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26 February 2014
A fistful of fossils (Devonian Helderberg Group of West Virginia)
More images for you today from my field trip a few weeks ago to West Virginia’s bizarro highway Corridor H, a quiet place built for roaring traffic. Its multistory roadcuts are fresh and profound; they offer the most incredible views into the mid-to-late-Paleozoic surface of Earth… and the creatures that lived there. In the Devonian period, the Helderberg Group of limestones was deposited. It’s full of interesting fossils, the remains …
17 February 2014
A marine incursion in the Hampshire Formation?
I went out last Tuesday to Corridor H, the exemplary new highway cutting through the Valley and Ridge province of eastern West Virginia. Joining me was former student Alan Pitts, a devotee of Corridor H from way back in the early days when we just called it “New Route 55.” The boondoggle highway is now open all the way west to the Allegheny Front, practically into the Canaan Valley. On Tuesday, …
13 June 2013
Another example of the perplexing mystery “fossil”
In April, I posted some images of an odd structure from some of the fossiliferous siltstones of the Fort Valley. Some of the commenters suggested it was no fossil, but simply a very small scale version of soft-sediment deformation. Now, another “Fortian” has shown me another example, and this one is better preserved. Its lobes are (apparently) arranged radially, and the individual lobes have a striated appearance. The lobes vary …
14 May 2013
An itty bitty brachiopod
Found this small, flat brachiopod fossil last fall just down the road from my place in the Fort Valley. Lovely little thing… That’s all I’ve got for you today!
7 May 2013
Brallier Formation 2: tectonic structures
Yesterday we examined primary sedimentary structures (including trace fossils) at an outcrop of Devonian-aged Brallier Formation turbidites between Deerfield and West Augusta, Virginia. Today, we’ll zoom in on the tectonic structures at the site: folds, faults, and joints. Remember, you don’t have to take my word for it. You can explore it for yourself in this M.A.G.I.C. GigaPan: link One thing that’s kind of cool about that GigaPan is the …
6 May 2013
Brallier Formation 1: primary structures
Last week, I mentioned some geologizing with the family in the Staunton area. The furthest west we ventured was to the road connecting Deerfield, Virginia, with West Augusta. There, the Brallier Formation is well exposed in a dramatic roadcut. Explore it for yourself in this M.A.G.I.C. GigaPan: link The Brallier is turbidites, shed off the Acadian Orogeny during the Devonian, kind of like Martinsburg Formation is turbidites shed off the …
6 April 2013
Mystery fossil (?) for crowd-sourced identification
A Fort Valley neighbor brought me this sample yesterday, asking me to tell her what it was. But while my brain’s pattern-recognition centers lit up when examining its “rows” of scale-like bumps, it didn’t match up with anything that I know from anywhere else here. Take a look, and click any of these images to enlarge it… The source unit is likely to be the Mahantango Formation, as that is …
14 December 2012
Friday fold: the folded xenoliths of Duck Creek
On Duck Creek (Ellendale, NC quadrangle), you can see folded xenoliths within the Toluca Granite (383 Ma, 378 Ma, or 368 Ma, depending on which mineral you ask). The granite there contains xenoliths that contain pre-exisiting fabrics and structures, and we stopped at Duck Creek on the pre-GSA-Charlotte field trip I took to the Neoacadian Inner Piedmont to check out these xenoliths. Here are some less impressive xenoliths, strung out …
16 November 2012
Friday fold: Neoacadian Inner Piedmont trip, part IV: Migmatitic metagraywacke
The Friday fold comes from a stop on the “Neoacadian Inner Piedmont” field trip that Callan attended prior to the GSA meeting in Charlotte, North Carolina, last week.
13 November 2012
Neoacadian Inner Piedmont trip, part II: more Walker Top
Today, I’ve got a batch of additional photos of the Walker Top Granite to share, variably mylonitized (sheared out under ductile conditions)… Nice garnets in some spots: Delta porphyroclast: Lovely sheared-out rocks…
Callan Bentley is Associate Professor of 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.