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Beachcombing: SoCal's geologic history, as told by the sand




Beachgoers relax at Point Dume in Malibu on July 9, 2013.
Beachgoers relax at Point Dume in Malibu on July 9, 2013.
Grant Slater/KPCC
Beachgoers relax at Point Dume in Malibu on July 9, 2013.
Sofia Maricopa of Burbank relaxes at Venice Beach on July 9.
Grant Slater/KPCC
Beachgoers relax at Point Dume in Malibu on July 9, 2013.
The sand at Point Dume State Beach.
Grant Slater/KPCC
Beachgoers relax at Point Dume in Malibu on July 9, 2013.
The sand at Venice Beach.
Grant Slater/KPCC


This story is part of our summer series "Beachcombing," in which KPCC reporters will explore  the ecology, economy and culture of Southern California's beaches and coast. Let us know what you think in the comments below or on KPCC's Facebook page.

If you’ve walked on a southern California beach, you’ve made direct contact with the region’s ancient geology. 

“I suppose I take it for granted,” says UCLA geology professor Tony Orme. He’s spent 40 years studying the way this coast has been shaped. Over millennia, sediment on beaches came down to the coast through mountain watersheds, and eroded off of coastal cliffs.

The sand on beaches between Point Dume and Redondo Beach comes in part from the San Gabriel Mountains: silvery mica, milky quartz, whitish-gray granite with flecks.

KPCC's Molly Peterson reports on what SoCal sand is made of.