Geology of playa 21, Lynn County, Texas

The geologic history of Playa 21, located in the Double Lakes Basin, Lynn Co., Texas, was investigated by examination of 1250 feet of test borings, core data and field observations. These data indicate that the basin formed in a depression on Tertiary Ogallala sediments. Dissolution of underlying Cretaceous carbonates and/or salts did not play a role in the development of the basin. Ponding occurred during wet periods, resulting in accumulation of up to thirty-five feet of lacustrine deposits. Later the ephemeral nature of the playa, characterized by alternating periods of mudcracking, piping, deflation and downward eluviation of fine material, deepened and widened the playa. Three separate areas of eolian deposits adjacent to Playa 21 record dominant sand-transporting paleowind directions. Beginning approximately 10,000 years before present, deposition of over 6 feet of Lofton Series soil reflects the most recent change in Playa 21's environment.