Monday, September 1, 2008

Coconino County Crater

It's been a while since we took a trip back to look at Coconino County history. So, here's an interesting excerpt from the 1906 Bulletin of the American Geographical Society, about Meteor Crater, then called Coon Mountain:

"COON MOUNTAIN'S SO-CALLED CRATER. — Messrs. P. M. Barringer and B. C. Tilghman have made an examination of Coon Mountain in Arizona, and the results of their work are published in the Proceedings of the Academy of Natural Sciences of Philadelphia (December, 1905). Coon Mountain or Butte rises above the plain about five miles south of Sunshine station in Coconino County, Arizona.

The evidence collected has convinced the investigators that the "crater" was produced by the impact of an iron body falling out of space. The so-called mountain consists of a circular ridge from 130 to 160 feet in height, surrounding an almost circular depression in the earth varying from 3,600 to 3,800 feet in diameter and about 400 feet deep.

Viewed from the inside the surrounding ridge is about 560 feet above the level of the crater bottom. As this hole has a general resemblance to a crater, some observers have surmised that it was really the crater of a long-extinct volcano. The rim around it, however, is not composed of volcanic outpourings; the hole penetrates strata of red sandstone, yellowish limestone, gray sandstone, and, finally, a brownish sandstone, in which it terminates. The writers dismiss as untenable the theory that this is a volcanic crater.

Another theory is that the hole was produced by a steam explosion; but the vast amount of steam required could be stored up only in regions of volcanic activity, and there is no evidence that this was ever such a region.

The writers believe the evidence to be overwhelming that the cavity was formed by the impact of a large meteorite. Much of the rock was ground by the collision into fine particles and almost impalpable dust, and a great part of the crater rim is formed of this debris. The colliding body itself was, to a large extent, broken into pieces. Borings have revealed small fragments and splinters of it, but no large piece has been found beneath the floor of the crater. On the other hand, several tons of meteoric iron have been collected around the crater. Seven pieces of it weigh from 600 to over 1,000 pounds each, and smaller pieces were found around the crater to a distance of two and a half miles.

These iron specimens contain iron, nickel, iridium, and platinum, and there are millions of particles of it scattered far and wide around the crater. A shaft is now to be sunk in the centre of the crater, and, if possible, sufficient depth will be reached to demonstrate whether or not there are parts of the supposed foreign body buried several hundred feet beneath the central plain."

Pages 306-307
Bulletin of the American Geographical Society
By American Geographical Society of New York
Published by The Society, 1906

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