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1956 Map of New Idria

Name: 1956 Topographic Map of New Idria
Creator: U.S. Geological Survey
Published: 1958
License: https://creativecommons.org/publicdomain/mark/1.0/

USGS Topo · Published 1958

About this map

The cinnabar-rich hills of the Diablo Range dominate this mid-century survey, centered on the mining operations at New Idria (Idria PO). The landscape is a network of mercury and mineral extractions, featuring significant sites like the Florence Mack Mine and the Santa Margarita Mine near the headwaters of the San Benito River. The topography rises steeply to San Benito Mtn, reflecting the geological complexity of an area defined by mineral exploration and high-elevation ranching.

Remote outposts such as Ashurst Ranch and Adobe Flat are connected by unimproved dirt roads, highlighting the isolation of these mountain settlements. Industrial activity is evident through specialized facilities like the San Benito Mill and the Jade Mill, which served the various claims scattered across Joaquin Ridge and the Ciervo Hills. This map offers a clear look at the infrastructure of the California Coast Ranges before later shifts in mining and land use changed the character of these high peaks.