Hillside materials and slopes of the San Francisco Bay region, California

This report describes the various bedrock and soil materials and slope gradients that constitute hillsides in the San Francisco Bay region. Distribution of materials and slopes is shown on 1:125,000-scale maps of the region. Approximately 360 materials units are described by bedrock composition, physical properties of bedrock (rock hardness, spacing of fractures and partings, and bed thickness), texture of the soil cover, expansivity, permeability, and stratigraphic thickness. Materials map units are based on compilations of geologic mapping of the region; descriptions are based on systematic field observations, free-swell tests for expansivity, examination of aerial photographs, and the literature.