BUREAU OF ECONOMIC GEOLOGY The University of Austin 12, Texas

John T. Lonsdale, Director

Report of Investigations—No. 39

Correlation of the (Neogene) in Western Texas With Type Localities in

By

JOHN C. FRYE AND A. BYRON LEONARD

August 1959

Contents

Abstract 5 Generalities 5

Depositional history .... 6 Previous work 7 Acknowledgments 11 Physical stratigraphy 12 Lithologic types within the Ogallala 12 Stratigraphic and geographic variations in lithologies 14 Physical criteria of correlation 16 Stratigraphic paleontology 18 Vertebrate faunas 18 Molluscan faunas 20 Fossil plants and floral zones 21 Geographic range of fossil seeds 21 Stratigraphic range of fossil seeds 23 Valentine floral zone 23 Ash Hollow floral zone 24 Kimball floral zone 26 Summary and conclusions 27 Measured sections 30 References 33 Index 43

Illustrations

FIGURES 1. Graphic correlation of the Ogallala formation in western Texas with type localities in Nebraska 8-9 2. Known geographic range of some significant Ogallala fossil seeds from Texas to Nebraska 22 3. Known stratigraphic ranges of some significant fossil seeds in the Ogallala formation 23 PLATES I. The Ogallala formation (Ash Hollow floral zone) in central western Texas 38 11. Distinctive lithologies of the Ogallala formation in Texas 41

Correlation of the Ogallala Formation (Neogene) in Western Texas with Type Localities in Nebraska

JOHN C. FRYE 1 AND A. BYRON LEONARD 2

ABSTRACT The Ogallala formation extends from the The lithology of the formation from north side of the Pecos Valley northward Nebraska to central western Texas is dis- across western Texas, Oklahoma, , cussed, criteria for correlation are con- and Nebraska into southern South Dakota. sidered, and the work on fossil vertebrates, With its southern limit within the Edwards mollusks, and fossil plant seeds is briefly Plateau, it underlies the upland surface of reviewed, with the purpose of correlating much of the High Plains section of the the Ogallala formation of central western Great Plains Province. The extensive flu- Texas with previously recognized type vial deposits of Neogene age are widely localities in Nebraska. Classification prob- exposed throughout the dissected plateau lems are discussed and it is concluded that region that flanks the Rocky Mountains on rock-stratigraphic subdivision of the Ogal- the east. The deposits have yielded large lala of Texas is not usable regionally, faunas of fossil vertebrates and mollusks whereas floral zones are recognizable and an abundance and variety of fossil throughout the High Plains. Three floral plant seeds. Relief on the sub-Ogallala zones recognized in the Texas Ogallala are erosion surface accounts for the range in correlated with the Valentine, Ash Hollow, thickness of the formation from a feather and Kimball ofKansas and Nebraska. edge to more than 500 feet.

GENERALITIES The Ogallala formation displays the established across Kansas. The correlation greatest geographic extent of outcrop area of the Texas Ogallala with the Nebraska of all the nonmarine (pre-Pleistocene) for- types therefore will serve to produce a mations of the . The forma- uniform frame of reference throughout the tion is almost continuous throughout a Great Plains. region extending more than 800 miles from From a practical standpoint the outcrop north to south and 300 miles from east to area of the Ogallala formation is coexten- west, and adequate exposures are generally sive with the High Plains physiographic available for study. For this widespread section. The intimate dependence of topo- depositional unit a relatively uniform stra- graphic expression on the Ogallala is most tigraphic framework, accompanied by strikingly displayed in Texas and New basic correlation, should be effected Mexico where the High Plains surface is through the region. The stratigraphic sub- sharply terminated on both the east and divisions of the formation, as well as the west sides by Ogallala scarps (PI. I,A). formation itself, are based on type localities However, the High Plains are gradational in Nebraska, and correlations have been with the Edwards Plateau to the south where the formation thins and eventually ¹ Chief, Illinois Stale Geological Survey, Urbana. ² Department of Zoology, University of Kansas, Lawrence. feathers out. 6 Report of Investigations—No. 39

In and north of the Texas Panhandle Plains, primarily because it constitutes the area, the scarps that bound the High Plains largest and most extensive groundwater become discontinuous and even where reservoir of the region. It also is a major present are less dependent upon the Ogal- source of sand and gravel and road metal lala. For example, in central and north- (caliche) and contains less extensive de- central Kansas the most prominent scarps posits of diatomite (Evans, 1946), vol- are developed on resistant limestones of canic ash (Swineford and Frye, 1946) and age and may or may not be siliceous-cemented rock. capped by Ogallala deposits. Farther north It is our purpose in this paper to present the High Plains surface is commonly evidence, and conclusions drawn there- mantled by a significant thickness of from, concerning the correlation of the Pleistocene deposits, and the upper part of Neogene deposits of the High Plains region the Ogallala has been removed by erosion of Texas with the type localities in Nebras- over large areas. Only in central western ka. The physical stratigraphy (including Texas and adjacent New Mexico is W. D. depositional history and physiographic ex- Johnson's (1901, p. 629) generality, "the pression) of the Ogallala formation is re- High Plains have endured as alluvial pla- viewed in general terms, but detailed de- teaus since Tertiary times," demonstrably scriptions are presented only as illustra- true (Frye, 1946). This physiographic tions, and evidence from fossil vertebrates situation is particularly favorable for stra- is reviewed insofar as these data have been tigraphic work in the High Plains of Texas presented in the literature.The degree and because the re-entrant canyons cut into the extent of utility of fossil mollusks and the scarp afford excellent exposures of virtually widespread occurrence of fossil plant ma- the entire thickness of the local Ogallala terials and their significance in correlation (Frye and Leonard, 1957a; and measured studies are discussed. sections, this publication). Depositional history.—The depositional There is a distinct contrast in the physio- history of the Ogallala is complex. After an graphic relations of the southern and early hypothesis favoring lacustrine origin northern limits of the Ogallala formation. (King. 1878) had been refuted, the con- In the southern area the Ogallala becomes cept of stream deposition was introduced generally thinner southward (fig. 1) and (Gilbert. 1896). Unfortunately, however, is discontinuous south of Howard County, it was thought that the mechanism of feathering out to scattered patches of the stream deposition was alluvial fan build- uppermost part of the formation. In ing (Plummer, 1933, p. 769) and that the Borden, Dawson, and Howard counties plain was developed by coalescence of a the Ogallala controls some scarps but in series of adjacent gigantic fans that spread other places the scarps are controlled by out over an essentially planate surface. It resistant Cretaceous limestones. South of is apparent that if such were the case the these counties the Ogallala is nowhere a oldest deposits in the alluvial complex significant factor of topographic control. should exist in the area of initial deposition In contrast, the northern limit of the for- (presumably relatively near the apical mation in Nebraska and southern South regions of the fans), the occurrences of Dakota is controlled by erosion rather than these oldest deposits should be roughly by stratigraphic pinch-out. It is not known aligned in a north-south direction parallel how far north the Ogallala originally was to the source area, and there should be pro- deposited, for in that region the uppermost gressive overlap of younger beds toward units have been removed and the northern the east. A test of this hypothesis is possible outcrops are typified by the truncated mid- by stratigraphic means once sufficiently de- dle and lower parts of the formation. tailed correlations are made within the The Ogallala formation is of great eco- mass of the deposits. nomic importance throughout the Great Recent work in Kansas (Frye, Leonard, Ogallala Formation Correlation 7 and Swineford, 1956) has led to the con- large mesas protected by resistant Cretace- clusion that the mechanism of deposition ous rocks stood prominently above this was quite different. It was possible to trace alluvial plain that surrounded them. The zones of several ages for considerable dis- Neogene deposits became progressively tances west to east, and to show that the thinner and more discontinuous southward younger units, instead of progressively over the surface of the resistant rocks that overlapping the older deposits to the east, form the surface of the Edwards Plateau. displayed a north and south overlapping The cause of the diminution of the rate relationship on the gently sloping sides of of alluviation and its eventual cessation in broad and relatively shallow pre-Ogallala late Neogene time is not known with cer- valleys. Although figure 1 is not plotted to tainty, but it seems plausible that climatic a uniform geographic scale and the strati- control by progressive desiccation (Frye graphic sections presented are relatively and Leonard, 1957b) was at least an im- widely spaced, it nevertheless confirms a portant contributing factor. In any case, similar relationship throughout western the evidence strongly indicates that the Texas. surface of this regionally extensive alluvial These data lead clearly to the conclusion plain remained in a state of essential equi- that the mechanism of Ogallala deposition librium for a significant interval of time. was not that of alluvial fan building but Interruption of equilibrium conditions rather was one of valley alluviation. Gen- throughout the High Plains was by the eralized reconstruction of the early Neo- initial pulse of early Pleistocene stream gene erosional topography indicates broad dissection, judged to have been produced eastward-trending valleys with gently slop- by the simultaneous effects of mild crustal ing (perhaps pedimented) sides, and a warping and sharply increased precipita- "local" relief in central western Texas of tion. more than 500 feet. The cause of initial Previous work—Stratigraphic studies alluviation in the bottoms of these valleys of the Neogene of the Great Plains started may have been either climatic or tectonic, nearly a century ago with the early scien- or both. In any case it seems certain that tific expeditions (Meek and Hayden, 1862; earliest deposition occurred along signifi- Engelmann, 1876; King, 1878), was fol- cant segments of the major valleys but did lowed by more localized work in some not reach into the mountains, and if it areas (Hawn, 1866; Hay, 1885;Cummins, reached a point of contact with marine sedi- 1891, 1892, 1893; Cope, 1892. 1893) that ments in the Gulf, it did so at few places. It included recognition of fossil vertebrate seems likely that throughout Neogene time faunas in Texas, and, near the close of the the competency of the depositing streams last century, by general studies of relatively was such that their major alluviation termi- large regions (Gilbert. 1896; Haworth, nated a considerable distance inland from 1897; Darton, 1899; Matthew, 1899; W. the coast. D. Johnson, 1901). During the present cen- In the High Plains belt, as alluviation tury, with the notable exception of a few proceeded through Neogene time, more reports (Baker, 1915; Gould, 1906, 1907; and more of the existing erosional topog- Reed and Longnecker, 1932), strati- raphy was laterally overlapped, the lower graphic studies of the Neogene deposits of divides were buried, and ultimately much western and northwestern Texas lan- of the region northward from Howard guished until the present decade (Evans, County, Texas, to at least southern South 1949, 1956; Brand, 1953; Frye and Leon- Dakota became a coalescent plain of allu- ard, 1957a, 1957b; van Siclen, 1957; viation with only local areas on the highest Leonard, 1958). of the former divides extending to or Farther north in the Great Plains, par- slightly above the regional surface. From ticularly in Nebraska and Kansas, studies Howard County southward, relatively have proceeded on the stratigraphy and 8 Report of Investigations—No. 39 Ogallala Formation Correlation 9

Fig. 1. Graphic correlation of the Ogallala formation in western Texas with type localities in Nebraska. 10 Report of Investigations—No. 39 paleontology of these deposits (e.g., Bar- nally spelled Ogalalla) was proposed b) bour and Cook, 1917; Darton, 1920; Darton in 1899 (p. 734) to apply to "a Thorpe, 1922; Elias, 1931, 1932, 1942; calcareous formation of late Tertiary age," Cook and Cook, 1933; F.W. Johnson, 1936, that in its typical development (p. 735) 1938; Hesse, 1935; Chaney and Elias, "is a calcareous grit or soft limestone con- 1936; Stirton, 1936; Lugn, 1938, 1939; taining a greater or less amount of inter- Frye and Hibbard, 1941; Frye and Swine- mixed clay and sand, with pebbles of vari- ford, 1946; Frye and A. R. Leonard, 1949; ous kinds sprinkled through it locally, and Swineford, Frye, and Leonard, 1955; a basal bed of conglomerate at many Frye, Leonard, and Swineford, 1956). The places." Although in 1899 and again in continuing work in the northern part of the 1905 Darton failed to designate a type Plains region has resulted in the develop- locality, in 1920 he indicated that the type ment of a usable stratigraphic framework was near Ogallala station in western Ne- and widespread correlation. The Nebraska braska. He stated (Darton, 1920, p. 6) that term Ogallala has gradually replaced a its age appeared to be and late large number of local names and is now and that the Ogallala did not in- commonly used for the rock-stratigraphic clude the. overlying deposits that had unit including deposits of Neogene age yielded bones of Pleistocene vertebrates. from Howard County, Texas, northward to Subsequent workers (Elias, 1931; Hesse, South Dakota. Stratigraphic terms for- 1935; Lugn, 1938, 1939) have fixed the merly in use in northwestern Texas have type section as on Feldt ranch sec * been summarized by Plummer (1933). 33, T. 14 N., R. 38 W.), approximately 2 The stratigraphic framework that has miles east of the town of Ogallala, and developed in the central and northern have described its contained fossils. Plains is based on type localities in Nebras- The Valentine floral zone is the lowest ka, and, even though the classification, unit recognized within the Ogallala for- rank, and type of stratigraphic unit based mation of Texas (fig. 1). The term Valen- on each of the type localities differ from tine was proposed by Barbour and Cook in Nebraska to Kansas to Texas, these type 1917 (p. 173) and the type locality was through- localities are nonetheless usable designated by F. W. Johnson (1936, p. out the region. It has been the practice in 467) as being between the old and new Nebraska (Lugn, 1939) to assign group railroad grades in the NE sec. 17, T. 33 rank to the Ogallala and formational rank N., R. 27 W., Cherry County, Nebraska. to its principal subdivisions, whereas in Although there has been controversy over Kansas (Moore and others, 1951) the the use of this name, definition Ogallala is given formation rank with con- Johnson's has been generally accepted (Lugn, 1939). tained members, and in Texas (Frye and Leonard, 1957a) formation rank with in- The Ash Hollow floral zone occurs next above the Valentine in western Texas (fig. cluded floral zones. As the units in each 1). The Ash Hollow first by area are based on and correlated with the was described same type localities, there is seemingly Engelmann (1876, p. 260), but Lugn small danger of confusion. In the north- (1938,1939) formally introduced the term ward correlation of the Texas Neogene we for a stratigraphic unit from exposures in are concerned with the type localities of the Ash Hollow canyon, on the south side of Ogallala, Valentine, Ash Hollow, and the Platte River valley, near Lewellen, Ne- Kimball. These have been discussed by braska. Lugn (1938, 1939) and subsequently re- The Kimball floral zone is the youngest viewed in connection with correlations into unit recognized within the Ogallala of Kansas (Frye, Leonard, and Swineford, Texas. It is correlated with the type locality 1956). described by Lugn (1938, p. 224) in Kim- The name Ogallala formation (origi- ball County, in western Nebraska. Ogallala Formation Correlation 11

Acknowledgments—The field work in Panhandle area in 1945-1947 also were Texas on which this report is based was used. We express our thanks to E. C. Reed, carried on during the seasons of 1954, State Geologist of Nebraska, for furnishing 1955, 1956, and 1957, under the auspices to us an unpublished measured section near of the Bureau of Economic Geology of The the type locality of the Ogallala and for University of Texas; some data obtained helpful suggestions. during brief periods of field work in the PHYSICAL STRATIGRAPHY

The Ogallala formation presents a gross ofmoderate coarseness, at a few places they aspect of meaninglessly monotonous li- have been observed to contain boulders thology that indicates a random inter- with a maximum diameter exceeding 1 mixture of channel and floodplain environ- foot. ment of deposition. It is in general an intri- Silts and fine-to-medium sands are a cate and extensive repetition of a few pre- major constituent of the Ogallala. They dominant sedimentary types, irregularly range from moderately well sorted to poor- cemented with calcium carbonate but with- ly sorted and locally are interspersed with out an orderly pattern in the recurrence of pebbles. These fine elastics range from well gravels, sands, and sandy silts. Interspersed bedded (PI. I, C) and locally thin bedded throughout the formation, although com- to irregularly bedded, thick bedded and posing a minor percentage of the total massive, and from loose through friable to volume, are strikingly distinctive lentils of well compacted. They range in color from volcanic ash, marls, limestones, clays, red brown and brick red, through tan and opaline-cemented sands and gravels, ca- greenish gray, to light gray. Although it liche, and silicified caliche. Notwithstand- is probable that detailed study of heavy ing prevalent sameness, when viewed mineral assemblages would produce evi* broadly geographically and stratigraphi- dence of source area, normal field exami- cally the sediments show significant trends nation does not. that import describable differences be- The type and degree of cementation of tween the Ogallala of central western Texas Ogallala sediments, even though the cement and northern Nebraska and between the consists predominantly of calcium carbo- Valentine and the Kimball zones. nate, range within extreme limits. Several Lithologic types within the Ogallala distinct types of carbonate cementation can Gravel and coarse sand, although volu- be recognized, but the prevalent use of metrically secondary to the finer elastics, such terms as "caliche" and "mortar beds" are the sedimentary types most commonly in a loose, general sense tends to minimize observed. These coarse clastic elements these differences. In physical appearance (PI. 11, C) are sensitive to source and, the carbonate cementation ranges from iso- particularly near the basal contact of the lated or disconnected nodules, "stringers," formation, in many places reflect local and "pipes" in relatively loose sand or silt, sources. The effect of local source is par- through patterns of interconnected streaks ticularly strong where thick, coarse gravels and zones of interlaced "stringers," immediately overlie the basal unconform- "pipes," and "sheets" (referred to as a ity; here, pebbles and cobbles of rocks honeycomb or "boxwork" pattern), to uni- occurring in the Cretaceous, , and formly weakly to densely cemented zones. may be relatively abundant. The The densities of the carbonate cements major source of the gravels is to the west range from a few percent of the rock by of the Great Plains region, and almost weight to the extreme of approximately 50 without exception the gravels of the Ogal- percent of the rock by weight. lala are characterized by rock types occur- Genetically the Ogallala carbonate ce- ring in the present mountainous region ments (not including the marls or fresh- west of the Plains. In the central High water limestones) may be placed in three Plains, granites of the Front Range type are general categories. Characteristic of the predominant, whereas farther south there Great Plains region are "soil caliches," is a greater diversity of rock types repre- calcium carbonate accumulations associ- sented. Although the gravels are commonly ated with developed soil profiles. Where Ogallala Formation Correlation 13 such strongly lime-accumulating soils are or gravel, but at others such a relationship buried within the stratigraphic sequence is not detectable. Alignment of these ce- (PI. 11, B) they account for a significant mented zones in some places suggests for- part of the carbonate cement in the Ogal- mation at the position of a temporary stand lala. Although differing somewhat in detail of the water table, but at other places such from the caliche that occurs as part of the an alignment is lacking. It seems reason- modern soils and that associated with able to conclude that this general class of buried soils in the Pleistocene deposits, the carbonate cement is related to percolating soil zones in the Ogallala display general groundwater below the actively developing similarity to the younger soils. soil profile. The thick, massive carbonate zone typi- Siliceous cements are far less common in cal of the stratigraphic top of the forma- the Ogallala than are carbonate cements tion (PI. 11, A) may be regarded as a soil but where present are quite distinctive. The caliche (Swineford, Frye, and Leonard, petrography and origin of silicified rock 1956), but its unusual development and in the Ogallala of the central High Plains subsequent modification merit its place- has been .discussed in detail (Frye and ment in a special class. It is judged that Swineford, 1946), and samples from three this zone, locally called "cap rock" and localities in northwestern Texas were pe- encrusted on its upper surface with the trographically described. In sands and so-called "Algal," or pisolitic, limestone gravels, the silicified cement is opaline, originated as a soil caliche under the sur- which commonly imparts a greenish color face of the temporarily stable plain of al- to the rock; in finer textured sediments, luviation that marked the close of Ogallala opal and chert replace the calcareous ce- deposition. This abnormally thick accumu- ment. The green siliceous-cemented sands subsequently lation of soil caliche was and gravels are generally in lenticular modified and near the surface by the at masses, which in a few areas have coalesced several succeeding cyclic pulses of cli- to form elongate irregular zones several mactic reversals (Frye and Leonard, miles in maximum dimension. The silice- a) that caused solution and secondary 1957 ous-cemented zones in fine-textured de- precipitation resulting in development of posits, on the other hand, have the present thick, dense, and distinctive generally "cap rock," and more particularly in the less distinct boundaries. The siliceous-ce- development of the distinctive layer of piso- mented Texas samples studied may be con- litic limestone at the top. sidered as intermediate between the two The third category of carbonate cement general types as they are pink tan in color in the Ogallala is less easily defined than and the cement occurs in a relatively fine- the preceding two and may include ma- textured deposit. terials of different origins. Cements of vari- The origin of the silica has been at- ous densities occur in the relatively per- tributed by Frye and Swineford (1946) to meable sands and gravels of the formation the weathering of the abundant volcanic (PI. I, A, B, D). The prevalence of weakly ash lentils of the Ogallala, and the green cemented zones of sand and sand and color to solution and reprecipitation of the gravel early gave rise to the term "mortar silica below the water table. The pink and beds" in the central Plains region. This gray zones may represent: (1) precipita- type of cement not only has a wide range in tion above the general water table; (2) a density and induration but is distributed silica derived from volcanic ash falls of irregularly and sporadically. At some Pleistocene age on the surface of the al- places it appears to be localized by varying luvial plain; or (3) silica derived from degrees of initial permeability of the sand the weathering of near surface sediments 14 Report of Investigations—No. 39 during the development of the Ogallala elastics of the Ogallala demonstrates that "climax" soil. they are a part of this formation. To date, Volcanic ash lentils are a distinctive comparable deposits of bentonitic clay lithology within the Ogallala. In the north- have not been observed in the Ogallala of ern Plains region a relatively large number Texas. of separate ash falls have been described Stratigraphic and geographic variation (Swineford, Frye, and Leonard, 1955), in lithologies In the northern High but in northern Texas only one Ogallala Plains region, as has been described (Frye, volcanic ash locality has been petrograph- Leonard, and Swineford, 1956), there is a ically described in Hemphill County progressive upward change in general (Swineford and Frye, 1946). The mode of lithology from Valentine to Kimball. Here, the lowest occurrence and bedding of the volcanic as throughout the High Plains, ash lentils indicate that they accumulated unit, Valentine, is restricted to the major in shallow ponds or depressions, perhaps early Neogene valleys and therefore occurs in abandoned channel segments on the al- in disconnected irregular bands trending luvial plains. generally east-west across the region. Diatomaceous marl and fresh-water These lowest and earliest deposits consist limestone are uncommon lithologies within of relatively uncemented sands, generally the Ogallala formation. Their occurrence gray to greenish gray in color, relatively and their contained fossil mollusks clearly well sorted and thick bedded. Some chan- indicate deposition in semi-permanent nel gravels occur in the Valentine of Ne- ponds. These marls and limestones range braska and Kansas, and it is within these from soft to hard, locally contain volcanic deposits that most of the green opal-ce- ash shards and snail shells or molds, are mented lentils are found. Greenish-gray light gray in color, and generally contain bentonitic clays also occur within the Val- abundant diatoms. The diatom content is entine of this area but are not found higher sufficient to warrant commercial mining in in the section. Although some volcanic ash Wallace County, Kansas; and in Arm- lentils (e.g., the Calvert bed) occur within strong County, Texas (Evans, 1946), the Valentine they are much less common test pits have been dug and commercial than in the overlying Ash Hollow. Dia- samples obtained. The stratigraphic occur- tomaceous marl has been found at many rence of diatomaceous marl beds and the stratigraphic positions within both the lithologic sequence of the lower Ogallala Valentine and Ash Hollow and even in the formation in Armstrong County are illus- basal part of the Kimball. trated by the following measured section, In Texas, the Valentine zone is less ex- 7 miles southwest of Goodnight. tensive and is restricted to more sharply Bentonitic, greenish-gray clays have developed early Neogene erosional valleys been described at several localities in the (fig. 1 and following measured section), Ogallala formation of northern Kansas but it attains a maximum thickness ap- (Elias, 1931; Landes and Keroher, 1942; proaching 300 feet. In the Texas sections Frye, 1945; Frye and A. R. Leonard, the sediments of the Valentine zone are 1949). These clays are thought to have coarser and less uniform than farther been formed by weathering of volcanic north, they are generally tan to pinkish tan ash within the Ogallala or by the concen- in color, in contrast to the predominant tration of weathering products from the greenish gray of northern Kansas and Ne- surface of the underlying Cretaceous braska, and they completely lack distinc- shales. They are locally in contact with tive green opal-cemented zones, bentonitic the underlying Cretaceous, but their oc- clays, and volcanic ash beds. South of the currence at other places above typical Panhandle region the Valentine zone is Ogallala Formation Correlation 15 greatly restricted in its distribution, but silicified zones and bentonitic clays disap- where it occurs it commonly contains a sig- pear from the section. Higher in the Ash nificant amount of gravel. Hollow, the greenish-gray and gray colors In the northern High Plains the Valen- are entirely replaced by pink, tan, and tine grades upward into the Ash Hollow reddish brown except where a prepon- through a zone that presents alternations of derance of carbonate cement produces an greenish gray and pink and tan sediments; ash-gray or pinkish-gray color. The degree the sorting diminishes in degree upward; of sorting and abundance of recognizable volcanic ash lentils become more abun- bedding diminishes and buried soils be- dant, as do evidences of buried soils; and come more common upward. In general the

Stratigraphic section measured in road cuts and canyons north of Mulberry Creek, approximately 7 miles southwestsouthwest of Goodnight, Lowe MeGehee ranch,ranch, Armstrong County, Texas (1957) (Section No. 12 of fig.fig.l).1). Thickness (feet) Neogene—Ogallala formation (Ash Hollow floral zone) 20. Sand, line, and silt, well cemented to an irregular dense limestone 2.0 19. Sand, fine, and silt, massive, brick red; caliche nodules throughout and locally cemented - . . ... 16.0 18. Marl, locally silicified and with irregular hardness, irregularly bedded, contains abundant silt, diatoms, and scattered sand grains, ash gray; contains shells, molds and casts of Helisoma cf. antrosa, Gyraulus cf. parvus, Lymnaea cf. palustris, Pisidium sp., Sphaerium sp., Physn cf. anatina 3.0 17. Sand, medium, grading upward into a silty clayey sand, massive, loose pinkish tan tn rVinonlate reH 17.0 (Valentine floral zone) 16. Marl, sandy and diatomaceous, locally silicified and of irregular hardness, irregularly bedded, ash gray; contains locally abundant snail fauna of shells, casts and molds of Lymnaea lavernensis, L. macella, L. sp., Physa cf. anatina, Helisoma cf. antrosa, H. valens, H. goodrichi, Promenetus blancoensis, Pisid- ium sp., Pseudosuccinea sp. 7.0 15. Sand, medium, massive, loose, with a few caliche nodules, reddish tan 8.0 14. Sand, medium, well cemented, pinkish gray 2.0 13. Sand, fine to medium, massive, irregularly cemented, pinkish tan; contains nod- \ilar caliche masses - - - - — - 15.0 12. Marl, diatomaceous to diatomite, bedded to massive, thickness ranges from 1 to 10 feet, ash gray, local zones and lentils cemented with calcium carbonate: base contains debris of grasses and other vegetation and molds of aquatic gastropods Promenetus, Helisoma, Physa, and Lymnaea; contains Stipidium commune and (?) zygospores of Chara -- 5.0

11. Sand fine to medium, massive, loose reddish tan, with a few caliche nodules .... 10.0 10. Sand' medium to fine, massive, well but irregularly cemented, dirty gray 20.0 9. Sand' fine and silt, massive, loose to poorly cemented, tan brown 20.0 8. Sand medium to fine, massive, well but irregularly cemented, dirty gray 10.0 7. Sand, medium to fine, massive, pale pinkish tan, weakly cemented; a few caliche nodules 30.0 6. Sand medium to fine, massive, pinkish gray tan; caliche nodules merging into bands at top and bottom 10.0 5. Sand, medium to fine, massive, weakly cemented, pale pinkish tan; caliche nodules and a few lenses of caliche 35.5 4. Sand with a few pebbles and cobbles, massive weathering to a blocky surface, well cemented, pale pinkish tan 6.5

3. Gravel, coarse, crystalline rock types, massive, loose to well cemented at top .... 2.0 2. Sand and gravel, coarse, cross-bedded to irregularly bedded to massive; con- tains a few lenticular zones of pink to red jsand and silt, loose with lenticular zones of cementation - 31.0 1. Sand and gravel, coarse, cross-bedded to irregularly bedded, gray tan to rusty red; alternating loose zones with well cemented; pebbles and cobbles predomi- nantly of crystalline rocks. Base unconformably on Permian red-beds, exposed level of Mulberry Creek 25.5 Total Ogallala measured 275.5 16 Report of Investigations—No. 39 texture of the Ash Hollow is coarser than somewhat finer than farther north as it is is that of the Valentine. In thickness the predominately silt and sandy silt. It also Ash Hollow ranges from less than 150 feet displays colors of tan, red, purple, and to a maximum of more than 250 feet. brown, and the deposits are generally mas- In central western Texas these trends sive to indistinctly bedded. are less distinct and in some cases are re- In Texas, the thickness of the Ogallala versed. The Ash Hollow is in general formation ranges from a feather edge to a somewhat darker in shades of red and presumed maximum of approximately 500 brown than is the Valentine, but the con- feet. The maximum thickness observed in trast between the two is indeed weak. Tex- continuous exposures is more than 400 turally, the Ash Hollow, although locally feet along the south side of Canadian containing lentils and zones of relatively River valley south of Canadian, Hemphill coarse gravel, is generally characterized County (note measured section). A com- central by fine to medium sands and silts and the mon thickness in western Texas is the more than general aspect is one of upward decrease 200 feet or less, but 500 of grain size. While the Ash Hollow of feet of relief on the unconformable surface northern Kansas and Nebraska is typified at the base of the formation renders aver- figures for thickness meaningless. With by the cemented zones generally called age exceptions, there is a progres- "mortar beds," the Ash Hollow zone in important sive decrease in thickness of the Ogallala Texas displays no higher degree of cemen- from the southern part of the Panhandle tation than does the Valentine of the same southward western Texas until area. area across it feathers out north of the Pecos Valley. The Kimball zone of the northern Plains Northward from Texas there is a general is generally gradational with the Ash Hol- thinning to central western Kansas, and low, although locally marked base by at its then, progressing northward, a thickening coarse channel gravels gravels of (Sidney through Norton County, Kansas, and into classification). It finer tex- Nebraska is Nebraska. Inadequate control suggests tured than the underlying deposits, is red, steeper valley side slopes on the pre-Ogal- brown, purple, or tan except where the lala topography in Texas than those de- color is masked by the abundant calcium veloped on the less resistant Cretaceous and is characterized carbonate, at the top shales and chalks to the north. This may a massive and resistant by zone of calcium account for the more abrupt changes in carbonate commonly encrusted with "piso- thickness in western Texas. litic limestone." It lacks volcanic ash, ben- Details of the lithologic succession of tonitic clays, and (except at a few places the Texas Ogallala are presented in figure in the base) diatomaceous marls fresh- or 1, in measured sections previously pub- water limestones. On the other hand, it lished (Frye and Leonard, 1957a), and in commonly displays thin bands of moss those included with this report. agate or opalized silts and contains irregu- Physical criteria of correlation—ln Ne- larly silicified zones in the capping calcium braska and northern Kansas physical cri- carbonate. In the thickness Kimball ranges teria have proved successful for approxi- from approximately 25 feet to more than mate correlation of the several units within 60 feet. the Ogallala formation even though they The primary change in the lithology of do not define sharply the two internal the Kimball zone as it is traced southward boundaries. These criteria have been previ- to Texas is the progressive increase in ously described in some detail (Frye, thickness and prominence of the capping Leonard, and Swineford, 1956) and con- zone of calcium carbonate or "cap rock." sist of: (1) petrographically distinct zones The texture of the Kimball in Texas is of volcanic ash that permit correlation of Ogallala Formation Correlation 17 a single ash fall over relatively wide areas scribed (Frye and Leonard, 1957a), the (Swineford, Frye, and Leonard, 1955) ; presence of thick and well-developed cap- (2) consistent and recognizable—even ping caliches in several of the Pleistocene though gradational—differences in lithol- units of the Texas region imposes the re- ogy among the several units; (3) distinc- quirement of great care for the safe use of tive rock types with restricted vertical this method. The use of bedrock configura- range within the formation; (4) recogni- tion should eventually have some value in tion of and downward measurement from Texas, but present sparsity of control and the distinctive and unique bed of "Algal" the relatively greater sharpness of the pre- or pisolitic limestone that marks the for- Ogallala topography reduces its present mation's stratigraphic top; and (5) the value. use (at best only suggestive) of topog- This analysis of physical criteria in- raphy of the erosional surface at the base dicates that in Texas, although the Ogallala of the Ogallala as an indication of deposi- as a formation can readily be identified tional sequence and thus of the relative and mapped by physical criteria, the rec- age of sediments within the formation. The ognition of units within it and the erection first four of these methods have proved of rock-stratigraphic subdivisions, or generally reliable throughout the northern members, on physical evidence alone is at High Plains, and where paleontological best precarious. It is for these reasons that checks have been possible they have members have not been recognized by us yielded consistent results. within the Ogallala of western Texas, and For correlation within western Texas, that correlations with the subdivisions de- however, these criteria are found to have fined in Nebraska and correlated into greatly reduced utility. Volcanic ash de- Kansas are treated here as floral zones. The posits are not known within the Texas fossil seeds on which these zones are based Ogallala south of Hemphill County. As are not sufficiently abundant to be consid- has been described, recognizable lithologic ered as elements of the lithology, and as the differences are much less apparent within boundaries of the several zones are not the Texas Ogallala than they are farther sharply defined by means other than the north, perhaps due to a lower water table contained fossils, these units are properly and dryer climate prevalent in the Texas considered biostratigraphic units. Even region during deposition of these sedi- though originally applied in Nebraska as ments. For that reason the second criterion rock-stratigraphic units, the names Valen- is of reduced value in Texas. Distinctive tine, Ash Hollow, and Kimball are retained rock types with restricted vertical range for these floral zones in Texas rather than are much less plentiful southward. The erecting zones named for contained fossils, fourth criterion, recognition of a down- because the floral assemblages logically fit ward measurement from a distinctive cap- this grouping. Furthermore, by following ping rock layer, is clearly as valid and this practice the correlations throughout more widely usable here than it is farther the Great Plains region become readily ap- north; however, as has been previously de- parent. STRATIGRAPHIC PALEONTOLOGY VERTEBRATE FAUNAS eluded within the Ogallala formation. Gid- The relative age of the Ogallala forma- ley considered that most of the sediments tion, its general regional correlation, and of the Texas High Plains were Miocene in its less precise intercontinental correlation age and correlated them with the Loup with the classic sections of the Mediter- Fork formation. This correlation might influenced fine ranean Basin are based primarily on evi- have been by the generally dence derived from its contained fossil ver- texture of the Cenozoic sediments in Texas tebrates. Serious attention to vertebrate and their superficial resemblance to the fossils contained in this formation began Miocene deposits of northwestern Nebras- with the studies of Leidy (1869), but it ka. Gidley assigned the Clarendon and beds to the he also was not until much later that more volum- Goodnight Pliocene, as he be inous and detailed information led to the did with all other deposits judged to presently held concepts of the Ogallala younger than Miocene. He considered all formation and its variously recognized these "younger" beds to be channel or subdivisions. eolian deposits of limited extent lying un- E. T. Dumble. State Geologist of Texas, conformably within or upon the more ex- in the preface to the Fourth Annual Re- tensive "Miocene" strata. port of the State Geological Survey of Osborn and Matthew (1909) made the Texas (1893), summarized in consider- first extensive and organized attempt at able detail the earlier geological observa- characterizing the mammalian faunas of tions made on the Texas High Plains and the various subdivisions of the Tertiary their eastern escarpment. It was, however, then recognized in North America. They only after Cope (1893) published an ac- included the then known faunas from the count of his observations of the region that deposits now included within the Ogallala the judgment of Professor F. C. Cummins formation. Although they assigned the (1891) the Cenozoic of concerning age Blanco beds to the upper Pliocene, they the rocks was con- uppermost exposed pointedly observed that the Blanco fauna firmed. Cope visited the area company in "distinct from and with Cummins and made collections of was decidedly younger vertebrate fossils that, together with the than" the faunas from the typical Loup collections made earlier, were the basis for Fork beds, the "upper Loup Fork" of the his assignment of these beds to the Cen- in Kansas, and the Ogal- ozoic. It is difficult, unfortunately, to in- lala formation of Darton. terpret fully the stratigraphic significance Stirton and McGrew's (1935) studies of of Cope's report as he did not give ade- the mammalian assemblages within de- quate locality data for his collections. In posits near Valentine, Nebraska, even the summers of 1899, 1900. and 1901, an though they led to a controversy (F. W. expedition from the American Museum Johnson, 1936; Lugn, 1938) concerning of Natural History, under the leadership the nomenclature and stratigraphic classi- of J. W. Gidley, collected fossil vertebrates fication of the beds concerned, eventually in an area bounded on the north by the resulted in confirmation of the lower Plio- town of Clarendon and by Mulberry Can- cene age of at least most of these yon (Donley and Armstrong counties) and sediments. to that on the south by Mt. Blanco (Crosby Subsequent time (Lugn, 1939k the County). The published results of this ex- Valentine consistently has been classed as pedition (Gidley, 1903) give us one of the lowermost recognized stratigraphic the earliest attempts to establish the age unit in the Ogallala formation (or group). and correlation of the deposits now in- McGrew (1938) and others later added to Ogallala Formation Correlation 19 the information on Valentine vertebrate arrangement of fossil vertebrate faunas in faunas in Nebraska. the Ogallala formation remains un- A significant milestone on the road to a changed, and no one, to our knowledge, better understanding of the stratigraphic has challenged the order in which Stirton significance of Tertiary vertebrate faunal arranged the faunas. assemblages was reached with the correla- The committee headed by Wood (Wood tional studies of Simpson (1933) and Stir- et al., 1941) refined and extended the cor- ton (1936). Stirton's report is less gen- relations made by Simpson and by Stirton eralized and consequently more useful to and expanded the several classic faunal those who are not professional vertebrate localities into faunal zones. The beds bear- paleontologists; he formally characterized ing the Blanco fossil vertebrate assem- vertebrate faunas of the lower, middle, and blage were classified as upper Pliocene and upper Pliocene on the basis of extinctions, correlated with the Astian—more recently new appearances, and characteristic gen- with Astian and younger Villafranchian era. Utilizing these criteria, he placed the (Simpson, 1947) —of southern Europe, Burge (McGrew, 1938) and Feldt Ranch but, as the Astian as originally defined is (Hesse, 1935) faunal assemblages of Ne- now known to traverse the Pliocene-Pleis- braska in the lower and middle Pliocene, tocene boundary currently accepted by respectively; the Beaver (Hesse, 1936a) international agreement, the question of and Optima (Hesse, 1936b) faunas of the exact placement of the Blancan faunal Oklahoma in the lower and middle Plio- assemblages with respect to the European cene; the Rhinoceros Hill (Elias, 1931), geologic time scale has not been definitely Edson (Martin, 1928; Adams and Martin, answered. However, as we have said, most 1929; Hibbard, 1939), and Long Island recent students of the problem have classi- (Cope, 1878) faunal localities ofKansas in fied the Blancan faunal assemblage as the middle Pliocene; and in Texas, he early Pleistocene in age, and as the Blanco classed the Clarendon (Cummins, 1893; formation containing the fauna has been Cope, 1893) fauna as lower Pliocene, the correlated with the Nebraskan glacial stage Higgins assemblage (Hesse, 1940) in the of interior North America and is separated lowermost part of the middle Pl.ocene, and from the underlying Ogallala formation by the Hemphill (Matthew and Stirton, 1930) a significant unconformity, we subscribe fauna in the upper part of the middle Plio- to its Pleistocene placement. cene. It is noteworthy for our purposes here Relatively recent studies of vertebrate that Stirton assigned the beds containing paleontology in the southern High Plains each of these faunas to the Ogallala for- have resulted in the recognition there of mation. typical lower and middle Pliocene mam- Stirton's concepts of the time-strati- malian assemblages. Evans (1949), on the graphic placement of these important authority of Dr. Grayson Meade, lists Plio- vertebrate faunal localities have been hippus pachyops, sp., Nan- somewhat altered by subsequently gather- nippus sp., Procamelus sp., and Metoredon ed information. Faunal assemblages from sp. in support of his judgement of the early lowe most Ogallala are now considered by Pliocene age of deposits in Crosby County, many vertebrate paleontologists to have Texas, classed by us as within the Valen- Barstovian (or late Miocene) elements, tine floral zone, and calls upon a species and 'the Blanoo assemblage is held by of Astrohippus to bear the burden of proof recei-t workers (Evans and Meade, 1945; of the middle Pliocene age of younger fos- Meac'e, 1945; Frye, Swineford, and Leon- siliferous deposits placed by us within the ard.' 1948) to be early Pleistocene in age, Ash Hollow floral zone (fig. 1, Section No. -it the essential framework of Stirton's 7). 20 Report of Investigations—No. 39

In summary, it can be said without per- ponds and lakes, greatly restricts the prac- adventure that, in spite of uncertainties in tical usefulness of these organisms in evaluating the ages of vertebrate fossil as- stratigraphic studies of the Ogallala. How- semblages and differences of opinion ever, a considerable fauna is now known among vertebrate paleontologists with re- from the Ogallala (Frye, Leonard, and gard to the exact stratigraphic placement Swineford, 1956, p. 35), and studies of of certain local vertebrate faunas, (1) ver- the Donley County, Texas, assemblage now tebrate paleontology supports the concept in progress by Leonard may add to the of Pliocene age for most, if not all, of the list. Ogallala formation, and (2) the known It has been shown, moreover, that fossil assemblages of fossil vertebrates in the molluscan assemblages characterize each Ogallala formation can be arranged in a of the three generally recognized subdi- stratigraphic sequence that is, for the most visions of the Ogallala formation (Frye, part, in harmony with stratigraphic con- Leonard, and Swineford, 1956, fig. 6, p. clusions reached by other lines of evidence. 37), and at one locality in Norton County, The extremely local occurrence of signifi- Kansas, the three characteristic faunas are cant assemblages of fossil vertebrates does found in stratigraphic sequence. While of necessity greatly reduce their practical these Ogallala faunas lack the distinctive- usefulness in field stratigraphy and makes ness of the Pleistocene molluscan faunal difficult the precise definition of vertebrate assemblages that occur throughout the faunal zones; but the major role of evi- same region, they are sufficiently distinc- dence derived from this source in estab- tive to be stratigraphically useful where lishing the general age of, and major cor- they occur. relations within, the Ogallala formation The Donley County fossil molluscan can scarcely be denied. locality contains a typical Valentine as- semblage of MOLLUSCAN FAUNAS species, characterized by Lymnaea lavernensis, L. macella, Helisoma Fossil mollusks were used for strati- valens, H. goodrichi, and H. cf. antrosa, graphic purposes by Frye, Leonard, and together with species of Physa, Pseudosuc- Swineford (1956) their studies of the in cinea, and Pisidium. As elsewhere in typi- Ogallala formation in northern Kansas, cal Valentine exposures, the fauna is are to occur they known in the Ogallala of characterized by species that first appear Nebraska where they have not been in the Great Plains region in the Laverne studied, and a single locality in Donley of northwestern Oklahoma (Leonard and County (see preceding measured section) Franzen, 1944), but many of the promi- represents the only known occurrence of nent elements of the Laverne fauna are these in Ogallala sediments in missing from the Donley County, Texas, Texas. assemblage, perhaps due to its somewhat For the most part, fossil mollusks in the higher stratigraphic position or the vagar- Ogallala are represented by external molds ies of preservation. The placement of the or by casts of the interior of the shell; at a molluscan fauna in the Donley County locality in Wallace County, Kansas (Frye, locality in the Valentine floral zone, how- Leonard, and Swineford, 1956, p. 32), and ever, is clearly confirmed by the occur- at the Donley County, Texas, locality, how- rence in the same exposures of Stipidium ever, the shells of some mollusks are commune a fairly , species of grass that has long well preserved. Poor preservation has made been known to be diagnostic of the Valen- the study of fossil mollusks in the Ogallala tine (Elias, 1942, p. 80; Frye, Leonard, formation a difficult task, and together with and Swineford, 1956, p. 41; Frye and the known occurrence of molluscan re- Leonard, 1957a, p. 16). mains limited to limestones in former The Donley County, Texas, locality is, OgallalaFormation Correlation 21

moreover, important because it contains, important to the field stratigrapher, fossil in addition to the Valentine molluscan as- seeds are distributed so numerously, both semblage, a poorly preserved, but distinc- vertically within the succession of Ogallala tive, Ash Hollow faunal assemblage (see rocks and geographically over the region bed no. 18, in preceding measured sec- covered by Ogallala sediments, that fossil seeds and the floral zones they characterize tion) . The occurrence is in a series of thin regional marl beds, in which most of the fauna oc- assume primary importance, in as well as local stratigraphic correlations. curs as molds or casts of shells, but the in This is illustrated by Lugn's (1939) re- recognizable species comprise a series of definition the Ogallala (which he aquatic pulmonates, intermediate between of treated as a group), as he relied heavily upon the those known from the Valentine and those floral zones established by Chaney and characteristic of the Kimball. This fauna Elias (1936) andbyElias (1932, 1935) to also is under continued at this time. study limit the four formations recognized by In general, the molluscan faunal as- him within the Ogallala group and indi- semblages, predominantly poorly pre- cated the stratigraphic position of the prin- served and of highly sporadic occurrence cipal vertebrate faunal assemblages then in the Ogallala, confirm to the extent of known in Nebraska in relation to the floral their limited occurrences the threefold zones. In Kansas, Frye, Leonard, and biostratigraphic zonation of the forma- Swineford (1956), while utilizing the va- tion recognized by us, and at no place have riety of physical stratigraphic criteria pre- the paleontological data from this source viously described, fossil vertebrate assem- been in conflict with stratigraphic conclu- blages, and assemblages of molluscan sions reached by other means. Because of species, found that associations of fossil the difficulty of identifying the poorly pre- seeds were of great practical importance in served molluscan remains, and, even more delimiting the three members (Valentine, important, the restricted local occurrence Ash Hollow, and Kimball) recognized by of usable molluscan faunas, assemblages them in the Ogallala formation of that of mollusks have only limited usefulness state. In Texas, where general lithological in stratigraphic correlations within the criteria are less reliable than they are in Ogallala. the Ogallala of northern Kansas or of Nebraska, Frye and Leonard (1957a) rec- FOSSIL PLANTS AND FLORAL ZONES ognized within the Ogallala formation The most useful paleontological mate- three floral zones, which they referred to rials for practical stratigraphic studies, as as Valentine, Ash Hollow, and Kimball in well as regional correlations within the ascending order. Ogallala formation, are the remains of In view of these facts and observations, plants, most numerous of which are the we rely upon floral zones definedby assem- hulls of grass seeds and the nutlets of blages of fossil seeds and hulls to furnish herbs. Preservation of these remains is the most practical means of correlating the generally excellent, and the seeds can be Ogallala formation in Texas with the type collected, prepared for study, and perma- sections in Nebraska. nently preserved without expensive equip- OF FOSSIL SEEDS ment or excessive outlay of time or effort. GEOGRAPHIC RANGE Furthermore, diagnostic anatomical fea- The geographic distribution of the more tures are generally so well exhibited that commonly occurring fossil seeds in the accurate classifications of the various seeds Ogallala formation is shown in figure 2, can be made without undue difficulty. The where it will be seen that many range vertical range of most of the plants is through all or most of the region con- limited and also is now well known. Most sidered in this report, or are replaced by 22 Report of Investigations—No. 39 related species that are judged strati- fit the same pattern as the foregoing ex- graphic equivalents. In this latter category amples. Berrichloa tuberculata Elias, B. may be considered Panicum eliasiLeonard amphoralis Elias, and B. conica Elias in and Panicum elegans Elias; the former is one floral zone and B. maxima Elias and a conspicuous element of the flora through B. minuta Elias in another, form com- most of the area in Texas but in Lipscomb plexes that extend through the greater part County occurs in the same assemblage with of the geographical region under consider- and at the same stratigraphic level as P. tion. Finally, Stipidium. commune Elias, and and elegans , which replaces it northward Prolithospermum johnstoni Elias, ranges well into Nebraska. Almost exactly Celtis willistoni (Cockerell) Berry, al- the same can be said of the respective though having different stratigraphic rela- ranges of Biorbia papillosa Leonard and tions. are species whose geographical Biorbia fossilis (Berry), which are clearly ranges are approximately coincident with stratigraphic equivalents. The geographi- the occurrence of the Ogallala formation. cal relationships of Stipidium intermedium Unfortunately, there are a few species, Elias with S. variegatum Elias and S. such as Krynitzkia coroniformis Elias, elongatum Elias are less clear but seem to with limited stratigraphic ranges that give.

Fig. 2. Known geographic range of some significant Ogallala fossil seeds from Texas to Nebraska, Ogallala Formation Correlation 23

them great value as precise stratigraphic (fig. 3) that are stratigraphically equiva- indices, whose known geographic range is lent with the Valentine, Ash Hollow, and limited to only a part of the region covered Kimball members of the Ogallala forma- by Ogallala sediments. tion of Kansas classification and with the From these observations, however, it is Valentine, Ash Hollow, and Sidney- clear that the geographic range of many Kimball formations of Nebraska. We have species of to fossil seeds is broad enough not found it practicable to consistently dis- make them extremely useful in studies of tinguish the Sidney from the Kimball by regional correlations within the Ogallala any means at our disposal and have not formation. recognized the Sidney as a separate strati- graphic unit. STRATIGRAPHIC RANGE OF FOSSIL SEEDS Valentinefloral zone—The lowest of the The well-preserved and generally nu- three floral zones in the Ogallala formation merous fossil seeds in the Ogallala forma- we have characterized as the Valentine tion can be arranged into three floral zones floral zone. It corresponds to the Stipidium

Fig. 3. Known stratigraphic ranges of some significant fossil seeds in the Ogallala formation. Zone of principal occurrence shown by wide bar. 24 Report of Investigations—No. 39 commune zone of Elias (1942, PI. 17). with the type of the Valentine formation The consistent element in the Valentine of Nebraska. floral zone is Stipidium commune, al- Ash Hollow floral zone—Lying strati- though in part of its range S. coloradoense graphically above the Valentine floral zone Elias and S. breve Elias are found with it. is the Ash Hollow floral zone, character- Stipidium commune is readily distinguish- ized by a large group of fossil seeds that able from S. dawsense Elias of the Sand are, for the most part, limited to it (fig. 3). Canyon member of the Miocene Sheep A few species, such ag Biorbia fossilis, B. Creek formation and from S. kansasense papillosa (Leonard, 1958), Panicum ele- Elias of the basal part of the Ash Hollow gans. and possibly P. eliasi may occur in floral zone. Stipidium commune is in rare the lowermost part of the Kimball floral instances found with Krynitzkia coroni- zone, and Berrichloa maxima Elias and B. formis at the very base of the Ash Hol- m 'nuta Elias. characteristically found in low floral zone, but for practical purposes the Kimball floral zone, may occur rarely it is judged that the extinction of S. com- in the uppermost part of the Ash Hollow mune marks the upward extent of the floral zone. Valentine floral zone. Unfortunately. Kry- The stratigraphic section on page 25 nitzkia coroniformis has not been found gives a concrete idea of the floral associ- in the southern range of Stipidium com- ations in the Ash Hollow assemblage in mune, and, in fact, occurrences of S. com- Texas, as well as illustrating the varied mune itself are rare in the southern part lithologies in which fossil seeds may be of its range, so that the recognition of the preserved. Valentine floral zone in Texas is locally This section is significant also because difficult. it reveals the overlap in distribution be- The Valentine floral zone of our Texas tween the essentially northern species Bior- classification of the Ogallala formation bia fossilis and Panicum elegans and their (Frye and Leonard, 1957a) is, however, southern stratigraphical and biological clearly equivalent to and correlatable with counterparts, Biorbia papillosa and Pani- the Valentine member of the Ogallala for- cum eliasi. The floras from this section, mation of Kansas classification and the and others still under study from expo- Valentine formation of the Ogallala group sures along Wolf Creek in Ochiltree of Nebraska classification. Lugn (1939, p. County, pose problems of intergradation 1260) in a rather circuitous manner, de- between the northern and southern popu- fined the Valentine formation of Nebraska, lations of Biorbia and of Panicum, and ". . of of but these as . underlying the typical 'mortar perhaps species Stipidium, are of beds' . . .", the lowest part of which he cor- properly problems a biological related with theKrynitzkia fossil seed zone rather than a stratigraphical nature and of Elias (1932, 1935; Chaney and Elias, need not concern us here. Where the two species occur, the base of 1936) ; that is to say, he limited the Valen- the Ash Hollow floral zone is characterized tine to those beds that underlie the lower- by the extinction of Stipidium commune most Ash Hollow. This is equivalent to and the first appearance of Krynitzkia correlating the Valentine formation with coroniformis. With these two species may the Stipidium commune zone of Elias, occur Stipidium ventricosum and perhaps which Frye, Leonard, and Swineford Biorbia fossilis, although the latter is rare (1956) found to be the correlative with at this stratigraphic level. Krynitzkia coro- Valentine member in Kansas, and with the niformis has a short range in the lower- Valentine floral zone in Texas (Frye and most part of the Ash Hollow floral zone Leonard, 1957a). In still other words, the and is succeeded by K. auriculata Elias Valentine floral zone of our Texas classifi- and K. chaneyi Elias, both of which are cation can be and is herewith correlated short-lived species of limited geographical Ogallala Formation Correlation 25 range and are restricted to the lower third nitzkia floral subzone, bearing the complex of the Ash Hollow floral zone. Throughout of species of that genus together with the the greater part of the Ash Hollow floral first appearance of species of Berrichloa zone in Nebraska, Kansas, Oklahoma, and and Stipidium (other than commune) and extreme northern Texas, Biorbia jossilis only rare Biorbia, constitutes the lower is the predominant species, but it is re- third of the Ash Hollow floral zone. The placed in Texas south of Lipscomb County Berrichloa subzone, with its great prepon- by Biorbia papillosa. These two species of derance of Biorbia associated with large Biorbia often occur with several species of populations of species of Berrichloa and Stipidium and Berrichloa, such as S. inter- Stipidium, forms the middle third of the medium Elias, S. elongatum Elias, S. kan- zone. The Panicum subzone, characterized sasense Elias, B. conica Elias, B. amphor- by the appearance of the genus and the alis Elias, and B. tuberculata Elias. In the decline in numbers of Biorbia, Berrichloa, upper part of the Ash Hollow floral zone, and Stipidium, includes the approximate the two species of Panicum are relatively upper third of the deposits bearing the common, P. elegans extending in range Ash Hollow floral assemblage. from northern Nebraska to northern Texas, Correlation of the Ash Hollow floral where it is replaced by P. eliasi. Although zone of Texas with the Ash Hollow forma- Elias quite rightly described a Panicum tion of Nebraska classification is estab- subzone (1942, PI. 17) within the upper lished by definition since Lugn (1939, p. third of the zone that we class as the Ash 1260) included as part of his type descrip- Hollow floral zone, many of the species of tion of the Ash Hollow formation reference Stipidium and Berrichloa that reach the to the fossil seed zones of Elias that col- peak of their population density in the lectively we have designated the Ash Hol- middle third of the Ash Hollow are to be low floral zone. Lugn points out that this found here also. formation contains at its base the Krynitz- Relatively precise stratigraphic place- kia coroniformis fossil seed zone, and that

. ment of even local outcrops containing . . "the formation includes most of the these floras is possible by the recognition Biorbia fossilia [sic] fossil seed zone of

of subzones over the greater part of the Elias. . . He goes on to say that assem- region covered by sediments of the Ogal- blages of fossil vertebrates are found in as- lala formation. The easily recognized Kry- sociation with these floral assemblages. In

Stratigraphic section measured along road cuts and adjacent canyons miles south of south end of Wolf Creek bridge at Lipscomb, Lipscomb County, Texas (1957) (Section(Section No. 16 of fig. 1).1). Thickness (feet) Neogene—Ogallala formation 7. Limestone, silty, with some sand, well but irregularly indurated, gray; platy and vugular -- - - 4.0 6. Sand, medium, finer upward, massive, pale brick red; zones of caliche nodules in middle and top 15.0 5. Sand, bedded to platy, well but irregularly cemented, gray to tan 10.0 4. Silt and sand, fine to medium, massive, locally cemented, pinkish tan to gray;

concentration of caliche and coarser at top ... 17.0 3. Sand, medium to coarse, with a few scattered pebbles, indistinctly bedded, well but irregularly cemented, gray; contains Celtis willistoni, Biorbia fossilis, B. papillosa, Berrichloa conica, B. amphoralis 8.0 2. Sand, fine to medium, massive, weakly and irregularly cemented, pale pinkish tan; scattered caliche nodules; contains abundant fossil seeds of Celtis willis- toni, Biorbia fossilis, B. papillosa, Berrichloa conica, B. amphoralis, B. tuber- culata, Panicum eliasi, P. elegans,P. (?) sp. 5.0 1. Poorly exposed. Sand, fine to medium, massive, loose, pale brick red to pinkish tan; contains some caliche nodules and scattered platy streaks.(Exposures north- . ward toward Wolf Creek indicate at least 50 feet of sand below this interval) .. 40.0 Total thickness of Ogallala measured 99.0 26 Report of Investigations—No. 39

Kansas, the localities that have yielded brate assemblages from the Kimball for- significant assemblages of fossil verte- mation of Nebraska are lacking, regional brates in the Ash Hollow member of the correlation of theKimball floral zone with Ogallala formation are associated with the Nebraska type sections is based on Lugn's Ash Hollow floral assemblage. We have (1939, p. 1263) definition of the Kimball not, to our knowledge, collected floral as- in terms of the occurrence of fossil seeds, semblages in direct association with the and, more importantly, the occurrence at vertebrate fossils reported by Evans the top of this stratigraphic and floral unit (1949), but collections of seeds made of the widespread pisolitic limestone (the nearby confirm the stratigraphic, placement "Algal limestone" of Elias) which has of the vertebrate faunas. been recognized and studied (Swineford, Kimball floral zone—Uppermost and Leonard, and Frye, 1958) over the entire youngest of the three floral zones we recog- region covered by the Ogallala formation nize is the Kimball floral zone. The diag- (or group). nostic element of the zone is Prolitho- Finally, we have found that in Texas spermum johnstoni, Elias, but Berrichloa where characteristic lithologies are not maxima and B. minuta are common associ- adequately developed for distinguishing ates. Biorbia fossilis, and in Texas B. papil- subdivisions of the Ogallala formation fos- at least the basal losa, range upward into sil seed zones serve the purpose admirably, of this floral zone and have been part found and that the rocks containing the Valen- in association with Prolithospermum john- tine, Ash Hollow, and Kimball floral zones stoni. The general transitional nature of are the stratigraphic equivalents of the the relations between the uppermost part Valentine, Ash Hollow, and Kimball mem- of the Ash Hollow floral zone and the bers of Kansas classification and the Val- lowermost part of the Kimball floral zone, Ash and Sidney-Kimball together with the lack of any consistent entine, Hollow, lithological datum at this stratigraphic formations of Nebraska. Furthermore, the level, have impelled us to discard the Sid- rocks containing the floral zones we recog- ney as a subdivision of the Ogallala forma- nize include both the known Valentine and tion in Texas (Frye and Leonard, 1957a, Ash Hollow vertebrate assemblages and p. 17) and in Kansas (Frye, Leonard, and the known assemblages of fossil mollusks Swineford, 1956, p. 12). from beds recognized as Valentine, Ash As published accounts of fossil verte- Hollow, and Kimball. SUMMARY AND CONCLUSIONS

The Ogallala formation consists of the except for a few localities in Texas, the partially dissected sediments underlying a stratigraphic top of the Ogallala is either coalescent plain of alluviation deposited at the High Plains surface or overlain only during Neogene time over much of the by eolian Pleistocene deposits. structural plains region lying east of the The Ogallala formation consists of central and southern Rocky Mountains. At sands, silts, and gravels that are well bed- the close of the Neogene this sheet of allu- ded to massive, gray, greenish gray, tan, vial materials may have extended more shades of red, and brown, well cemented than 1,000miles north-south and 500 miles to loosely cemented or uncemented. In east-west in maximum dimensions. In parts general the formation presents a monoto- of western Nebraska the Ogallala forma- nous repetition of lithologic types. Minor tion rests upon Oligocene and early Mio- amounts of silicified rock, bentonitic clay, cene strata, but southward it buries an ero- diatomaceous marl, and volcanic ash occur sional topography that was cut in Creta- within the formation. In the central and ceous, Triassic, and Permian rocks. The northern High Plains, three major subdivi- formation ranges from a feather edge to sions, Valentine, Ash Hollow, and Kimball, more than 500 feet thick. even though gradational, generally can be Deposition of the formation started dur- recognized in the field by their character- ing late Miocene time along major valleys istic minor contrasts in lithology. South- that extended through Crosby and Floyd ward in western Texas, however, their counties and parts of the Panhandle in lithologic distinctiveness largely disap- Texas, northern Kansas, and several posi- pears and some textural contrasts may even tions in Nebraska, including Cherry be reversed. The source of the Ogallala County. Initial alluviation was localized in sediments as reflected by the coarse clastic the lowest parts of independent valley sys- elements is predominantly in the moun- tems, and as these erosional valleys were tainous region immediately to the west of filled there was progressive obliteration of the Plains, but near the basal contact local the erosional topography, accompanied by sources are strongly reflected at some shifting of channels across former minor places. divides, with ultimate burial of most major Stratigraphic classification of non- divides. The surface of the alluviating plain marine sediments is at best a difficult prob- was not without character as natural levees, lem because of the lack of geographically and inter- abandoned channel segments, continuous or persistent beds, the general imparted sig- fluve depressions must have heterogeneity of such sediments, and the locally shallow nificant relief and produced absence of strongly marked or sharply de- water-table lakes. The fact that some areas finable lithologic contrasts. This funda- flood plains were stable for signifi- of the mental problem of type and class of strati- of time during late stages of cant periods graphic unit is particularly acute in the Ogallala deposition is attested by the pres- Ogallala because not only is it a fluvial sence of buried soil profiles. but the environmental factor was After completion of Ogallala deposition deposit uniform the ex- the surface of the constructional plain re- monotonously throughout of Nebraska mained in equilibrium long enough to per- tensive region deposition. In mit the development of a thick lime- and northern Kansas there seemingly was accumulating soil profile that is now ex- a progressive, although slight, upward pressed by the "cap rock caliche." Con- change in environment that produced ditions of equilibrium were distributed by recognizable zonation with gradational the initial pulse of Pleistocene erosion and, boundaries. However, southward across 28 Report of Investigations—No. 39 western Texas even this gross zonation be- two vertebrate fossil faunal zones are coin- comes less recognizable. cident with the limits of the Valentine and These physical characteristics, plus the Ash Hollow floral zones as used here, we relative abundance of fossil plant seeds, judge that they are approximately so. may be considered as justification of the Correlation of the Ogallala formation as gross rock-stratigraphic classification cur- a unit extending southward from its type rently in use in Nebraska that classes the locality in western Nebraska is readily Ogallala as a group containing four named achieved by physical tracing of the beds, formations. A more realistic rock-strati- by fossil plants, by fossil vertebrates, or by graphic classification has been used in fossil snails. In fact, in traversing this re- northern Kansas where the Ogallala is gion in detail, this correlation could be recognized as a formation with three made by physiographic expression alone, named members. Even this, however, is as the stratigraphic top of the formation is judged to exceed the limit of modern coincident with the undissected plateau accepted usage of member because the surface of the High Plains, except where boundaries of the Kansas members gener- the plateau surface is mantled by easily ally cannot be sharply drawn in the field recognizable eolian deposits. The basal without paleontologic evidence—whereas contact is recognizable with almost equal the limits of the Ogallala formation as a certainty across this region, in spite of the whole can be recognized clearly without extreme range in thickness of the forma- the presence of fossils. tion. because everywhere south from south- These problems of lithologic subdivision western Nebraska it rests on an unconform- are even more acute in Texas and for that able surface cut in distinctive rocks of reason we have not recognized a rock- Cretaceous. Triassic, or Permian age. stratigraphic subdivision (members) but Correlation of the three floral zones that rather have proposed the use of floral zones comprise the Ogallala of Texas previously —biostratigraphic units—within the Ogal- has been made from the type localities in lala of this region. It is fortunate indeed Nebraska into central Kansas (Frye, Leon- that biostratigraphic units can be recog- ard. and Swineford, 1956), and we are nized here that coincide both with formerly concerned here particularly with the ex- recognized faunal zones and with the pa- tension of these correlations into central leontologic criteria of the supposed rock- westernTexas. Assemblages of fossil plants stratigraphic units in Kansas and Ne- are used in each case, but also in each braska. In view of these facts the type lo- case a few species may be used practically calities of previously described units in as diagnostic of the zone. This is particu- Nebraska may be accepted as types for the larly true of the lowermost, the Valentine floral zones recognized in Texas, thus zone, where Stipidium commune occurs avoiding, by the extension of existing sub- throughout the zone and from Kansas and division names throughout the High Texas is restricted to it (figs. 2, 3). The Plains region, a complex nomenclature uppermost Kimball zone similarly may be and a resulting confused terminology. characterized by two species, Prolithosper- It also is fortunate that the type of the mum johnstoni and Berrichloa maxima, Clarendonian faunal zone and Clarendon- which are restricted to it but do not occur ian Provincial Age ( Wood et al., 1941) in its barren uppermost part (fig. 3). Al- falls within the Valentine floral zone, and though not as widely ranging as Stipidium that the type of the Hemphillian faunal commune, both of these species occur well zone and Hemphillian Provincial Age falls into central western Texas (fig. 2). within the Ash Hollow floral zone. Al- The Ash Hollow floral zone that occurs though it is impossible for us to determine between the Kimball and the Valentine is whether the regional extensions of these characterized by a more diversified as- Ogallala Formation Correlation 29 semblage and lacks any single species that Where Biorbia is found with Berrichloa may be used everywhere as an index to it. amphoralis, B. conica, B. tuberculata, or Biorbia fossilis in the north and B. papil- Stipidium intermedium, it identifies the losa in the south, with their area of overlap middle two-thirds of the zone. Where Bior- in the Texas Panhandle region, approach bia is found sparsely only with Celtis willi- this degree of utility (figs. 2 and 3). Al- stoni, particularly if stratigraphically though B. papillosa locally extends upward below the mid-range assemblage or above into the base of the Kimball zone, the Stipidium commune, it serves as an index genus is in general restricted to the Ash to the basal part of the zone. Unfortun- Hollow and ranges through its entire thick- ately, Krynitzkia coronijormis, so diagnos- ness. In the Texas region where Biorbia is tic of the basal Ash Hollow in Nebraska found in association with Panicum eliasi, and northern Kansas, has not to date been it indicates the upper part of the zone. found in the Texas region. MEASURED SECTIONS

Stratigraphic section measured along canyon side and road cuts, south of dam at Lake McClellan, CGray7ray County, Texas (1957) (Section No. 13 of fig. 1). Thickness (feet) Neogene—Ogallala formation 15. Sand, fine, with some silt and medium sand, massive, pale pinkish tan; caliche nodules disseminated sparsely throughout and locally concentrated 15.0 14. Sand, fine, massive, pale pinkish tan with patches of brick red; caliche through- . out but concentrated at top .. 10.0 13. Sand, fine, with some silt, massive, pale brick red; stringers and irregular platy masses of caliche concentrated at top 10.0

12. Sand, fine, densely cemented, platy to massive, gray .... 1.0 11. Sand, fine to medium, with some silt, massive, pale brick red; a few scattered caliche nodules ..... 15.0 10. Sand, fine, and silt, with some medium sand, massive weakly cemented through-

out, pale pinkish tan: caliche nodules throughout with concentration at top .... 14.0 9. Sand and gravel, containing cobbles with maximum diameter to 8 inches, cross- bedded to thin bedded, irregularly well cemented, locally lentils of sand and silt, pink tan, occur in the middle part of interval; contains Berrichloa amphor- alis. B. conica. Celtis willistoni 24.0 8. Sand, fine, with some silt and medium sand, massive, pale pinkish tan; caliche nodules throughout but concentrated at top 10.0 7. Sand, medium, well bedded and cross-bedded, light tan 8.0 6. Sand, fine, and silt, massive, pale pinkish tan; caliche nodules sparsely through- out ...... 5.0 5. Silt and clay, with some fine sand increasing upward, blocky to massive, pale pinkish tan to pale chocolate; caliche nodules throughout and concentrated at top 8.0 4. Sand, medium, massive, loose, tan 2.0 3. Silt and sand, massive, irregularly well cemented, pinkish gray 2.0 2. Silt and clay, with a few thin zones of sand, massive to blocky, light chocolate to coffee color 5.0 1. Sand, fine to medium, with some silt and coarse sand, massive, tan; caliche nodules throughout with local platy zones; locally at base a zone 1 to 5 feet thick densely cemented, contains cobbles of Permian shale; base unconformable on Permian red-beds . 55.0 Total Ogallala measured 184.0

Stratigraphic section measured along canyons and in road cuts of U. S. Highway 60, Vy22 mile south of Roberts-Gray County line,line, Gray County, Texas (1957) (Section No. 14 of fig. 1). Thickness (feet) Neogene—Ogallala formation 11. Interbedded: Silt, with fine sand and silt, with fine sand, individual lentils mas- sive to indistinctly bedded; pale pinkish tan, light brown, pinkish gray; a weak zone of soft caliche at top 25.0 10. Silt and sand, fine, massive to blocky, reddish brown at base to pale pinkish tan at top; caliche nodules throughout,increasing to a band at top 12.0 9. Sand, fine, and silt, massive to blocky, brick red to pinkish tan; caliche nodules and stringers with local platy zone at top 20.0 8. Sand, fine, and silt in a caliche matrix, irregularly blocky to massive, dirty gray, contains local pockets of uncemented sand and silt; contains Celtis

willistoni .. 4.0 7. Sand, fine, with some silt, massive to blocky, pale brick red to pinkish tan; a few caliche nodules ____ 5.0 6. Sand, fine to medium, irregularly platy, well cemented but with small patches of loose sand, pale pinkish gray _____ 3.0 5. Sand, fine, massive, weakly and irregularly cemented with concentration at top, pale pinkish tan 15.0 4. Sand, fine, and silt, massive; caliche nodules throughout with irregular ce-

mented zone at top ____ 9.0 Ogallala Formation Correlation 31

3. Sand, fine, and silt, massive, weathering to columnar structure expressed in nearly vertical canyon walls; caliche abundantly but irregularly distributed throughout, pale pinkish tan to pinkish gray 25.0 2. Silt, and fine sand, prismatic to blocky, olive drab to gray tan; a few caliche nodules and a few platy caliche lenses 5.0 1. Sand, medium to coarse, irregularly bedded to thin bedded, generally loose but containing cemented zones, olive green to pinkish tan to gray; contains thin lenticular zones of silty clay and sandy silt. Base of section in creek channel 38.0 Total Ogallala measured 161.0

Stratigraphic section measured in road cuts and canyons east of U. S. Highway 83, 6 miles south- southwestsouthwest of south end of Canadian River bridge at Canadian, Hemphill County, Texas (1957) (Sec- tion No. 15 of fig. 1)., Thickness (feet) Neogene—Ogallala formation 35. Sand, fine, and silt, massive, pale brick red to pale pinkish tan; caliche nodules throughout and concentrated in zones in the middle and at the top 15.0 34. Silt with some clay and fine sand, massive to blocky; caliche nodules sparse, pale olive drab to pinkish gray tan 5.0 33. Sand, fine to medium, and silt, massive to blocky, irregularly cemented, brick red to dirty gray 10.0 32. Sand, medium, bedded to massive, loose to weakly cemented, pinkish gray 15.0

31. Sand, medium to fine, well but irregularly cemented throughout, pinkish tan ... 8.0 30. Sand, medium to fine, massive, loose, interbedded with silt and silty fine sand, pinkish tan; contains Berrichloa maxima, Celtis willistoni, Prolithospermum johnstoni 8.0 29. Sand, fine and medium, densely but irregularly cemented, pinkish gray; contains scattered nodules of opal 6.0 28. Sand, weakly cemented throughout,platy, gray to gray tan 5.0 27. Sand, medium to fine, massive, loose, brick red 2.0 26. Sand, massive, pinkish gray, caliche nodules throughout and concentrated in a zone at top . 9.0 25. Silty clay, grading upward to clayey silt, massive, weathers to blocky structure, chocolate red to tan 6.5 24. Sand, medium and fine, massive, gray tan; contains scattered caliche nodules 2.5 23. Clayey silt, massive, weathers blocky with checked surface, maroon brown; con- centration of caliche at top 4.5 22. Sand, fine, and silt, massive, tan: caliche nodules throughout 29.0 21. Silty clay, massive to blocky, light olive drab; caliche nodules in upper part 2.5 20. Sand, medium, massive, red; this unit with immediately overlying and under- lying zones is a soil profile 2.0 19. Sand, fine to medium, massive, pinkish tan; scattered caliche nodules except at top, which contains a zone of soft caliche 26.0 18. Clayey silt, massive, maroon brown, sparse caliche nodules in lower part, in- creasing upward 8.0 17. Sand, massive, loose in lower part to weakly cemented at top, pinkish tan to dirty white 14.0 16. Sand, medium with some fine, ranges from thin bedded to massive, light gray to pinkish tan; caliche nodules locally sparse, to concentration in thin zones, to local concentration; contains Celtis ivillistoni 25.0 15. Sand, fine to medium, massive, loose in lower part to weakly cemented in upper part, pinkish tan; contains caliche nodules and platy caliche 40.0 14. Silty clay, massive, maroon brown; soft caliche nodules in upper part 5.5 13. Silt with some clay and sand, massive to laminated, tan to yellow tan 3.0 12. Silty clay, sandy at base, massive, maroon brown, weathers to checked surface 3.5 11. Silt, sandy and clayey, grading upward into silty sand, massive, loose, chocolate brown grading upward to brick red 9.0 10. Sand, medium, loose but with local cemented zones, brick red 12.0 9. Sandy silt, grading upward into silty sand, massive, dirty gray to light choco- late brown; caliche nodules more abundant at top 12.0 8. Sand with some silt, loose, dirty gray; abundant caliche nodules and local

cemented zones .... 5.0 7. Silty clay, clayey silt, sandy clayey silt, and silty sand in an alternating series of massive to blocky, chocolate gray to pinkish tan zones; locally sparse caliche nodules 44.0 32 Report of Investigations—No. 39

6. Silt and clay with some sand, columnar to blocky structure, chocolate gray, a 4.0 5. Sand, medium, thin bedded to cross-bedded, loose with a few thin streaks of 5.0 4. Silt and clay, with streaks and thin lenses of sand, muddy tan; irregular in 0.5 3. Sand, medium, massive, rusty tan, scattered caliche nodules with irregular 5.0 2. Sand, fine to medium, massive, loosely cemented and with open honeycomb network of caliche, brick red to rusty gray 5.0 1. Sand, medium, massive, loose, tan to reddish tan; contains a few thin discon- tinuous streaks of caliche. (Scattered exposures along the south side of Ca- nadian River valley indicate approximately 50 feet of sand and gravel underlies 7.0 Total Ogallala measured 363.5 REFERENCES

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, , and SWINEFORD, A. JOHNSON, W. D. (1901) The High Plains and (1956) Stratigraphy of the Ogallala formation their utilization: U. S. Geol. Surv. 21st Ann. (Neogene) of northern Kansas: Kansas Geol. Rept., pt. 4, pp. 601-741. Surv. Bull. 118, 92 pp. KING, CLARENCE (1878) Systematic geology: U. S. , and LEONARD, A. R. (1949) Geology Geol. Explor. of 40th Par. Rept., vol. 1, 803 pp. and ground-water resources of Norton County LANDES, K. K., and KEROHER, R. P. (1942) Min- and northwestern County, Kansas: Phillips eral resources of Phillips Kansas Geol. Geol. 144 pp. County: Kansas Surv. Bull. 81, Surv. Bull. 41, pt. 8, pp. 277-312.

, and A. (1946) Silicified SWINEFORD, LEIDY, (1869) The extinct mammalian faunas rock in the Ogallala formation: Kansas Geol. J. of Dakota and Nebraska, including an account Surv. Bull. 64, pt. 2, pp. 33-76. of some allied forms from other localities, to- A. B. , , and LEONARD, gether with a synopsis of the mammalian re- (1948) Correlation of the Pleistocene deposits mains of North America: Acad. Nat. Sci. of the central Great Plains with the glacial Philadelphia Jour., vol. 7, 472 pp. section: Jour. Geol., yol. 56, pp. 501-525. LEONARD, A. B. (1958) Two new fossil plants GIDLEY, J. W. (1903) The fresh-water Tertiary from the Pliocene of northwestern Texas: Ex- of northwestern Texas, American Museum Kansas Univ. Sci. Bull., vol. 38, pt. 2, pp. 1393- peditions of 1899-1901: Bull. Amer. Mus. Nat. 1403. Hist., vol. 19,pp. 617-635. and FRANZEN, D. S. (1944) Mollusca GILBERT, G. K. (1896) The underground water of the Laverne formation (lower Pliocene) of of the Arkansas Valley in eastern Colorado: Beaver County, Oklahoma: Kansas Univ. Sci. Rept., U. S. Geol. Surv. 17th Ann. pt. 2, pp. Bull.,'vol. 30, pt. 1, pp. 15-39. 551-601. LUGN, A. L. (1938) The Nebraska Geological GOULD, C. N. (1906) The geology and water Survey and the Valentine problem: Amer. portion resources of the eastern of the Pan- Jour. Sci., 5th ser., vol. 36, pp. 220-228. handle of Texas: U. S. Geol. Surv. Water-Sup- Tertiary ply Paper 154, 64 pp. (1939) Classification of the system of Nebraska: Bull. Geol. Soc. Amer., geology (1907) The and water re- vol. 50, pp. 1245-1276. sources of the western portion of the Pan- handle of Texas: U. S. Geol. Surv. Water-Sup- MARTIN, H. T. (1928) Two new carnivores from ply Paper 191, 70 pp. the Pliocene of Kansas: Jour. ., vol. 9, pp. 233-236. HAWN, F. (1866) Report of Major F. Hawn, in SWALLOW, G. C., Kansas Geol. Surv. Prelim. MATTHEW, W. D. (1899) A provisional classifi- Rept., pp. 95-112. cation of the fresh-water Tertiary of the West: HAWORTH, E. (1897) Physical properties of the Amer. Mus. Nat. Hist. Bull. 12, pp. 19-75.

Tertiary: Kansas Geol. Surv., vol. 2, pp. 247- , and STIRTON, R. A. (1930) 284. from the Pliocene of Texas: Calif. Univ. Dept. Geol. Sci. Bull., vol. HAY, ROBT. (1885) Preliminary report on the 19, pp. 349-396. geology of Norton County, Kansas: Kansas MCGREW, P. 0. (1938) The Burge fauna, a Acad. Sci. Trans., vol. 9, pp. 17-24. lower Pliocene mammalian assemblage from HESSE, C. J. (1935) A vertebrate fauna from the Nebraska: California Univ. Dept. Geol. Sci. type locality of the Ogallala formation: Kansas Bull., vol. 24, no. 11, pp. 309-328. Univ. Sci. Bull., vol. 22, no. 5, pp. 79-117. MEADE, G. E. (1945) The Blanco fauna: Univ. (1936a) Lower Pliocene vertebrate Texas Pub. 4401, Jan. 1, 1944, pp. 509-556. fossils from the Ogallala formation (Lavern MEEK, F. 8., and HAYDEN, F. V. (1862) Descrip- zone) County, Carnegie of Beaver Oklahoma: tion of new lower (Primordial) Juras- Inst. Washington, Pub. no. 476, pp. 47-72. sic, Cretaceous, and Tertiary fossils, collected (1936b) A Pliocene vertebrate fauna in Nebraska, by the exploring expedition from Optima, Oklahoma: California Univ. under the command of Capt. Wm. F. Rey- Dept. Geol. Sci. Bull., vol. 24, no. 3, pp. 57-69. nolds, U. S. Top. Engrs.; with some remarks (1940) A Pliocene vertebrate fauna on the rocks from which they were obtained; from Higgins, Lipscomb County, Texas: Univ. Acad. Nat. Sci. Philadelphia Proc. 1861, pp. Texas Pub. 3945, Dec. 1, 1939, pp. 671-698. 415-447. HIBBARD, C. W. (1939) Notes on additional fauna MOORE, R. C., FRYE, J. C., JEWETT, J. M., LEE. of Edson quarry of the Middle Pliocene of W., and O'CONNOR, H. G. (1951) The Kansas Kansas: Kansas Acad. Sci. Trans., vol. 42, pp. rock column: Kansas Geol. Surv. Bull. 89, 457-461. 132pp. JOHNSON, F. W. (1936) The status of the name OSBORN, H. F., and MATTHEW, W. D. (1909) "Valentine" in Tertiary geology and paleon- Cenozoic mammal horizons of western North tology: Amer. Jour. Sci., 5th ser., vol. 31, pp. America, with faunal lists of Tertiary mam- 467-475. malia of the west: U. S. Geol. Surv. Bull., vol. 361,138 pp. (1938) Further comments on the usage of "Valentine": Amer. Jour. Sci., 5th PLUMMER, F. B. (1933) Cenozoic systems in

ser. ? vol. 36, pp. 215-219. Texas, pp. 519-818, in SELLARDS, ADKINS, and Ogallala Formation Correlation 35

PLUMMER, The geology of Texas, Vol. I, Stra- limestone" in Kansas and adjacent states tigraphy: Univ. Texas Bull. 3232, Aug. 22, (abst.) : Jour. Sed. Petrology, vol. 26,186 pp. 1932, 1007 pp. , LEONARD, A. 8., and FRYE, J. C. REED, L. C., and LONGNECKER, 0. M. (1932) The (1958) Petrology of the Pliocene pisolitic geology of Hemphill County, Texas: Univ. limestone in the Great Plains: Kansas Geol. Texas Bull. 3231, 98 pp. Surv. Bull. 130, pt. 2, pp. 97-116. SIMPSON, G. G. (1933) Glossary and correlation STIRTON, R. A. (1936) Succession of North charts of North American Tertiary mammal- American continental Pliocene mammalian bearing formations: Amer. Mus. Nat. Hist. faunas: Amer. Jour. Sci., 5th ser., vol. 32, Bull., vol. 67, pp. 79-121. pp. 161-206. (1947) Holarctic mammalian faunas , and MCGREW, P. 0. (1935) A pre- and continental relationships during the Cen- liminary notice on the Miocene and Pliocene ozoic: Bull. Geol. Soc. Amer., vol. 58, no. 7, mammalian faunas near Valentine, Nebraska: pp. 613-688. Amer. Jour. Sci., 5th ser., vol. 29, pp. 125-132. SwiNEFORD, A., and FRYE, J. C. (1946) Petro- THORPE, M. R. (1922) Some Tertiary carnivora graphic comparison of Pliocene and Pleisto- in the Marsh collection, with descriptions of cene volcanic ash from western Kansas: Kansas new forms: Amer. Jour. Sci., sth ser., vol. 3, Geol. Surv. Bull. 64, pt. 1, 32 pp. pp. 423-455.

, (1957) , and LEONARD, A. B. VAN SICLEN, D. C. Cenozoic strata on the (1955) Petrography of the late Tertiary vol- southwestern Osage Plains of Texas: Jour. canic ash falls in the central Great Plains: Geol., vol. 65, pp. 47-60. Jour. Sed. Petrology, vol. 25, pp. 243-261. WOOD, H. E., et al. (1941) Nomenclature and , , (1956) Pe- correlation of the North American continental trography and genesis of the Ogallala "Algal Tertiary: Bull. Geol. Soc. Amer., vol. 52, 48 pp.

Plates I and II 38 Report of Investigations—No. 39

PLATE I

The Ogallala formation (Ash Hollow floral zone) in central western Texas A. East-facing scarp southwest of Post, Garza County. Ogallala formation exposed in scarp; these beds are assigned to the Ash Hollow floral zone (1955).

B. Uppermost Ash Hollow floral zone exposed i» High Plains scarp, 3 miles west of Post, Garza County. Type locality of Biorbia papillosa Leonard (1955).

C. Even-bedded silts and fine sands in the Ash Hollow floral zone, north side Tule Canyon, Briscoe County (1955).

D. Thin Ash Hollow floral zone above Triassic rocks, north of Coahoma, Howard County, Texas. Southernmost fossiliferous section shown in figure 1 is from this locality (1956). Ogallala Formation Correlation Plate I Ogallala Formation Correlation Plate II Ogallala Formation Correlation 41

PLATE II

Distinctive lithologies of the Ogallala formation in Texas A. Within the Kimball floral zone, north of Buffalo Lake, Randall County. Note isolated pebble in matrix of silt, fine sand, and caliche (1945).

B. Buried soil within the Ash Hollow floral zone, exposed in fresh road cut northwest of Miami, Roberts County. Soil profile is overlain by uncemented reddish sand; pocket knife marks top of friable A-horizon, which is indented into the surface by overwash (1957).

C. Pit in sand and gravel of channel deposit within the Ash Hollow floral zone. North side of Yellowhouse Canyon, 5 miles north of Slayton, Lubbock County (1955).

Index abandoned channel segments: 27 Calvert bed: 14 algal or pisolitic limestone: 13,16,17, 26 Canadian: 16, 31 alluvial fan: 6, 7 River and/or valley: 16, 31, 32 alluviation, valley: 7 capping caliches: 17 American Museum of Natural History: 18 cap rock: 13,16 amphoralis, Berrichloa: 22, 25, 29, 30 caliche: 27 antrosa, Helisoma: 15, 20 Celtiscarbonatewillistoni:cement:22, 13,1525, 29,30,31 anatina, Physa: 15 Celtis willistoni: 22, 25, 29, 30, 31 aquatic pulmonates: 21 cementation: 12 Armstrong County: 14,15, 18 Cenozoic age and/or sediments: 18 Ash Hollow— chaneyi, Krynitzkia: 24 faunal assemblage: 21 Chara: 15

floral assemblage: 26 Cherrychert: 13County, Nebraska: 10,27 floral zone: 5, 10, 14, 16, 17, 19, 24, 25, 26, 28, chert: 13 29, 38, 41 Clarendon: 18 section: 15 beds: 18 formation: 25 fauna:19 member, Ogallala formation: 21, 23, 26 faunalzone: 28 subdivision: 27 Provincial Age: 28 assemblages— classification, rock-stratigraphic: 28 Ash Hollow faunal and/or floral: 21, 26 clays: 12 Higgins: 19 bentonitic: 14, 15,16, 27 Pliocene mammalian: 19 climaticCoahoma: control36 and/or reversals: 7,13 Valentine molluscan: 20, 21 Coahoma: 36 vertebrate fossil: 20 coloradoensis, Stipidium: 24 Astian: 19 commune, Stipidium: 15, 20, 22, 24, 28 Astrohippus: 19 conica, Berrichloa: 22, 25, 29, 30 auriculata, Krynitzkia: 24 coroniformis, Krynitzkia: 22, 24, 29 Cretaceous: 14 Barstovian elements: 19 age: 6,28 Beaver fauna: 19 limestones: 6 bentonitic clays: 14, 15,16, 27 rocks: 7,12, 16, 27 Berrichloa amphoralis: 22, 25, 29, 30 Crosby County: 18,19, 27 conica: 22, 25, 29, 30 crystalline rocks: 15 maxima: 22, 24, 26, 28, 31 minuta: 22, 26 dawsense, Stipidium: 24 subzone: 25 Dawson County: 6 tuberculata: 22, 25, 29 diatomaceous marl: 14,16, 27 Biorbia fossilis: 22, 24, 25, 26, 29 d'atomite: 6 papillosa: 22, 24, 25, 26, 29, 38 Donleydiatoms:County:14,1518,20 biostratigraphic units: 28 Donley County: 18, 20 Blanco—- beds: 18 Edwards Plateau: 5, 7 fauna:18 elegans, Panicum: 22, 24, 25 formation: 19 eliasi, Panicum: 22, 24, 25, 29 fossil vertebrate assemblage: 19 elongatum, Stipidium: 22, 25 blancoensis, Promenetus: 15 erosion, Pleistocene: 27 Borden County: 6 Europe: 19 boulders: 12 Evans, Glen L.: 19 boundary, Pliocene-Pleistocene: 19 breve, Stipidium: 24 fan, alluvial: 7 Briscoe County: 36 faunal— Buffalo Lake: 37 assemblage, Ash Hollow: 21 buried soils: 15, 41 localities, Long Island and/or Rhinoceros Hill soil profiles: 27 19 zone, Clarendonian and/or Hemphillian: 28 calcium carbonate: 12 faunas— caliche: 12 Beaver: 19 capping and/or cap rock: 17, 27 Blanco: 18 nodules: 15 Clarendon: 19 road metal: 6 fossil vertebrate: 19 soil: 13 Hemphill: 19