Grain-Shape Analysis of Littoral and Shelf Sands, Southern California

Estimation of the exchange rates and determination of transport mechanisms and pathways associated with the onshore-offshore vector is one of the greatest sources of error in sediment budget analysis. Fourier grainshape analysis in the Oceanside Littoral Cell indicates that approximately 35 percent of the medium sand-size detrital quartz in foreshore samples was dervied from the adjacent shelf during a relatively recent, but unknown time interval. Similar research in the Santa Monica Littoral Cell shows the addition of 42 percent inner shelf sand to the foreshore within one year following the severe storm of January 17-18, 1988. Clearly, large volumes of inner shelf sand may be delivered to the foreshore during a relatively short time interval.