<P> The word comes from the Latin pluvia, which means "rain". </P> <P> Pluvial lakes represent changes in the hydrological cycle: wet cycles generate large lakes, and dry cycles cause the lakes to dry up leaving large flat plains . Accumulated sediments show the variation in water level . During glacial periods, when the lake level is fairly high, mud sediments will settle out and be deposited . At times in between glaciers (interglacial), salt deposits may be present because of the arid climate and the evaporation of lakewater . </P> <P> Several pluvial lakes formed in what is now the southwestern United States during the glaciation of the late Pleistocene . One of these was Lake Bonneville in western Utah, which covered roughly 19,000 square miles (49,000 km). When Lake Bonneville was at its maximum water level, it was 1,000 feet (300 m) higher than the Great Salt Lake . </P> <P> Fresh water mollusks have been found in mud deposits from Searles Lake in California and suggest that the water temperature was about 7 degrees Fahrenheit (or 4 degrees Celsius) cooler than current temperatures . Radiocarbon dating of the youngest mud beds yield dates from 24,000 to 12,000 years ago . </P>

Where did pluvial lakes form during the last ice age