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27 February 2015

Friday folds: Three tweets

Back at the beginning of January, I asked for help on Twitter for Friday fold fodder. Here are three responses I got: @callanbentley one of my favorites from South Georgia Island. Have more on the laptop. pic.twitter.com/UaRtxM77Vm — John Van Hoesen (@Taconic_Musings) January 8, 2015 @callanbentley 2 folds from my SC Inner Piedmont MS thesis mapping field work (1997). biotite gneiss and amphibolite. pic.twitter.com/cnoyzwK3cL — Doug (@dropstones) January 8, 2015 …

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13 February 2015

Friday fold: Ptygmatic Irving Fm., Colorado

Friday fold: Ptygmatic Irving Fm., Colorado

Another one from Kim: Kim says: Pygmatic folds in the Precambrian Irving Formation. I think this is 1.7 Ga deformation, late in the Yavapai orogeny, which added various arcs in Colorado to North America. Good place to think about strain ellipses in progressive deformation. Zooming in on the best part, and dialing up the contrast a bit: That’s intense! Seriously strained rocks. What fun!

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6 February 2015

Friday fold: Ouray Limestone, Colorado

Friday fold: Ouray Limestone, Colorado

Kim Hannula shares a fold today: Kim says: The rocks folded here mostly the Devonian Ouray Limestone. There’s a fault through the outcrop, and another fault to the left of the photo. Regionally, the faults are mapped as normal faults, mostly with the east (right in photo) side down. Locally, that’s not what I see in this outcrop, which makes this a funky place to look at a fold with …

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23 January 2015

Friday fold: Rainy Cove, Nova Scotia

Friday fold: Rainy Cove, Nova Scotia

Elizabeth Kosters contributed this week’s Friday fold: It’s from Rainy Cove, Nova Scotia, Canada. Click through to read Elizabeth’s post on the site. Happy Friday!

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16 January 2015

Friday fold: the Ross Sandstone, Ireland

Friday fold: the Ross Sandstone, Ireland

Zoltán Sylvester has contributed today’s Friday fold, an anticline in the Ross Sandstone of Ireland: Click image to go to the source (full sized). Thanks Zoltán! Happy Friday everyone.

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9 January 2015

Friday fold: a surging rippled whale of Grinnell Formation

Friday fold: a surging rippled whale of Grinnell Formation

The Friday fold is asymmetric, overturned, and chock full of primary sedimentary features. Join us in Glacier National Park’s Mesoproterozoic Belt Supergroup.

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2 January 2015

Friday folds: Cabbage Island, Maine

Friday folds: Cabbage Island, Maine

Devonian metamorphic rocks (garnet-bearing gneiss) exposed on the western side of Cabbage Island, Maine: And here it is in GigaPan form: link

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26 December 2014

Friday fold: another gem from the Chancellor Slate

Friday fold: another gem from the Chancellor Slate

That pretty much speaks for itself, I reckon.

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19 December 2014

Friday Fold: Mist Mountain Formation in Canmore, Alberta

Friday Fold: Mist Mountain Formation in Canmore, Alberta

Let’s journey to the Cretaceous today, to see sandstones, shales, and even some coal strata that have been folded during the eastward thrusting that built the Canadian Rockies. Here’s the same fold, in context, shot in GigaPan on a different day, from a different angle. Can you match it up? link Ben Gadd showed me (and my field class) this site last summer. It’s a little west of Canmore. There’s …

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12 December 2014

Friday fold: Miette slate, Alberta

Friday fold: Miette slate, Alberta

The Friday fold returns to Canada, looking at Neoproterozoic slate and quartzite at the southern terminus of the Icefields Parkway. Bonus features include ripple marks, graded beds, cross-bedding, cleavage, and boudinage.

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