Sunday, August 24, 2014

A Visit to Meteor Crater

Last Sunday I visited Meteor Crater for the first time in just over a decade. The crater (once called Coon Mountain Butte), also known as Barringer Crater, is the first confirmed asteroid impact crater on Earth.

For a long time many thought that the site was a volcanic feature. Likely the presence of the San Francisco volcanic field (on the horizon in the photo below), northwest of the crater, clouded the judgement of the early geologists, but the clues as to its origin are everywhere. 
There's no volcanic rock within or immediately around the crater. The prevailing rock formation on the surface in the surrounding countryside is the reddish brown siltstone of the Moenkopi formation. You can see it in the photo above, especially framed by the road in the upper right. All of the whitish rocks in the foreground in this photo are part of the crater's ejecta--deeper rocks that were thrown out on top of the red rocks during the formation of the crater.
Within the crater's inner walls are steeply tilted sedimentary layers (above) of whitish limestone and sandstone that were once horizontal. The impact explosion that created the crater shattered and tilted these layers upward.
The countryside surrounding the crater was once littered with Iron-Nickel meteorites (they've mostly been collected now), remnants of the asteroid that formed the crater. The single largest piece recovered is known as the Holsinger Meteorite (above). It weighs 1,406 pounds.

There's a nice museum that's well worth looking at. I was especially happy to see so much devoted to Eugene Shoemaker, the man who proved that the crater was created by an asteroid impact. If you haven't read it, I highly recommend David Levy's biography of him, Shoemaker by Levy and if you want to read about the crater I suggest tracking down the classic book by H.H. Nininger Arizona's Meteorite Crater.

 Here is one of the panoramas I shot of the crater:

1 comment:

  1. I've been there twice and it is well worth the visit.