The San Saba Member of the Wilberns Formation of central Texas is mostly coarse-grained, trilobitic limestone that grades eastward to dolomite and contains sandstone intervals in its westernmost exposures. Faunas from the limestone place the middle part of the San Saba within the Trempealeauan Stage (Saukia zone) of the Upper Cambrian, but the uppermost part belongs to the Lower Ordovician. Three subzones within the Saukia. zone are described.

Lower Cretaceous sands have long been important aquifers in Central, North-Central, and North Texas. In recent years these sands also have been sources of high-silica industrial or specialty-purpose sand. Lower Cretaceous sands of northern Texas and Cenozoic sands of the Texas Coastal Plain comprise the main resources of high-silica sands in the State. Knowledge of their occurrence, distribution, stratigraphic relation, quality, and suitability for industrial uses is necessary to their future development.

This report deals with the occurrence and potential production of industrial sand in the Gulf Coast area of Texas. The study area covers approximately 23,000 square miles underlain by alluvial, deltaic, beach, and eolian deposits of Pleistocene and Recent age. Deposits are intermixed and interbedded sands, gravels, silts, and clays. Sand bodies are irregular in size and shape depending on environment of deposition; they vary in physical character and mineralogical and chemical composition.