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You are browsing the archive for devonian Archives - Mountain Beltway.

16 August 2022

Kinked metavolcanics of the Castine Formation, eastern Maine

Callan shares a few outcrops from coastal Maine, part of the Avalonia terrane that accreted to ancestral North America during the Acadian Orogeny. They are volcaniclastic rocks, coarse and fine, and showing both overprinting kink bands and cross-cutting basaltic dikes.

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7 August 2020

Friday fold: syncline in Helderberg Group limestones

I went on a day of field work last week to Corridor H, West Virginia, to help make drone-based photogrammetric 3D models of the huge outcrops there. One site we stopped at is this beautiful V-shaped syncline in Devonian-aged Helderberg Group limestones. Click to enlarge Here are two layers traced out: Here is a GigaPan that Alan Pitts shot of this outcrop several years ago, when it was a bit …

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18 October 2019

Friday folds from the Foreknobs Formation

TGIF! That’s my seven year old field assistant showing off the shape of a syncline in shale, siltstone, and fine sandstone of the Foreknobs Formation, a Devonian nearshore package of clastic sediment in the Valley & Ridge Province of eastern West Virginia. Want to see something freaky for Halloween? Photoshop can make it happen: Ewwww. Creepy! Another shot of the same fold, with a thick massive sand above a thicker …

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14 March 2018

New media to show off exemplary features of the Devonian-aged Hampshire Formation along Corridor H, West Virginia

Last week, I was in Morgantown, West Virginia, to deliver a colloquium talk to the geology department at West Virginia University of geological visualization. The next day, I took some time on the way home to geologize a bit on the road called Corridor H, a gorgeous transect through the eastern Allegheny Plateau and western Valley & Ridge provinces. I focused that day on the Hampshire Formation, Foreknobs Formation, and …

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29 September 2017

Friday folds: soft sediment deformation in thin sections of MTD sandstone

The Friday folds are small soft-sediment deformational features within a dismembered, folded sandstone (a “ploudin”) from a mass transport deposit from the latest Devonian of West Virginia.

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11 August 2017

Friday fold: Eagle Rock

For the Friday fold, Callan digs out images of Eagle Rock, Virginia, well aged in his digital archive for a decade!

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1 June 2017

The geology of the Yesnaby coast, Orkney

Ahhhh, a raw Scottish coast. …Let’s go there. There’s sedimentology to be learned here, and coastal geomorphology to be ogled. This is Yesnaby, on the west side of Orkney. The rocks there are part of “the Old Red Sandstone,” a neat package of Devonian strata, flavored here and there with an igneous dike, a fault, etc. But overall, I’d like to focus on the strata. The strata I saw at …

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9 May 2017

Ripples in Foreknobs

The Foreknobs Formation is a Devonian unit in the Valley & Ridge province of the Mid-Atlantic Region. It was deposited in relatively shallow near-shore conditions during the Acadian Orogeny. On a field trip to Corridor H, a new highway transecting the West Virginian Valley & Ridge province on Monday, I stopped to document a couple of beds showing very nice ripple marks. These ones are symmetrical, and thus likely represent …

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2 March 2017

A virtual field trip to the Grind of the Navir

On the northwestern coast of the Northmavine Peninsula of Shetland, there is an unusual coastal landform: a gate-like entrance to an elevated amphitheater, like something out of Tolkien, and a storm beach of slab-like boulders inland of that.

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27 February 2017

Bedding / cleavage intersections at Indian Spring, Fort Valley

A new outcrop in Fort Valley shows Devonian fossil-rich mudrocks overprinted by a tectonic cleavage imparted during Pangaea’s birth throes.

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