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Arizona's crater site fascinating glimpse into science
Wow, what a hole in the ground! When that meteor hit, I bet it got the attention of the mammoths, sloths and whatever other prehistoric creatures were around back then. Not exactly a scientific response, but it was my first impression of Arizona's Meteor Crater.

About 50,000 years ago, the crater was created in less than 10 seconds when a meteor about 150 feet across slammed into what is now Northern Arizona's Colorado Plateau at an excess of 26,000 miles per hour. Vaporizing on contact, it left behind a crater that is more than 550 feet deep and nearly a mile across. Can't comprehend those numbers? Imagine 20 football games being played at the same time on the crater floor with 2 million fans seated along the crater walls. A 60-story building wouldn't reach the rim.

There are other meteorite impact craters in the world, about 150 are known, but this was the first proven and, thanks to dry desert conditions, is the best preserved impact site on earth. Since Meteor Crater is so similar to craters on the moon, NASA's Apollo astronauts trained here. There is an actual test capsule on display.

The best place to start the visit is with the 10-minute film "Collisions and Impacts," shown in the 80-seat, widescreen theater in the Discovery Center. This may be a good time to clear up some confusion about meteors and meteorites. A meteor is an object in the sky. Those shooting stars we see at night are usually quite small, some even dust particles. When a meteor hits the ground, what remains is a meteorite. The Arizona crater is officially known as Barringer Meteorite Crater.

The hourly guided tour, included in the cost of admission, starts just outside the theater doors and 15 minutes past the hour. It is a one-mile, roundtrip walk along the rim of the crater on a dirt path. The tour lasts 45-60 minutes. Be sure you wear appropriate footwear and dress for the weather. Summers can be more than 100 degrees and winter temperatures well below freezing. High winds are common in the area. There is a T-shirt that reads "I Survived the Wind at Meteor Crater" that can be appropriate.

A large group congregates around the 1,406 pound Holsinger Meteorite. Even if you aren't taking the tour, stop to listen to the lecture and to touch the meteorite. This is the largest fragment of the parent meteor that produced the crater. It probably broke off from the main meteor in the atmosphere and fell as a separate piece. All the little indentions and ridges on the outside of the rock formed as it burned and melted during its trip through the extreme friction of the Earth's atmosphere.

About half of the group goes on the guided tour while the others either look through the large window at the crater or venture out on the viewing platforms. A variety of telescopes are focused on items down in the crater. A short cement path with stairs leads down below the rim a short distance. The public is not allowed to hike down to the bottom of the Meteor Crater

The Discovery Center answers many questions about meteors. Scientists track potentially hazardous objects, such as asteroids that might cross Earth's orbit and impact the planet.

A Rogue's Gallery, a large wall display, shows 10 of these named objects, their relative distance from Earth, their estimated arrival date and how close they will pass. I carefully study each display until I'm assured that none pose a serious threat to Earth. I learn that several thousand meteorites weighing about one-quarter-pound or more hit Earth each year. A meteor the size of the one that formed the crater only arrives about once every 50,000 years.

Some children cluster around a large video magnifier where they can examine "shocked" rocks, left from the impact, then they head to the Put Yourself at Ground Zero exhibit, where they stand inside the display as a film and sound effects re-create the impact. My husband is fascinated by a display of a comet hitting Jupiter.

While scientists now readily accept that the crater was formed by a meteoritic impact, it wasn't until the middle of the 20th century before it was proven. Early Native Americans must have noticed the giant crater, but it wasn't reported until 1871, when an army scout named Franklin made a written report.

For years, it was known as Franklin's Hole. In 1886, shepherd Mathias Armijo picked up some heavy rocks that he thought might be silver. When he had the rocks analyzed five years later, they turned out to be 92 percent iron, 7 percent nickel and ½ percent cobalt, with a few trace elements of platinum and iridium -- in other words meteorites. The nearest post office was Canyon Diablo, so the estimated 15 tons of meteorites found near Meteor Crater were labeled "Canyon Diablo Irons."

It was believed that the crater was volcanic such as the many volcanic craters around Flagstaff. Local cowboys had taken to calling it Coon Butte. In 1902, Daniel M. Barringer first learned of the unusual crater. During intermission at a boring opera in Tucson, Ariz., he struck up a conversation with government agent Samuel H. Holsinger. The agent casually mentioned Coon Butte and the legend claiming it was formed by something falling from space. Amazed that he had never heard of this crater, Barringer peppered Holsinger with questions. It was the beginning of Barringer's obsession.

Barringer investigated the site and became convinced it was indeed a meteorite crater. However, his radical theory differed from that of G. K. Gilbert, the most prominent geologist of the time.

In 1891, Gilbert had examined the crater briefly and pronounced it caused by a volcanolike steam explosion. Gilbert was easy-going and well-liked while Barringer lacked people skills, so most other scientists believed Gilbert's hypothesis.

In the years to follow, Barringer organized the Standard Iron Company. He reasoned that the meteorite must still be in the bottom of the crater and, if mined, the minerals would be worth a fortune.

All they had to do was drill down to the object and extract it with a simple hoist.

Barringer's grand plan soon met up with reality. Quicksand, dense rock, water, bent and dulled drill bits, temperature variations from 105 degrees in the summer to below zero in the winter, and vicious wind all stymied the fortune hunter.

Barringer eventually drilled 28 holes in the bottom and sides of the crater but found no sign of a meteorite. He was still positive he had a meteorite crater, but his detractors pointed out he didn't have the proof. They were both right. The huge recess formed when a meteor collided with Earth, but most of the meteor itself vaporized on contact.

Barringer continued his search through 1928, then his money ran out. He had literally poured his money down a hole. A final insult occurred when a 1928 National Geographic article, "The Mysterious Tomb of a Giant Meteorite," admitted the impact possibility, but didn't mention Barringer's name. Full credit for the theory was given to Gilbert, the man who had staunchly argued against the idea. Barringer tried futilely to attract more investors, but new calculations proved that even if they could locate the meteorite, the profits couldn't cover the cost of extraction. Barringer went home, wrote his final letters and three days later, on Nov. 30, 1929, died of a massive heart attack. It wasn't until the 1960s that geologist Eugene M. Shoemaker presented scientific evidence proving that the giant bowl formation was indeed caused by a meteor impact. Shoemaker said, "I had a personal goal that inspired me to begin studying craters on the Earth. I wanted to be the first geologist to the moon." He died in 1997, but he did make it to the moon in 1999 when his ashes accompanied the spacecraft Lunar Prospector.

Ironically, the crater's value didn't lie in its mineral wealth, but in its scientific value and the thousands of visitors annually who flock to see the natural phenomenon. The Barringer family entered into a long-term lease with the Bar-T-Bar Ranch, owners of the land around the crater, to develop the attraction.

Meteor Crater Enterprises operates the crater for the Barringer family. Movies such as "Meteor" starring Sean Connery and "Starman" with Jeff Bridges were filmed at the crater.

Despite the years of controversy, today the site is recognized as the best preserved crater of its kind on the planet and, wow, it is one impressive hole in the ground.

Author: Janet Webb Farnsworth | Source: Las Vegas Review-Journal [April 24, 2011]

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