A study of the hydrogeology of deep sedimentary basins using the Neogene deposits of the northern Gulf of Mexico basin as a model was initiated by the U.S. Geological Survey in the 1960's (Jones, 1969). This study led to investigations of geopressured-geothermal resources in this basin (Papadopulos and others, 1975; Wallace and others, 1979) and of the waste storage capabilities of the Wilcox Group in Texas (Jones and others, 1976). Techniques for delineating pressure, temperature, and salinity variations within the geologic framework were developed in conjunction with these and related studies. The purpose of this hydrologic atlas is to delineate the hydrogeology of the onshore Cenozoic aquifers of south Texas, using these techniques.
The location of the study area in Texas is shown in figure 1. Hydrogeologic cross section A-A' is shown in figure 2. The surface geology of the area and the line of section A–A' are shown in figure 3. Geophysical logs of oil tests provided the framework for this section. Interpretations presented are based upon data from these logs; information from published ground water and geological reports; and structural and geologic interpretations from maps prepared by Peppard, Souders and Associates for the U.S. Geological Survey under Purchase Order Numbers 67482 and 67.483.
