Posted by: Alan Pitts | May 12, 2010

Structural Geology Trip Part 4: Veach Gap

After a great day driving along Skyline Drive enjoying the beautiful scenery and blustery weather, we made our way to the fourth field area, Veach Gap.

This area was probably my favorite of the trip for the following reasons; It involved a nice hike to our study area and once we got there I saw some of the coolest structures I’ve ever seen.

This picture by one of my geology buddies Stephanie S. features myself inside my dream home.

A nice little antiform. Just large enough to house 1 Alan plus his gear. This fold here is in the Massanutten formation (also correlative with the Tuscarora) and is a clean Silurian age ( 438-408 million years ago)  quartz arenite which has been metamorphosed and folded up in a deformation event, most likely the Alleghanian orogeny . This fold seen in the picture is an asymmetric and similar fold just like all the other folds along this hill.

After taking some measurements I found the trends of the axial planes to be around 230 degrees and the plunge an average of 14 degrees.

In this next picture also by Stephanie you can see how numerous these great little antiforms are:

I’ve been calling these antiforms in order to introduce a precautionary measure when identifying “anti-shapes”. As a rule, just because something is shaped like an “A” doesn’t necessarily mean its an anticline.  In order to confidently categorize  them as anticlines, we must first be certain that they are not overturned. Which was verified when we found cross bedding further up the hill (not pictured… I know, lame). These are in fact right side up and we may safely proceed with referring to them as anticlines…(phew)

These smallish anticlines are a feature that fit in to a larger regional context . These are all parasitic folds on the Massanutten synclinorium. It is called a synclinorium because it is a synclinal structure ( oldest rocks on the outside)  with smaller folded structures along the edge.


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