30 May 2014 12:30 in devonian, faults, folds, Friday Fold, west virginia by Callan Bentley
Click to enlarge You owe it to yourself to click through and make this bigger. Check out the prominent lower left to upper right thrust fault, and the shattering in the shorter limb of the underlying syncline. Is that another one to the right? Happy exploring, and happy Friday!
29 May 2014 12:10 in devonian, glaciers, sediment, valley and ridge, west virginia by Callan Bentley
While on Corridor H last week with Team “Border to Beltway” (and USGS research geologist Dan Doctor), we stopped at the putative mass transport deposit. We still haven’t figured out which unit this is (It’s not the Foreknobs), but as we approached it, Dan wondered aloud, “I wonder where the top of the Devonian is. Maybe we could find some of Dave Brezinski’s glacial deposits.” If you’re not aware of …
29 April 2014 13:22 in appalachian plateaus, sandstone, sediment, shale, west virginia by Callan Bentley
Remember this past winter when Alan Pitts and I found what we interpreted to be a mass transport deposit (a submarine landslide/slump) along the new section of Corridor H leading up the Allegheny front? Well, I was back out there yesterday, with Dan Doctor (USGS Reston) and Jay Kaufman (University of Maryland). One new thing we found was lots of weathered-out “ploudins” (pillows/boudins), many of which had a “sleigh” shape …
17 March 2014 12:35 in devonian, sediment, shale, west virginia by Callan Bentley
Where the Needmore Formation is falling apart on Corridor H, sloughed-off shale is piling up in a tiny talus slope: You could slap a protractor on that photo and get a pretty good measurement of the angle of repose of this chippy, flaky granular material. Eyeballing it, that looks like about 45° to me.
6 March 2014 12:50 in devonian, sandstone, shale, unconformities, west virginia by Callan Bentley
The Wallbridge Unconformity is a surface of stratigraphic hiatus or erosion between the depositional influence of the Tippecanoe and Kaskaskia epeiric seas. After Alan Pitts and I located ourselves in the Oriskany Sandstone (terminal Tippecanoe stratum), we looked stratigraphically above the quartz sandstone for the overlying unit, which should be the Needmore Formation shale (beginning of the Kaskaskia sequence). Indeed, the quartz sandstone was overlain by a black shale at …
5 March 2014 12:29 in devonian, fossils, mollusks, quartz, sandstone, valley and ridge, west virginia by Callan Bentley
Today, a few more photos from the field trip last month to Corridor H, the fine new superhighway with so little traffic out in eastern West Virginia. Our antepenultimate stop of the day was at an outcrop we inferred should hold the Oriskany Sandstone, a Devonian quartz arenite that lies stratigraphically above the Helderberg Group limestones and below the Needmore Shale. We were using Lynn Fichter’s indispensible stratigraphic column for …
28 February 2014 12:04 in folds, Friday Fold, limestone, structure, valley and ridge, west virginia by Callan Bentley
For the Friday fold, let’s journey back to the Silurian, as exposed in the limestones of that age that were deformed during Alleghanian mountain-building (Pennsylvanian and Permian), and exposed along Corridor H in eastern West Virginia. Some buckling (cuspate-lobate form) seen in that one… A little pop-up with hinge collapse: And, finally, as a digestif, consider this little morsel: That’s a bite-sized Friday fold. Have a good weekend!
27 February 2014 12:05 in ice, valley and ridge, west virginia by Callan Bentley
Over the past 2 weeks, I’ve been sharing some images here from a field trip the previous week to Corridor H in eastern West Virginia. I love this road, but I guess it’s fair for me to point out that sometimes in the middle of winter, this is what the outcrops look like: …Yep. Next road-cut, please.
20 February 2014 12:42 in gigapan, limestone, m.a.g.i.c., structure, stylolites, valley and ridge, west virginia by Callan Bentley
While out on the Corridor H field trip last week before the heavy snow, I found this squeal-inducingly-lovely example of a stylolite in Helderberg Group limestones (Devonian passive margin carbonates): The stylolite is a pressure-solution surface, made especially apparent in this example because of the starkly different grain sizes and colors on either side of the dissolved-away rock: This is a gorgeous sample to explore in macro GigaPan view. Enjoy: …
18 February 2014 12:18 in valley and ridge, west virginia by Callan Bentley
See the size of those road cuts? Count all those cars? Exactly. Why this place isn’t swarming with geologists, I cannot for the life of me comprehend.