Lacustrine deposits, young
Lacustrine deposits, young
Holocene to late Pleistocene
Young fine-grained lacustrine deposits. Occurs in tectonic basins such as Sierra Valley, Owens Valley, Mono Basin, and locally elsewhere in relatively low areas with water accumulation, such as in the Great Valley. Unconsolidated or minimally consolidated, commonly thinly bedded to laminated clay, silt, and lesser sand. May contain evaporite minerals; includes deposits in playas; locally may include beach sand and gravel deposits. Includes Modesto Formation lacustrine facies (Davis and Hall, 1959; Marchand and Allwardt, 1981) and many other undifferentiated lacustrine and playa map units.