Wednesday, March 24, 2010

Meteor Crater


1. Nuclear holocaust
2. Super-virus
3. Climate change
4. Vampire-Robot-Nazis-Zombies take over the world

The list goes on and on…

One of the most frightening doomsday scenarios is something that will eventually occur; our planet’s collision with another extraterrestrial body. The idea that something could strike Earth wasn’t seriously recognized until scientists first began searching the vastness of space for the objects. And while in this case the expression “trying to find a needle in a haystack” is dead on, it’s much more difficult than that. To help understand the effects of an asteroid’s impact, scientists began to look for evidence of impacts here on Earth.

Meteor Crater

Today, what is the largest and considered to be the best conserved impact crater on Earth is Meteor Crater in Arizona. Approximately 43 miles east of Flagstaff there is a landmark so breathtaking that its image takes you back 40,000 years. At the time, this dessert was still open grassland dotted with woodlands inhabited by woolly mammoths and giant ground sloths. Perhaps on what was a crisp, summer morning, the creatures raised their heads to a bright light. The meteorite would have been the brightest thing in the sky for a few seconds during its descent into the atmosphere. Traveling at 28,600 mph (12.8 kilometers per second), the chunk of nickel and iron slammed into the ground like a golf ball in a sand trap.

satellite image of Meteor Crater

The resulting damage was immense, leaving a crater 4,000 feet (1.2 Km) in diameter and 570 feet (170 meters) deep. Believed to have been around 50 meters in diameter, scientists speculate that about half of the meteorite’s weight (300,000 metric tons) was vaporized in its descent.

While looking at the crater it’s obvious a lot of energy was transferred into the ground, although most of it was actually projected skywards. 30 tons of meteoritic iron were scattered within a 4-5 miles radius of the impact site. Closer to the crater’s lip is a 150 foot (45 meters) high rim composed of the debris.

When scientists checked if humans would have inhabited the area during this time, it was proven that most likely no one would have made their way to America yet. The crater’s existence did not become known to modern men until European settlers stumbled across it in the 19th century. Dubbed “Canyon Diablo crater”, it was believed to be the result of volcanic forces. The idea did not harbor much criticism since the San Francisco volcanic field only lies about 40 miles (64 Km) to the west.

It wasn’t until 1903, when a mining engineer and businessman by the name of Daniel Barringer suggested that the crater had been formed by a meteorite impact. Through research, Barringer found small pieces of meteoritic iron that were mixed with rocks on the crater’s border. He knew that if the meteorites had fallen at a different time from that at which the crater was formed, they would have been lodged in distinct, separate layers in the surrounding soil. In fact, upon closer examination these different classes of rock were set in the opposite order of the underlying bedrock. When Barringer found no volcanic rock near the crater, scientists began accepting his theory as the reality. To see the effect of an impact of extraterrestrial bodies, watch the simulation below.

Thinking he was sitting on a gold mine, Barringer's company, the Standard Iron Company, purchased 640 acres around the crater for private use. While it was estimated 300,000 tons of iron could be harvested from the site, later research found the material unusable for manufacturing purposes.

Did you know?- Barringer made attempts to find what remained of the meteorite for 27 years. Since impact physics was poorly understood at the time, Barringer was unaware that most of the meteorite had vaporized on impact. Over the years he would drill to a depth of 1,376 feet (419 meters) with no significant finding of iron.

mining site inside the crater

Today, the Barringer family continues to own the surrounding area around Meteor Crater and has turned the feature into a popular tourist attraction. Next to the crater is the Meteor Crater Visitor Center that contains interactive exhibits and displays about meteorites and asteroids, space, the solar system and, comets. Also, interestingly enough it contains the American Astronaut Wall of Fame. The center also contains a movie theater, gift shop, and observation areas with views inside the rim of the crater. Guided tours of the rim are offered daily through their website

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