5. Upheaval Dome, Utah
With a diameter of about 3 miles, this formation in Canyonlands National Park looks like a New Age swirl from the air. Some controversy has centered on whether Upheaval Dome is the result of a meteorite impact or is instead a pinched-off salt dome. In 2007, German researchers found evidence of shocked quartz, lending credence to a swift, catastrophic formation. The impactor is estimated to have been about one-third of a mile in diameter.
4. Odessa Meteor Crater, Texas
In a state known for tall tales, the discovery of the Odessa Meteor Crater sounds perfectly reasonable — this formation was discovered in 1892 by a rancher searching for a stray calf. About 550 feet in diameter, Odessa Meteor Crater is the largest of several known craters in the region, all of which were formed by an object that broke up in our atmosphere between 20,000 and 50,000 years ago. It is no coincidence that several of the most pristine impact craters are out west, as the arid conditions and relative lack of modern development act to preserve these structures. The Odessa formation offers a museum and visitors center, which contains several examples of meteorites excavated from the site.
3. Middlesboro Crater, Kentucky
The only crater on this list located in the Eastern U.S., the town of Middlesboro, Kentucky, holds the rare distinction of being nestled in the bowl of an impact crater 3 miles in diameter. (The town of Nordlingen, Germany is another town in a crater.) Situated in the Appalachian Mountains, settlers initially exploited the region for minerals exposed by the impact, and the area served as a key pass opening up the westward expansion of the nation via the Cumberland Gap. Geologists in the 1960s identified signs of an impact caused by a rock about 1,500 feet in diameter about 300 million years ago.
With an ailing economy, the town of Middlesboro hopes to capitalize on its cosmic origins, adopting the motto “The City Built Inside A Meteor Crater.” Be sure to visit the town’s golf course, which includes remnants of the crater’s central peak. This is currently the only place in the solar system where you can “tee off” from such a feature.
2. Sierra Madera Crater, Texas
The state of Texas is home to another crater of cosmic origins, the 6-mile-wide Sierra Madera crater, located south of Fort Stockton in southwestern Pecos County. Although the crater itself is on private property, it is highly visible from U.S. Highway 385, appearing as a ring of mountains surrounding a central peak. Estimated to be less than 100 million years old, Sierra Madera dome originally attracted the interest of oil drillers who discovered the feature was in fact an impact scar.
1. Barringer Crater, Arizona
If you find yourself in northern Arizona, be sure not to miss the famed Barringer Crater, also known simply as Meteor Crater, near Winslow, Arizona, just a day trip away from Flagstaff and the Grand Canyon. This is one of the few places you can stand on the rim of what looks like an actual crater of extraterrestrial origin. Known to 19th century settlers as the Canyon Diablo crater, the impact hypothesis was first proposed by Daniel Barringer in 1903. Eugene Shoemaker’s research in 1960 confirmed the impact theory. Later that decade, Apollo astronauts trained in the crater prior to lunar missions, and Apollo hardware is on display at the extensive museum on the crater rim.
Now for the wow factor: with a diameter of about 4,000 feet, Barringer crater was formed by an impactor an estimated 160 feet across striking the now-desert area about 50,000 years ago. That impact would have released energy in excess of 20 million tons of TNT, largely vaporizing the 300,000-ton impactor along with a huge amount of surface material. By the way, Daniel Barringer also has his name on a large crater on the lunar surface, perhaps giving him the unique distinction of being the only person with two craters in the solar system bearing his name.
One More: Manson, Iowa
Honorable mention goes to Iowa’s Manson Impact Structure. One of the largest known in North America at an estimated 24 miles in diameter, this crater was formed by a stony meteorite about a mile in diameter striking the region about 74 million years ago during the tail end of the Cretaceous period. The effects of glaciers removed any surface evidence of the impact, but measurements during the early 1900s revealing oddities in well drilling samples first gave geologists an idea that something unique had occurred in northwest Iowa. The 10 billion ton impactor struck the area at an estimated 45,000 mph, toppling trees for a radius of about 300 miles around the site. Keen to capitalize on the impact, the town of Manson hosts a Greater Crater Days celebration each June.
And finally, can’t get enough of meteorites and meteorite craters? On average, an impacting body is about 1/10th to 1/20th of the diameter of the resulting crater; variables include the speed, angle of impact, and the type of material that the body is striking. An interesting simulation tool to this effect can be seen (and played with for hours) at the fascinating Earth Impact Effects Program site.