3 September 2014
Here are some rugose coral fossils (along with some cross-sectioned articulate brachiopod shells) to be seen in the Clearville member (~80 feet thick) of the Mahantango Formation, exposed on the north side of route 55, just west of the West Virginia / Virginia border.
These fossils are cool in their own right (what fossils aren’t?) but here they’re serving another purpose – they’re letting us know where we are in the stratigraphic stack. This is really useful when you’re out in the Valley & Ridge, and all the strata are folded and faulted and “reshuffled” in a way that makes it hard to keep track of where/when you are. They serve, in other words, as a marker horizon. I’m grateful to Dan Doctor (USGS) for cluing me into them.