The distribution and characterization of sands along the coast of Southern California have several important consequences. They have a large impact on coastal development such as residential structures on the beach or sea cliffs and on coastal structures such as harbors and breakwaters. Our study was undertaken in southern Orange County, a region with high erosion rates and much coastal development. In particular, we studied the beaches from Dana Strands southward to Lower Trestles including the sea cliffs and the creeks that feed sediment onto these beaches. Using the methods of statistical analysis of grain size distributions, plus observations on grain shape, beach orientation, and mineral trends allow us to understand the southward movement of sand along these beaches and the relative contributions by littoral drift, creeks, and the sea cliffs. Our results show distinct boundaries of a littoral cell at Dana Point in the north and San Mateo Point in the south. We also see a general trend of southward fining of grain sizes in the swash zones within the Capistrano subcell and a coarsening of backshore grain sizes southward within the cell.
