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.
folds
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.
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.
New discoveries in the Martinsburg Formation
A virtual field trip to examine some deepwater clastic sediments shed off the first phase of Appalachian mountain building, and deformed in the third phase. It’s a lovely day for a field trip to the late Ordovician!
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!”
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.
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.
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.
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.
Friday fold: Falte an der Riedbergpaßstraße im Allgäu
A Friday fold from Germany showing an overturned sequence of sedimentary layers. Bedding / cleavage relationships show which limb is tectonically inverted. Furthermore, this fold was an “Aha!” moment for the budding geological mind of a small boy.
Friday fold: Two spectacular folds from Oman
The William & Mary “Rock Music” class has returned from Oman, bearing cultural insights and Friday fold photos!
Friday folds: more Marli Miller
Four Friday folds from Marli Miller’s online photo archive of geological images.
Friday fold: Saluda Dam, South Carolina
Scott White (@SeafloorScott) of the University of South Carolina pitched in with today’s Friday fold: Click to enlarge This shows a section of high grade gneiss in the spillway of the Saluda Dam in Columbia, South Carolina. Zooming in there, you can see a nice fold hinge on the left edge: Although I don’t know … Read more
Friday fold: more from Utah
For the final Friday fold of 2018, we return to Utah’s Slate Canyon, where “Mountain Beltway” reader Octavia Sawyer shares an anticline with parasitic folds shaped like “sea serpents.”
Friday fold: Samaria Gorge, Crete II
The Friday fold is a guest submission from AGU’s new Chief Digital Officer, and shows a spectacular set of recumbent folds in Crete.
Friday fold: Titus Canyon Anticline
A guest Friday fold brings us to a position in the sky somewhere over eastern Death Valley National Park. Join us in contemplating the Titus Canyon Anticline.
Friday fold: loopy limestone in Utah
The countryside near Provo, Utah yields a terrific Friday fold in an outcrop of Cambrian limestone.
Friday folds: more deformation from Cinque Terre, Italy
A return to coastal Italy on this wintry Friday… You’ll recall that The Other Callan shared some fold imagery with us a few weeks back as he explored the Cinque Terre region of Italy. He is back in the States now, and has been kind enough to share his geology-themed photos with me, so I … Read more
Friday fold: gneiss from the Southside Virginia Piedmont
Reader and former student Paxton DeBusk shared this lovely folded gneiss with me at the conclusion of the Virginia Geological Field Conference a few weeks ago: That’s a lovely hand sample, with a high folding:volume ratio! Happy Friday, all
Friday fold: Refolded marble from Corsica
The Friday fold comes to us from Corsica via University of Washington structural geologist Darrel Cowan. It’s a marble that’s been folded *twice!*