The Cincinnati Anticline

There's a natural formation known (primarily to geologists) as the Cincinnati Anticline. It's a vast oval-shaped area that extends over the three-way intersection of Ohio, Kentucky and Indiana, and extending well into central Kentucky. The oval's Eastern side runs along Cincinnati, hence the name.

According to the book Elements of Geology by William Harmon Norton, the anticline is of great interest to those studying the fossil record. The anticline is almost entirely composed of Ordovician strata, and the Silurian and Devonian decrease as they approach it. Norton takes this to mean that the anticline is "an island upwarped from the sea at the close of the Ordovician or shortly thereafter."

Supposedly it's this anticline that makes much of Kentucky so rich in fossils from the ancient ocean, including the Falls of the Ohio along Louisville's riverside - and yet the Falls of the Ohio is said to be of Devonian origin, not Ordovician. I leave the matter for professional geologists to sort out.

According to a surprisingly florid bit of text in the usually dry Kentucky Encyclopedia, the anticline is also indirectly responsible for Kentucky being the thoroughbred horse capitol of the world. Early settlers noticed the geological qualities of the anticline contributed to making Kentucky a land with densely fertile soil, rich in calcium and phosphorus, and this in turn led to it being prized by horse ranchers:

"This legacy of phosphatic limestone, inherited from millions of shells and skeletons, deposited millions of years earlier when central Kentucky was an ocean bed, was now to be used to build the skeletons of horses... the phosphatic limestone which forms the basis of central Kentucky's soil has proved its efficacy."

The anticline also just happens to roughly correspond to the area affected by the 1895 Charleston, Missouri, earthquake along the New Madrid Fault (see area indicated in red in the image above).

Kentucky Earthquakes

You may have heard about the New Madrid Fault Line, which runs underneath this very region we occupy, my fellow Kentuckians.

Although not much of major seismic importance has occurred in our lifetime, we still must take note that in 1812, the New Madrid quake was an estimated 8.0 or greater. Described as "the most intense intraplate earthquake series to have occurred in the contiguous United States", it was powerful enough to make church bells ring in Boston.

A University of Kentucky website calls the Western Kentucky area "the most seismically active region in the United States east of the Rockies". And if that wasn't bad enough, to the East, we're bounded by the Southern Appalachian Seismic Zone, which is also extremely active and produces tremors that affects Kentucky greatly. We're surrounded.

July 27, 1980: Sharpsburg, in Bath County, was struck by an earthquake that measured 5.1 on the Richter scale. This quake put a huge deep crack across the back concrete patio of the my parents' home in Richmond.

June 6, 2003: an earthquake struck Bardwell, measuring 4.5 on the Richter Scale. Considerable damage was caused.

June 19, 2005: Blandville was hit by an earthquake of 2.7 magnitude. Blandville had also already been affected by the Bardwell quake two years prior.

September 2005: Sharpsburg was hit again with a 2.5 quake, 25 years after the 1980 incident.

January 02, 2006: an earthquake measuring 3.6 was recorded in Equality, Illinois (very close to the Kentucky-Illinois border). Shaking was felt in many neighboring Kentucky counties.

April 2008: The Kentucky-Indiana border at Evansville was hit by a 5.4 earthquake. The quake was powerful enough to shake skyscrapers in Chicago, 240 miles north of the epicenter, and in Indianapolis, about 160 miles northeast of the epicenter.

May 8, 2009: an earthquake measuring 2.3 was felt in Kentucky, at 36.92N 83.67W, approximately 20 miles North of Middlesboro and 35 miles Southwest of Hazard.

May 10, 2009: a 1.1 earthquake hit near Jellico, TN along the Kentucky border.

Despite its strongest shocks having taken place a century ago, some say the New Madrid Fault is just getting warmed up because it's such a very young geological feature. Wikipedia says:

Because uplift rates associated with large New Madrid earthquakes could not have occurred continuously over geological timescales without dramatically altering the local topography, studies have concluded that the seismic activity there cannot have gone on for longer than 64,000 years...