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20 January 2021
Peering through
When hiking recently in my neighborhood, I saw this gleaming apparition appear in an eroded gully in a dirt road: Those multicolored stripes are varying compositions in a zone of ultramylonite: ductilely-sheared-out rock that formed in the deep equivalent of a “fault” in the Blue Ridge basement complex. We call it a “shear zone” most of the time, but a better descriptor would be “high strain zone.” These rocks are …
31 July 2020
Friday fold: Two Mile Run Overlook
I spied an anticline last weekend while engaging in a day of solo geologizing along Skyline Drive in Shenandoah National Park. At Two Mile Run Overlook, I gazed west toward the southern tip of Massanutten Mountain, and noted what appeared to be an anticline in the Blue Ridge foothills: Annotated: And here it is in Google Maps, with the perspective rotated to looking ~along strike to the north, and I …
24 July 2020
Friday fold: Totier Creek phyllite
Exploring his new digs in Charlottesville, Callan is introduced to a large exposure of phyllite at a dam’s spillway. The foliation there is folded in many ways. Share in a dozen field photos of the site…
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!
20 March 2019
The Dinosaur Artist, by Paige Williams
A book review of Paige Williams’ “The Dinosaur Artist,” a tale of international trade in dinosaur skeletons.
18 March 2019
New discoveries in the Martinsburg Formation
A virtual field trip to examine some deepwater clastic sediments shed off the first phase of Appalachian mountain building, and deformed in the third phase. It’s a lovely day for a field trip to the late Ordovician!
1 January 2019
2018 Yard List
New year’s day is the time I tally up and report the bird species seen in my yard on the forested slope of Massanutten Mountain in Shenandoah County, Virginia. This is my seventh such annual list. Here are the previous iterations: 2012 (39 species) 2013 (51 species) 2014 (58 species) 2015 (65 species) 2016 (59 species) 2017 (56 species) It’s been a good year. Two new “seen for the first …
9 November 2018
Friday fold: gneiss from the Southside Virginia Piedmont
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
21 September 2018
Friday fold: quartz veins in metagraywacke of the Mather Gorge Formation
It’s Friday! Here’s a lovely sight, contributed by reader Fred Atwood: 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 Goat Trail’s “A” Loop, are exemplary in many regards. That’s why I am taking my Physical Geology …
27 August 2018
Beautiful Swimmers, by William Warner
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 and calm, paced very similarly to John McPhee’s writing, rich in quotes from the watermen …
Callan Bentley teaches geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.