Everything sits on bedrock
Alameda County
https://pubs.usgs.gov/of/1996/of96-252/
Contra Costa County
https://pubs.usgs.gov/of/1994/of94-622/
Marin/SF Counties
https://pubs.usgs.gov/mf/2000/2337/
San Mateo County
https://catalog.data.gov/dataset/preliminary-geologic-map-of-san-mateo-county-california-ngmdb
