The lake is situated in the northern portion of the Flint Hills, which are characterized by flat-topped hills with long, steep slopes, limestone rock outcrops, and well-defined stream channels. Relief between the stream floodplains and the hilltops adjacent to the lake averages about 300 feet. Much of the land is too stony to cultivate.
Geology and Soils
From about Randolph Bridge north, glacial drift forms a discontinuous mantle, attaining a maximum thickness of 300 feet. South of Randolph Bridge, alluvial deposits range from 10 to 50 feet deep. Bedrock consists of a sequence of cherty limestones and shales of the Permian age.
Upland soils are commonly very shallow, stony and gravelly. They are developed from limestone and limy shales and occupy slopes of 7 to 20 percent or more. The topsoils are silty clay loams 3 to 5 inches thick. The unweathered parent material is usually encountered at 8 to 20 inches.
Lower slope and bottomland soils are moderately deep, dark, friable, silty clay loams 5 to 10 inches thick. They are derived from loess, limestone, and limy shales. The subsoils are silty clay loams found to a depth of 38 inches.
Under normal erosion conditions, exposed topsoil may be totally displaced.
Mineral resources include sand, gravel, crushed rock, and gypsum. Gypsum is mined near Blue Rapids, and sand, gravel, and limestone are extracted at several locations around the lake area.