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18 October 2017

VGFC 2017: Limbs of arkose

The 2017 Virginia Geological Field Conference had a heavy arkose infusion. Meet some of these feldspar-rich Neoproterozoic sediments of the Lynchburg Group.

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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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15 April 2017

Basement xenoliths in Catoctin Formation, Compton Pass

My son and I hiked Compton Peak in Shenandoah National Park this morning, and saw these two lovely examples of xenoliths. The example above is small, but it shows clearly the difference between the coarse, felsic basement rock (Mesoproterozoic granitoid, comprising the xenolith) and the surrounding fine-grained dark green metabasalt of the Catoctin Formation (Neoproterozoic). Here’s another, bigger example: These two Blue Ridge examples both illustrate the principle of relative …

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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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13 February 2017

Q&A, episode 2

A new edition of “science and nature question and answer.” This week: why Massanutten Mountain isn’t longer, and why you’re never going to walk on the Sun.

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31 December 2016

2016 Yard List

Eastern bluebird (and its lunch, a camel cricket) Purple finch (male) At New Year’s, I post my “yard list” here. It’s a list of all the bird species observed in my yard in Fort Valley, Virginia, over the course of the previous calendar year. I have been posting this list every year since I moved here: 2012 (39 species) 2013 (52 species) 2014 (58 species) 2015 (65 species) Yellow-billed cuckoo …

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8 December 2016

Silent samples, holey samples

Two very different samples tell stories that are full of holes. What’s going on with this weathered sandstone? What’s going on with this fossil scallop shell?

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29 October 2016

New digital media of Shenandoah National Park feeder dikes

In Shenandoah National Park, astride Virginia’s Blue Ridge, feeder dikes of Catoctin Formation (meta-)basalt cut across the Grenvillian-aged granitoid basement. Due to their mafic composition and columnar jointing, these feeder dikes generally weather more rapidly than their host rocks. I led a field trip in the park on Thursday for my son’s school, and my student Marissa was there the weekend prior, checking out the autumn leaves and geology with …

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