"The Geysers" Area of Sonoma County, 1946
Map of the "The Geysers" area (Sonoma County) showing minerals and locations, made by the State of California Department of Natural Resources. This map was issued as a folding piece, on thin vellum-like paper, accompanying the state mineralogist's report from July 1946. The Geysers is the world's largest geothermal field spanning an area of around 30 square miles in Sonoma, Lake and Mendocino counties in California, centered in the area of Geyser Canyon and Cobb Mountain. Power from The Geysers provides electricity to Sonoma, Lake, Mendocino, Marin, and Napa counties. in fine condition with minor toning along the crease folds, measures approximately 12 x 12.5 inches.