folds

Friday fold: a new 3D model

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Here’s a good sample, another one I inherited from Declan de Paor when he retired from Old Dominion University. It’s an interesting sample – I guess I’d call it a graphitic clay shale, but it’s surprisingly lightweight, so I’m not super confident that’s right. The bedding surfaces are glossy and slick, indicating some flexural slip … Read more

Friday fold: Three from Alaska

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Earlier this week, I was alerted to an online photo collection from the Alaska Division of Geological and Geophysical Surveys. For those of us who are feeling the lack of field work over the past year, it’s pleasant to browse through them and get a taste of backcountry Alaska. Many of the photos are shot … Read more

Friday fold: Torcross

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Looks like we’re sticking with the U.K. for Friday folds, for the time being… This lovely beast comes to us from Torcross, via Danny Stubbs, who shared it on Twitter this past week. That’s from the Meadfoot Group of slates, cross-cut by quartz veins. In this follow-up image, Danny shares that sometimes the quartz veins … Read more

Friday fold: syncline in Helderberg Group limestones

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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 … Read more

Friday fold: Two Mile Run Overlook

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I spied an anticline last weekend while engaging in a day of solo geologizing along Skyline Drive in Shenandoah National Park. At Two Mile Run Overlook, I gazed west toward the southern tip of Massanutten Mountain, and noted what appeared to be an anticline in the Blue Ridge foothills: Annotated: And here it is in … Read more

Friday fold: Scaglia Rossa chevrons at Lago di Fiastra

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My friend Alan Pitts is orchestrating a virtual field camp for George Mason University this summer, utilizing outcrops in central Italy’s Apennine Mountains. Here’s a 3D model he just posted of one of the most impressive outcrops there: the chevron folds in the Scaglia Rossa limestones at Lago di Fiastra. I featured the site as … Read more

Friday fold: Harbledown Island

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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 … Read more

Friday fold: Anticline in Glacier National Park

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Some web research led to a serendipitous discovery and further exploration. Wherever you’re sheltering in place, you don’t have a view that’s this grand. Slip away for a few moments to the high country of Montana’s Glacier National Park, where an anticline may be seen in the towering cliffs…

Friday fold: Argentinian turbidites

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Zoltán Sylvester brings us this Friday’s fold: And there’s more where that came from: These are deepwater strata of the Lower Cretaceous Rio Mayer Formation, exposed near Lago Argentino, Argentina, south of the lake’s northwest “arm,” about here. They were deformed so exquisitely during Andean mountain-building. Zoltán is a talented photographer, and you should check … Read more

Friday fold: Wills Mountain Anticline

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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 … Read more