I dug out the book (no pun...) the other night and the first thing I read was how complicated the Coast range is - with a hodgepodge of sediments thank include volcanic extrusions... and miscellaneous upheavals, of course....
Then I got into something else and forgot about your rocks for a couple of days :) I have, I think, every book in the Roadside Geology series - at least as of a few years ago. Geology was my minor. It looks like your rocks are part of something called the Franciscan that "consist of dark colored muddy sediments , red, green and brown cherts and lava flows of black basalt. The banded stuff may be that Franciscan chert that has gotten scrunched :) Anyway, if you are in a bookstore check out the roadside geo book - There is a map that points pretty much right to where you were that says 'roadcuts in red-brown chert with contorted ribbon layering." Possibly the outcrop you were photoing. ann [EMAIL PROTECTED] wrote: > > In a message dated 8/19/2006 3:48:23 AM Pacific Daylight Time, [EMAIL > PROTECTED] > writes: > Marnie - > tell me, as close as you can, exactly where you were when > you took it > (the highway number, etc...) > > I'll look up the formation in Roadside Geo for you :) > > The lack of scale makes it hard to pin it down... > > ann > ========== > Ann, had my book in the car telling me where I was exactly. So took me a > while to get back to it. > > I was on the Marin Headlands right next to the Golden Gate Bridge. Conzelman > Rd is the actual name, not a highway. But the book says it's right off 101, > and I suppose it was. I follow directions and know how to get places, but > later > I forget the actual hwy number or street name. > > Hope that helps. I think this roadside geologist thing is super neat. > > And maybe someday I'll show more pictures of roadside dirt (although this was > rock). Actually I probably only have three more that are decent, but now that > I know that a few others might enjoy them, I will be trying harder in the > future too. > > To me it's sort of Mother Nature revealing her bones. Something like that. > > Marnie :-) > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
