The eastern Shawnee County and vicinity study area, encompassing about 355 square miles of northeastern Kansas, was mapped as part of a study of Upper Pennsylvanian rocks. The area includes eastern Shawnee County and parts of southeastern Jackson, southwestern Jefferson, and westernmost Douglas Counties. Topographic coverage is provided by the Elmont, Grantville, Meriden, Richland, 'Topeka, and Wakarusa 7lh-minute quadrangles and the northernmost parts of the Carbondale and Overbrook quadrangles.The unexposed sedimentary rocks in the area range in age from Late Cambrian to Late Pennsylvanian and are as much as 2,700 feet thick. Biotite granite of the Precambrian basement complex has been penetrated in two wells.Exposed sedimentary rocks in the area are about 725 feet thick and are in the Shawnee and Wabaunsee Groups, of Late Pennsylvanian (Virgil) age. Relatively thick shale formations of claystone, siltstone, and sandstone and alternating thinner limestone formationsrecord a cyclic pattern of deposition. The shale formations were deposited largely under nonmarine conditions. The limestone units were deposited largely under marine conditions ranging from beach or extremely shallow water to deeper, fairly quiet water of normal salinity. The claystone and siltstone in the limestone formations were deposited in estuarine, shallow lagoonal, and normal-marine environments. The widespread Nodaway coal bed of the Howard Limestone was deposited during subaerial conditions. Local channels have eroded several formations, particularly the Topeka and Howard Limestones.Scattered deposits of chert gravel of pre-Kansan age occur in the area but are too small to map. Kansan glacial drift, consisting mainly of unstratified and unsorted clay till, covers most of the area. Thick deposits of stratified glacial outwash occur along the Kansas and Wakarusa Rivers.Alluvial material of Quaternary age fills the Kansas and Wakarusa River valleys and the valleys of the larger creeks. In the Kansas River valley, extensive deposits correlated with the Newman terrace of Wisconsin age occupy much of the valley floor, and a broad band of• Recent alluvium borders the river In the Wakarusa River valley the alluvial fill is also correlated with the Newman terrace, but small terrace remnants, questionably correlated with the Buck Creek terrace of Illinoian age, locally occur along the valley sides.