Wendel quadrangle is entirely within the Edwards Plateau province and is situated southwest of the Llano region.

The geology of the Wendel quadrangle is shown on a planimetric map, and the only topographic map available is the reconnaissance 30-minute Kerrville quadrangle. Elevations ranging between 2,041 and 2,284 feet were determined during traversing for control, but neither the highest nor the lowest elevation was reached. However, it is estimated that the relief within the quadrangle is about 270 feet, ranging between 2,020 and 2,290 feet.

The quadrangle has diverse drainage patterns. About half the drainage flows westward and northward to Little Devils River, ultimately reaching the Llano River by way of James River. White Oak Creek, Fall Prong, and Burr Oak Draw are the chief tributaries of Little Devils River. The headwaters of the Pedernales River occupy about one-third of the quadrangle, centered in the southeastern part. A small area in the northwest corner drains into Threadgill Creek and then into Beaver Creek and Llano River. A small area in the southwestern part of the quadrangle is in the Guadalupe River drainage basin, reaching the river by way of Rough Hollow and Johnson Creek.

The Wendel quadrangle is on the southwestern side of the Llano uplift, and Cretaceous rocks crop out throughout the quadrangle. Rocks of Ordovician and Carboniferous age are probably less than a thousand feet below the surface. The Cretaceous rocks are essentially horizontal.

References cited below deal more broadly with some of the stratigraphic, structural, economic, and geophysical problems of the region. This publication on the Wendel quadrangle is one of a series of similar publications, an index to which is shown on the opposite page. The reader is referred to the index map to locate other quadrangles mentioned in the present text.