Basinal deposits, young
Basinal deposits, young
Holocene to late Pleistocene
Young fine-grained alluvium occurring in low-relief lower elevations of the Great Valley bordering the western range margin. Unconsolidated or minimally consolidated, poorly stratified, silt, clay, and fine sand deposited by still or slow-moving water in floodplains, overbank environments, marshes, and locally in intermorainal ponds, sag ponds, and other similar environments. Includes fine-grained basinal facies of Modesto Formation (Davis and Hall, 1959; Marchand and Allwardt, 1981), and several undifferentiated young basinal deposit map units.