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February 10, 2020
The Pigeon River is perched, which is geologically bad news for it
At Canton, North Carolina, the headwaters of Hominy Creek, a French Broad River tributary, are VERY close to capturing the Pigeon River. In human terms, this is still probably a long way off, but it is most certainly geologically “imminent.”
February 3, 2020
The mountain that has it all (at least it did in the pick-and-shovel days)
Back in 1830, The Catawba Iron and Coal Company got an outrageous deal on a plot of land at the foot of North Mountain in western Botetourt County, Virginia. Within about 1 square miles, coal, iron ore (oxide), and high-purity limestone could be mined, and thick layers of quartz pebble conglomerate could be quarried for much sought-after millstones.
January 23, 2020
Denali Park Road failings and other stories
By the summer of 2020, a landslide will bury a portion of the road from the Denali National Park entrance to Wonder Lake. That’s the conclusion of Zena Robert, a UAF graduate student who visited the park in summer 2019. Last summer, she did a ground survey of giant blobs of frozen hillside that sometimes ooze over the 92-mile road, which workers built from 1923 to 1938.
Discount inverted basin models: You get what you pay for (mostly)
A basic Google search of “inversion geology” will produce a tremendous number of results, including conceptual illustrations, analog model results, and actual cross sections generated from subsurface imaging and drilling exploration.
January 13, 2020
An abandoned river valley and the “true depth” of Appalachia’s deepest river gorge
This post centers around an oddly meandering, dry valley 800 ft above the northwest wall of the gorge. It’s not much to look at in Google Earth imagery alone, but with enhanced maps and some understanding of how river gorges spread through topography, it gives great context for different ways of thinking about gorge development.
January 6, 2020
Surface uplift and deep fault structure in sandbox models
A particularly interesting method of attempting to understanding deep fault geometry is using patterns of surface landscape evolution to identify the moving zone of uplift above a deep fault ramp. A useful analogy for this concept is to visualize sliding a spatula underneath a cooking egg.
December 19, 2019
Spreading volcano follow-up: Cross sections showing normal faults and thrust faults
Geo Models: The GIF shows the results of about 15 minutes of deformation with fresh sealant straight out of the tube. The summit of the cone collapses into a graben, and the flanks of the cone spread outward, creating compression that generates thrust faults and folds.
November 19, 2019
A different take on the model volcano, the “most cliché science experiment” you can do (at least that’s what the internet says)
While eruptive demonstrations will always be cool, I think the gravity-driven structural evolution of large volcanoes is equally interesting and consequential and subject to illustration with models.
October 30, 2019
“Oreo cookie” stratigraphy and the geologic setting of the Frog Legs Gorge
While the “frog legs gorge” post was supposed to be a bit funny, the real purpose of it was to link outcrop patterns with geologic structure. This follow-up post tries to put the frog legs’ underlying structure into a broader context within the Appalachian Valley and Ridge…
October 22, 2019
Google Earth and a simple model explain a weird pattern seen in LiDAR hillshade
Is this a bizarre and gigantic fossil discovery? An unsolved mystery akin to the face on Mars? Unfortunately, this is just another set of compressional folds within the Appalachian Valley and Ridge, but they do stand out in the hillshade due to their interesting topographic pattern.
