I came across this little gem of a fault propagation fold last year while driving back from Washington DC along Corridor H (Highway 48) in eastern West Virginia.


If you don't know or remember what a fault propagation fold is, it's a thrust-related fold where part of the displacement on the fault goes into faulting new rock ahead of the fault tip, and part of the displacement goes into folding, or bending the layers above the thrust.

In this particular outcrop, the thrust ramp has propagated along cross beds in the Tuscarora Sandstone.  This complicates the classic fault propagation fold geometry that we might see with originally horizontal stratigraphy (as shown in the image above), but it's still a fault propagation fold.  What's nice here is that it's possible to match beds that were cut by the thrust and see that displacement decreases toward the fault tip: a diagnostic feature of fault propagation folds.  The fault tip is also visible in outcrop.

In the 3D image below, click through the annotations to see how the thrust has propagated up-section.  There are several other fault related folds in the view.  Can you find them?  Try clicking the full screen button on the bottom right for the full view.
(This will work best in Chrome or Firefox, but possibly not as well in Internet Explorer).  

This is a press release about some funding I received from NRCCE to study fractures in shale outcrops to develop a "fracability index" and relate fractures in outcrop to those in the subsurface.

Here's my first attempt at creating a 3D outcrop.  Changing spatial perspective is very important in structural geology, and models like this can open up new ways of visualizing and analyzing geology.  In this case, I'd like to document fracture sizes and scaling in 3D (more on that below)

The Devonian Helderberg Group is exposed along large roadcut on Highway 48.  These predominantly limestones were deposited in an epeiric sea that existed between the Taconic highlands to the southeast and the Cincinatti and Algonquin arches to the west (Smosna, 1988).  The unit has been evaluated as a possible seal for CO2 sequestration purposes associated with the Burger electric power plant (Lewis, et al. 2009).

My interests in digitizing the outcrop are mainly in testing the photogrammetry technique for the purposes of documenting fracture network geometries in 3D.  This outcrop is actually fascinating to view from different angles, because several different fracture sets come into view depending on how we rotate the model.

• Rotate the view looking from left to right and you can see the white faces of calcite filled fractures
• Once your eye is trained on the calcite filled fractures, rotate the model the other way and the spacing between those fractures becomes much more obvious.
• As you look closer, you might also notice at least 1 other fracture set whose faces are stained reddish brown.

I can't wait to dive into this a bit further, especially using these 3D models to help with digitizing fracture data while on the outcrop.  There's also great potential for generating orthorectified images of the cliffs in various orientations that are conducive to fracture measurement.


I'll post another outcrop when I get a sec.

Lewis, J.E., McDowell, R.R., Avary, K.L., Carter, K.M., 2009. Characterization of the Helderberg Group as a geologic seal for CO2 sequestration. Environmental Geosciences 16, 201–210.
 
R. Smosna, Paleogeographic reconstruction of the Lower Devonian Helderberg Group in the Appalachian basin in N. J. McMillan, A. F. Embry  and D. J. Glass (eds.), Devonian of the world: Canadian Soc. Petrol. Geol., v. 1, p. 265-275, 1988.

Having left this "News" section empty for a while, I thought I'd post something fun.  I've purchased AgiSoft Photoscan to reconstruct 3D surfaces from photogrammetry.  Here's my first attempt at reconstructing the top of a landslide that's active at Dorsey's Knob Park in Morgantown.

The 3D image is a bit incomplete, but what you're looking at is a series of fault scarps where each break in the asphalt marks a series of "fault cutoffs".  Notice that you can see a yellow parking line in the middle block that was connected to the bock above.  Also notice the series of poles (originally vertical and in a row) that have been transported and locally rotated due to the internal deformation of the slide.  I hope to return and get the whole scarp when I've perfected the technique.

I plan to use this technique to reconstruct fracture geometries in 3D, similar to the LiDAR based technique including this excellent study: Wilson, C.E., Aydin, A., Karimi-Fard, M., Durlofsky, L.J., Sagy, A., Brodsky, E.E., Kreylos, O., Kellogg, L.H., 2011. From outcrop to flow simulation: Constructing discrete fracture models from a LIDAR survey. AAPG Bulletin 95, 1883–1905. doi:10.1306/03241108148