Geology is an unpredictable master, isn’t it? One minute you’re lying in bed, the next your bed is disappearing into a sinkhole. That’s what tragically happened to Florida man Jeremy Bush on March 1 as a sinkhole opened under his house and his bedroom collapsed into it. You might think this is a relatively rare phenomenon, but in Florida it’s so common, that you have to get insurance against for your home. Ironically, Mr Bush’s home had just been checked for potential sinkhole damage just two weeks before, but no signs were spotted.
As well as being very dangerous, sinkholes are also a very dramatic geological feature. Where they occur in the wild, they can even be beautiful. Either way, it is a fascinating phenomenon, so we present our Top 10 Most Interesting Sinkholes
10. Cave of Swallows, Mexico
This amazing, cave-like hole has been known to locals since the dawn of history, but was only explored by outsiders in 1966. Caused by water erosion along a fault line, it is the largest known cave shaft in the world and at 370m deep, it could fit the Chrysler Building into it. It’s a popular spot for extreme sports fans – you can abseil down it in 20 minutes, or jump with a parachute in 10 seconds. Only problem is, it takes an hour of hard, vertical climbing to get back out. So not one for amateurs!
A milder tourist activity is watching the birds that the cave is named for. Every morning, they fly out in circles until they reach the opening, and in the evening they glide back in in a kind of free-fall. It’s a beautiful spectacle and less dangerous than hurling yourself off the edge!
9. Red Lake Croatia
Another beautiful natural structure now, with this water-filled sinkhole near the city of Imotski, Croatia. Named “The Red Lake” because iron oxide has colored the surrounding cliffs a red-brown color, it is 530m deep and is the 3rd largest in the world.
It’s also home to a rare species of fish known as Delminichthys adspersus. This fish has occasionally been found in neighboring lakes and streams, suggesting that there is some kind of underwater passage between this lake and others.
8. Xiaozhai Tiankeng, China
One of the deepest sinkholes in the world, at 662m with near-vertical walls, Xiaozhai tiankeng was formed when the carbonate rock was eroded by rain and washed away, leaving a huge chasm in its place. “Tiankeng” is a word in Chinese that refers to an especially large sinkhole, and can mean “heavenly pit” or “sky hole”.
It’s a pretty amazing tourist attraction, and almost untouched. Worth a visit for keen geologists!
7. Macungie Sinkhole, Pennsylvania
Pennsylvania was recently named one of 7 states most at risk of sinkholes. And the 1986 appearance of this sinkhole in the village of Macungie is a good example of why Pennsyvanians should be very worried about that.
At lunchtime on June 23, a section of road just collapsed, leaving a gaping hole 87 feet across and 41 feet deep. Luckily, no-one was driving on that stretch of road at the time and so no-one was hurt. Had it happened a few meters away, near the houses, it would have been disastrous. As it was, it caused huge amounts of damage to the sewage and water systems, and the repairs cost $450,000. Research after the event threw up photos from the 1940s and 50s that showed sinkhole-like ponds in the area, so it was concluded that the local geology lent itself to forming sinkholes. Bet the home insurance is pretty expensive in Pennsylvania now too!
6. Bimmah, Oman
After an inconvenient, messy sinkhole like the Pennsylvanian one, it’s nice to know that sinkholes can still be things of beauty. This one, dubbed ” World’s most stunning sinkhole” by a British newspaper is in Oman and measures 40m wide. Tourists flock to see it and take a swim in it, aided by steps cut into the rock. Apparently, it also contains tiny fish that will nibble swimmers’ toes, in a similar way to a fish pedicure. A foot-nibbled outdoor swim in a sinkhole? It would certainly be a memorable one!