Date of Award
Master of Science (MS)
Michael E. Nelson
The Cheyenne Sandstone is composed of light brown to dark yellowish - orange, medium-to fine-grained, friable, cross-stratified sandstone, and lenses of sandy shale and conglomerate. These rocks crop out as an irregular narrow band about 50 km long around the headwaters of several streams in Barber, Kiowa and Comanche counties, Kansas. The Cheyenne was studied to determine the depositional history of the unit, the significance of fossils found in the sandstone, and the probable source of the detrital minerals. Thin section and sieving analyses, as well as outcrop examinations, suggest the Cheyenne represents deposition in a fluviatile-estuarine complex. The lower medium-to-fine-grained sandstones and conglomerates of the Cheyenne are deposits of southeastward flowing streams. As the early Cretaceous sea transgressed northward, stream gradients decreased and the upper fine silts and muds represent the onset of estuarine conditions. With increasing water depth, the thinly-laminated, marine, black shales of the overlying Kiowa Formation were deposited. Reworking of upper Permian rocks is prevalent at most outcrops and may account for part of the detrital composition and clay mineral assemblage of the Cheyenne fossil terrestrial plant fragments indicate the Cheyenne was deposited in a warm and partially arid climate.
Copyright 1977 Roger D. Fisher
Fisher, Roger D., "The Petrology of the Lower Cretaceous Cheyenne Sandstone of South-Central Kansas" (1977). Master's Theses. 1659.