Comments on: The Crestmont serpentine patch http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/ focused on, near and under Oakland, California Sat, 25 May 2013 18:52:29 +0000 hourly 1 http://wordpress.com/ By: Andrew http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/#comment-381 Wed, 03 Sep 2008 16:35:21 +0000 http://oaklandgeology.wordpress.com/?p=211#comment-381 Todd, your first photo shows a typical blueschist from that serpentinite belt. I call it blueschist not because I’ve checked it out under the microscope but just to differentiate it from the slippery-looking serpentine rock. I have a piece from nearby that is full of holes. All I can think is that there was another mineral, perhaps talc, that has weathered away from around and inside it. The second striped stone is hard to tell from the photo. Serpentinite has great variety. I have a fat book of research papers on serpentinite that I’m partway through; we have a lot to learn still.

]]> By: Todd http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/#comment-379 Wed, 03 Sep 2008 02:05:58 +0000 http://oaklandgeology.wordpress.com/?p=211#comment-379 several more (I realized i had more of this lying around)

http://www.flickr.com/photos/30153017@N07/2823739794/

http://www.flickr.com/photos/30153017@N07/2823739278/

http://www.flickr.com/photos/30153017@N07/2823738712/

]]> By: Todd http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/#comment-378 Wed, 03 Sep 2008 01:52:02 +0000 http://oaklandgeology.wordpress.com/?p=211#comment-378 Hi All,
I thought I’d put up some photos
http://www.flickr.com/photos/30153017@N07/2822862467/

is a very craggy serpentinite I found up near the prairie that Mary mentions, but in the median of the roadway. I wonder why it has such a funny shape?

The next one is one with bands.

http://www.flickr.com/photos/30153017@N07/2823696028/

I am not 100% sure it is serpentinite.
Please let me know what you think about each.
Thanks, Todd

]]> By: Andrew http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/#comment-375 Thu, 28 Aug 2008 17:21:37 +0000 http://oaklandgeology.wordpress.com/?p=211#comment-375 Excellent, Mary. That’s the same body of serpentinite, just over the city line on the other side of the ridge. Now I must visit there.

]]> By: Mary http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/#comment-374 Thu, 28 Aug 2008 15:50:53 +0000 http://oaklandgeology.wordpress.com/?p=211#comment-374 It makes me happy beyond measure that other people keep their eyes out for serpentinite.

I tend to collect it here and there, pretty specimens I’ve found out and about, and photographically, with my favorite Oakland example being the big boulder at Serpentine Prairie.

]]> By: Andrew http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/#comment-371 Tue, 26 Aug 2008 16:56:15 +0000 http://oaklandgeology.wordpress.com/?p=211#comment-371 Fortunately I’ve visited New Idria (twice now) only in the dry season. But those are dirt roads. Marin County has plenty of serpentinite but its paved roads seem to be OK—equally prone to slumping, I mean—on all kinds of rock. Maybe they just keep up their roads well.

By the way, I have a gallery of serpentinite on my About.com site; in fact I’ll be adding a picture of bastite to it today.

]]> By: sheldon white http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/#comment-370 Tue, 26 Aug 2008 16:39:13 +0000 http://oaklandgeology.wordpress.com/?p=211#comment-370 Serpentinite weathers rapidly and is a lousy material to build a house on. If you ever drive into the mountains behind New Idria you will see roads carved into a huge body of serpentine – the worst roads I’ve ever seen in California. When it rains it’s like driving on toothpaste.

]]> By: christie http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/#comment-369 Sun, 24 Aug 2008 19:58:15 +0000 http://oaklandgeology.wordpress.com/?p=211#comment-369 There’s plenty of blue serpentine on Ring Mountain -

]]> By: Andrew http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/#comment-368 Fri, 22 Aug 2008 20:25:49 +0000 http://oaklandgeology.wordpress.com/?p=211#comment-368 The serpentine here is fresh rock, exposed when the land was developed, so I didn’t notice any deterioration . . . yet. On the other hand, my very first post showed deterioration of this same serpentinite.

]]> By: Ken Clark http://oaklandgeology.wordpress.com/2008/08/20/the-crestmont-serpentine-patch/#comment-364 Thu, 21 Aug 2008 19:35:53 +0000 http://oaklandgeology.wordpress.com/?p=211#comment-364 I’ve noticed when driving around a lot of the serp exposures in road cuts on small roads (around Cloverdale in particular) that there is a lot of creep and other mass wastings in this stuff, is there any particular problem in this location with such effects? I ask becuase people are footing thier houses in it.

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