Description
The distribution and characterization of sands along the coast of southern California affects residential, commercial, and other coastal structures such as harbors and breakwaters. This study of sands took place in southern Orange County, a region of high erosion and significant coastal development. In particular the shoreline from Dana Strands southward to Lower Trestles, including the cliffs and creeks feed sediment to these coastal beaches. Statistical analyses of grain size distribution (mean, mode, sorting, skewness, and kurtosis) and mineral trends at these beaches are used to understand the direction of sediment transport and the relative contributions form the littoral drift, creeks, and sea cliffs to the beach sediments. The results show a predominant north to south littoral drift direction during the late winter and spring months, with distinct littoral cell boundaries at Dana Point in the north and at San Mateo Point in the south. The swash zone sediments fine to the south within the cell, while the backshore sediments (where they exist) coarsen to the south because of cliff and creek contributions. The non-resistant sandstone sea cliffs in southern San Clemente are an important source for local beach sands, but this reduces the integrity of the cliffs that are vital to the stability of residential structures.
