ABSTRACT

Fourteen samples of sand were collected along a range line extending from shore across the shelf near Oso Flaco, California. These samples are representative of coastal dune, beach, modern shelf and possible relict shelf sands present in that area. The samples were sieved to obtain grain size parameters, and surface microtextures of grains from similar size fractions were studied with a scanning electron microscope. Grain size distribution parameters show that anomalously coarse shelf sands are similar to the modern beach and dune sand and are distinct from the finer inner shelf sand. Scanning electron microscope (SEM) examination of the sand grain surface microtextures indicates that the coarse offshore sands have "V" shaped impact pits and etch patterns similar to present day beach and grains, which suggest that they are paleo-beach sands deposited on the outer shelf during a lower stand of sea level.