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Introduction
Geologic Exploration in Northwestern Kansas
General Conditions
The northwestern part of Kansas, though not infrequently visited by geologists and paleontologists, has never been given systematic geologic study. Some particular natural resources of this region have received moderate attention. Water supplies and volcanic ash deposits have been described and possibilities for oil and gas have been discussed in a general way in papers on western Kansas. It is worthy of notice that the present detailed geological survey of the county by the Kansas Geological Survey revealed the presence of some other useful minerals that are or may become of commercial importance.
No topographic sheets of the northwestern part of Kansas have been issued by the United States Geological Survey, and this is a considerable handicap to the geologic study of the area. Though the lack of base maps showing positions and comparative elevations of topographic features has retarded the geologic study of northwestern Kansas considerably, their absence has not prevented paleontologists from collecting fossils. Northwestern Kansas has become famous because of the many excellently preserved specimens, chiefly of vertebrates, which have been found in the outcropping rocks of Upper Cretaceous and late Tertiary ages. The exact stratigraphic position of these fossils in the local beds, however, and even the exact geographic locations where many of the fossils were collected has been unknown. Tying of both the earlier and the newly collected fossils to the geographic localities and to the particular beds of the formations was one of the tasks of the present survey.
Erroneous geographic, and especially erroneous stratigraphic, references of fossils collected in various countries has led frequently to invalid conclusions and to controversies, the correction and settlement of which has taken much effort and time. On the other hand, the precise determination of the stratigraphic position of fossils not only brings important results for the area where they have been found, but also contributes considerably to the progress of geologic knowledge of the other regions and countries where formations of similar age were deposited.
The absence of topographic maps for northwestern Kansas is not the only difficulty that confronts the geologist who undertakes the survey of this area. The mantle of loess, which is 50 feet thick in many places and in the northwestern corner of the state 180 feet locally, conceals the underlying Tertiary and Upper Cretaceous formations, so that their outcrops are very scarce. The Upper Cretaceous rocks are in general exposed only along the canyons and larger draws, and these exposures are separated from one another by wide stretches of loess which conceal the underlying rocks entirely (Pl. XXIII B). This concealment of the bed rock is most nearly complete in the regions where the soft Pierre shale underlies loess (Pl. XXXV B). The monotonous lithology of the Upper Cretaceous and Tertiary formations that are commonly exposed in northwestern Kansas adds another difficulty to their study. The Pierre shale of Wallace and adjacent counties is mostly dull gray, and the slight variations in shade are mostly not characteristic of any stratigraphic subdivisions or members. There are no continuous hard ledges in the Pierre. The Tertiary of northwestern Kansas, called the Ogallala formation, is mostly arenaceous throughout. It contains prominent hard ledges, but these are not easily identified as to exact geologic horizon and traced from one outcrop to another.
The difficulties outlined above can be largely overcome by determined work. In most places in this area a geologic survey requires more caution and more checking and rechecking in the field than the survey of some other areas of the state, where the various members and beds of the exposed formations are easier to identify and to trace as continuous units. It may be stated that a proper selection of constant lithologic features and a selection of characteristic and easily identified fossils, where they are present, is essential for a successful surficial geologic survey in northwestern Kansas and in the adjacent territory. The task of selecting these features may be termed research in the field geology of the area.
The results of the survey of Wallace County here presented include topographic, geologic and structural maps of the county, geologic sections through the county and stratigraphic columns of the outcropping and of some underground formations. They include, also, data and discussion of the proved and potential mineral resources of the county. A special chapter is devoted to the phenomena of the local ground subsidences in northwestern Kansas, and a special paleontologic part is prepared in which some of the most important fossils of the area are described.
History of Geologic Explorations
In this chapter the explorations that concern directly the geology of Wallace County in its present limits (Fig. 1) receive chief mention, and only brief notes on some of the most important works of general application to the geology of western Kansas are added.
In 1868 E. D. Cope described a new huge swimming reptile, Elasmosaurus platyurus, (in J. L. Leconte, 1868, p. 68.) which was collected by Dr. Theophilus H. Turner, physician of the garrison at Fort Wallace. This was the first recorded vertebrate fossil obtained from the Upper Cretaceous of Kansas, where in succeeding years a great many of the most wonderful and beautifully preserved swimming and flying reptiles of the same period were collected.
A brief geologic note on the Upper Cretaceous rocks at Fort Wallace was made in 1869 by F. V. Hayden (Hayden, 1869, pp. 13-14.), who concluded erroneously, as was proved later, that the No. 2 beds (or Fort Benton group) of Meek and Hayden's Upper Missouri section of Upper Cretaceous is exposed in this area (Hayden and Meek, 1872, Part I, Chapter IV).
The first state geologist of Kansas, B. F. Mudge, made the earliest systematic collection of fossils from the Cretaceous of Kansas, including the vicinity of Fort Wallace. According to S. W. Williston (Williston, 1898, pp. 28-29), Mudge visited this area in the summer of 1870. The fossils collected by Mudge were identified by E. D. Cope (Williston, 1898, pp. 29-30). Later in the same season (1870) an expedition from Yale college under the leadership of O. C. Marsh collected vertebrate fossils at Fort Wallace and at McAllaster (formerly Sheridan), chiefly along the north fork of Smoky Hill river. Marsh published a brief description of his discoveries in 1871 (Marsh, 1871, pp. 447-459). Among the collected material a foot bone of a new gigantic flying reptile, now known under the name Ornithostoma (formerly Pterodactile and Pteranodon), was discovered after additional bones of the same beast were obtained by the expedition (Marsh, 1871 a, p. 472; Williston, 1898, p. 30).
Yale college continued to send expeditions each year to collect more reptile material from the same beds. E. D. Cope also visited the region in 1871 and, besides making some discoveries of new vertebrates, studied the stratigraphy and published some important notes concerning the geology of the beds from which the fossils were collected. He speaks of these beds as the "Niobrara group" or No. 3 of the Missouri section of Meek and Hayden (Cope, 1875, pp. 16-19).
Marsh, in his descriptions of the reptiles collected by the Yale expeditions, refers them to "gray and blue Cretaceous shale" and to "yellow Cretaceous limestone." Possibly the fossils were collected from both the Niobrara and lowermost beds of the overlying Pierre, both of which formations, as we know now, outcrop in the area. In 1866 Mudge made first reference to chalk, which "is said to have been found" in the Cretaceous of western Kansas (Mudge, 1866, p. 12), and in 1876 he gave a description of the physical features of the Niobrara and separated the Niobrara from the underlying Fort Hays (Mudge, 1876). He makes the important statement that Hayden mistook the exposures near Fort Wallace for Benton, and refers them to the Niobrara, to which formation he refers also a bed with Baculites, which he discovered near Sheridan (McAllaster). Mudge forwarded this fossil to F. B. Meek, who identified it as Baculites anceps and expressed a doubt that the form could come from the Niobrara, because elsewhere in the "far west" it has been found only in the Pierre and Fox Hills formations (Mudge, 1877, p, 284). Williston in 1892 recognized for the first time (Williston, 1893) that the Fort Pierre formation actually outcrops at Wallace and McAllaster and expressed his support of Meek's opinion that Baculites anceps from near McAllaster belongs to the local Pierre, which is undoubtedly correct.
During his earlier explorations at Fort Wallace Mudge made some observations of moss agate in local Tertiary beds (Mudge, 1874, pp. 113-117) and published the first description of these younger beds in Wallace County and elsewhere in western Kansas.
Among early geologists we must mention F. W. Cragin, who made some explorations in far western Kansas and named the shale exposed above the Niobrara "Lisbon shale" after the small Lisbon station (now abandoned) of the Union Pacific railroad about 2 1/2 miles east of McAllaster. The "Lisbon shale" of Cragin corresponds to the Sharon Springs member of the Pierre formation described in this report. The name Lisbon is preempted in geologic literature and therefore cannot be retained for this shale member.
Some excellent remains of reptiles from the Pierre and Niobrara of Fort Wallace and McAllaster were collected by Charles H. Sternberg (1875 and later years), E. P. West (1890), H. T. Martin (between 1894 and 1922) and others.
The exploration of water resources of Wallace County began in 1893-'94, when Robert Hay was employed by the Division of Hydrography of the United States Geological Survey to make an investigation of "underflow" and subsurface waters of a typical area of the "semiarid west." The northwestern part of Wallace County was included in the stretch of country along the 102d meridian explored by Hay. The data on twenty-six water wells in Wallace County, collected by Hay, were published in the progress report of the Hydrography division (F. H. Newell, 1895, pp. 116 and 124-126), and the general geologic description of the outcropping formation, and a discussion of the surficial and underground water resources of the area surveyed by Hay was published in a separate paper in the sixteenth annual report of the United States Geological Survey (Hay, 1895, pp. 535-588). In this important paper a precise stratigraphic distinction is made between the three most important outcropping units of the rocks: The Cretaceous, the "Tertiary grit" (Ogallala formation of modern authors) and the "Plains marl" (loess, as now recognized). The names selected by Hay for the last two stratigraphic units indicated briefly the physical features of the rocks ("grit," "marl") that were thought by Hay, and really are, the most characteristic for the Ogallala and the Pleistocene deposits of the area. Such names for geologic formations became, however, a source of misunderstanding and gave ground for criticism, because in what Hay termed "Tertiary grit" there appear in places thick beds of clay and marl. On the other hand, also, the "Plains marl" or loess of the High Plains commonly becomes sandy at the base and in many places is underlain by "grit" or coarse sand and gravel, which also belong to the Pleistocene, and together with the overlying loess makes an indivisible stratigraphic unit which is here named Sanborn formation. It must be added that Hay himself observed the sandy basal facies of his "Plains marl," which shows again that the names "Tertiary grit" and "Plains marl" were introduced by this author for the stratigraphic units (and not merely for the types of rocks), which he recognized perfectly in the field outcrops and in well borings, and which we now term Ogallala and Sanborn formations, respectively. Hay was also aware that what he called "marl" has been called loess by geologists of both Nebraska and Colorado (Hay, 1895, p. 674). The relation of the underground waters of the High Plains to the above-mentioned stratigraphic units was also correctly explained by Hay, and he was the first to describe the local "sink holes" and give a plausible explanation of them (Hay, 1895, pp. 555-556, sink hole in Sherman County).
An important contribution to the understanding of the physical character of the Tertiary of western Kansas and a notably advanced explanation of the accumulation of the bulk of these deposits of the High Plains, the essential features of which are accepted by modern authorities in geology, was made by the former state geologist of Kansas, Erasmus Haworth (Haworth, 1897, pp. 247-281). This author also contributed considerably to our knowledge of the water resources of western Kansas, but this part of his geologic work does not much concern Wallace County.
In 1901 W. D. Johnson discussed at considerable length the water resources and the origin of the Tertiary deposits of the High Plains and expressed views somewhat modifying the conclusions reached by Haworth.
Neither of the last authors considered the mantle of loess of western Kansas, the "Plains marl" of Hay, to be a separate stratigraphic unit, and not until Darton's report on the Central Great Plains was the "smooth-surfaced, thick mantle" of loess of northern Kansas, "lying on a somewhat irregular surface composed of Tertiary deposits and the several upper Cretaceous formations," treated again as a distinctly different formation from the underlying Tertiary (Darton, 1905, p. 155). In Darton's report we find a separate brief paragraph on the water resources of Wallace County (Darton, 1905, p. 320) with a special discussion on the possible water supply in the Dakota sandstone of the county.
Though the special study of the distribution and movement of underground water in western Kansas brought about a much better understanding of the physical properties and stratigraphy of local formations, a more precise and complete knowledge of their lithology, thickness, fossil content and mutual relations and areal distribution were obtained from very recent deep drilling and geologic surveys, the chief aim of which was to explore the possibilities of oil and gas accumulation. Two test wells for oil have been drilled in Wallace County-the Robidoux and the Wulfekuhler wells. Though these wells did not discover any commercial quantities of oil and gas, they nevertheless contributed much to our knowledge of the deeper formations, which do not outcrop in the county or in the surrounding area. In 1927-'28 a survey party (which included the writer) employed by the Etnyre Syndicate made a thorough topographic and geologic survey of the northwestern portion of the county. The stratigraphy and structural geology of this area was worked out by the writer with the able assistance of O. R. Smith as instrument man, and other members of the party. Systematic collection and identification of paleontologic material was started by _William Wenk and continued and finished by the writer. The report on this survey (except the chapters. on the underground formations) along with the geological and structural maps and cross sections was prepared by the writer in the spring of 1928. This report is the property of the Etnyre Syndicate and has not been published. W. L. Russell, who joined the survey crew early in 1928, made a detailed survey east and southeast of the area studied by the writer. To Russell belongs the credit for the separation, on lithologic and partly paleontologic grounds, of the Lower Weskan shale member of the Pierre formation of Wallace County, a member which is not exposed in the northwestern part of the county. In papers written by Russell on some stratigraphic and geologic problems of Wallace and adjacent counties, the preliminary results of the writer's work on the stratigraphy and key beds of Ogallala are included, though the comparison of the topmost limestone of this formation with the caliche deposits belongs to Russell and is not shared by the writer (Russell, 1929, p. 599). This author also gives a very brief note on the stratigraphy of the basal 400 feet of the Pierre, apparently of Wallace County, within which he recognizes five members,distinguished by lithologic changes in the shale. No estimation for the separate thickness of these members is given.
The sudden local subsidence known as "Smoky Basin cave-in," east of Sharon Springs, in Wallace County, which occurred in 1926, attracted wide public attention. It was a subject of a note by the state geologist of Kansas, Raymond C. Moore, in which the cause of the subsidence was discussed (Moore, 1926, pp. 95-96, and 1926a, pp. 130-131). A different theory as to cause of this and similar cave-ins of various ages in Wallace County and the adjacent area was advanced by W. L. Russsell (Russell, 1929a, pp. 605-609). The opinion of the writer on the same subject, which agrees more nearly with the theory advanced by Moore, was published in 1930 and is included in the section on local subsidences in this report (Elias, 1930, pp. 316-320).
In the last decade expeditions sent by the Museum of Natural History of the University of Kansas have collected many beautifully preserved remains of vertebrates, chiefly from the Tertiary of Wallace County, but recently also from the Pierre shale. H. T. Martin discovered a rich locality of Tertiary vertebrates at the Marshall ranch in the northeast corner of the county and opened there a quarry in the summer of 1925. The locality has yielded already a considerable amount of valuable paleontologic material and is far from being exhausted. In 1930 the Museum expedition was sent by Martin to collect from new localities of vertebrate remains in the Tertiary and in the Pierre shale discovered by the writer in the course of his surveys in 1927-'28 and in 1929-'30. During these surveys the writer also recognized and studied commercial deposits of diatomaceous marl and bentonitic clays, both of Tertiary age and not previously recognized in Wallace or in adjacent counties.
Some other references on the geologic explorations in western Kansas and adjacent states are given in appropriate parts of this report. A complete bibliography on the geologic and paleontologic papers pertaining to western Kansas up to 1892 has been published by Robert Hay (Hay, 1896, pp. 261-278) and the history of the exploration of the Cretaceous of western Kansas up to 1898 by G. I. Adams (Adams, 1898, pp. 13-32).
Field Work and Mapping
As mentioned above, the writer made his first acquaintance with the geology of Wallace County and the adjacent area in 1927-'28, when he studied the northwestern part of the county for the Etnyre Syndicate. The survey of all of Wallace County for the State Geological Survey of Kansas was made in part during six weeks in October and November of 1929 and was resumed in May and June of 1930, when five weeks additional were spent on this work.
As no detailed topographic base maps of the county existed, the writer used the county road map prepared by the county engineer, to which he added more detailed drainage, schoolhouses, farmhouses and other geographic details in the Wallace County atlas published by Geo. A. Ogle & Co., Chicago, 1908. The map compiled from these two sources was checked and corrected during the field work. To this map elevations taken by Paulin altimeter were added, and contours with 50 feet interval were then drawn. The following method of work with the altimeter was adopted: For base points the three railroad stations of the Union Pacific--Weskan, Sharon Springs and Wallace--were used, their elevations being known. The automobile was driven first along the principal roads of the county, chosen so as to make an open loop starting at one station and ending at another. The elevations on such loops were taken twice, the car returning along the same route to the initial point of observation. The points on the principal roads with the elevations thus obtained were used as secondary starting points for lateral loops of observation covering the rest of the county. The readings of the altimeter were taken on some of these points more than twice. The mean of the calculated elevations was usually accepted, unless one reading was outstandingly different from the other, owing to a sudden drop or rise of the atmospheric pressure or to an erroneous observation. In these cases the apparently erroneous readings were discarded. The temperature of the air was always observed and the temperature corrections made. During a complete day's work with the altimeter at least five or six readings were made on the points, the elevations of which were well established. This number of readings was usually sufficient for plotting a curve of the daily variation of the air pressure. Altogether elevations of 250 points in Wallace County were observed and calculated, and based on these data, contour intervals of 50 feet were drawn on the topographic and structural maps of the county. The errors due to the imperfection of readings and to the differences between actual variation in the pressure of the atmosphere and that taken from the plotted curves of the daily variations are estimated by the writer to be as a rule hardly more than 10 feet in either direction.
Acknowledgments
During his field work the writer received the most friendly help of various kinds from the residents of Wallace County and adjacent territory, to whom he wishes to express his sincere appreciation. He is especially indebted to Messrs. Arthur Bowman, Joe De Tilla , J. Aug. Johnson, Roy Johnston, Worth Lacey, Frank T. Madigan, Jas. T. Madigan, Harry A. Wheeler, Guy Woodhouse, and L. H. Wulfekühler. The particular help that they rendered is mentioned at appropriate places in the report.
During the preparation of the report and identification of the fossils much help and useful suggestions have been rendered to the writer by W. H. Bradley, R. W. Chaney, R. G. Cuyler, F. H. Hilman, A. C. Hitchcock, W. H. Horr, G. L. Knight, K. K. Landes, H. T. Martin, Raymond C. Moore, R. G. Moss, J. W. Ockerman, J. B. Reeside, Jr., W. C. Stevens and Grace Wilmarth, to whom his thanks are due. The manuscript has been read by Raymond C. Moore and K. K. Landes. The photographs and sketches illustrating the report were made by the writer, unless otherwise acknowledged.
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Kansas Geological Survey, Geology
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