Rocky reefs are composed of bedrock, boulders, and cobbles. They occur at a variety of depths, can be many meters in height, and span kilometers of coastline.
In Santa Monica Bay, hard bottom, rocky reefs and outcrops are primarily located in the shallow subtidal zone off of Malibu—from the Ventura County line to Sunset Blvd. Off Palos Verdes, from Malaga Cove to Point Fermin, the reefs are generally larger and achieve much greater depths, over 100 feet deep.