Bristol Dry Lake, California

Salt has been extracted from the dry lake bed since 1909, and continues to be mined today. The surface layer on much of the lake, which is three to seven feet thick, is removed in order to get at the salt, and is dumped in long rows of conical piles along the trenches. Tetra Technologies, an oil and gas services company, is one of two companies operating on the lake, producing sodium chloride and calcium chloride for industrial use and food products.