Accompanied by 3 oversized plates : Geologic Map of Black Gap Area, Brewster County, Texas. Structure Contour Map on Top of Santa Elena Limestone and Fault Relief Diagram (Inset), Black Gap Area, Brewster County, Texas. Composite Measured Section from Black Gap Area
2 maps and 1 plate : 1 col., 1 b.&w. ; 75 x 78 cm. and 34 x 39 cm.