GoSF9: Pleistocene dunes
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.
Callan Bentley
GoSF8: Fractures
The 8th edition of the ongoing “Geology of San Francisco” series examines brittle fractures and the chemistry they host along their planar surfaces.
GoSF7: Serpentinite and mélange
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.
GoSF6: Graywacke turbidites
The geological tour of San Francisco continues with an examination of the graywacke deposits of the
Friday fold: Mars Hill terrane
Today’s Friday Fold comes to us via Pete Berquist of Thomas Nelson Community College in Hampton, Virginia. Check it out: Pete explains what’s going on here: I cannot provide an exact location but this is within the Mars Hill Terrane (MHT), which is an distinctive swath of Mesoproterzoic basement extending ~50 km x 100 km … Read more
GoSF5: (Wildlife interlude)
“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
GoSF4: Kirby Cove
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.
Travels of 2010
I’ve been asked to put up a post detailing travels from the year now concluding. You got it! The first day of January dawned for me in Buenos Aires, Argentina. I had just gotten done with one of the best trips I’ve ever taken, to Patagonia in December 2009. The capital of Argentina was a … Read more
GoSF3: Chert
Episode three in the multi-part series on the geology of San Francisco. This post focuses on the chert layers of the Marin Headlands
GoSF2: Basalt
Second in the on-going series about the geology of San Francisco: this post explores the pillow basalts of the Marin Headlands Terrane.
GoSF1: Introduction and overview
The first in a multi-part series on the geology of San Francisco and the surrounding area.
AGU, day 4
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
Friday fold: monastery brick
Sometimes you find folds in funny places, like the side of a monastery. Guest fold from Maitri.
AGU, day 3
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
AGU, Day 2
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
AGU; Days -1, 0, and 1
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
Faultcano
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.
Three joints
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
Friday fold: sketchy syncline
For the structural geology fans among AGU’s readership, enjoy the weekly installment of the Friday fold.
Animated laminae
More of the new scientific medium* I showed you on Wednesday: animated GIFs of super-small stuff, to give a sense of depth. This time, I included a 1 mm scale bar: These are laminations of silt and clay in the rhythmites of the lower Konnarock Formation. If the above image moves too fast for your … Read more