A photo of Soda Lake

This view is looking south from Overlook Hill toward the Caliente Range. Soda Lake Road passes just east of the fringes of saltbush habitat. Plant-stabilized clay-dust dunes are in the foreground area.

During the summer months when daily temperatures typically range above 100 degrees F, the surface of the playa and other sag ponds along the San Andreas Fault become encrusted with sodium sulfate (less than 10 percent is sodium-chloride salt). Salt and sodium sulfate were mined intermittently from the playa between the 1880s and 1940s (Hildinger, 1995). 

Today, the Carrizo Plain is a closed basin, However, the occurrence of Plio-Pleistocene Paso Robles Formation gravels beneath the Soda Lake basin sediments suggest that the Carrizo basin drainage once extended to Monterey Bay. During the Pleistocene, tectonic warping and faulting associated with San Andreas Fault and uplift along on the southwest side of the basin blocked drainages, allowing a large freshwater lake to stand in the Soda Lake basin during wet periods. Studies of clay dune deposits in the Soda Lake basin suggest that the lake became saline before 16,700 years ago (Rhodes and others, 2005).