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Soda Lake and Little Soda Lake are two maars located on the southwestern floor of the Carson Sink northwest of Fallon, Nevada. The maars were formed as basalt erupted explosively through the water table or shallow lakes.
Location: Nevada, Churchill County
Latitude: 39.52° N
Longitude: 118.88° W
Elevation: 1,251 (m) 4,104 (f)
Volcano type: maars
Most recent eruption: Holocene
Nearby towns: Fallon
Threat Potential: Moderate*
*based on the National Volcano Early Warning System
The larger maar, Soda Lake, is oblong, about 1.1 x 1.5 km (0.7 to 0.9 mi), elongated northeast to southwest. The 300 m (about 1000 ft) wide Little Soda Lake lies 250 m (820 ft) south of Soda Lake. The maars are the site of a geothermal prospect that may have discharged hot springs through the end of the 19th century. Although undated by absolute methods, they postdate the Pleistocene glacial Lake Lahontan and are estimated to be younger than 6 thousand years old.
At the end of the 19th century, geologist Israel Russell investigated the geologic history of Lake Lahontan and visited Soda Lakes. At that time the water level was significantly lower, so he could see more of the crater walls and explosion strata. He noted bomb sags within the deposits, which indicate that the damp earlier-erupted strata could deform plastically under the weight of larger explosively erupted products (projectiles). Diversion of Sierran stream water to the Carson Sink, as part of the Newlands Irrigation Project, which began in 1903, raised groundwater levels, corresponding to an approximately 20-m (60-ft) rise in the lake level.