Reader and former student Paxton DeBusk shared this lovely folded gneiss with me at the conclusion of the Virginia Geological Field Conference a few weeks ago: That’s a lovely hand sample, with a high folding:volume ratio! Happy Friday, all
It’s Friday! Here’s a lovely sight, contributed by reader Fred Atwood: [youtube_agu id=Au-jIGfbs8g] Those are quartz veins in one of my favorite local rock units, the Mather Gorge Formation. Fred reports, This is at Madeira School in Great Falls between Black Pond and the Potomac. The rocks around Great Falls, particularly those on the Billy … Read more
The subtitle of this wonderful book is “Watermen, Crabs, and the Chesapeake Bay.” It’s an excellent account of crab ecology in the Chesapeake Bay as it stood in the mid-1970s, and simultaneously a sympathetic portrait of the lives of the locals who capture those crabs for sale to the seafood market. The writing is thoughtful … Read more
A reader asks: “What is foliation and what makes it so important to the structure of rock?”
Callan answers with a lot of images of beautifully foliated rocks.
Break out your paddle and sunhat. We’re going kayaking on Lake Moomaw, in search of Friday folds…
Stop the presses! This late-breaking Friday fold has just been submitted here at Friday Fold Headquarters. This is from Philip Prince/Virginia Division of Geology and Mineral Resources: It’s a recumbent fold of Harpers Formation metasandstone in the James River Face area. Pretty lovely exposure. This outcrop would make a good 3D model. Happy Friday to … Read more
A solo hike in search of anticlines yields new outcrops and good views!
On a family hike, Callan’s son finds some interesting smooth lines on a rock. What are they? What do they tell us? Tune in for a brief history of Appalachian geology.
Remember the Virginia Geological Field Conference from back in October? Well here’s a folded quartz vein we observed along a small shear zone in the Blue Ridge basement complex. There are two views of it, from approximately perpendicular points of view: These rocks are Mesoproterozoic, but the vein would obviously be younger than that, and … Read more
New year’s day is the time I tally up my accumulated bird species seen in my yard on the forested slope of Massanutten Mountain. This is my sixth such annual list. Here are the previous iterations: 2012 (39 species) 2013 (51 species) 2014 (58 species) 2015 (65 species) 2016 (59 species) Here we go, in … Read more
I believe in tinkering with my teaching, and reflecting on the new approaches to see if I think they’re worth keeping or not. One of the topics I teach is the geologic history of Virginia. I do this because it’s essential knowledge to put the students’ upcoming field trip in context, but it’s also a … Read more
What does it mean for a vein to be “quantankerous?” Well, to start with, it’s quartz. Second, it has to be disagreeable or cantankerous. This vein, seen in meta-arkose of the Catoctin Formation near the summit of the Blue Ridge at Rockfish Gap (not Afton Mountain), is such a quantankerous individual: You’ll notice its “S” … Read more
The 2017 Virginia Geological Field Conference had a heavy arkose infusion. Meet some of these feldspar-rich Neoproterozoic sediments of the Lynchburg Group.
For the Friday fold, Callan digs out images of Eagle Rock, Virginia, well aged in his digital archive for a decade!
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). … Read more
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!
A new outcrop in Fort Valley shows Devonian fossil-rich mudrocks overprinted by a tectonic cleavage imparted during Pangaea’s birth throes.
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.
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.
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 … Read more