1905.] NATURAL SCIENCES OF PHILADELPHIA. 865 



known. This seems to be the uppermost member of what are known 

 as the "Red Beds/' for underneath this yellow sandstone there is a 

 reddish-brown sandstone, the thickness of which is given by the United 

 States Geological Survey as more than 1,000 feet. The following 

 record of a well driven by the Railroad Company at Winona, less 

 than thirty miles distant in an air line from the crater first men- 

 tioned, shows the thickness of these various strata at that point. 

 It is assumed that the Geological Survey obtained these figures from 

 the Railroad Company, since the figures which they give as to the 

 thickness of these strata, at the place where the A., T. & S. F. Ry. 

 crosses the Canon Diablo gorge, closely approximate the record of the 

 well.* There are no eruptive rocks of any sort in this neighborhood, 

 the nearest eruptive rocks to the so-called crater above referred to 

 being a mountain known as Sunset Mountain about twelve miles in a 

 southeast direction, the Black Mesa in a west and southwest direction 

 about twenty miles distant, and the San Francisco Mountains and the 

 flows therefrom about forty-five to fifty miles distant in a northwest 

 direction. The latter, as is well known, are composed of many vol- 

 canic craters and the material ejected therefrom. Some of these 

 craters are of comparatively recent origin, geologically considered, but 

 presumably of much greater age than Coon Mountain and the crater it 

 contains. The Black Mesa above referred to is supposed to be a flow 

 from the San Francisco craters. In the San Francisco Mountains 

 there are many volcanic cones containing more or less perfect craters. 

 These are true volcanic craters. Such, for instance, is the well-known 

 ' ' Sunset" crater, a few miles north of the Santa F6 Railroad and easily 

 accessible from Flagstaff. I have no hesitancy in saying that there is 

 absolutely no connection between the first mentioned crater, which I 

 shall hereafter attempt to describe, and these volcanic craters. And 

 more than that, there is not a single point of similarity, excepting per- 

 haps that of the round shape of the interior basin. 



As above stated, the crater which is the subject of this paper is to be 

 found in an area composed of level beds of stratified rocks (Carbonifer- 

 ous sandstones, limestones and shales), which extend uninterruptedly, 



^ Record of Winona well: Aubrey limestone, 185 feet; Dakota sandstone, 456 

 feet; Red sandstone, 16 feet plus. 



"Although no direct measurements have been made in that immediate vicinity, 

 the thickness of the Aubrey limestone at Canon Diablo is probably not far from 

 300 feet. At Winona, where its surface is considerably eroded, 185 feet remain. 

 The gray sandstone next below is between 400 and 500 feet thick. The Red 

 Beds are about 1,000 feet thick. Next below is the Redwall limestone which is 

 600 feet or more in thickness." From information furnished by U. S. Geological 

 Survey. 

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