Geology of the San Francisco North quadrangle, California

San Francisco is a heavily built up city in a region of active faults and is subject to earthquakes and landslides. In such an area careful selection of building sites and foundations is imperative. This geologic investigation of the San Francisco North quadrangle was carried out to obtain basic geologic data to aid in construction and other civil engineering problems. The study also contributes to a better understanding of the geology of this part of the Coast Ranges in general and of the Franciscan Formation and surficial deposits in particular.

On the geologic map (pl. 1) , consolidated rocks are delineated by their composition, age, and origin. Such a classification also gives an approximate indication of the engineering properties of each formation. To make the map more useful to the civil engineer, unconsolidated deposits are shown where thick enough to be depicted. This report and the accompanying map should be a useful guide for planning foundation studies necessary in engineering design.