<P> Lake Bonneville was a prehistoric pluvial lake that covered much of the eastern part of North America's Great Basin region . Most of the territory it covered was in present - day Utah, though parts of the lake extended into present - day Idaho and Nevada . (Its counterpart Lake Lahontan occupied much of northwestern Nevada while extending into California and Oregon .) Formed about 32,000 years ago, Lake Bonneville existed until about 14,500 years ago, when a large portion of the lake was released through the Red Rock Pass in Idaho . Following the Bonneville flood, as the release is now known, the lake receded to a level called the Provo Level . Many of the unique geological characteristics of the Great Basin are due to the effects of the lake . </P> <P> At more than 1,000 ft (300 m) deep and more than 19,691 square miles (51,000 km) in area, the lake was nearly as large as Lake Michigan and significantly deeper . With the change in climate, the lake began drying up, leaving Great Salt Lake, Utah Lake, Sevier Lake, Rush Lake, and Little Salt Lake as remnants . </P> <P> Lake Bonneville was named by the geologist G.K. Gilbert after Benjamin Louis Eulalie de Bonneville (1796--1878), a French - born officer in the United States Army, who was also a fur trapper, and explorer in the American West . Bonneville was noted for his expeditions to the Oregon Country and the Great Basin . </P> <P> Like most, if not all, of the ice age pluvial lakes of the American West, Lake Bonneville was a result of the combination of lower temperatures, decreased evaporation, and higher precipitation that then prevailed in the region, perhaps because of a more southerly jet stream than today's . The lake was probably not a singular entity either; geologic evidence suggests that it may have evaporated and reformed as many as 28 times in the last 800,000 years . </P>

Evidence of freshwater lake deposits in geologic history do not come from