Salton Sink: see Salton Sea.

Carson Sink, swampy area, c.100 sq mi (260 sq km), W Nev.; a remnant of ancient Lake Lahontan. Fallon National Wildlife Refuge is located there. The Carson River (c.125 mi/200 km long), fed by melted snow, flows into the sink. The river's course was followed by California-bound travelers in the 1850s and 1860s. Mercury used in the mining of gold and silver in the latter half of the 19th cent. contributed to massive pollution of the river. Lahontan Dam, part of the Newlands project, impounds river water for irrigation and produces electricity.

or sink or doline

Depression formed as underlying limestone bedrock is dissolved by groundwater. Sinkholes vary greatly in area and depth and may be very large. The two main varieties are those caused by the collapse of a cavern roof, and those caused by the gradual dissolving of rock under a soil mantle. Collapsed sinkholes generally have steep rock sides and may receive streams that then flow underground. Soil-mantled sinkholes are generally shallower; they may become clogged with clay and hold a small lake.

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