The Cristianitos Fault
The Cristianitos Fault is easily found. The bluff to the north is identified by the wide light-colored band known as the San Mateo Formation. This band abruptly ends here.
Scramble 10-15 yards up this hill and see the strike plate of the Cristianitos Fault.
The layer of rubble above the San Mateo Formation, as well as the alluvial material above that, has been undisturbed. Geologists have dated that material to be 125,000 years old, so we know that the fault has not been active for at least 125,000 years.
This is why there were able to build the San Onofre nuclear plant less about a mile away from the fault line -- the fault is essentially "dead."
When you finish exploring the fault, head back south down the beach, retracing your steps.