Posted 21 April 2016 by A.G. Sylvester ©
You may gain an up close and personal view of sand dunes near San Felipe Creek, about a mile down a poorly marked and unmaintained side road east of CA 86, 10 miles south of Salton City and about 4 miles north of the Agricultural Inspection Station at the junction of CA 86 and CA 78. The side road terminates at a small field of barchan dunes but it once continued to a dormant U.S. Navy testing base on the edge of the Salton Sea. The road is paved but do not drive onto the sand or your vehicle will get stuck when you park or turn around! The testing facility itself is off-limits to the public.
Barchan dunes are crescent-shaped with a long, gentle back slope and a steep frontal slope that is horn-shaped. Individual barchans are 25 to 100 feet across and six to 30 feet high. In front of the dune is bare ground with some pebbles and vegetation that will be buried eventually as the dune advances. If you happen to be there when a gentle wind is blowing, you will see sand struggling up the rippled back slope and then cascading down the frontal slope. The horns advance almost imperceptibly. Look also for tracks in the sand made by lizards, stink bugs, and the occasional sidewinder.
The horns of barchan dunes point and migrate in the direction of the prevailing wind. The crescents of these dunes point east, indicating a prevailing west wind. They move eastward about 50 to 80 feet per year to their ultimate demise in the Salton Sea. The mineralogy of the sand indicates that the bulk of the sand comes from the poorly consolidated and easily weathered Cenozoic sedimentary strata in the hills west of CA 86. Lesser amounts come from nearby stream washes.
 |
The Salton barchan dunes are located below the high-water level of old Lake Cahuilla, so the dune field is probably less than 400 years old. (33° 10.9N, 115° 51.1W) |
Roadside Geology of Southern California 