You are browsing the archive for Friday Fold Archives - Mountain Beltway.
19 April 2019
Friday fold: Angel Island “III”
For the third Friday in a row, “Mountain Beltway” features folds from Angel Island, in northern San Francisco Bay, California, This time, it’s meta-cherts on Perles Beach, showing impressive metamorphic recrystallization reactions.
12 April 2019
Friday fold: Angel Island “II”
Happy Friday, all. Here are a few shots of crinkled, thin, multicolored cherts from Kayak Beach on northern Angel Island, California, piggybacking on the folds I showed you last week.
5 April 2019
Friday fold: Angel Island “I”
The Friday fold is on the north shore of Angel Island, San Francisco Bay, showing blueschist-facies high-contrast metalliferous cherts with folds on many scales.
29 March 2019
Friday fold: Plunging Purisima
AGU’s Centennial year is also the 35th anniversary of the publication of Clyde Wahrhaftig’s unique field guide to the geology of San Francisco. A team of geologists is updating “A Streetcar to Subduction” for a modern digital audience, and recently did some California field work to visit key sites. Check out one of them here with the Friday fold, as we visit a plunging syncline in the Purisima Formation on the coast near San Mateo.
22 March 2019
Friday fauxld: concentric weathering rinds
Here’s a deceptive Friday “faux”ld I saw last week on the South Page Valley Road whilst learning about the Martinsburg Formation outcrops there: Looks like an isoclinal fold in this slab of siltstone, but the curvy lines are just concentric weathering rinds. Not a real fold at all! I hope everything you see this weekend is more straightforward and less deceiving. Happy Friday!
15 March 2019
Friday folds: two more from Oman and Chuck Bailey
Friday is that special day of the week where we take a break from our hurried lives and gaze longingly at great photos of folded rocks in exotic corners of the world. Today, we return to Oman, and we say, “Oh, man!”
8 March 2019
Friday fold: Dent de Morcles
The Friday fold is a recumbent anticline/syncline pair, deforming the K/Pg boundary in the Swiss Alps, as photographed from the air by Bernhard Edmaier.
1 March 2019
Friday fold: Gold Harbour, South Georgia
Near Antarctica, South Georgia Island is a good place to find glaciers and penguins. And, as it turns out: massive recumbent folds! Let’s take a look.
22 February 2019
Friday folds: Sardinian tuff
It’s the last day of the work week. Some photos of isoclinal syn-depositional folding in Sardinian tuff will get your Friday off on the right foot.
14 February 2019
Friday fold: an arch of gypsum in Sicily
Ahh, Sicily on a Friday morning. Join us to examine a spectacular arch of gypsum from the Messinian evaporite package.
Callan Bentley is an assistant professor of geology at Northern Virginia Community College. He is a fellow of the Geological Society of America and the 2018 National Association of Geoscience Teachers' James Shea Awardee. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. Callan is a contributing editor at EARTH magazine and Past President of the Geological Society of Washington and the Geo2YC division of NAGT. He lives in the Fort Valley of Virginia.