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June 4, 2020
Looking for southern Appalachian rockfall scars using a high-resolution LiDAR dataset
I was able to find what I believe to be a few examples of “boulder tracks” using outstanding LiDAR hillshade imagery from the North Carolina Geological Survey. All features shown occur in generally gneissic bedrock on extensively forested slopes that have been logged within the last century.
May 22, 2020
Slump landslide models, with some rock or debris avalanche characteristics
New from The Geo Models blog: “The model landslides in this post were produced at the same time as the Llusco landslide model I wrote about last year. They were created using a similar setup, but the slide masses behaved very differently during movement.”
May 15, 2020
A simple rift basin sandbox model with normal faults
A simple model of a continental rift basin that develops some characteristics of the real thing can be made by constructing a layered sand cake on top of two overlapping sheets of paper, one of which is anchored to the underlying board, etc. This model setup will produce an asymmetric half-graben style of basin, which has a single, high displacement breakaway fault on one side and several smaller faults on the other.
April 22, 2020
Listric normal faults with glass microbeads
Latest from from The Geo Models: Deformation associated with listric (downward flattening) normal faults produces very interesting patterns.
April 8, 2020
Virtual field trip: East Arm Morant River, St. Thomas Parish, Jamaica (pics & video)
Exploration a slot canyon with a camera between your teeth. Philip Prince takes us on a virtual tour in Jamaica’s Blue Mountains.
April 7, 2020
Interesting reverse faults in a simple extensional sandbox model
The different mechanical properties of the layers are apparent in the dip angles of the normal faults in the model. The master fault on the left side of the model (black line) is less steep in the weak microbeads, an expression of how their failure behavior differs from the stronger layers above and below.
March 25, 2020
Cracked mountaintops Part 2: Sinking summits?
Some upper Devonian sandstone mountains in the Virginia Valley and Ridge show evidence of deep-seated landsliding, resulting in the formation of a downthrown block (graben) along the summit ridge.
March 20, 2020
Cracked mountaintops of the Virginia Valley and Ridge
A newly-released LiDAR data set reveals impressive ridge-top cracks associated with large rock slides in the Virginia Valley and Ridge. While the cracks are easily visible with LiDAR hillshade imagery, they appear to be covered by normal forest vegetation and would probably look like elongated depressions in the forest.
March 10, 2020
A sandbox model without fault(s)?
Fold-thrust belts (both real and model, like this one) develop fault and fold patterns that reflect the properties of the rock (or sand-like materials) being deformed. The model section shown (shown here) is interesting because it results from shortening a granular layer sequence by 50% and does not show any major thrust fault structures that cut through all of the layers…
February 27, 2020
Where did that boulder come from? A LiDAR perspective on a large Appalachian rockfall
I have always wondered about the possibility of finding the specific outcrop source of large boulders, which is very difficult in the field due to vegetation and continued evolution of the cliff line after a boulder falls off and makes its way downhill. Using LiDAR-derived hillshade imagery of a portion of the Blue Ridge Escarpment in western North Carolina, I recently came across a particularly large boulder that appears to be traceable to a scar on cliffs hundreds of feet further up the slope.
