Friday 30 October 2015

'Mysterious' crack on Wyoming hillside linked to slow-moving landslip.

A group of hunters in Washakie County in northern Wyoming reported finding an apparently mysterious crack on the side of a hill in the Bighorn Mountains on Friday 23 October 2015. The crack is roughly 750 m in length, and 50 m wide at its widest, and is located about 16 km to the south of the town of Tensleep. This initially caused some alarm in the area, due to the proximity to the Yellowstone Caldera, a vast hotspot volcano that covers an area of roughly 55 by 75 km which last erupted about 70 000 and which has been suggested as a potential future hazard to settlement over a wide area of the central United States.

Large crack which appeared on the side of a hill in Washakie County, Wyoming. SNS Outfitter & Guides.

However the Wyoming State Geological Survey have suggested that the crack is more likely to be the result of a slow moving landslide, with one section of rock and soil moving slowly away from another, creating a visible crack at the surface, and have warned the public to stay away from the area as it may present a hazard to health. An underground spring is thought to have provided moisture which fueled this event, running over a layer of hard rock, through a more porous, weakly consolidated layer above. Such underground streams can lead to landslips when the pressure of pore water overcomes the cohesion of the sediment, allowing the wet layer to flow like a liquid, effectively becoming a lubricant for the movement of overlying deposits. Such events are more common in Wyoming in the spring, when rainfall is higher, but can happen at any time of year.

Detail of the rack which appeared on the side of a hill in Washakie County, Wyoming. Randy Becker.

See also....

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The United States Geological Survey recorded a Magnitude 3.4 Earthquake at a depth of 9.2 km in the Yellowstone National Park in northwest Wyoming...


A worker has been killed at the Peabody Energy operated North Antelope Rochelle Minein Campbell County, Wyoming, on Wednesday 4 June 2014. The incident happened at about 6.00 a, when...


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