This traverse is a composite of six localities (Fig. 1)—four in the Trinity Group and one each in the Fredericksburg and Washita Groups (Fig. 2)—exposed along a route extending from near Eastland (Eastland County) on the west to a point near Blum (northwestern Hill County) on the east, a straight-line distance of about 75 mi (120 km). The section transects the eastern margin of the Trinity Shelf and ends near the western margin of the East Texas Basin (Fig. 3). The section extends from the Western Cross Timbers across the Glen Rose Prairie, the Lampasas Cut Plain, and the Washita Prairies, which together make up the Grand Prairies of Texas (Hill, 1900) (Fig. 4).