The geologic map (at a scale of 1 :24,000) depicts the full extent of the Ripsey Wash compound half-graben, which occupies an elongate area of approximately 15 sq km parallel to the Ripsey fault, and represents a revision and update of previous mapping (Schmidt, 1971; Cornwall and Krieger, 1975a, 1975b; Dickinson, 1991, Figure 40). Access to the interior of the study area, which lies within the Grayback and Kearny 7.5 minute USGS quadrangles, is provided by an unimproved road that turns up the floor of Ripsey Wash from the graded Florence-Kelvin highway, which crosses Ripsey Wash just above its mouth near the A-Diamond Ranch. The regional geologic relationships of the Ripsey Wash half-graben are discussed elsewhere (Dickinson, 1991, 1995).