The Houston-Galveston Area Council of Governments (HGAC) encompasses over 12,000 square miles of southeast Texas (fig. 1). It is an area undergoing rapid development and population growth due to the presence of vast agricultural, mineral, and energy resources, expanding industrial activity, and diverse recreational areas. Planning is particularly critical in the HGAC to ensure orderly development.

Geologic map that depicts the surface geology of Goliad, Refugio, and Calhoun Counties and parts of Karnes, De Witt, Victoria, Jackson, Matagorda, Aransas, San Patricio, Bee, and Live Oak Counties. The 4-page booklet indicates geologic formations, abbreviations, and ages.