The final episode of the 10-part “Geology of San Francisco” series concludes with a visit to the spot where the San Andreas Fault runs off the edge of California and down into the sea. Mussel Rock, site of the opening vignette of John McPhee’s “Assembling California” is located there.
When I was out in California in October 2009, about the same time that Garry Hayes passed me on the highway heading up to Yosemite while I was headed down towards the Modesto Airport, I pulled over to check out some rock exposures on the side of the road. This was near the Don Pedro … Read more
The penultimate episode of Callan’s more-than-a-week-long series on the geology of the San Francisco region: today we briefly visit the sand dunes that covered San Francisco Peninsula during the Pleistocene.
The 8th edition of the ongoing “Geology of San Francisco” series examines brittle fractures and the chemistry they host along their planar surfaces.
Merry Christmas! Along with the red cherts of last Tuesday, enjoy today’s green rocks — serpentinite and serpentinite mélange of Marshall Beach, west of the Golden Gate Bridge in San Francisco.
The geological tour of San Francisco continues with an examination of the graywacke deposits of the
“GoSF” = Geology of San Francisco As I am sure you are aware, I’m taking this week to write up the three field trips I took last week to examine the geology of San Francisco and neighboring areas. My plan is to cover: Introduction and overview Seafloor basalt Deep sea chert Kirby Cove, Marin Headlands … Read more
Part 4 of the ongoing series examining the geology of the San Francisco area. In today’s post, Callan visits Kirby Cove in the Marin Headlands, where intensely deformed chert can be found on one end of the cove, pillow basalts on the other, and an “artificial dune” in the middle.
Episode three in the multi-part series on the geology of San Francisco. This post focuses on the chert layers of the Marin Headlands
Second in the on-going series about the geology of San Francisco: this post explores the pillow basalts of the Marin Headlands Terrane.
The first in a multi-part series on the geology of San Francisco and the surrounding area.
My final day at AGU was Thursday, and I spent a lot of it working on school stuff, but I did zip down to the Moscone Center for a session on communicating science to the public in an age of increased public scrutiny. Michael Mann of Penn State was the big draw here, discussing his … Read more
I took a break yesterday morning from nonstop AGU meeting stuff, and got out into the city a bit. A former student of mine, Alan P., lives in San Francisco these days, and works at a local bike shop. So Alan scored us a couple of bicycles and we went for a ride from North … Read more
Man, this meeting is intense. There’s so much going on all the time that for every session or talk you commit to, you’re missing literally dozens of others. This is kind of like going to the library and picking out a book, knowing that there are many other books you’re not reading — but with … Read more
San Francisco is great. I got out here Friday night and spent a lovely day Saturday hiking over the Golden Gate Bridge and through the Marin Headlands with my fiancee. That evening, for my 36th birthday, we went out to the Tadich Grill, source of the best cioppino (Italian seafood soup) in the city. Sunday, … Read more
Visit the “faultcano” in the Owens Valley of eastern California: a cinder cone which has been cut and offset along a normal fault associated with Basin & Range extension.
Long-time readers (and students) know that I have a special corner of my heart reserved for plumose structure and hackle fringes, that finely-filigreed anatomy of a fracture surface. Fractures are everywhere in rocks, and often they show neat little “topographic” details that show fracture propagation direction and stress fields. Here are three that I haven’t … Read more
Here’s a sample from my 2004 geology M.S. thesis work in the Sierra Crest Shear Zone of eastern California. The rock is a sheared ignimbrite (ashflow tuff) tuff bearing a porphyritic texture and a nicely-developed “S-C” fabric. With annotations, showing the S- and C-surfaces, and my kinematic interpretation: S-C fabrics develop in transpressional shear zones: … Read more
Today, our theme is vesicles. Here are some images of vesicles in basaltic lava flows in the Owens Valley of California, the same spot where we saw the baked fanglomerate that I showcased a few days back. In this photo (and the zoomed-in detail shot below), you can see a couple of things. One is … Read more
Searching through my photo archives this morning for something suitably “Eastery”… something in pastel colors, perhaps? … a petrified lagomorph? … how about an egg, or something egg-shaped? This is as close as I got: This is in the Owens Valley of eastern California, showing a boulder of the Mesozoic Sierra Nevada Batholith bearing a … Read more