Beach Processes and Geology of Southern California

September 30-October 3 1994

We thought we'd have a difficult time convincing the Department to send us to the beach, but it turned out that a real scientific opportunity came our way. The scientific planning group for an advanced Mars orbiter mission (possibly part II of the Pathfinder program) wanted to know what kind of resolution would be needed on an orbiter to see beach features that may be interpreted as ancient shorelines. We examined beach formation processes and their manifestations on the shores of Southern California to determine the features characteristic to shorelines and the scales on which they occur. We determined that one-meter resolution was probably fine to identify major shoreline features. Plus, we got to splash in the surf, too.

The features we examined ranged from fine laminae in beach sands to large estuary systems, and everything in between: swash marks, ripples, beach cusps, sand spits, wave-cut platforms, offshore bars, lagoons, and submarine canyons. The physics of breaking waves, rip currents, beach profiles, grain movement, tides, and wave generation were all studied. We discussed ancient shorelines as well--Lake Bonneville in Utah and the possibilities on Mars and Titan. Related to the beach environments were talks at the Channel Islands and Santa Barbara Harbor.

We didn't miss the inland geology, though. Highlights of this part of the trip were the Portuguese Bend Landslide near Palos Verdes Estates and the natural tar occurring on the beaches at Carpenteria. Other geology included discussions of the Sentinel volcanic field in Arizona and the regional geology of Los Angeles. The trip concluded with a stop for date shakes at the fabled Shields Date Farm in Indio, CA.

Photos courtesy of Barb Cohen. Please bring contributions to room 326!!