Thomas S. Meredith Sean M. Bryn Ronald G. Borman 1984 <p>The southern High Plains of Colorado, an area of about 2,800 square miles in the southeastern part of the state, is underlain by the Ogallala Formation of late Tertiary age, The southern High Plains of Colorado extend from the Colorado State line on the east and the ans south to the edge of the Ogallala Formation on the north and west. The Ogallala Formation is an unconsolidated or partly consolidated seposit of sand, gravel, clay silt, and caliche.&nbsp;</p> application/pdf 10.3133/ha673 en U.S. Geological Survey Geology, altitude, and depth of the bedrock surface; altitude of the water table in 1980; and saturated thickness of the Ogallala aquifer in 1980 in the southern High Plains of Colorado reports