Thin, compact, fossil-poor limestone laid down as sea level rose. Additional limestone and shale beds may be present in some cyclothems. Section in the Oread Limestone at Atchison, Kansas. Two shale and two limestone members are exposed. The Plattsmouth, Heebner, and Leavenworth make up the fundamental marine triad of this classic upper Pennsylvanian cyclothem.
Coal beds formed in lagoons or estuaries, and thin limestone beds represent minor marine incursions.
Plant fragments and petrified wood are found in sandstone. The bedrock of the Kansas City region is flat-lying and relatively undisturbed. The region has been tectonically stable since the Paleozoic. In spite of this apparently simple setting, the bedrock has undergone subtle deformations and contains small disturbances. Gentle flexing of the crust has created ubiquitous vertical fractures, which are especially prominent in limestone beds.