A majority of this map of California is colored to reflect geological knowledge and coded in accordance with a legend at the left. The legend identifies nine geological types as mapped by Lieut. R.S. Williamson of the Topographical Engineers. There are interesting details throughout, and especially along the American River. A huge Mono Lake is shown, but not Lake Tahoe; rather, in its place is a small lake named Lake Bonpland. In Southern California, Los Angeles, San Gabriel and San Pedro are located. Interestingly, the water between San Pedro (Long Beach) and San Diego is called "Earthquake Bay." Prepared to accompany the report of William P. Blake, Geologist of the Expedition. Lithographed by Sarony, Major & Knapp of New York.

References: Marcou & Marcou #678.

Condition: B+

Issued folding with light foxing, minor extraneous creasing at lower left, and marginal toning along the left and top edges.