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27 February 2015
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 …
13 February 2015
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!
6 February 2015
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 …
23 January 2015
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!
16 January 2015
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.
9 January 2015
The Friday fold is asymmetric, overturned, and chock full of primary sedimentary features. Join us in Glacier National Park’s Mesoproterozoic Belt Supergroup.
2 January 2015
Devonian metamorphic rocks (garnet-bearing gneiss) exposed on the western side of Cabbage Island, Maine: And here it is in GigaPan form: link
26 December 2014
That pretty much speaks for itself, I reckon.
19 December 2014
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 …
12 December 2014
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.