This report documents the stratigraphy beneath playa lakes and associated lake-margin, playa-basin, and upland settings. Genetic facies interpretation of the observed lithologies was undertaken to better predict the nature of interplaya stratigraphic variation and to extract information about the long-term geologic and paleoclimatic evolution of the area.ABSTRACTPlaya lakes are abundant small ephemeral lakes (generally ~0.5 km in area) that occur in shallow depressions (generally <11 m deep) on the surface of the Southern High Plains.

Chert reservoirs of the Lower Devonian Thirtyone Formation represent a substantial part of the hydrocarbon resource in the Permian Basin. More than 700 million barrels of oil has been produced from these rocks, and an equivalent amount of mobile oil remains.