Natural Resources, School of
Date of this Version
Soil Survey of Cheyenne County, Nebraska, 1997. USDA, NRCS, & University of Nebraska, Conservation and Survey Division, pp. 2-4.
The oldest rock unit exposed in Cheyenne County is the upper part of the Brule Formation, which is the youngest formation of the White River Group of the Oligocene epoch (33-29 million years old). Surface outcrops, road cuts, and railroad cuts through the Brule Formation occur along the sides of valleys along Lodgepole Creek from just east of Sidney westward to the vicinity of Brownson, along the valley sides of Sidney Draw and its tributaries, and along the sides of an unnamed drainageway northwest of Colton. Test drilling and drilling for wells along the floor of Lodgepole Creek have revealed that the alluvial (stream) deposits from the Deuel-Cheyenne County line in the east to the Point of Rocks in the west are also underlain by the Brule Formation.
The Brule Formation, which underlies all of Cheyenne County, generally yields only small amounts of water to wells. Large initial yields often followed by rapid declines during pumping may come from wells in fractured parts of the Brule Formation. Wells along the eroded valley sides and on the floors of the valley of Lodgepole Creek and Sidney Draw may be supplied by water from this aquifer.