While generally illustrated as an extension of the Miocene-PlioceneOgallala Aquifer, this aquifer is composed of alternating beds of sand and clay mostly deposited in the later Pleistocene and was named the "McPherson Equus Beds" for having characteristic modern horse fossils.[5][6]
The aquifer beds overlie, and are partially recharged by the Dakota Aquifer and certain Permian aquifers. These particular High Plains Aquifers are also known sources of widespread natural salt contamination, including portions of the Equus Beds, which can be aggravated by human extraction of water as well as by salt mining and oil wells.[7][8]
Erasmus Haworth and J. W. Beede (1897). "The McPherson Equus Beds". Geological Survey of Kansas. Vol. 2. Retrieved 2023-04-07. ... a formation of considerable economic and scientific interest ....
^"ABOUT GMD2". Equus Beds Groundwater Management District No. 2. Retrieved 2023-04-07. The Equus Beds aquifer is part of a regional aquifer system known as the High Plains aquifer system.
^Bevans, Hugh E. (1989). "Water Resources of Sedgwick County, Kansas"(PDF). Water-Resources Investigations (Report 88-422). United States Geological Survey: 4. Retrieved 2023-04-07. Results of an investigation of the geology and ground-water resources of the Equus beds, the principal aquifer in the area, ...
^"Geologic Unit: Equus". National Geologic Database. Geolex — Significant Publications. United States Geological Survey. Retrieved 2023-04-07. The USGS in general calls the beds containing EQUUS remains the EQUUS zone, ...