Geology and ground-water resources of Medina County, Texas

The Edwards limestone of Cretaceous age is the principal water-bearing formation in Medina County and makes up the major part of a ground-water reservoir, or aquifier, which in places includes thinner limestone formations both above and below the Edwards. The Glen Rose limestone, also of Cretaceous age, yields moderate amounts of water to wells and springs in the northern part of the county. Other Cretaceous formations, including the Austin chalk, Anacacho limestone, and Escondido formation, yield only small amounts of water, and that of the Austin and Escondido is of generally inferior quality.