It Came From Outer Space

Nestled in the rolling hills of Central Kentucky, the quaint little town of Versailles is a welcome respite from the rigors of city life. It is better known for its picturesque scenery of Thoroughbred horse farms and the fine bourbon whiskey produced in the region, but there is evidence of a violent catastrophe that struck the region long ago, in the Paleozoic.

The Versailles “cryptoexplosive” is an enigmatic 1.5 km circular structural feature located a few kilometers north of the town. The structure was originally referred to as ‘crypto'(ie, hidden) because an explanation for this, and a couple of other similar structures in the region, was lacking.

At the time, it was thought that a plume of water enriched magma approached the surface; out gassed, and then the structure collapsed-resulting in the features now observed at the surface(I’m not a tectonic guy, so could someone explain how a water rich magma can be found this far from a convergent boundary; are there examples??? Or, was this before the mechanisms of Plate Tectonics were understood?).

By the ’60s, geologists began to recognized the similarities of the structural features of the Versailles abnormality to other structures that were better explained as extra-terrestrial, in nature. In the ’70s, geophysical surveys were conducted in the area in an effort to determine whether, or not, the abnormality was an at-depth structure associated with mantle plumes, or whether the structure was a shallow feature that was not associated with the basement tectonic features observed in the region.

While lacking primary structures such as shatter cones or shocked quartz, the consensus among geologists, due to structural features, is that the Versailles cryptoexplosive is the eroded remains of an impact of a meteoroid.

USGS 7.5 min quad of the area(Versailles Ky)

Cross section of structure(again, from the USGS quad)

Explanation(from same)

Google relief map of the area(annotated)

Further reading and references:

A shallow seismic refraction study of the Versailles cryptoexplosion structure, central Kentucky.
Harris, 1990

The Geology of Kentucky
USGS

Earth Impact Data Base

Geophysical Investigation of the Versailles, Kentucky, Astrobleme(pdf)
SEEGER

Kentucky Academy of Science: 92 annual meeting(pdf)

Addendum-the stratigraphic nomenclature of the area has changed; now, the Cynthiana is recognized as part of the Lexington Limestone. The Million Shale of Nichols is now known as the basal part of the Clays Ferry Fm.

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4 Responses to “It Came From Outer Space”

  1. Roy Says:

    Very cool. It doesn’t seem to stick out as much as other impacts I have seen. Is it at all obvious or suspect from ground level?

  2. Shamalama Says:

    Don’t forget about the Serpent Mound Crater near Louden, OH. I think it’s neat to be able to see evidence for past meteor impacts preserved in this way. We may not have a clear crater with walls and a smoking bolide but the fact that we can infer what happened is so cool.

  3. Solius Symbiosus Says:

    There are a couple of nice ones in Tn, too… the Wells Creek and the Flynn Creek

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