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Riley and Geary County Geology

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This report on the geology of an area somewhat greater than 1,000 square miles is based chiefly on field studies made during the summer of 1930, but supplemented by a few weeks of study in August,1938. The two counties, selected by the state geologist and assigned to me, have afforded a wide variety of subjects of geologic interest, as the area includes exposures of several hundred feet of strata of Pennsylvanian age, almost the entire thickness of the truly marine Permian rocks of the state, a few feet of Cretaceous sediments, some glacial drift of the Pleistocene series, and three exposures of igneous rock. The physiography is almost as interesting as the stratigraphy, for the Flint Hills in this part of Kansas are as rugged and as beautiful as any other surface features in the state. The exposed strata are described in detail and their distribution is shown on the accompanying map. The structure is discussed and the physiography is generally described. A portion of the report concerns economic geology. Neither oil nor gas has been found in commercial quantity in the two counties, but the area has been tested by only a few wells, so should not be regarded as having been proved barren.

The layers of rock that are exposed in eastern Kansas are deeply buried in the western part of the state. As an acquaintance with these strata is extremely important to petroleum geologists seeking to discover or extend oil fields in western Kansas, the measurements of thickness and the detailed descriptions of color, texture, and composition of each of the strata outcropping in Riley and Geary counties should be useful to persons so employed.

Field Work

During the field season of 1930, details of stratigraphy were studied and the areal map was prepared. Faunal and lithologic studies begun in the field were continued in the laboratory. Subsequent shorter visits to the two counties and study of the same rock layers in other parts of Kansas, in Nebraska, and in Oklahoma have been helpful. Additional studies were made in the summer of 1938.

One method that was used in mapping rock exposures had not previously been used in Kansas. Aerial photographs, which were prepared by the United States Air Corps in the summer of 1926 and which are now the property of the United States Geological Survey, were lent to the Kansas Geological Survey and were used in making a portion of the map. The scale of the air photographs is 1:17,500. A base map, scale 1:2,000, was obtained from the Federal Survey and after the rock strata had been identified in the field their pattern was transferred from the photographs to the base map. The base map itself had been made from air photographs, so drainage and other features are accurately pictured. The base map covers all the area except that portion north of an east-west line passing through Leonardville in northern Riley County and an area of about 75 square miles south and east of Manhattan. Available air photographs did not cover the whole area of this base map. The portion covered by the large-scale base map, but not by the air photographs, was mapped by using as base maps the State Highway Department map and the soil map of Riley County published by the United States Bureau of Soils. As a check in a few small, scattered areas, maps made by commercial geologists were used. It is believed that the outcrop pattern was almost exactly delineated, especially because of the map's accuracy, within the area of the large-scale base map.


R.C. Moore, state geologist, gave directions, suggestions, and criticisms that were indispensable to the successful completion of the project, and visited areas in the field. G. E. Condra, state geologist of Nebraska, who has given much study to the Permian rocks of the northern midcontinent area, also gave assistance of great value; later he kindly supplied several measured sections that were useful in making correlations. Citizens of the counties were courteous and helpful whenever accosted. J. E. Ames, manager of the Chamber of Commerce, Manhattan, and H. P. Reaume, secretary of the Chamber of Commerce, Junction City, provided data concerning industries and population. John Ockerman, formerly of the Kansas Geological Survey, made the stereoscope that was used in studying the air photographs. M. K. Elias, formerly of the Kansas Geological Survey, was very helpful, sharing his knowledge of the stratigraphy of the "Big Blue" series. Several petroleum geologists have suggested types of data, obtainable by study of the outcrops, that are helpful in their studies of subsurface cuttings. I appreciate the magnitude of the help I have received from these persons.

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Kansas Geological Survey, Geology of Riley and Geary Counties
Web version Nov. 2000. Original publication date Dec. 1941.
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