Geologic Trips, Point Reyes Peninsula

Point Reyes Lighthouse


The Point Reyes Peninsula is separated from the mainland by the San Andreas fault. Many of the rocks on the peninsula are from south and central California and have been carried to their present position by movement along the San Andreas fault over the last 25 million years.


The Point Reyes Lighthouse is built on the Point Reyes Conglomerate. This conglomerate is extremely hard and has resisted erosion so that it now forms the east and west tips of the Point Reyes Headlands. Similar conglomerate occurs near the Monterey Peninsula, 100 miles to the south. It is likely that these are the same conglomerate and that the Point Reyes Conglomerate was carried northward from the Monterey area along the San Gregorio fault, one of the many faults of the San Andreas fault system.

Point Reyes Lighthouse and the 308-step-path down to the lighthouse.

Related Links

Geologic background: Point Reyes Peninsula (pdf)

Geologic trips: Earthquake Trail Point Reyes Lighthouse


Exterior Websites

National Park Service: Lighthouse Visitor Center

USGS: Geology of Point Reyes National Seashore

Wikipedia: Point Reyes Lighthouse