Regional surface and subsurface studies indicate that thick deltaic (Queen City Formation) and thin shelf (Reklaw and Weches Formations) sequences compose the stratigraphic interval between the top of the Carrizo Sand and the base of the Sparta Formation.

Geologic map that depicts the surface geology of Shackelford, Stephens, Palo Pinto, Callahan, and Eastland Counties and parts of Jones, Taylor, Runnels, Coleman, Brown, Comanche, Erath, Parker, and Hood Counties, Texas.

The Van Horn-Sierra Blanca region lies athwart part of the boundary between two contrasting geologic provinces. The contrast between these two provinces, splendidly displayed by Holocene landforms in the present map area, has a history that dates back to at least Late Precambrian time.

This Guidebook represents an updating of Bureau of Economic Geology Guidebook No. 5, Field Excursion-Geology of Llano Region and Austin Area. It also represents a modification of Geology of the Llano Region and Austin Area, Texas, published by the Shreveport Geological Society in 1971.

The Eastern Shelf was a constructional platform developed on the margin of the sediment-starved Midland Basin during Late Pennsylvanian and Early Permian time. A mixed terrigenous-carbonate sedimentary province characterized the shelf during most of its history.

The Texas Coastal Zone is marked by diversity in geography, resources, climate, and industry.

Mountain-bounded basins or bolsons are the most important aquifer systems throughout most of southwestern and western United States and northern Mexico.

Fresh-water pond deposits at Ingleside, San Patricio County, Texas, have yielded a large Pleistocene vertebrate fauna. The bones are derived from calcareous sands and marls which overlie a marine lagoonal clay. The locality is located just west of the axis of Live Oak Ridge.

The West Chinati stock, well exposed in San Antonio Canyon and immediately westward on slopes of the southwestern part of the Chinati Mountains, Presidio County, Texas, is a large stocklike body of porphyritic hornblende granite cut by numerous dikes and irregular-shaped plutons of rhyolite, rhyo