Geological Overview of the Palos Verdes Peninsula

Arthur R.Brown(Dick)
Geological Consultant, 296 College Park Dr., Seal Beach, California 90740

Rocks and sedimentary deposits in the Palos Verdes Peninsula range in age from Cretaceous to Holocene. The Pleistocene deposits have yielded a wealth of fossils, which resulted in hundreds of publications. Middle to late Miocene Monterey Formation covers much of the Palos Verdes Hills and overlies, on a profound unconformity, the Cretaceous Catalina Schist basement. A small deposit of San Onofre Breccia locally lies between these formations. Terraces that ascend the hills are evidence of tectonically rising land that was sculpted by Pleistocene sea-level fluctuations. Canyons and an ancient Los Angeles River channel reflect the influence of the rising land and developing structures. Major tectonic structures are the Palos Verdes fault and the Palos Verdes anticlinorium, with its subsidiary folds (some of which are recumbent). The Palos Verdes Peninsula is well known for its landslides, the largest of which is the Portuguese Bend landslide complex, and another is the South Shores landslide. Grabens near the crest of the anticlinorium were produced by uplift and folding or by mega-landslides. Tectonic evolution of the Los Angeles Basin-Inner Borderland has greatly affected the Palos Verdes geology. Economic geology included exploration for oil and quarrying for construction materials and diatomite. Environmental geology studies include offshore investigations of waste toxic chemicals deposited on the shelf via the Whites Point sewer outfall and post-landfill planning. Engineering geology for housing and commercial developments and offshore seismic fault studies has added much new geologic data.

AAPG Search and Discovery Article #90076©2008 AAPG Pacific Section, Bakersfield, California