PHYSIOGRAPHY Smoky Hills Cretaceous rocks of Kansas are confined to the Great Plains physiographic province which, in the part of the State described in this guidebook, is divided into two contrast- ing sections, the Smoky Hills to the east and the High Plains to the west (Fig. 1). During most of the first day we will be traveling across the Smoky Hills and during the second day we will be in the High Plains. The Smoky Hills are composed of rocks belonging mainly to the Dakota Formation and lower part of the Colorado Group, and they are separated from the High Plains by a prominent escarpment capped by the Fort Hays Limestone Member of the Niobrara Chalk. The eastern half of the section is characterized by hilly topography developed on shale and sandstone units of Cretaceous rocks older than the Greenhorn Limestone. Prominent hills are held up by sand- stone bodies within the stratigraphically complex Dakota Formation. The distinctive topo- graphic aspect of this part of the section prompted Schoewe (1949) to restrict use of the name Smoky Hills thereto and to use the term Blue Hills for the western part of the section. Along the route of this excursion the most conspicuous development of this rough topography is south of Interstate Highway 70, just west of Brookville, where the landscape bears close resemblance to the "stagecoach country" of the familiar "Western" motion picture. Figure 1.- Map showing physiographic divisions of Kansas (adapted from Frye and Schoewe, 1952). Route of field trip is indicated by heavy line. 4