There are not many intact meteor impact craters on Earth’s surface—erosion usually wipes them away pretty quickly. I had previously visited an impact crater at Tswaing in South Africa. Yesterday I got to visit Meteor Crater, near Winslow AZ. It is about the same size as Tswaing but is much younger and therefore much better preserved.
The first written reference to the crater is in 1871, when a US Army scout found it—it was referred to as “Franklin’s Hole”. For the next thirty years it was assumed to be an old volcanic crater. Then in 1902 a mining engineer from Philadelphia named Daniel Barringer visited the site, and concluded that it was not volcanic and contained no igneous rocks, but was most likely a meteor impact. At that time almost nothing was known about impact craters, so nobody took him seriously. But Barringer not only thought the crater had been caused by a meteorite, but concluded that the impactor was still there buried beneath the surface, and he could become rich by mining its iron and nickel. So he filed a mining claim and dug a number of drillholes to find it. After thirty years of searching, he went broke, having found nothing. (Alas, he was only half-right—the crater was an impact, but there was no buried meteorite. It had exploded on impact.)
Since Barringer had mined the claim for ten years, he had received legal title to the land, and when he died in 1929, his children inherited what they thought was a big worthless hole in the ground. But in the 1930’s and 40’s tourists began showing up to see the crater, and the Barringer family began charging admission. They still own the crater today.
During this time, most geologists still considered the crater to be volcanic. But in 1960 NASA scientist Dr Eugene Shoemaker found shocked quartz in drill samples at the site, establishing conclusively that it was an impact site. Today, scientists estimate that the meteor was about 150 feet wide, hit at about 26,000 mph, and had the energy of a 20-megaton nuclear bomb. It struck about 50,000 years ago.
Here are some photos from my visit.
The crater itself is not visible from the surface: as you approach all you can see is the uplifted rim
The view as you climb the rim
The crater is a little less than a mile wide, and about 500 feet deep
Me, at the crater’s edge
A tour group. Visitors used to be able to hike all the way around the rim, but alas there are always assholes who would graffiti and vandalize the rocks, so that trail was closed.
One of the observation decks
There is shattered rock everywhere you look
This rock layer is the original surface area, made of red sandstone. Below it is white limestone. The impact blew huge sections of rock up and out, flipping them over and depositing them on the rim. So now the sandstone layer is doubled, with the top half upside down, and above it lie sections of blasted and flipped limestone
House-sized blocks of limestone, thrown up and over the crater rim
Another large chunk of blown-out limestone, about half a mile away from the crater rim
Some of the mining equipment and boreholes that Barringer dug are still visible at the bottom of the crater
A chunk of the meteorite. This piece weighs around 1200 pounds. Most of the meteorite, however, got blasted into marble-sized pieces that are now scattered over the entire site.
A “boilerplate” Apollo test module. Because the crater is so similar to those on the Moon, the Apollo astronauts trained here to prepare for their lunar landings.