|Western Earth Surface Processes Team|
Geology of the Mojave Desert Province
Geologic Framework of the Mojave River Channel Region
The USGS has been involved in geologic-mapping and subsurface investigations that will clarify the geologic setting and geologic history of sedimentary materials and faults in the vicinity of the Mojave River channel. Investigations include:
Much of these activities were conducted in support of regional studies of the Mojave River aquifer system. Mapping is being conducted to determine the surface and subsurface extent and thickness of various deposits that store and transmit ground water to wells along the Mojave River. In general, the seismic studies confirmed the presence of shallow bedrock at Nebo, Hinkley, and Helendale, and the absence of shallow bedrock near Daggett Road and the Mojave River; discontinuous zones of cementation in the shallow subsurface near Helendale yielded uneven results. The trenching at Nebo showed that a Pleistocene aggradational fluvial terrace and filled channel of the Mojave River was strongly deformed by folding and faulting along both high-angle and bedding-plane parallel shears. We will have an event chronology containing at least two and perhaps three events; there is adequate radiocarbon for time control on the latest event (Holocene, on the basis of soil development).
Recent PublicationsCox, B.F., and Hillhouse, J.W., 1999, Pliocene and Pleistocene uplift of the central Transverse Ranges and origin of the Mojave River, based on borehole stratigraphic studies near Victorville, California: U.S. Geological Survey Open-File Report.
Cox, B.F., and Tinsley, J.C., III, 1999, Origin of the late Pliocene and Pleistocene Mojave River between Cajon Pass and Barstow, California, in Reynolds, R.E., and Reynolds, Jennifer, eds., Tracks along the Mojave: A field guide from Cajon Pass to the Calico Mountains and Coyote Lake: San Bernardino County Museum Association Quarterly, v. 46, no. 3, p. 49-54.
Cox, B.F., and Wilshire, H.G., 1993, Geologic map of the area around the Nebo Annex, Marine Corps Logistics Base, Barstow, California: U.S. Geological Survey Open-File Report 93-568, 36 p., scale 1:12,000.
Cox, B.F., and Wilshire, H.G., 1994, Geologic map of the Yermo Annex and vicinity, Marine Corps Logistics Base, Barstow, California: U.S. Geological Survey Open-File Report 94-681, scale 1:12,000.
Cox,B.F., Hillhouse, J.W., Sarna-Wojcicki, A.M., and Tinsley, J.C.,III, 1998, Pliocene-Pleistocene depositional history along the Mojave River north of Cajon Pass, California-Regional tilting and drainage reversal during uplift of the central Transverse Ranges: Geological Society of America Abstracts with Programs, v. 30, no. 5, p. 11.