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Stratigraphy
Formations not Exposed
Our direct information concerning the underground rocks of Wallace County is limited to the logs of the two deep dry holes that have been drilled in the eastern part of the county. Unfortunately the cuttings of these wells have not been preserved (except a few samples from the Wulfekuhler well), and consequently the precise correlation of the rocks penetrated by the two wells is considerably handicapped. The data available on the deep wells drilled in the immediate neighborhood of Wallace County are no better for study and correlation. In a little more distant area, north of Wallace County, several deep wells have been drilled recently, and the cuttings have been collected. The most valuable contribution to knowledge of the underground stratigraphy of the northwestern part of Kansas is given by the George Andrews No. 1 well of the Phillips Petroleum Co., in sec. 3, T. 2 S., R. 42 W., about one mile west of the Kansas state line. The well is 5,055 feet deep and is the deepest for a considerable area of western Kansas and northeastern Colorado.
G. W. Bastian, of Atwood, who drilled a well 3,076 feet deep at his ranch in sec. 5, T. 3 S., R. 34 W., in Rawlins county, Kansas, has preserved the cuttings from the depth of about 1,000 feet down to the bottom of his well. The cuttings of the well that is now drilling in the southwest corner of sec. 3, T. 2 S., R. 35 W., in Rawlins county, by the Danciger Refining Co., of Tulsa, Okla., belong to that company. The writer did not have an opportunity to study the cuttings of the latter well, but has made a preliminary examination of Mr. Bastian's samples, which have been kindly submitted for his study.
As the study of the cuttings of the other wells is now in progress by geologists of oil companies, there is no need to speculate as to the correlation of the formations penetrated by these wells on the ground of the well logs alone. It will suffice to note at present that the Andrews well was drilled through red beds and was continued down to 4,850 feet into interbedded gray to white limestone and blue shale of possibly Lower Permian and Pennsylvanian age. The top of the red beds was reached at 3,195 feet, and the base of the lowermost red rock of appreciable thickness was reached at 4,560 feet. A well in northwestern Kansas east of Wallace County, which also was undoubtedly drilled through red beds and entered the Permian-Pennsylvanian sequence of limestones and shales; is the Moffet and Andrews No: 1 well of Coons, in sec. 14, T. 14 S., R. 33 W., Logan County, Kansas. This well is 3,855 feet deep. The top of the red beds was reached at 1,500 feet, and the base of these beds at 3,165 feet, below which only a few thin red beds are recorded among the interbedded limestones and blue shales. The deep wells of eastern Wallace County have been stopped after penetrating 154 1/2 feet (Wulfekuhler well) and 455 feet (Robidoux well) of red beds. These beds consist chiefly of interbedded sands, sandy shales and shales. The red beds that are exposed in eastern and south central Kansas are classified with the Permian. The red beds of Wallace County, either as a whole or at least their lower part, probably belong to this epoch, The upper part may belong to the lower Mesozoic (Triassic?), representing possibly equivalents of the "Red beds" of the Lykins formation of Colorado or of the Chugwater formation of Wyoming.
The 20 feet of "green shale," with possible addition of 30 feet of "light shale" below and 10 feet of blue shale above in the Wulfekuhler well, may correspond to Morrison marls of northeastern Colorado, and the sand and gravel between this shale and the red beds may be equivalent to the arenaceous Sundance formation. Both the sand and the shale above the red beds and below the overlying Dakota have been recorded also in the Robidoux well.
The sands with interbedded shale referred by the writer to the Dakota group are 365 feet thick in the Robidoux well and 405 feet thick in the Wulfekuhler well. Bass estimates the thickness of Dakota sandstone, a formation "consisting of sandstone, sandy shale, and clay," to be about 300 feet in western Kansas (Bass, 1926, p. 85). The upper limit of the formation is ordinarily fairly recognizable in the wells, owing to the change from shale of the Benton to sands, usually with a large flow of water, at the top of the Dakota. The lower limit of the formation, on the contrary, is not easy to define. In the Wallace County wells the lower limit of the Dakota group is arbitrarily placed at the base of the lowermost sand above the "green shale" of the provisional Morrison. Within the "Dakota group" thus limited there may be in Wallace County, besides the Dakota sands proper at the top, equivalents of the Fuson fine sands and shale in the middle and of the Lakota sandstone at the base.
The Benton group, which includes the rocks above the Dakota and below the Fort Hays and is among the most clearly recognized beds in the drilled wells, consists chiefly of shale with occasional sands and limestones. A bed of "brown limestone" only 5 to 6 feet thick is recorded in both the Robidoux and Wulfekuhler wells near the base of the Benton group. This bed may possibly correspond to the Lincoln limestone member. Slightly above this brown limestone there was met in both wells a thick (62 to 75 feet) bed of "white sand" with strong water and traces of oil and gas. If this "white sand" is merely a porous limy rock, it could correspond to the limy beds of the Fairport or to the upper beds of the Greenhorn.
The Codell sand, which is a topmost member of the Benton in west-central Kansas (Bass, 1926, p. 28), was not recorded in either of the two Wallace County wells, where "black shale" was met immediately below the "white lime" of the Fort Hays. However, according to the record of a boring at Cheyenne Wells in Colorado, about 17 miles west of Wallace County, 30 feet of fine sand has been encountered below 70 feet of chalky rock with brackish water, which is apparently Fort Hays (Darton, 1905, p. 329). The Fort Hays limestone in the wells of Wallace County is 55 to 60 feet thick, which corresponds fairly to the very persistent thickness of this limestone all over western Kansas.
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Kansas Geological Survey, Geology
Placed on web Nov. 17, 2014; originally published April 1, 1931.
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