On this date in 1972 "December Giant" the largest sinkhole in the US collapsed in Alabama. 10 facts about sinkholes:
What is a sinkhole? Basically a hole in the ground where surface rock, usually something easily eroded, like limestone, has dissolved over time. Most sinkholes are caused by karst processes, ie the chemical dissolution of carbonate rocks.
Sinkholes can also be caused by human activity such as abandoned mines collapsing or water main breaks.
They can be just several inches across, or they can be vast. The deepest and largest sinkhole in the world is the Xiaoxhai Tiankeng in China which 660m deep, with a volume of 130 million cubic metres.
According to the U.S. Geological Survey, Alabama, Florida, Kentucky, Missouri, Pennsylvania, Tennessee, and Texas are the states where sinkholes are most common. That said, the same survey puts the probability of a major sinkhole occurring in any given year at about 1 in 100.
In Florida, you can get insurance against sinkholes happening on your property.
Sometimes there is a sudden collapse with virtually no warning, but others form more gradually. It’s possible, if you live in a high risk area, to know the signs to look out for. These include fence posts or trees sagging and leaning; doors and windows not closing properly and rainfall collecting in an area where it didn’t before.
If a sinkhole is caught early, it’s possible to inject grout into the hole to rebuild a foundation over the degrading bedrock.
Sinkholes are known by other names in some parts of the world. For example, in the Yucatán Peninsula in Mexico they are known as cenotes. These often expose underground rivers and caves, and were used by the Mayans as places to hide treasure or for human sacrifice. If you visit a cenote, it’s the done thing to ask the protection of the Mayan gods, so there will be no further collapses while you are in there.
Ancient sinkholes along coastlines, which flooded as sea levels rose, are known as Blue holes. They are so called because of the deep blue colour of the water. They are like vertical caves and are home to many species of marine animal, but divers need to be extra careful because it is hard to gauge how deep you’re going.
Sinkholes don’t just happen on Earth. Some were found on the comet 67P/Churyumov-Gerasimenko by the Rosetta space probe.
Christmas is coming!
A Very Variant Christmas
Last year, Jade and Gloria were embroiled in a bitter conflict to win back their throne and their ancestral home. This year, Queen Jade and Princess Gloria want to host the biggest and best Christmas party ever in their palace. They invite all their friends to come and bring guests. Not even the birth of Jade's heir just before Christmas will stop them.
The guest list includes most of Britain's complement of super-powered crime-fighters, their families and friends. What could possibly go wrong?
Gatecrashers, unexpected arrivals, exploding Christmas crackers and a kidnapping, for starters.
Far away in space, the Constellations, a cosmic peacekeeping force, have suffered a tragic loss. They need to recruit a new member to replace their dead colleague. The two top candidates are both at Jade and Gloria's party. The arrival of the recruitment delegation on Christmas Eve is a surprise for everyone; but their visit means one guest now faces a life-changing decision.
Meanwhile, an alliance of the enemies of various guests at the party has infiltrated the palace; they hide in the dungeon, plotting how best to get rid of the crime-fighters and the royal family once and for all. Problem is, they all have their own agendas and differences of opinion on how to achieve their aims.
Not to mention that this year, the ghosts who walk the corridors of the palace on Christmas Eve will be as surprised by the living as the living are by them.
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