For the Friday fold, let’s visit one of the more scenic locations that I visited on my Inner Piedmont field trip, Boomer Falls.
The contact here is between the Walker Top Granite and sillimanite schist. The contact is mylonitic, and shows drag folds, so I’m labeling it as a fault:
Here’s the sillimanite in the schist:
Here’s a granite dike, cross-cutting the Walker Top in float:
Garnet herd and a sigma porphyroclast (also seen in float):
Some of the mylonitic layering, once again seen in float (the actual outcrop was covered in slime):
So where are the folds? Here’s a isoclinally folded vein in the schist:
Here’s a fold in the foliation of the sillimanite schist:
The field trip crew had a nice time exploring the site:
There aren’t too many places I’ve visited where you can clearly identify sillimanite in hand sample. I guess I’ll add this stop on my next pilgrimage to the Appalachians.