The Texas Panhandle includes primarily two physiographic provinces: the High Plains which overlies the Dalhart and most of the Palo Duro Basin and the Rolling Plains characterizing the eastern part of the Palo Duro Basin area. These two provinces are separated by the Caprock Escarpment, a prominent erosional feature along which relief locally exceeds 1,500 ft (500 m). The High Plains is developed on the Tertiary Ogallala Formation and forms a broad, flat plain having a regional slope to the southeast of 8 to 10 ft per mile. The Rolling Plains were formed by erosion of the Ogallala Formation which exposed the varying lithologies of the underlying Permian and Triassic age units. The easterly flowing Canadian River divides the High Plains into two sections: the Northern High Plains overlying the Dalhart Basin, and the Southern High Plains, or Llano Estacada, overlying the Palo Duro Basin. Prominent escarpments bounding the High Plains on the west, east, and along the Canadian River Valley are the result of Quaternary erosion. These escarpments provide most of the Tertiary and Triassic rock exposures. The flat surface of the High Plains is interrupted by numerous playas, dunes, and a surface drainage system composed of linear draws or channels. Pleistocene strata are exposed in some stream-cut channels and large playas on the High Plains surface. With the exception of the Canadian River drainage system and minor streams, major portions of the High Plains surface are without external drainage.Bureau of Economic Geolog
