene Wisconsin in age (Richmond, 1962b). Soils on the tills age occur on the plateau, but rock glaciers of Holocene are less well developed than are soils on tills of the age are present locally at the base of its marginal cliffs Placer Creek Formation. Deposition of the two mor- (Flint and Denny, 1958). aines and their associated outwash terraces was separ- ated by an interval of pronounced glacial recession that San Francisco Peaks, Arizona may correlate with a mid-late Wisconsin recession Deposits of three glaciations were recognized about 17,000 BP in the Rocky Mountains. I infer that initially in the San Francisco Peaks (Fig. 1, area 23) the till of the upper member of the Beaver Basin (Sharp 1942). Source rocks are rhyolite, andesite, 120 Quaternary Science Reviews dacite, and basalt. Till of the Lockett Meadow glaci- (1969) in the Sierra Nevada, California, but a some- ation (Pewe and Updike, 1976) (Chart IB) overlies the what earlier late Illinoian age cannot be excluded Sugarloaf Mountain tephra. K-Ar dated 218 ± 21 ka* (Chart lB). (Damon et ai., 1974; Sheridan and Updike, 1975). The Till of the Smith Cienega glaciation (Chart IB) forms Illinoian age of the till, proposed by Sharp (1942), thus subdued but commonly sharp-crested moraines about is substantiated. The till of the Lockett Meadow 15 m high. Surface boulders are conspicuous but not glaciation forms large, gently sloping end moraines abundant, and they are much less weathered and pitted about 7.3 km from the cirques. Upvalley, moraines of than are boulders on deposits of the Purcell glaciation. the Core Ridge glaciation (Pewe and Updike, 1976) Soils are em thick. The maximum extent of the (Chart IB) are about 4.6 km from the cirques. Two sets till is about 3.5 km from the cirques. Merrill and Pewe of massive, undulating, little modified moraines as assigned the deposits an early Wisconsin age. I suggest much as 65 m in height are recognized. Terminal loops their correlation with the Tahoe moraines of Black- are dissected. The deposits are assigned an early welder (1931) in the Sierra Nevada (Chart IB). Wisconsin age (Pewe and Updike, 1976). I suggest their Till of the Baldy Peak glaciation (Chart IB) forms correlation with Tahoe moraines of Blackwelder (1931) steep, sharp-crested moraines more than 30 m high, in the Sierra Nevada (Chart IB). whose surfaces are characterized by abundant boulders Moraines of the Snowslide Spring glaciation (Chart and many closed depressions. Surface boulders are only IB) are less than 2 km from the cirques (Pewe and slightly weathered and are not pitted. Soils are about 20 Updike, 1976). They are fresh in appearance and em thick and weakly developed. Three or four closely steeply sloping. The soils on them are less well spaced, locally discordant, recessional moraines are developed than are soils on moraines of the Core Ridge nested within the outer terminal moraine in places, and glaciation. Two sets of lateral and end moraines a sequence of recessional moraines is present upvalley. represent two advances during the Snowslide Spring Merrill and Pewe (1977) recognized two major ad- glaciation (Chart IB). A late Wisconsin age is assigned vances, the maximum extending about 2.6 km from the to these moraines (Pewe and Updike, 1976) on the cirques. On the basis of morphologic and soil character- basis of their degree of preservation, weak soil devel- istics, they assigned a late Wisconsin age to the opment, and relative extent. I suggest their correlation moraines of both advances. I suggest that the recession with the Tioga moraines of Blackwelder (1931) in the separating them is correlative with that estimated to Sierra Nevada. No Holocene moraines have been have occurred about 17,000 BP in glaciated areas of the identified, and only a single rock glacier of Holocene Colorado Plateau and Rocky Mountains (Chart IB). age is recorded. Till of the Mount Ord glaciation forms a small, densely forested, bouldery moraine in one north-facing RANGES OF THE GREAT BASIN cirque. The till has a weak azonal soil; Merrill and Pewe (1971) assigned the deposit a neoglacial or early The Great Basin (Fig. 1) includes approximately 22 Holocene age. I suggest that it may be latest Pleisto- mountain ranges that are known to have been glaciated cene in age (Chart IB) on the basis of its thick forest during the Pleistocene, but very few of them have been cover, a characteristic not reported on Holocene studied in detail. All of the glaciers were valley glaciers moraines elsewhere in the region. and most were small. The largest glaciers were in the Wallowa Mountains, actually a part of the Northern Ruby-East Humboit Range, Nevada Rocky Mountains but included here because of its Deposits of two, and possibly three, glaciations are isolated location south of the limit of Cordilleran ice recognized in the Ruby-East Humbolt Range (Fig. 1, sheet glaciation. The deposits of three areas are area 25). Source rocks are quartzite, granite, granite discussed here. gneiss, pegmatite, mica schist, marble, and siliceous White Mountains, Arizona metamorphic rocks. Moraines of the Lamoille glaci- Deposits of two glaciations were recognized in the ation (Blackwelder, 1931) are present at the mouths of White Mountains by Merrill and Pewe (1972, 1977) the canyons. They are massive and have subdued, rounded, smooth slopes mantled with gruss and (Fig. 1, area 24). Source rocks are latite and quartz latite. The tills are sandy. Till of the Purcell glaciation sparsely scattered boulders (Sharp, 1938; Wayne, (Chart IB) is represented chiefly by isolated deposits 1984). Boulders on the surface are chiefly quartzite, lacking morainal form and by erratic boulders. A gently whereas many rock types are present in the till at depth (Sharp, 1938). End moraines have been extensively sloping moraine is present locally. The deposits are eroded (Sharp, 1938) and are overlapped by younger weathered to depths of more than 50 ern and surface boulders have deep weathering pits. The maximum alluvial fan deposits. Two sets of prominent lateral moraines are present at the mouths of some canyons. extent of the till is about 7.7 km from the cirques. On the basis of weathering characteristics the Purcell Aerial photos indicate that the inner moraine cross-cuts glaciation is assigned a late Illinoian age. I suggest its the outer moraine diagonally, which suggests that they probable correlation with the Mono Basin Till of Sharp may represent two distinct glacial advances. However, no buried soils have been reported. Low arcuate end *Calibrated after Dalrymple, 1979. moraine ridges in the terminal zone appear to mark Quaternary Glaciations in the Northern Hemisphere 121 minor glacial fluctuations prior to the overall recession can be cut with a shovel. Crandell indicates that the (Wayne, 1984). Soils on all of the moraines of the older till is truncated by a moraine of the younger till, Lamoille glaciation are similar and more maturely which is similarly weathered, and that the two tills may developed than soils on younger moraines (Sharp, represent separate glaciations. Drift J (Chart 1B) 1938). They are described in detail by Wayne (1984). locally forms a series of broad smooth end moraines Surface boulders also are markedly more weathered lacking closed depressions. Granodiorite boulders are than those on younger moraines (Sharp, 1938; Wayne, not present on the surface. Soils lack a pronounced Bt 1984). horizon but have a thick Cca horizon. Five secondary Moraines of the Lamoille glaciation initially were moraines locally are nested behind the terminal considered to be 'early Wisconsin = Iowan' in age moraine. (Blackwelder, 1931, 1934; Sharp, 1938). Based on Drift T forms two end moraines with smooth slopes, relative preservation of morainal form, relative integrated drainage, few depressions, and abundant weathering characteristics, and relative soil develop- surface boulders, 10 to 30 percent of which are ment, Wayne (1984) has interpreted them to be of granodiorite. Soil profiles are about 1mthick; Bt and Illinoian age. I suggest that they are late Illinoian in age Cca horizons are of about equal thickness. The outer and that they may represent two distinct advances moraine locally is truncated by the inner, suggesting (Chart 1B). If they are Illinoian in age, they probably that they represent two advances. are correlative with the Mono Basin and equivalent tills Drift W forms two terminal moraines, the younger of in the east-central Sierra Nevada (Chart 1B) (see which partly breaches the older at the foot of the lake. Fullerton, Sierra Nevada, this volume). They have irregular surfaces and abundant depressions. Moraines of the Angel Lake glaciation are present Granodiorite boulders are abundant at the surface; km upcanyon from the Lamoille moraines. They many are essentially unweathered. Soils are immature. are steep, irregular, hummocky, and commonly sharp- Crandell assigned an early or middle Pleistocene age crested. Closed depressions are common. Boulders are to drifts C and J and a late Pleistocene age to drifts T abundant on the surface and are little weathered and W. I suggest the modifications shown on Chart 1B, (Sharp, 1938). Soils are weakly developed (Wayne, based chiefly on a change in the age of correlatives of 1984). The moraines are correlated with the Tioga drift T to late Illinoian. The two moraines of drift W moraines in the Sierra Nevada and are assigned a late probably are older late Wisconsin in age. Younger late Wisconsin age (Blackwelder, 1931; Sharp, 1938, Wisconsin moraines between those of drift Wand the Wayne, 1984). Recessional moraines upcanyon were cirques are difficult to identify because they are in noted by Sharp (1938), and three were mapped in some heavily forested terrain. However, at least two such canyons by Wayne (1984). A date of 13,000 ± 900 BP moraines are recorded in some drainages (Crandell, was obtained from peat at the base of a bog on the 1967; Kiver, 1974). Deposits of three episodes of outer of the three moraines (Wayne, 1984). In the Holocene glaciation in the cirques have been differen- upper part of the canyon, a Mazama tephra (age about tiated on the basis of maximum lichen diameters, 6,845 ± 50 BP) occurs at the base of sediments in a percent of lichen cover on boulders, relative weather- pond (Thompson, 1984) on the inner moraine. I ing characteristics, relative soil development, suggest its correlation with the Donald Creek moraines vegetation type and percent cover, and frontal slope (Wind River Range, Wyoming) and Satanta Peak angle (Kiver, 1974). Kiver assigned an early Holocene moraines (Front Range, Colorado) in the Rocky age to the Glacier Lake moraine (Chart 1B), an early Mountains (Charts lA, 1B). The moraine occurs below neoglacial age to the Prospect Lake moraine, and a late a cliff, 110 m high, at the lip of a cirque complex. A neoglacial age to three successively more barren Eagle rock glacier of Holocene age was mapped by Wayne Cap moraines. No radiometric ages are available. (1984) in one of the cirques (Chart 1B).

Wallowa Mountains, Oregon CONCLUSIONS Deposits of four Pleistocene glaciations have been recognized in the Wallowa Mountains (Fig. 1, area 26). Tills of eight and possibly nine Pleistocene glaci- Source rocks are granodiorite, quartz diorite, green- ations" are recognized in the region of the Rocky stone, hornfels, schist, marble, quartzite, and basalt. Mountains, the Colorado Plateau, and the ranges of the Crandell (1967) distinguished deposits of different Great Basin (Charts lA, 1B), except in the Yellow- glaciations on the basis of differences in depth of stone National Park area, where twelve are recognized. oxidation, relative amount of secondary clay and Deposits of seven glaciations are recorded in the calcium carbonate in the soil profile, and relative Glacier National Park area (Fig. 1, area 1), eight in the abundance of granodiorite boulders at the surface. Wind River Range (Fig. 1, area 9) and seven in the La Lateral and end moraines enclose Wallowa Lake. Drift C (Chart 1B) includes two tills. The older till lacks * Early Wisconsin and late Wisconsin glacial advances are treated morainal form and has a Bt horizon more than 1m as separate glaciations for purposes of this discussion because, although they were not separated by an interglacial, glacial depo- thick. Grandiorite boulders are lacking at the surface sition in the terminal areas of those advances, was separated in time and basalt boulders 1 m in diameter beneath the surface by about 40,000 years. 122 Quaternary Science Reviews

Sal Mountains (Fig. 1, area 21). Six tills are distin- sediments in Yellowstone National Park and the lack of guished in the southwestern Salmon River Mountains available dates between 30 and 40 ka have been cited as (Fig. 1, area 8), and in the Wallowa Mountains (Fig. 1, suggesting that the area was covered by an icecap in area 26); five tills (and at least two older fluvioglacial middle Wisconsin time (Pierce et al., 1976, Pierce, gravels) are differentiated in the Sawatch Range (Fig. 1979; Porter et al., 1983). Most of the 'greater than' 1, areas 16a, b), and five tills and at least six older ages now are superseded (see Richmond, Yellowstone gravel deposits of probable fluvioglacial origin are Park, this volume). Three represent earliest Wisconsin differentiated in the San Juan Mountains (Fig. 1, area time; one represents early middle Wisconsin time; and 19). The widespread geographic distribution of these one 'appears to be around 29,000 BP, but could be glaciated areas suggests that deposits of at least seven greater' (Meyer Rubin written commun., 1985). glaciations probably exist in all but the more southerly Positive evidence for more than minimal middle and southwesterly ranges in the region. Wisconsin glaciation is not available (Richmond, In terms of age (Charts lA, 1B), one early Pleisto- Yellowstone Park, this volume). cene till is present in the Glacier National Park area, in Glacial deposits of late Wisconsin age are present in the La Sal Mountains, and possibly in the Wind River all glaciated ranges. The following ages limit maximum Range. Two early middle Pleistocene tills are differen- age of the late Wisconsin advance in four ranges: Wind tiated in Glacier National Park, and one till that is River Range, 24 ± 6 ka; Wasatch Range, associated with two outwash gravel terraces and may BP; Front Range, BP, BP; represent two glaciations is known in other areas. Two Sawatch Range, Bp, BP. It is middle middle Pleistocene tills are recorded in the believed to have occurred about 22,000 BP. End Wind River Range, the La Sal Mountains, the Wallowa moraines of at least six readvances during glacial Mountains and, by one interpretation, in the San Juan wasting are recorded in the Bitterroot Range, Lemhi Mountains. One middle middle Pleistocene till is Range, Wind River Range, and Front Range; and five present in several ranges. Two late middle Pleistocene or four are recorded in many other ranges. In the Wind tills are recorded in many ranges, and in ten of those River Range, the oldest of these moraines is older than discussed (Charts lA, 1B), they represent separate 20,800 ± 100 BP and the second oldest probably is glaciations (early and late Illinoian). In other ranges, older than 18,700 ± 600 BP. Based on a warm interval two large terminal moraines may be early and late documented by pollen and dated at about 17,000 BP in Illinoian in age or both may be late Illinoian in age. Yellowstone Park, I estimate that by that time pied- Two superposed late Illinoian tills are present in the mont glaciers had receded into the canyon mouths in Wind River Range. In the San Francisco Peaks area, a Glacier National Park and in the Wind River Range, single Illinoian till is younger than 218 ± 21 ka. Two and into the upper canyons in the Front Range and end moraines and their associated outwash terrace Wasatch Mountains. A readvance about 15,000 BP, deposits in the San Juan Mountains by one inter- also based on dating in Yellowstone National Park, is pretation may be Illinoian in age. By an alternate indicated by canyon mouth to upper valley moraines in interpretation, they may be 'Eowisconsin' in age and 15 ranges. Canyon mouth moraines commonly were correlative with deposits of two 'Eowisconsin' glaci- deposited by glaciers flowing from ice caps on extensive ations recorded in Yellowstone National Park (Chart high uplands. In the San Juan Mountains, central 1A). End moraines of possible 'Eowisconsin' age also glaciated divides and at least some cirques were ice-free are present in other ranges. by 15,450 ± 220 BP to 14,010 ± 140 BP. Moraines of End moraines of possible early Wisconsin age are the last late Pleistocene readvance occur just below differentiated in five ranges (Lemhi Range, south- sheltered cirques in many ranges, but locally they are western Salmon River Mountains, Front Range, San present in the upper valleys and they outline a small ice Francisco Peaks, and White Mountains). However, cap on the high glaciated plateau of the Wind River throughout the region, deposits of possible early Range. Although not closely dated, they are younger Wisconsin age are not closely controlled chronologi- than 13,140 ± 700 BP and are older than 11,600 ± 350 cally. In Yellowstone National Park, till at one locality BP. One early Holocene moraine and three sets of is older than 54,550 ± 550 BP (Gr N-8140) and at neoglacial moraines are present in cirques in some another locality ice-dammed lake sediments containing ranges. However, the youngest two late Wisconsin dropstones are younger than BP (Gr N- moraines appear to be lacking in many southeast- to 7332) (Richmond, Yellowstone Park, this volume) west-facing cirques in some southern and southwestern (Chart 1A). Pierce et al. (1973) have suggested that ranges, and Holocene moraines are lacking in a great obsidian hydration age measurements of 45-70 ka from many similarly oriented cirques in ranges from the occasional obsidian pebbles in Pinedale terminal mor- Canadian border to southern New Mexico. aines (Madison Canyon moraines, Chart lA, Yellow- Correlation of the alpine glacial deposits of the stone Park) imply a glacial maximum earlier than the Rocky Mountains, the Colorado Plateau and the ranges average age of 28 ka indicated by most of their of the Great Basin with those in Yellowstone National measurements from obsidian pebbles in the moraines. Park and those in the Sierra Nevada on the basis of No glacial deposits of middle Wisconsin age have available chronometric controls is shown in Charts 1A been identified. Six 'greater than' 14C ages from lake and lB. Quaternary Glaciations in the Northern Hemisphere 123

Based on stratigraphy and relative age data, the Alden, W.e. (1953). Physiography and glacial geology of western sequence of glaciations in the Cascade Mountains Montana and adjacent areas. U.S. Geological Survey. Pro- fessional Paper 231,200 pp. parallels that in the Rocky Mountains but lacks Alden, W.e. and Stebinger. E. (1913). Pre-Wisconsin glacial drift in chronometric control (see Richmond, Cordilleran ice the region of Glacier National Park, Montana. Geological Society sheet, this volume). Correlations of alpine glacial of America Bulletin, 24, 529-572. Atwood, W.W. (1909). Glaciation of the Uinta and Wasatch deposits with known deposits of the Cordilleran ic sheet Mountains. US. Geological Survey, Professional Paper 61,96 pp. are chiefly late late Wisconsin in age. The Deckard Atwood, W.W. (1915). Eocene glacial deposits in southwestern Flats moraines in Yellowstone Park (dated about 15 ka Colorado. U.S. Geological Survey, Professional Paper 95-B. pp. B1-B26. BP) and correlative moraines (Charts lA, IB) are Atwood, W.W. and Mather, K.F. (1912). The evidence of threc correlated with end moraines of the maximum advance distinct glacial epochs in the Pleistocene history of the San Juan of the Cordilleran ice sheet (also dated about 15 ka Mountains, Colorado. Journal of Geology, 20, 385-409. Atwood, W.W. and Mather, K.F. (1932). Physiography and Quater- BP). The Lamar Valley moraines in Yellowstone Park nary geology of the San Juan Mountains, Colorado. U.S. (dated between 13.1 ka BP and 11.6 ka BP) and Geological Survey, Professional Paper 166, 176 pp. correlative moraines (Charts lA, IB) are correlated Atwood, W.W., Jr. (1937). Records of Pleistocene glaciers in the Medicine Bow and Park Ranges. Journal of Geology, 45, with the youngest end moraines and related deposits of 113-140. the Cordilleran ice sheet on which the Glacier Peak B Bacon, e.R. (1983). Eruptive history of Mount Mazama and Crater tephra (dated 11.2 ka DP) occurs. Correlation of alpine Lake Caldera, Cascade Range, U.S.A. Journal of Volcanology and Geothermal Research, 18, 57-115. glaciations and Laurentide glaciations in central Ball, S.M. (1908). Geology of the Georgetown quadrangle. U.S.A. is discussed in Summation of Quaternary Colorado. U.S. Geological Survey, Professional Paper 63, pp. Glaciations in the United States of America (Richmond 29-63. Barnhardt, M.L. (1979). Late Quaternary glacial geomorphology of and Fullerton, this volume), but correlations of late the Kearney Creek - South Piney Creek area, Bighorn Moun- Wisconsin readvances are not included. At least three tains, Wyoming. Ph.D. dissertation, University of Illinois. late Wisconsin advances in the two regions appear to Urbana, Illinois. Benedict, LB. (1968). Recent glacial history of an alpine area in the have been broadly parallel in time. The Deckard Flats Colorado Front Range, U.S.A., II. 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