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23 September 2016

Friday fold: Shetland geopark rock wall at Northmavine

Friday fold: Shetland geopark rock wall at Northmavine

Can a Friday fold be a work of art as well as a source of geologic insight? The answer can be found as you enter Shetland’s Northmavine region.

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16 September 2016

Friday fold: Centenary migmatite

Friday fold: Centenary migmatite

The Friday fold is a guest submission from Bill Burton, who took the photo of these lovely ptygmatic folds in migmatite in a national park on the 100th anniversary of the founding of the Park Service.

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9 September 2016

Friday folds: A study in contrasts at the Walls Boundary Fault, Shetland

Friday folds: A study in contrasts at the Walls Boundary Fault, Shetland

A virtual field trip to the Walls Boundary Fault in Shetland reveals an embarrassment of Friday fold riches.

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2 September 2016

Friday fold: isoclinal fold in ferruginous pelite and chert of the Fig Tree Group

Friday fold: isoclinal fold in ferruginous pelite and chert of the Fig Tree Group

A quick Friday fold – Ulundi Formation, basal Fig Tree Group of the Barberton Greenstone Belt, exposed in a creekbed etched into the trace of the Sheba Fault. This is one of the outcrops I visited one week ago today as part of the pre-IGC field trip to the Barberton. The rocks are iron-rich cherts and pelites that have enjoyed some serious strain, presumably due to movement along the Sheba …

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19 August 2016

Friday fold: marble, Kings Canyon, California

Friday fold: marble, Kings Canyon, California

My friend Bill Burton (USGS, Reston) shared today’s Friday fold — Chevron folds in marble, Kings Canyon, California. Nice! Thanks for sharing, Bill!

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5 August 2016

Friday fold: roadside in Ladismith/Kleinkaroo

Friday fold: roadside in Ladismith/Kleinkaroo

Martin Schmidt again contributes a fold – this time from his summer trip to South Africa: Pretty great! This is part of the Cape Fold Belt. Perhaps some of you will drive by it when you go to the International Geological Congress in South Africa later this month! You can view the site in the context of Google Street view here. Thanks for sharing, Martin.

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29 July 2016

Friday fold: Lewisian gneiss near Tarbet, North-West Highlands, Scotland

Friday fold: Lewisian gneiss near Tarbet, North-West Highlands, Scotland

A quick Friday fold here from the North-West Highlands of Scotland: These are Lewisian gneisses exposed on a headland northwest of the little outpost of Tarbet (where the Handa Island ferry departs from). I was out there in search of shear zones, but I found plenty of nice folds, too. There are two main folds in the image – a synform in the foreground (yellow), and an antiform in the …

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22 July 2016

Friday fold: The walls of Scalloway Castle

Friday fold: The walls of Scalloway Castle

When in Shetland, one of my first stops was the museum in Scalloway, and one of the ancillary benefits of visiting there is the castle next door: Scalloway Castle includes building stones derived from the local limestone – a Neoproterozoic unit that has recently been chemostratigraphically correlated with Snowball Earth cap carbonates elsewhere in the world. But that need not concern us today. Today we are here for the folds! …

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8 July 2016

Friday folds: Kinkell Braes, Scotland

Friday folds: Kinkell Braes, Scotland

When I took you on a virtual field trip to Kinkell Braes earlier this week, I didn’t mention that the sandstones are folded there, now did I? Let me remedy that omission now: That is a plunging anticline that you could actually take a plunge into: And here’s a syncline to match. Happy Friday. Hope your week was a good one, and that your weekend is even better.

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1 July 2016

Friday fold: Clarely, an anticline

Friday fold: Clarely, an anticline

Eric Pyle sent in today’s Friday fold – Eric reports that you can find this fold seaside, near Poulatedaun, Co. Clare, Ireland. Thanks for sharing, Eric!

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