Point Arena Lighthouse (Point Arena, CA)


Point Arena Lighthouse

The San Andreas Fault that runs through much of California runs out to sea at Point Arena. We wondered if we could “see” the fault from the top of the lighthouse that lies north of the town. Unfortunately, we couldn’t. It turns out that the fault meets the sea at a point further north in Manchester State Beach. Nevertheless, from the top, there was a splendid view of the ocean and the shoreline which still shows evidence of geological forces at work. Evidence of subduction is clear when you look at the rocks below whose layers are tilted at extreme angles.

Extreme tilt of these rock layers shows evidence of subduction

Extreme tilt of these rock layers shows evidence of subduction


The lighthouse was damaged by the 1906 San Francisco earthquake. A new one was erected with steel reinforcement rods encased in concrete to withstand future quakes. At the time of its installation, the Fresnel lens in the lighthouse was a technological marvel from France, consisting of 666 hand-ground glass prisms and weighing more than six tons at a diameter of six feet. The lens, no longer operational after having been replaced by modern automated rotating-light beacons, is now on display inside the lighthouse.

The original Fresnel lens is displayed in the lighthouse

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