A gravity survey was conducted in the San Gorgonio Pass, near Banning, California. Approximately 540 new gravity measurements were made in generally north-south trending cross-sections. Nine new gravity profiles with spacing of 500 feet between stations were constructed. These profiles were used in addition to gravity data of previous investigators to generate a total of 12 north-south gravity profiles, spaced at approximately 1- to 2-mile intervals from Beaumont to Whitewater. These data were used in conjunction with driller's logs, geophysical logs, and geologic maps to construct geologic cross-sections from residual Bouguer anomaly profiles. Data gathered from the gravity profiles were used to construct geologic cross-sections that locate features, such as faults and changes in basement elevation, that might influence the movement of ground water within the pass. Results of this study show that depth to basement is deepest on the north side of the pass and ranges from an excess of 4,000 feet north of Beaumont to less than 1,000 feet west of Whitewater. The presence of prominent stepped decreases in the residual Bouguer anomaly are evidence for numerous steep north dipping faults along the north side of the pass in contrast to the southern side where a steep but generally smooth increase in the residual anomaly does not suggest the presence of faults located on the south side of the pass. Evidence was also found to support the presence of a basement high that forms a ground-water barrier at the eastern part of the pass, west of Whitewater, California.
