Generalized configuration of the base of the High Plains Aquifer in Kansas

The High Plains aquifer in Kansas is part of a regional system that extends from South Dakota to Texas. In Kansas, the aquifer underlies an area of 30,900 square miles in the western and south-central part. The aquifer is a hydraulically connected aggregation of unconsolidated water-bearing deposits. The High Plains aquifer is composed principally of unconsolidated alluvial deposits of Tertiary and Quaternary age. These materials were deposited on an erosion surface that had been cut into consolidated rocks of Permian, Cretaceous and Jurassic age. Dissolution of underlying Permian evaporites by ground water has been a significant factor in the faulting and subsidence of the bedrock surface in southwestern and south-central Kansas. Maps published at a scale of 1:500,000 show the altitude and configuration of the base of the aquifer. The regional gradient of the base is from west to east at about 10 feet per mile, but the gradient of the base is from west to east at about 10 feet per mile, but the local gradient may exceed 100 feet per mile in the vicinity of faults, collapsed areas, and erosional features. (USGS)