Mummy bags are great. I have one that keeps me warm in cold temperatures as low as 0 °C. Problem is, the temp dropped below freezing our last night of camping. We know this because our water was partially frozen the next morning. As the night progressed, the further I slunk into the footing of my mummy bag. Despite my desire to get there I am apparently larger than the space allots. The point is I was cold, and everyone else was too. But a nice cup of coffee in the morning did the trick in warming me up on the last day of our trip. Today we were venturing into West Virginia to take a look at the newly constructed Route 55 and the fresh outcrops that were made in its path.
We made two major stops; the first of which (Google Earth file) included a large anticline exposed on both sides of the road. I climbed to the top of the southern end and Nik climbed to the top of the northern end so we could determine the axial hinge’s trend of 204° from the north and 026° from the south. While up top it was noticeable that the mountain to the north of the one I was on exhibited the same sense of folding.
The outcrops are composed of the Tuscarora Sandstone which is the same lithology as the Massanutten Quartzite, just further west. Within this sandstone were other features such as: cross bedding, faults, ripple marks, and more mud rip-up clasts like seen in the Swift Run Formation. The cross bedding shows that the current direction during deposition was to the west; which is attributed to an ocean basin being located on the western edge of these mountains during the Silurian.
While the faulting seen exhibits dextral behavior on the northern side and sinistral on the southern side, both are evidence of West over East thrusting. On the northern fault we also found the presence of slickenlines and a brecciated layer.
The Tuscarora would have been deposited after the previous Appalachian Orogenies, the Taconian and the Acadian, and then folded broadly during the Alleghenian. Similar to that of the Massanutten Sandstone, but since it was further from the collision center not as severe deformation.
The second stop we made (Google Earth file) was further west than the first, and now the depositional environment was different. At this outcrop instead of sandstone we found river / floodplain mudstone deposits of the Hampshire Formation put in place after the Acadian Orogeny. At this outcrop there are two more folds, but less intense than the more eastern examples seen on this trip. On the northern end a very broad anticline, and a monocline on the southern end.
Here we found a plethora of smaller scale structures such as: plumose (lots of plumose), flame structures, drag folds, and ripple marks though not in citu. The most impressive to me being the flame structures which are examples of soft sediment deformation, and my first seeing them in outcrop. They are formed when the overlying heavier sediment pushes down onto the softer sediments which then propagate up giving the look of a flame.
Piling back into the vans the structural students and professor travelled the few hours back to campus. Though tired, spirits were high. The unlucky ones that gave in to slumber’s temptation found themselves bearing the brunt of Brunton compasses across their face. Once back at the school, bags and rock samples were collected into individual cars and the remaining snacks were divvied and devoured. Farewells were said, and all made way back to their homes.
I had a great time, learned / saw a lot and was too worked up to fall asleep before a reasonable hour that evening. Work was terrible the next day.
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