Impact Crater
Written by Jerry Coffey
There is an impact crater in nearly every country on Earth. Every continent can boast at least one. Some of the oldest are over two billion years old and the most recent, near the Tunguska River in Siberia, is just reaching 100 years old. The asteroid 2008 TC3 hit the Earth last year, but it burned up in the atmosphere. It left a pretty light show, but no impact crater. The Earth has nearly 200 impact craters, but only 46 of them are considered to be of significance. We will go over four of them, today.
Wilkes Land
Wilkes Land impact crater is Antarctica's biggest claim to fame. It has not been verified yet, so it can not be “technically” called an impact crater, but when it is it will become the largest one on Earth. The crater is around 550 km across. Some people break in down into two separate craters, but that is only conjecture. The crater can not be verified because it is under more than 2km of ice.
Vredefort Crater
Vredefort Crater is currently the king of craters. It is the largest verified crater on Earth (that's why I stressed that Wilkes Land is not verified yet). The impact crater has a diameter that is roughly 250-300 km. It is hard to be exact because of the effects of erosion over the 2 billion years of the craters existence.
Chicxulub Crater
The Chicxulub Crater is important because it is thought that the asteroid that formed it caused the death of nearly all of the dinosaurs on Earth 65 million years ago. The widespread climate changes killed plant life as well. The impact crater is more than 180 km in diameter, making it the 3rd largest on Earth. It also has a ring of sinkhole(cenotes) around its rim.
Sudbury Basin
The Sudbury Basin crater is the second largest in the world. It is the largest impact crater in Canada. Sudbury is located near a number of other geological structures including the Temigami Magnetic Anomaly. The large impact crater filled with magma contain several profitable ores. Currently nickel, copper, platinum, palladium, and gold are mined from the area. The Sudbury area is one of the largest mining communities in the world.
The four impact craters mentioned above all have a unique claim to fame, but there are many more craters that are of great interest to astronomers and geologists alike. There are also several other sites that are unverified that may well change the current face of astronomy and science.
There are a couple of really good related articles here on Universe Today and an excellent episode about craters on Astronomy Cast.
Filed under: Astronomy
