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20 July 2018

Friday fold: Alpine peak containing a high elevation recumbent fold

Via Twitter, a Friday fold from Maddy Rushing: #FridayFold, @callanbentley? pic.twitter.com/eaKIuuvFgB — Maddy Rushing (@komaddyite) May 25, 2018 This is in the Alps of Switzerland; I don’t know more about it than that. If you recognize the site or the geology, educate us in the comments!

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15 July 2018

Chickie’s Rock, Pennsylvania

A virtual field trip to the deformed quartzites and metaconglomerates of Chickie’s Rock and Sam Lewis State Park in Lancaster County, Pennsylvania.

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13 July 2018

Friday fold: the anticline at Chickie’s Rock

Chickie’s Rock is a prominent cliff of Cambrian quartz arenite (sandstone) in Lancaster County, Pennsylvania. I visited it last month with field trippers at the eastern section meeting of the National Association of Geoscience Teachers. One of the aspects of the site is this gentle anticline with axial planar cleavage: The yellow rectangle is my field notebook for scale. Another shot: Happy Friday to all!

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6 July 2018

Friday fold: twisted turbidites at Usal Beach

Last week, I spent two perfect days camping with family at Usal Beach, in Mendocino County, California. Along the beachside cliffs there, I spotted plenty of lovely turbidites: graywacke and shale and a little bit of conglomerate that had been scraped off the subducted Farrallon Plate to help contribute to the bulk of the Franciscan complex. That accretionary process imparted some stresses on these deep-sea deposits, and in many places …

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22 June 2018

Friday fold: Connemara Marble, Ireland

Another guest Friday fold (keep ’em coming, folks!) – This time from Eric Pyle of James Madison University: This is a weathered outcrop of the Connemara Marble in western Ireland, about a meter wide. Thanks for sharing, Eric!

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15 June 2018

Friday fold: scenes from the Schilthorn cable-car

My friend Karen Aucker from NAGT’s Eastern Section shared these images (and a video!) of the folds she glimpsed from the cable-car on her way up the Schilthorn in Switzerland. I reckon they will do for our Friday fold: Thanks for sharing, Karen! These are great. Happy Friday, all!

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9 June 2018

Friday fold: contorted carbonates of the Conestoga Formation

Today, in Millersville, Pennsylvania, on the campus on Millersville University, I saw these contorted carbonates. They are of the Cambrian Conestoga Formation, and I saw them on a NAGT Eastern Section field trip led by Lynn Marquez of Millersville University. This deformation is purported to be Taconian, but it looks very much like Alleghanian deformation in similar aged and composition rocks in Virginia. Interesting!

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1 June 2018

Friday fold: a quartet from Marli Miller’s website

Marli Miller is a senior instructor at the University of Oregon. She is the author of Roadside Geology of Oregon and (with Darrel Cowan) Roadside Geology of Washington. She’s also a very talented geological photographer. She launched a website recently to showcase her work and make it available for instructors: Geology Pics. After chatting with Marli a bit in Flagstaff at the Rocky Mountain / Cordilleran section meetings of GSA …

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25 May 2018

Friday fold: 3D model of intense folding

This is a block of rock I found in the rock garden at Northern Arizona University a few weeks ago: It’s intensely folded. Not sure what kind of rock it is, but it was quite dense.

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18 May 2018

Friday fold: Corsican blueschist sheath fold

The Friday fold takes us to the French Mediterranean island of Corsica. Are you ready to dip into the blueschist facies in search of sheath folds?

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