|A fence at right angles to the fault line split by the 1906 rupture of the San Andreas Fault|
Earthquake Trail within the Point Reyes National Seashore park in rural west Marin County, Northern California, you can see a split fence that still provides evidence of the 1906 fault movement.
Alongside the Earthquake Trail, interpretive signs describe the geology and earthquake history of the San Andreas Fault, which separates Point Reyes on the Pacific Plate from the North American plate. Tomales Bay and Olema Valley cut through the landscape of the joining plates. The Earthquake Trail is located in the rift zone between the Bear_Valley_Visitor_Center and Olema. Here, as elsewhere between San Juan Bautista and Cape Mendocino, the rupture of the San Andreas Fault during the Great 1906 San Francisco Earthquake on April 18 left its mark. As an interpretive panel tells you, Point Reyes moved northwest up to twenty feet and the fence split by this distance. Blue posts indicate the active fault trace.
Another interpretive panel explains that the two plates move, on average, two inches annually. We—and those fences we like to build—are only around for a geologic moment and “if lifetimes were measured in eons rather than years, we would witness tremendous movement and change along the western edge of North America. The San Andreas fault, the boundary between the North American and Pacific plates, is part of a 30 million-year geologic story that is still unfolding. 10 million years from now, the plate boundary will likely shift inland east of the Sierra. The Gulf of California will expand and most of California will be transferred to the Pacific plate.” I guess, Nevada will then be the prime state of ruptures, slips and shakes.
Getting there (not to Nevada, but to the Point Reyes Earthquake Trail)
Go to the Bear_Valley_Visitor_Center at Point Reyes National Seashore (see park map). Find the picnic area just across the street & parking strip next to the visitor center. The Earthquake Trail loops through the fault zone east of the picnic site. It takes less than half a mile to get to the split fence. And even if earthquake history does not belong to your main interest, this short and scenic loop trail is worth a walk. Looking for another short trail nearby? What about the Kule Loklo Trail northwest of the visitor center?
|Earthquake Trail crossing a creek in Olema Valley|