The Gulfian section of Central Texas is illustrated by a transect extending from northwestern Hill County southeastward to northeastern Limestone County (Figs. 1 to 6). This transect begins in latest Washita rocks of Comanchean age (locality 1; Figs. 1, 3), and crosses in succession the outcrop belts of Woodbine Sand (localities 1 and 2; Fig. 3); Eagle Ford Group (locality 3; Fig. 4); Austin Chalk (locality 4; Fig. 4); Taylor Group (locality 5; Fig. 5); and Navarro Group, all of Gulfian age, to end at the Midway Group (locality 6; Fig. 6) of Paleocene Age (Hill, 1901; Adkins, 1933; Bureau of Economic Geology, 1970, 1972). Structurally, it originates near the eastern margin of the Central Texas Platform (Fig. 3), and trends downdip across the northern end of the Balcones Fault Zone (Fig. 4) into the East Texas Basin (Fig. 3), to terminate in the Mexia Fault Zone (Fig. 6; Oliver, 1971). Geomorphically it begins at the eastern margin of the Grand Prairies (Fig. 3), and crosses the Eastern Cross Timbers and the Black Prairies (Figs. 4,5, 6) to end at the western margin of the East Texas Timber Belt (Fig. 6; Hill, 1901 ). Throughout this route, the geology, landscape, history, and land use are clearly related.
Figures & Tables
One of six volumes generated by each GSA section for the Decade of North American Geology (DNAG) project, this Centennial Field Guide contains descriptions of 100 sites or site clusters representing outstanding geologic locations in Arkansas, Kansas, Oklahoma, and Texas.