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10 March 2017

Friday fold: Sheba Mine sample

Friday fold: Sheba Mine sample

When touring the geology of the Barberton Greenstone Belt last August, our group visited the Sheba Mine, a gold mine high in the hills. Their geologist kindly showed us around and allowed us to visit his history-laden office. I have no idea where this sample originated, but it was the only fold I saw in the place, nestled between sepia-toned photographs and old lanterns and rusty picks. I wonder what …

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3 March 2017

Friday fold: Kink folded Dalradian metasediments

Let’s reminisce back to the Walls Boundary Fault on the Ollaberry Peninsula of Shetland today. Here’s a 3D model to go along with the ones I posted last time: It’s a little ragged, but so am I at the end of the workweek! Happy Friday. Have fun spinning this thing.

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24 February 2017

Friday fold: 3D model of kinked schist from Rhode Island

Friday fold: 3D model of kinked schist from Rhode Island

For your Friday fold this week, I present to you a 3D model of a sample of kinked schist from Beavertail State Park, Rhode Island. Spin it right round, baby: This is another sample from the structural geology collection of Carol Simpson and Declan De Paor.

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17 February 2017

Friday fold: Buckled at Baltinglass

Friday fold: Buckled at Baltinglass

Garnetiferous beds from the aureole of the Leinster Granite east of Baltinglass, County Wicklow, Ireland (Declan De Paor’s senior thesis mapping area, 1973). Manganese-rich metasediments. The prominent ‘elasticas’ or fan folds (folds with a negative inter-limb angle) are superimposed on isoclinal folds: so the brownish layer at top and bottom are the same, though that is not obvious from the image. This is a sample from the structural geology collection …

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10 February 2017

Friday fold: the Grand Canyon

Friday fold: the Grand Canyon

Deep in the Grand Canyon of Arizona, Steve Mirsky found a Friday fold to share with you.

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3 February 2017

Friday fold: Squaw Creek Schist, Idaho

Friday fold: Squaw Creek Schist, Idaho

The edge of ancestral North America can be found in the canyon of the Salmon River in western Idaho. Folds exposed the Squaw Creek Schist near Riggins record the stresses of adding terranes on during North America’s westward movement since the breakup of Pangaea. The Friday fold crinkled up during the accretion of a terrane to the growing North American continent.

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27 January 2017

Friday fold: the Bradshaw Layered Amphibolite

Friday fold: the Bradshaw Layered Amphibolite

The Friday fold can be found along the Fall Zone, where crystalline metaigneous rocks of the Piedmont meet the gently sloping strata of the Atlantic Coastal Plain. Contemplate their high metamorphic grade and their tight folding, and imagine the mighty mountains that once rose on this spot.

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20 January 2017

Friday fooled

It’s Friday, time for a … discussion of the role of misinformation in the modern media landscape and civil society? Yep, no fold this week, folks.
In honor of the Inauguration, it’s our first ever Friday Fooled.

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13 January 2017

Friday fold: Smaull Graywacke at Saligo Bay, Islay

Friday fold: Smaull Graywacke at Saligo Bay, Islay

On the western coast of Islay, Saligo Bay showcases turbidites of the Neoproterozoic Colonsay Group. The Smaull Graywacke shows Caledonian (late Ordovician) folding and cleavage superimposed on world-class graded bedding. There’s also a nice dolerite dike to examine.

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6 January 2017

Friday fold: helicopter and anticline in the Yukon

Friday fold: helicopter and anticline in the Yukon

The Friday fold is airborne over the Yukon Territory’s border with the Northwest Territories, high up in Canada’s Mackenzie Mountains. Helicopter for scale.

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