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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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16 June 2017

Friday fold: toothpasty Tomstown

I spent last weekend at the National Association of Geoscience Teachers’ Eastern Section meeting, based out of the Community College of Baltimore County in Catonsville, Maryland. One of the two field trips I took headed out to the western Piedmont, Blue Ridge and Valley & Ridge provinces of western Maryland. On that trip, we took a tour of Crystal Grottoes, a commercial cave south of Boonsboro. I was impressed at …

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6 June 2017

Loading sags in homogeneous lithologies?

Can soft sediment deformation “loading structures” (ball & pillow) occur when the two strata are identical in composition? Grok on these field photos and chime in with your best hypothesis.

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23 May 2017

Silurian tidal flat carbonates of the Tonoloway Formation

Journey to the Silurian period in what is today the Valley & Ridge province of eastern West Virginia to see some exquisite sedimentary rocks that represent deposition in a very arid, very shallow setting.

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13 May 2017

Slump palimpsest, Corridor H

There’s a section of my favorite road, the lovely nowhere-to-nowhere Corridor H, that seems to be having some issues with slumping. I noted this in November of 2015, and I return to the topic today. Here’s a look at the slope, with old drainage “French drains” installed, and a fresh scarp transecting it just the same: I see at least three small scarps there. A short distance further to the …

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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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27 March 2017

Cleaved, boudinaged, folded Edinburg Formation southwest of Lexington

Explore a dozen photos highlighting the structural geology of an outcrop of limestone and shale near Lexington, Virginia. Cleavage refraction, overturned beds, boudinage, folds, and even a small fossil – we’ve got something for everyone. Bring the whole family!

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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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25 February 2017

Concretions in the Millboro Formation, Fort Valley

Some enormous concretions are encountered in a shale quarry in the central Fort Valley. Concretions like these are typical of the Devonian-aged Millboro Formation.

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