Alluvium, old
Alluvium, old
early Pleistocene
Old alluvial deposits mostly occurring in old alluvial fans. Well consolidated and highly dissected; grain size is variable, generally coarse, but includes cobbles, gravel, sand, silt, lesser clay, and locally boulders. Composition highly variable; dependent on source rock types. Includes debris flow and lag gravel deposits, and locally may include somewhat older and younger alluvium, and relatively minor and undifferentiated glacial deposits. Includes North Merced Gravel, Turlock Lake Formation (Marchand and Allwardt, 1981), and many undifferentiated old alluvial units from map sources.