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7 August 2020

Friday fold: syncline in Helderberg Group limestones

I went on a day of field work last week to Corridor H, West Virginia, to help make drone-based photogrammetric 3D models of the huge outcrops there. One site we stopped at is this beautiful V-shaped syncline in Devonian-aged Helderberg Group limestones. Click to enlarge Here are two layers traced out: Here is a GigaPan that Alan Pitts shot of this outcrop several years ago, when it was a bit …

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5 June 2020

Friday fold: Harbledown Island

Reader Christian Gronau writes with this Friday fold contribution: Greetings from Cortes Island, BC – at the opposite end of the Strait vis-a-vis Lopez Island. Your Mountain Beltway blog is always of interest, and I have been following it for several years by now. Thank you for putting the effort into this worthwhile website. Quite regularly your posts elicit “echoes” and make me go back to some of my own …

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29 May 2020

Friday fold: Lopez Island tension gashes

The Friday fold shows some sheared quartz-filled tension gashes in sandstones of one of the San Juan Islands in Puget Sound.

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8 May 2020

Friday fold: Wills Mountain Anticline

Eric Fulmer (who pitched in with last week’s Friday fold) returns this week with another treasure. He writes, I was in Hopeville, WV a couple of years ago. The entire area between Cabins and Hopeville is a real joy (geologically and recreationally) as some of the most resistant rocks of the Mid-Atlantic Appalachians are folded and exposed in quick succession and with great relief. I am particularly fond of seeing …

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27 March 2020

Friday fauxld: a false syncline in Titus Canyon

What day is it again? Hard to keep track in the days of raging coronavirus infections, but it is in fact Friday, which means that if you want a dose of the halcyon pre-COVID-19 days, you can enjoy this example of a false fold from Death Valley National Park’s Titus Canyon.

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31 January 2020

Friday fold: tension gashes near Sunflower, Arizona

Reader John Christian shared these folds with me via email last week. They are quartz veins in slightly metamorphosed Precambrian igneous rocks found near Sunflower, AZ in the Mazatzal Mountains. The second photo is a close-up shot of the curviest, cleanest batch of folds from the first shot. These are beautiful examples of folds in similarly oriented quartz veins; we call them “en echelon” for the way you have a …

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11 July 2019

A submarine slump complex at Sandy Cove, Newfoundland

Traveling in Newfoundland, Callan visits a seaside outcrop showing a Proterozoic submarine slump complex, overprinted by tectonic cleavage and weathered by the sea.

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3 May 2019

Friday fold: Monarch Canyon

When a dike is subjected to shear, how does it deform? A guest Friday fold from Darrel Cowan of the University of Washington teaches a nice little lesson. Join the field trip in Monarch Canyon of Death Valley National Park…

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25 January 2019

Friday folds: more Marli Miller

Four Friday folds from Marli Miller’s online photo archive of geological images.

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18 January 2019

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 the precise location of this outcrop, I did a bit of internet sleuthing… According to …

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