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8 November 2019

Friday fold: Rist Canyon cobble

From a creek bed in northern Colorado, the Friday fold distorts foliation in early Proterozoic quartzofeldspathic gneiss, peppered with small almandine garnets.  

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1 November 2019

Friday fold: Newfoundland beach cobble

This Friday’s fold is found in a metasedimentary beach cobble I found last summer in southeastern Newfoundland: A lovely little “pocket fold,” it came home with me and is among the handful of “deskcrops” I keep in my home office. Happy Friday and happy November!

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25 October 2019

Friday fold: Identity of a BIF

The Friday fold is a slab of banded iron formation now dwelling in the University of Washington’s Department of Earth & Space Sciences. But where did it come from? India? Brazil? Perhaps you can help identify its provenance.

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18 October 2019

Friday folds from the Foreknobs Formation

TGIF! That’s my seven year old field assistant showing off the shape of a syncline in shale, siltstone, and fine sandstone of the Foreknobs Formation, a Devonian nearshore package of clastic sediment in the Valley & Ridge Province of eastern West Virginia. Want to see something freaky for Halloween? Photoshop can make it happen: Ewwww. Creepy! Another shot of the same fold, with a thick massive sand above a thicker …

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11 October 2019

Friday fold: Watern Cove

A moderate mesoscale monocline at Watern Cove, Newfoundland, shows off multicellular animal fossils of the Ediacaran Mistaken Point Formation.

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4 October 2019

Friday fold: Angel Island “IV”

Hey, let’s go back to Angel Island for today’s Friday fold. We’ve been there once, twice, thrice previously. The rocks in question are metaconglomerates that Jess Ball and I found at first only as float on the beach at Camp Reynolds, like these two examples: …Look at those beautiful elongated pebbles, transected by wee white veins! Where there’s float, there may be outcrop — Sure enough, with a minute or …

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27 September 2019

Friday folds: O’Shaughnessy Boulevard, Glen Canyon Park, San Francisco

The western edge of O’Shaughnessy Boulevard, near Glen Canyon Park in San Francisco shows beautiful examples of crumpled cherts. Here are a few dozen photos of these glorious outcrops, and instructions on how to visit.

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6 September 2019

Friday fold: Gonzen, Switzerland

Science writer Gabe Popkin shared two fold photos with me this week – both from near Sargans, Switzerland, adjacent to the Rhine River Valley and the border with Lichtenstein. The photos shows the mountain called Gonzen. There, Jurassic limestones crop out in a very wavy pattern: I don’t know the geology of this area in any kind of detail, but I decided to trace out a distinctive upper surface of …

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30 August 2019

Friday fold: Calafia State Beach

The Friday fold is a guest contribution to “Mountain Beltway” from the manager of the AGU Blogosphere, Larry O’Hanlon. It shows apparent crumpling of a few sedimentary layers at the toe of a soft sediment slump at Calafia State Beach in southern California.

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23 August 2019

Friday fold: a return to coastal Greenland

We return for today’s Friday fold to a site on the coast of Greenland’s King Oscar Fjord, featured in photographs by Alistair Knock, that first graced Mountain Beltway’s digital pages eight years ago.
Who wouldn’t want to buy that fold?

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