6 May 2013

Brallier Formation 1: primary structures

Posted by Callan Bentley

Last week, I mentioned some geologizing with the family in the Staunton area. The furthest west we ventured was to the road connecting Deerfield, Virginia, with West Augusta. There, the Brallier Formation is well exposed in a dramatic roadcut.

Explore it for yourself in this M.A.G.I.C. GigaPan:


The Brallier is turbidites, shed off the Acadian Orogeny during the Devonian, kind of like Martinsburg Formation is turbidites shed off the Taconian Orogeny during the Ordovician.

I saw plenty of trace fossils there…

There were also some non-biogenic primary sedimentary structures, like graded beds:

Here are two mud chip rip-up clasts in a graywacke block:

A few blocks showed Bouma sequence details:

I’ll return to this same site tomorrow, for a look at the secondary (tectonic) structures…