|1962 Black Corvette|
The museum estimated millions of dollars in damage. The sinkhole was approximately 40 feet in diameter and 20 feet deep.
What causes sinkholes? A glimpse at this fascinating map of Kentucky groundwater flow routes confirms the well-known fact that sinkholes are not uncommon there, given features with such names as "Sinking Creek", "Auburn Bluehole," and "Lost River Rise."
|Simplified geology of Kentucky|
The Mississipian rocks of western Kentucky are comprised mostly of limestones, shales and sandstones. The limestones contain a oil reservoirs underground and where exposed at the surface, the limestone is quarried--the Reed quarry producing more limestone than any other quarry in the U.S. The limestone also includes Mammoth Cave, part of the Mammoth Cave-Flintridge system, the longest cave system in the world. These limestones were deposited in shallow seas.
|Karst features from UTexas here.|
CaCO3 + CO2 + H2O → Ca(HCO3)2
There is a similar reaction for aragonite, a magnesium containing carbonate that is another common component of limestone. The dissolution of calcite and aragonite produces caves underground. The caves are often connected through fissures leading to extensive networks. As the dissolution proceeds over time, the caves approach the surface and when the surface rocks or soils can no longer support the load of trees or human structures, they collapse, producing sinkholes. Notice also the sinking streams on the illustration, and the name of the stream "Sinking Creek" mentioned above.