Friday, June 24, 2011

San Andreas Fault Rocks and Young Volcanism and Basalt Near Palm Springs

These rocks are right on the Mission Creek strand of the San Andreas Fault, a few miles east of the town of Desert Hot Springs, CA, within the Mission Creek Reserve. This is a mile or so along the reserve road, once you pass the gate into the reserve, and at the first oasis. This outcropping of typical San Andreas' highly deformed rock, except for the darker basalt that is also present here, which is not typical of the San Andreas fault system this far north. This is a unique area where the big strike slip transform fault, San Andreas, borders a complex geologic area that includes the young volcano and basalt system associated with the Joshua Tree National Park's parallel faulting. This parallel faulting and basalt within Joshua Tree, to the east of Mission Creek, is typical of a rifting zone, where the crust is spreading. I would need to study more before I conclude that Joshua Tree NP sits on a rifting zone. But it appears to be after a glance at a geological map, and after a few hikes. The location in these photos are a few miles from a point along the San Andreas where it is "locked up", meaning that it has not had a significant earthquake for a long time, and that it has changed course earby, making a bend - and where it is pushing up 11,000 foot mountains!

Although it hard to see the reddish basalt volcanic rock in this photograph, if you look hard, you can see it. It's the light magenta area of profound erosion. It's the darker area just below the wire. If you visit the site, you can really see the volcanic red pumice like rock and basalt. The colors of the rock are seen with the human eye more than with an average camera and lens. At the time of this photograph, I was with young children, and didn't want to take them in tow across the desert brush to take a closer look. I am going back, though, and studying this young volcanic system.

This picture better shows a light band, and then below blackish volcanic basalt. This is a bowl like formation that requires more study indeed!

For fun, go into Google Earth, type in 'Mission Creek Reserve, CA' and explore the oasis and formations in the area. Click on the blue photo icons and look at the photos. Then wonder to the west and look at White Water, and then to the east to look at Joshua Tree National Park. Next, Google 'White Tank granite', read, then Google 'young volcanos, Joshua Tree National Park' and read up on that. That should keep you curious and amazed for a few hours. And then physically come on out and Visit Joshua Tree National Park, and it's surrounding reserves! The desert is amazing, with it's bare naked rocks!

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