This amazing piece of float was located under the Route 15 Bridge in Point of Rocks, MD. My current thinking is that the lower left corner is Catoctin formation but I am scratching my head over the upper right portion. Perhaps it is also Catoctin Metabasalt just with a different, more rigid consistancy. However, the presence of micas and what look like sand sized grains suggests that this may not be the case. Or is it a lense of some sort of sandy mudstone within the Catoctin? A litte bit of research showed that the Loudoun Formation (a pyroclastic unit) overlies the Catoctin Formation discontinuously in Maryland. So does this piece show the Catoctin-Loudoun Contact? Or, another explanation is that it could be a silty expression of the Weaverton (which overlies the Catoctin formation where the Loudoun Formation is mission). Or, I could be completely wrong. Anyhow, I am open to suggestions and the Description will be updated when I can come up with a more satisfactory explanation.
By: magic-gigapans
Image: Chris Johnson, Mid-Atlantic Geo-Image Collection
License:
Creative Commons Non Commercial ⧉
Uploaded: 13 May 2020
Last Updated: 19 May 2020
548 megapixels
30,064 x 18,220 pixels
100.2 in X 60.7 in at 300dpi