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12 November 2021
Happy Friday, all! Two shots today from my friend Joe up in Vermont. He sends these from the Champlain Valley, at a place called Raven’s Ridge. It looks like an alternating series of sandstones and shales, arched into an anticline, perhaps during the Acadian Orogeny (??). According to the Nature Conservancy’s website, porcupines live in this anticline, which is called “The Oven.” Looks like most of the strata around there …
25 June 2021
Inside the Blue Ridge (in an 1850s-era railroad tunnel), Callan finds folds and boudinage that formed during Appalachian mountain-building.
11 June 2021
It’s Friday! Adam Forte, a geology professor at LSU, posted this image yesterday on Twitter: It’s a box of sheets of newsprint, stored vertically and ignored for a while, now rotated 90° so we’re looking at a cross-sectional view. To me, this is an excellent example of a physical analogue modelling experiment (albeit inadvertent) that demonstrates the process by which kink folds form. The key parameters to get this distinctive …
7 May 2021
On his way to get his COVID vaccine, Callan visits a new outcrop showing folded and faulted strata of the Neoproterozoic Lynchburg Group.
16 April 2021
Friday means folds –
This week, we head to the Colorado Rockies for a butterfly-like presentation of a ptygmaticly folded granite dike within biotite schist.
26 March 2021
It’s Friday, and it’s been a few Fridays since I offered you a fold. Let me make up for that with five Friday folds today, all from the incredible collection of free 3D models by Sara Carena on Sketchfab. Sara is a senior scientist/lecturer in Geology at Ludwig-Maximilians University in Munich. Absolutely super models of absolutely super folded rocks. Well done, Sara! Viewing these should get everyone’s weekend off on …
5 February 2021
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 between the layers. In terms of composition: It’s too beautiful to cut up and make …
15 January 2021
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 on old slide film, but that kind of adds to the “Alaskaness” of them in …
13 November 2020
A quick “Friday fold” that is expressed in three dimensions – “stairstep” style folds deforming a bed of Tonoloway Formation dolostone…
9 October 2020
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 have enjoyed some folding too: Happy Friday to all.