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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.


December 13, 2019

Redoubt’s big impact 30 years ago

On December 15, 1989, a pilot who had flown a 747 passenger jet all the way from Amsterdam was looking forward to landing in Anchorage. There, he would take a short break before continuing to Tokyo.


December 4, 2019

There are tension gashes in my yogurt (but I ate it anyway)

As a student, I thought the gash patterns were great, but I always struggled to understand their relationship to shear zone orientation in the context of the stress field…This is where the yogurt comes into play. Some very nice en echelon tension gash sets appeared in my Greek yogurt a few weeks ago when I squeezed the plastic container.


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.


October 17, 2019

Simulating varying rock strength to create an interesting model anticline

From The Geo Model: Modeling the Aguaragüe Anticline, a structure in the sub-Andes fold-thrust belt in northwest Argentina.


October 11, 2019

Searching for the deepest gorge in the Appalachian Mountains

The question of the deepest gorge east of the Mississippi River came from a reader of the “biggest mountains” post. I think it’s a really good question because it addresses another landscape superlative (deepest, tallest, oldest, etc.) that is claimed by several locations in the Appalachians.


October 8, 2019

An interesting geothermal energy prospect in the Vienna Basin…and its connection to oil and gas

In effect, the hydrogeothermal project is doing just what oil and gas exploration does–looking for and extracting desirable fluids in the subsurface. In this case, the desirable fluid is hot and readily flowing water…


September 28, 2019

Searching for the “biggest” mountain in the Appalachians…and why is “biggest” in quotes?

A recent visit to Cattail Peak (6,583 ft/2,006 m), a summit in North Carolina’s Black Mountains, left me wondering where the most topographically prominent peaks and biggest possible summit climbs in the Appalachians are located.


July 10, 2019

Using sand models to explain the concept of geologic mapping

Geologic maps can be very visually engaging, but non-geologists may find it difficult to extract the information that a map is supposed to communicate…. Cross sections included with a map can help, but it can still be tough to pull it all together if you don’t look at this sort of material all the time.