Advertisement

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.

Read More >>

No Comments/Trackbacks >>


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.

Read More >>

No Comments/Trackbacks >>


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.

Read More >>

4 Comments/Trackbacks >>


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.

Read More >>

2 Comments/Trackbacks >>


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!

Read More >>

No Comments/Trackbacks >>


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!”

Read More >>

No Comments/Trackbacks >>


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.

Read More >>

1 Comment/Trackback >>


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.

Read More >>

No Comments/Trackbacks >>


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.

Read More >>

No Comments/Trackbacks >>


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.

Read More >>

2 Comments/Trackbacks >>