The Geology of a Portion of the San Pedro Hills

The San Pedro Hills represent a line of heights adjacent to the sea coast, and extending in a northwesterly direction from the town of San Pedro to Santa Monica Bay, a distance of about ten miles. The width of the hills is about four miles. The highest point is San Pedro Hill, which rises to an elevation of 1480 feet. The area investigated by this survey comprises about the eastern half of these Hills, and includes about twenty square miles. Most of this territory is included in the "San Pedro Hills'" quadrangle, but the eastern quarter of it lies in the "Wilmington" quadrangle. The town of San Pedro covers a portion of the eastern third of the area, and the consequent cultivation there renders mapping rather difficult, although several road cuts and excavations expose some excellent sections. The remainder of the area is more or less free from habitations, except for some ranches devoted to the cultivation of beans and hay. The exposures are as a whole rather poor, except inroad cuts and on canyon walls. The area is well cut up by good roads, and an automobile can be used to advantage in mapping. Practically the only work published on this area was done by Ralph Arnold, whose work, included the paleontological study of Dead Man's Island, and a section along the west shore of San Pedro Bay. Arnold's work, though now questioned by later investigators, has been accepted by the writer in the age determination of the different formations. The survey made by the writer and Mr Bell, as a senior thesis for the California Institute, was done during the winter of 1927 and the spring of 1928, and included the mapping of the formations as defined by Arnold, and an investigation of the structure and physiography of the area. The paleontological work done by this survey was limited to an investigation of the foraminifera from Timm's Point.