30 November 2019

"Devil's corkscrews" explained

An article at Smithsonian explains the history and science behind the unusual trace fossils known colloquially as "devil's corkscrews."
One of the most unusual fossils ever to be found are strange tall structures recovered across Nebraska, primarily in the state’s northwestern badlands and in neighboring parts of Wyoming. Known locally as Devil’s Corkscrews, each structure is the infilling of a left- or right-handed spiral or helix that can extend up to seven feet into the ground. At the deep end of the spiral, a tunnel extends sideways and up at an angle. These structures became exposed by weathering of the soft rock enclosing them on the sides of bluffs or ravines. They mainly occur in the fine-grained sandstones of the Harrison Formation, which dates from the Miocene epoch and are about 20 to 23 million years old...
Martin and Bennett found that the incisor teeth of the extinct beaver Palaeocastor were a perfect match for the grooves on the infillings of the Devil’s Corkscrews. These tooth marks affirmed that they were, in fact, burrows, spiraling tunnels that the beaver Palaeocastor built mainly by excavating the soil with left- and right-handed strokes of its large, flat incisors. The animal also left claw marks, but they tended to be confined to the sides and bottom of the burrows. The initial burrow extended down as a tightly coiled spiral. At the bottom, the beaver started digging upwards at an angle of up to 30 degrees to create a chamber for itself. This portion of the burrow sometimes extended up to 15 feet. 
More at Smithsonian.


  1. their article mentions that plants grew in these tunnels because there was moisture. what about light getting in that deep - plants growing with no light?

    the spiral would have made it easy to walk up and down the tunnel rather than climbing up/down a columnar tunnel.

    are there more of one spiral than the other?


  2. I thought this post was going to be about duck penises at first.

  3. The always-excellent PBS Digital Studios series Eons did a great video about these. It's worth looking up on YouTube, but I'm not responsible if you begin binge-watching the episodes like I did when I discovered them.

  4. I had the pleasure a visiting Agate Fossil Beds National Monument. It was created to preserve the devil's corkscrews or daimonelix (plus another excellent fossil bed). They are just as odd in person as they seem like they'd be in the article.
    I was there for the eclipse in 2017, they normally receive about 15,000 visitors a year. They had about 11,000 on the day of the eclipse and handled it perfectly
    I'd recommend a visit to anyone who's out on a ramble around the country and I say that because it is a little out of the way.


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