Impact craters on the Earth
It's a lively place, the surface of the Earth. The rain falls, the winds blow and the sands drift, and over a slightly longer period, the continents move about and recycle large chunks of the planet's crust. So impact craters may appear at a steady rate, just like they do on the other planets and satellites, but after a while, erosion means that they cease to be visible. In any case, most of the Earth is covered in water most of the time, so smaller impacts make a splash but do not leave a permanent record.
The best place to hunt for craters is in areas such as the Canadian shield where a flattish, rocky surface has been exposed to celestial bombardment for hundreds of millions of years.
In addition, all this hustle and bustle means that there are always several possible explanations for any crater-like object on the Earths surface. It could be a sink-hole made by rain falling on limestone, or a leftover bit of a volcano, or a bay caused by the natural action of the sea. The one that I investigated during my university fieldwork, St Magnus Bay in Scotland, is now generally regarded as a sort of glacial/marine double act.
So any list of the Earth's meteorite craters should be filled with caveats. But the top ten more or less visible craters should probably look something like this:
- Meteor Crater, Arizona the world's top tourist crater
- Clearwater Lakes, Quebec, Canada a classic double impact feature like many seen on the Moon
- Sudbury, Ontario, Canada a huge 60km by 30km structure about 1.8 billion years old and now mined for nickel and other metals
- Lake Manicouagan, Quebec, Canada about 212 million years old and 70km across. Described by the local tourist board as “wild yet accessible”
- Chicxulub, Mexico hard to see, like the dinosaurs it may have killed off
- Ries Kessel, Bavaria, Germany “crater” is the Latin word for a cup but the Germans call it a kettle or cauldron
- Henbury, Australia a set of craters about 42,000 years old
- Roter Kamm, Namibia tough to get to but the satellite images are spectacular
- Tenoumer, Mauritania same applies
- Wabar, Saudi Arabia remote group of craters first described by British traveller St John Philbyand now yielding interesting meteorite science