The urban corridors associated with the Dallas, Austin, and San Antonio metropolitan areas lie on Austin Chalk outcrop. In these areas of rapid urbanization, ground-water information is needed to resolve environmental issues. The Austin Chalk also produces hydrocarbons in the deep subsurface. Fluid migration in both oil-field and ground-water environments is strongly controlled by fractures. In each geologic setting, a conceptual model of fracture intensity is required to model or predict flow. Using geologic and engineering data collected during development of the U.S.

Facies architecture, structure, and diagenesis control reservoir geometry and distribution of remaining oil in shoreface, fluvial, and deltaic reservoirs of Miocene age in the 18-mi2 (46.7-km2) Mioceno Norte Area in northern Lake Maracaibo. This mature field is undergoing depletion and nearing the final stages of primary recovery.

Big Bend Ranch State Park, the largest in the Texas State Parks System, lies in the rugged Big Bend country of West Texas (figs. 1 and 2). The primary attraction of Big Bend country is its scenery, and scenery is geology. The mountains, canyons, plateaus, rivers, waterfalls, and, indeed, every aspect of the natural landscape result directly from geologic processes of rock formation and erosion. In Big Bend country, these processes include mountain building, volcanism, faulting, and erosion. Taken together, they have shaped the land into the rich vistas we enjoy today.