1 February 2012
Today, two examples of outcrops that reveal an overprinting relationship between metamorphic cleavage and sedimentary bedding. Both are Devonian in depositional age, from the new stretch of New Route 55 in West Virginia, west of Moorefield. The first is from limestones of the Helderberg Group, and the second is from shale of the Brallier Formation. In both cases, the metamorphic overprint came during the late Paleozoic Alleghanian Orogeny, the mountain-building episode that closed the Iapetus Ocean and built the supercontinent Pangea.
“Bedding/cleavage relationships” — it sounds so lascivious! But it’s really quite tame.
So are these rocks sedimentary or metamorphic?
I’d say the answer is, “yes.”