Geology illustrated on this map and accompanying geologic map database was revised using field, aerial-photograph, and LiDAR interpretations following a review of previous work on the area’s geology.

The Fredericksburg Group is one of three groups of rocks which comprise the outcropping Lower Cretaceous sediments in north central Texas. Four formations form this group; from the base upward these are the Paluxy, Walnut, Comanche Peak and Edwards (fig. 1).

A thick sequence of Lower Cretaceous limestone and dolomite, known traditionally and informally as Edwards," covers much of west-central Texas and composes one of the dominant physiographic elements of the State, the Edwards Plateau.