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25 June 2021

Friday fold: The Blue Ridge Tunnel

Inside the Blue Ridge (in an 1850s-era railroad tunnel), Callan finds folds and boudinage that formed during Appalachian mountain-building.


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7 May 2021

Friday fold: Lynchburg Group

On his way to get his COVID vaccine, Callan visits a new outcrop showing folded and faulted strata of the Neoproterozoic Lynchburg Group.


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9 August 2019

Friday fold: crumpled green metavolcanics from St. Anthony

The Friday fold erupted out of a volcano, completing the second part of its two stage cooling history, then later got folded and metamorphosed. It was found atop a high cliff near the northern Newfoundland town of St. Anthony.


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11 July 2019

A submarine slump complex at Sandy Cove, Newfoundland

Traveling in Newfoundland, Callan visits a seaside outcrop showing a Proterozoic submarine slump complex, overprinted by tectonic cleavage and weathered by the sea.


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22 March 2019

Friday fauxld: concentric weathering rinds

Here’s a deceptive Friday “faux”ld I saw last week on the South Page Valley Road whilst learning about the Martinsburg Formation outcrops there: Looks like an isoclinal fold in this slab of siltstone, but the curvy lines are just concentric weathering rinds. Not a real fold at all! I hope everything you see this weekend is more straightforward and less deceiving. Happy Friday!


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5 June 2018

Cross-bedding in Archean komatiitic ash deposits

Cross-bedding isn’t just for modern sedimentary deposits; you can find it in truly ancient ash deposits too! Let’s head to South Africa and take a look.


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8 February 2018

A spectacular display of Earth science in the Alabama Hills

A detailed examination of an elegant photo of the eastern front of California’s Sierra Nevada, from the perspective of the Alabama Hills. How many different geologic phenomena can be packed into a single image? Let’s find out!


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2 February 2018

Friday fold: 3D model from the Portsoy Shear Zone

The Friday fold is a really cool 3D model of differentially-weathered calc-silicate rocks in Scotland that were folded during the Caledonian Orogeny.


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2 November 2017

Weathering in komatiite

This morning on Twitter I was reminded of komatiites, those “extinct” ultramafic lavas that were relatively common eruptions during the Archean. I’ve actually got a good number of komatiite photos to share from my time last year in South Africa’s Barberton Greenstone Belt. But since time is short this morning, I’ll start with a short photo set of three images, all showing different aspects of how these ultramafic rocks weather …


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18 August 2017

Friday folds: the Roman Forum

When in Rome, do Friday folds as the Romans do? Here are some images from my brief, sweltering visit to the Roman Forum(s) this past summer. The whole region is a jumblepile of ancient ruins in a thousand styles. Almost nothing is labeled. It looks like this: This particular building held up a bit better, and its lovely columns sported some folded marbles: Close-up shots to show the folding internal …


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