Original antique geological map of the mountains between Novato and Petaluma, just north of San Francisco. Showing an area of some 100 square miles in size in great detail, this map includes an extremely detailed early look at the geology of the region. Showing topography, settlements, and more, this would have been one of the most detailed maps of the region produced at the time. The map was produced by the USGS based on information compiled by Charles E. Weaver.
The geology of this region includes many intrusive and extrusive igneous rocks, typical of the coast ranges of central and northern California. In the north and northeast, very young sedimentary rocks are visible.