Posted by: Alan Pitts | April 12, 2011

Slicks in the Catoctin

In my last entry I wrote about a fault breccia found where the Blue Ridge Province meet the Valley and Ridge Province.

Today is more from the Blue Ridge Province, in the Catoctin formation in Linden Virginia, where I found some interesting features.

Here is a view from above of columnar jointing.

This looks a lot like the the columnar jointing I saw on my Structural Geology trip last year to the Limberlost Trail in Shenandoah National Park

At the base of the out crop above I found some boulders with what appear to be slickenlines.

If these are who I think they are, then they are a tectonic structure and caused from the sliding between two rock surfaces.  In the picture above the rock adjacent to it would have been moving downward.   Here are some other slicks I wrote about last year in the Valley and Ridge Province.

Here is another picture of the same area but from a different angle, what I found strange is how sections of these appear to be curved.

I found this on a nearby rock:

And these little folds:

And one more picture which is less evident, but seems to have a folded, ductile fabric to the right of my thumb.

I remember learning in structural geology that joints with slickenlines could be shear fractures but I’m not entirely sure.  I do know that this area has many natural springs which travel along fractures in the bed rock.   Another idea is that these slicks developed on wet fracture planes which encouraged slippage.


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