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You are browsing the archive for The Geo Model Blog Archives - The Field.

January 11, 2021

The Ray Sponaugle well: A 13,000-ft lesson in Appalachian Valley and Ridge structure

“To the surprise of the drillers and geologists involved with the project, the well bore never got anywhere close to the Cambrian quartzite. At 10,000 ft (3,010 m) below the surface, the well passed through a thrust fault and entered a tight, nearly recumbent syncline cored by the same Ordovician shale unit into which drilling began.”

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December 4, 2020

Lidar hillshade imagery hints at the location of a future coal spoil landslide

A coal spoil landslide in southeastern Wise County, Virginia, appears traceable to a faint scarp visible in the spoil pile in a 2017 lidar dataset. The slide pre-dates October 2019 Google Earth imagery and post-dates the 2017 lidar data acquisition.

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October 15, 2020

Normal fault, reverse fault, or both?

The new model, whose color scheme is admittedly quite shocking (think Pepto-Bismol bottle), is shown… The interesting fault is at the center of the image. The fault is traced in black in the lower image, with arrows indicating movement sense.

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October 5, 2020

Interesting “sideways” movement of a large sandstone blockslide

A large sandstone blockslide in Highland County, Virginia presents an unusual appearance in LiDAR hillshade imagery–it appears to have moved sideways across a slope instead of directly down the slope.

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September 24, 2020

LiDAR reveals the cloth-like appearance of a “wrinkled” translational landslide

The Virginia Valley and Ridge hosts plenty of amazing landslide features, but this wrinkled translational slide in Botetourt County, Virginia is particuarly eye-catching. It reminds me of the wrinkling that might occur in a thin layer of cloth pushed along a smooth surface–something like pushing a napkin or tablecloth along a tabletop.

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September 14, 2020

The interesting geologic setting of Thomas Cole’s “The Oxbow”

New from The Geo Models blog: “Earlier this year, I became aware of the longer, geographically-specific title and learned that the painting does portray a real location with a particularly interesting geologic context…. Cole’s vantage point on Mt. Holyoke is east-northeast.

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August 28, 2020

The Geo Models: Landslides associated with historic iron mining in the Virginia Valley and Ridge

The sharpness of these landslide features suggests they may still be slowly moving, but very little disruption to vegetation is visible in satellite imagery, so movement is probably very slow. Since their maximum age is known (the time of mining; late 1800s-1920s), they offer interesting comparison to older, natural landslides in the area, which tend to have softened, rounded features due to weathering and erosion.

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July 28, 2020

Fault-propagation folds in a sandbox model

New from The Geo Models: “These anticlines are recognizable as fault-propagation folds because the fault that offsets the deepest blue layer does not cut upward through the entire section. Displacement along the fault at depth is accommodated by folding of the overlying, un-faulted layers.”

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July 21, 2020

Is this Florida’s most famous landslide?

New from The Geo Models blog: “I asked Google and was rewarded with a vintage paper called…wait for it…’A Florida Landslide.’ Written in 1948 by Richard Jordan of Florida State, the paper describes a surprisingly impressive landslide that occurred in Gadsden County, Florida…”

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July 17, 2020

Anticlines and synclines in exhumed model rift basins

Several Mesozoic rift basins have been exhumed along the Atlantic margin of North America, creating interesting patterns in sedimentary rock layers and igneous intrusions that originated during the breakup of Pangaea.

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