Cars and Karst

The iconic spire and dome at the National Corvette Museum in Bowling Green, KY, site of the (in)famous cave-in in 2014.

I am usually one of those people who has itineraries all planned out well ahead of time.  For my recent trip to Nashville, other than attending the symphony concert, I didn’t.  I was visiting good friends in Louisville along the way, and beyond that and arriving safely, I didn’t make plans.  Once in Louisville, I figured out I pretty much had to visit Churchill Downs (and I will be sharing those thoughts in my next post).  Beyond that, I figured I’d drive down to the hotel ahead of the concert and relax.  I briefly considered a visit to Mammoth Cave, which I had visited as a kid (on the same trip I’d visited Churchill Downs the first time) but really didn’t have time to do it justice.  Travelling south along I-65, however, I spotted a sign for the National Corvette Museum.  I like Corvettes.  I’m decidedly a GM girl when it comes to classic US muscle and sports cars, and while Firebirds are my favourite (because I owned one) I have a real fondness for several Corvettes, particularly the 1963 split-window models, the C3 Stingray, and and the latest C7 models.  That showed promise. I looked at the clock. The time change had given me an extra hour. I’d have just the right amount of time, and I’d probably kick myself if I didn’t stop.  There was also that other thing….

The last time I’d heard about this museum was in 2014, when an enormous sinkhole had opened up in the iconic spire structure that is its main display area and swallowed eight of the rare Corvettes on display there. The disaster junkie in me perked right up.  I’d heard the odd bit here and there in the subsequent years–I knew they had recovered all of the cars, but had lost track as to whether any of them were restorable, and I knew they had repaired the damage to the building.  I was curious whether they’d have a display about it, assuming that they would be focused on making everything there good as new and putting the disaster behind them.

I was wrong about that.

According to their website, more people visited the museum in the year after the disaster than had ever visited before.  It became not just a shrine for Corvette junkies, but an interesting stop for those with a fascination for local geology.  As the extent of the cave that underlies the display hall was discovered, and as the cars were delicately fished out of the hole, more and more people came to see.  As a result, the decision was made to dedicate a section of the museum to the disaster–its causes, its timeline, the reconstruction of the dome, and the fate of the eight cars.

As the presence of the massive Mammoth Cave complex a few miles to the north attests, this area of Kentucky is known for its caves and sinkholes, all the result of karst formations, where acidic water dissolves away limestone (in this case) bedrock along cracks and fissures, creating underground drainage systems that lead to caves. I became acquainted with karst features quite recently when I hiked through the Eramosa Karst conservation area just a couple of kilometres away from my home.  In this case, the karst is caused by the erosion of dolomite, rather than limestone, and the resulting caves, sinkholes, and blind valleys are relatively shallow, but I immediately understood how the collapse had happened when I learned that it was built in a karst area.

Before the National Corvette Museum was built, a thorough survey was done of the area, but failed to reveal the cave beneath the area chosen for the domed display hall.  Overnight at 5:38 am February 12, 2014, a 40-ft wide, 25-ft deep sinkhole opened up underneath the hall, swallowing eight cars.  The collapse was caught on security cameras.  It is thought that recent rains and issues with water flow and storm drainage allowed the water to seep in and subsume the roof of the large cave that was subsequently discovered.

Map of how the cave underneath the dome, and where the cars landed after the cave-in.

Eight cars fell into the sinkhole.  All were pulled out before it was repaired, but only three were deemed to be salvageable.  (More on the cars in a moment).  The museum contemplated leaving the sinkhole in place, but it was determined it would be more difficult and more expensive to stabilize it than to rebuild the floor of the dome.  Micropilings were sunk down to bedrock this time (some nearly 300 ft. deep) to support the new floor, and the hole was partially filled in.  The museum now has a whole section devoted to the cave-in, including a walk-in exhibit simulating the collapse from underground.  On the display floor itself, red and yellow lines outline the contours of the sinkhole and the cave, respectively, and a double-doored hatch allows one to peer down into the hole and helps engineers monitor the area. You can see a 3D model of what the sinkhole and cave looks like today here.

Most strikingly, however, all of the cars that fell into the sinkhole have been placed where they were before the cave-in.  GM restored two of the cars.  The one millionth Corvette, manufactured just a couple of miles away at the Bowling Green assembly plant, was discovered to be covered in signatures of the plant workers who built it;  all were saved but one, and the worker who signed it was able to re-sign the restored part. The 2009 “Blue Devil” ZR1 was also only lightly damaged and was the first to be restored. Finally, the restored Tuxedo Black 1962 Corvette was unveiled on the fourth anniversary of the cave-in.   The other five cars — the 1.5 millionth Corvette, a ZR-1 Spyder, the Mallett Z06, the PPG Pacecar, and a 40th Anniversary “Ruby Red” Corvette–were too damaged to be restored.  Because of their historic value and association with the cave-in, the museum decided to allow the wreckage to speak for itself–although they were unable to preserve the sinkhole, they were able to at least preserve the damage it wrought on the cars.  (In the case of the Ruby Red Corvette, a replacement was donated to the museum and is seen in the photo below, above the restored Black Tuxedo Corvette).

There were lots of other gorgeous, not-wrecked Corvettes on display as well  Here’s one of the last of the C2s in Marlboro Maroon (a rare colour), from 1967, and the 1969 Manta Ray concept car:

But it was the story of the cave-in–its cause and aftermath–that made this visit more than just a collection of gorgeous cars.  And I was able to bring home my very own jar of dirt from the sinkhole–they sell them in the gift shop.  It’ll find a home next to the jar full of ash from the eruption of Mt. St. Helens, another reminder of the forces of geology.