I took my structural geology students to that fine outcrop of the Swift Run Formation in eastern Shenandoah National Park on Friday. There, we saw lovely primary structures with tectonic fabric overprinting (as I have showcased here previously). Consider this graded bed with subsequent (vertical) cleavage:
And here’s the hinge of a nice passive fold, bearing well-developed axial plane cleavage:
Annotated:
Close-up of the cleaved central bed:
