13 June 2014

Friday fold: tortured turbidites at Devil’s Slide

Posted by Callan Bentley

Marek Cichanski (of De Anza College near the south end of San Francisco Bay) contributed this week’s Friday fold:


Marek says:

The locality is a place near San Francisco called Devils Slide. It is a piece of the coastal highway built along a steep mountainside above the ocean. This unstable stretch of road was recently (finally!) replaced by some tunnels. And, amazingly, the old roadbed finally got converted to a nice paved hiking and biking trail! I never thought I’d live to see the day.

Most of the rocks here are Paleocene turbidites, IIRC. There is also Mesozoic granitic basement rock of the Salinian terrane at one end of the trail.

In the past, I couldn’t take my class here, because there was no safe place to park vehicles nor to stand by the side of the road. Now it’s all safe! I haven’t actually taken any students here yet, since the parking areas are small, and I didn’t even know the trail was finished until I was done leading my trip yesterday. But I sure hope I can take classes here, even if all we do is gawk at the cool geology and views!

This is also a great example of cool geology that people can visit when they go to AGU. A car would be pretty handy, although I think a bus line serves one of the trailheads – shades of `Streetcar to Subduction’. I think that for the more geologically-minded AGU attendees, it’s well worth skipping the least interesting half-day of talks to see this, if the weather isn’t rainy/windy. That blue-sky weather that seems to prevail so often during AGU week would be ideal, if one could get here before dark.

This image is one of a nice set that Marek shot at the trail. You should check them all out.