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May 14, 2019

Back to the Rocky Mountain Front Range…thrust faults at a thick-skinned structural front

This post steps back to the Rocky Mountain Front Range models from a few weeks back in which I used a model that took a large-scale perspective on the Front Range for comparison to some published work.

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April 29, 2019

The landslide that is too big to notice

The southeast slope of Sinking Creek Mountain in Craig County, Virginia hosts what is certainly one of the largest landslide complexes in eastern North America–and possibly the least noticeable. Despite extending for 15 miles (25 km) along the mountainside…this group of translational blockslides was not documented until 1986 by Art Schultz of the USGS.

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March 25, 2019

A sandbox model perspective on the tilted sedimentary layers of the eastern Rocky Mountain Front Range

One of my earliest recollections as a geology student was a discussion of the upturned sedimentary rocks in The Garden of the Gods at the eastern foot of the Rocky Mountain Front Range in Colorado. I distinctly remember hearing about the vertical movement of a large block of crust, which would ultimately produce the high mountains, tilting the overlying sedimentary layers out of its way as it rose.

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March 7, 2019

The Breaks rock slide: Revisiting Schultz and Southworth (1989) 30 years later

By Philip S. Prince, Virginia Division of Geology and Mineral Resources (Scroll down for summary video link) The Breaks rock slide, a large slide feature at the western edge of the Appalachian fold-thrust belt, was first described 30 years ago in Schultz and Southworth (1989). In an impressive display of imagery analysis and general geologic know-how, the authors successfully identified several large but topographically subtle ancient landslide features without the …

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February 26, 2019

Some examples of the geology of “gaps” and travel on the early American frontier

The topographic features of the Powell Valley Anticline (PVA) played a significant role in the lives of both indigenous and Euro-American peoples on the American frontier in the late 18th century… Here I focus on two subjects inextricably connected to PVA topography: The Wilderness Road and Robert Benge, also known as Chief Benge, Captain Benge, Bob Benge, or simply “The Bench.” Benge and Wilderness Road users had two very opposite goals, leading to numerous clashes and Benge’s ultimate demise in the mountains of the PVA.

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February 15, 2019

A LiDAR perspective on a 1965 geologic map

…how much existing geologic maps, particularly those produced without any digital topography or remote sensing, could be enhanced by checking them against LiDAR hillshade. The answer varies, and to continue the Powell Valley Anticline discussion, I draped a 1965, hand-drafted geologic map over the new LiDAR hillshade background.

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February 12, 2019

Southwest Virginia’s Powell Valley Anticline has never looked so good…

The Mississippian-aged sedimentary section in the northeastern portion of Virginia’s Powell Valley Anticline (PVA) offers up stunning hillshade imagery on the flanks of the aptly-named Cliff Mountain.

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February 4, 2019

An Appalachian karst landscape seen in LiDAR hillshade

By Philip S. Prince, Virginia Division of Geology and Mineral Resources Karst landscapes are really cool to look at with good hillshade imagery. In the sedimentary Appalachian Valley and Ridge, karst systems aren’t terribly hard to find. Carbonate rock units susceptible to karst development are distributed throughout nearly all of the Appalachian sedimentary section, from Cambrian- to Mississippian-aged units. Stratigraphy does vary somewhat along strike; Mississippian carbonates that are prolific …

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January 28, 2019

LiDAR hillshade imagery highlights topographic evolution of the southern Appalachian Valley and Ridge

Hillshade imagery brilliantly highlights the alluvial fans developed along the southeast slope of Brumley Mountain in the southwest Virginia Valley and Ridge. The fans represent an interesting stage in the topographic evolution of Brumley Mountain and the Valley and Ridge in general, whose namesake results from different rock types producing different types of topography.

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January 22, 2019

The Mapenduma Anticline: “Wood-chipper” erosion along a tropical thick- skin mountain belt

The island of New Guinea offers outstanding examples of just about any type of type of tectonic process you might want to see, and the Mapenduma Anticline of West Papua, the Indonesian-administered northwest half of the island of New Guinea, is no exception.

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