Sunday, September 11, 2011

Meteor Crater

Meteor Crater is the site of a 50,000 year old well preserved meteor strike in northern Arizona. The location is 6 miles south of Interstate 40 about 35 miles east of Flagstaff. The Meteor Crater is a privately owned site and in 2011 charges a $15 entry fee.

The crater is thought to have been caused by an Iron-Nickel meteorite, about 150 feet across that struck the earth at a velocity of 26,000 miles per hour. The resulting impact crater is currently about 4000 feet across, 2.25 miles in circumference and 500 feet deep.

Over 175 million tons of limestone and sandstone were ejected and now form a blanket around the impact site for over a mile. Some geological material that should be at the bottom of the crater was lifted and deposited at the rim, providing important evidence that this was an impact site and not an extinct volcano, as was originally thought.

There are three levels of viewpoints close to the entry area. The highest point has a short paved trail leading to a platform with some installed telescopes. From above the flat dry terrain surrounding the site is visible.

The dry climate here is mainly responsible for the excellent preservation of the crater and how easy this site is to view. The geology layers here are familiar to hikers who have visited the Grand Canyon. The formations that were impacted here include the Coconino, Toroweap, Kaibab, and Moenkoepi.

The middle level viewing area has several installed telescopes that are aimed at particular points of interest. At the bottom of the crater, there are some drill holes and left over mining equipment. In the early years of development, there was some thought that there might be a deposit of iron here, but most of the material was pulverized at impact.

Mining Engineer Daniel Barringer was one of the early believers that this was an impact site and was eventually proved correct. Though an iron mine here was not feasible, the Barringer Family has maintained the site as a public trust.

There is a good small museum to help interpret the Meteor Crater. On display in the museum area is the largest found fragment of the meteorite, named the Holsinger Meteorite. This heavy fragment is 92% iron and 7% Nickel with 1% of mixed other components.

Part of the museum includes a small comfortable theater where a 10 minute video is shown. After the video, an interpretive guide conducted a 20 minute presentation at the lowest level outdoor view point where there is some shade and some benches.

One of the displays includes a map of impact craters around the world. I was interested to note that there is another impact crater in the Four Corners area. In the Island of the Sky District of Canyonlands National Park in southeast Utah, the Syncline Loop Trail circles a feature that is thought to be an impact crater, though there is the alternative salt dome theory for that site.

At one time it was possible to hike down into the crater, but that practice was stopped in the 1970s due to erosion. There isn’t a trail around the crater that is available to the public. Although the hiking distance is short, this is an interesting and well interpreted natural feature in this area that also includes many volcanic and archaeological sites.

I visited on a sunny early September afternoon for about 1.5 hours. The parking area was about 30% full. The viewing was uncrowded and comfortable.

No comments: