Alluvium, very old
Alluvium, very old
early Pleistocene to Pliocene
Very old fluvial deposits occurring primarily within elevated terraces and abandoned fans along the western Sierra foothills, the margins of the San Emigdio Mountains, and margins of basins on the east side of the range. Moderately to well consolidated and commonly deeply dissected; grain size is variable and includes gravel, sand, cobbles, boulders, and lesser siltstone (locally diatomaceous) and claystone. Composition highly variable; dependent on source rock lithologies. Locally may include lag gravel, debris flow deposits, and lesser undifferentiated glacial outwash and lacustrine deposits. Includes Laguna (Piper and others, 1939; Marchand and Allwardt, 1981), Meeke Mine, and Horned Toad Formations (Dibblee, 1958, 1967), the informally named Hallelujah formation of Van Couvering (1962), and many undifferentiated Pliocene to early Pleistocene alluvial units.