874 PROCEEDINGS OF THE ACADEMY OF [DeC, 



much erosion, such as must have taken place in order to account for 

 the great amount of tahis which is to be ol^served on the inside of the 

 crater, supposing it to have accumulated in the usual way, the crater 

 would certainl}' not be as round as it is. If originally round, it would 

 certainly have been greatly deformed by the process. It could not 

 weather round. It is perfectly clear that this is contrary to any known 

 mode of action of erosion. Therefore it is certain that the talus did 

 not accumulate in the usual way, and that its presence and distribution 

 must be explained on some other theory than that of weathering. 

 This view receives further support from the fact that the very low 

 angle (about twenty degrees from horizontal) which the upper portion 

 of the talus on the interior of the crater makes in its descent from the 

 base of the almost perpendicular cliffs, is a very unusual one. 



Fifth : Granting that such a single violent steam explosion is not an 

 absurb hypothesis, it would seem that on this hypothesis there would 

 be abundant evidences of solfateric activity within and without the 

 crater, especially in the immediate vicinity; such as redeposited or 

 secondary silica, carbonate of lime and other minerals which are 

 usually deposited b}" hot spring action. These minerals would cer- 

 tainly be found within the crater and in the cracks which, under this 

 hypothesis, it would seem should be found traversing the horizontal 

 stratified rocks forming the plain on the outside of the crater. Neither 

 the cracks nor the minerals are to be found. In short, there is no evi- 

 dence of any sort at or near this spot of solfateric action. 



Sixth : If a steam explosion had formed this crater, it is inconceiv- 

 able to me that it would not have thrown up rocks from a greater depth 

 than that represented by the three uppermost strata, together with a 

 very small portion of the upper part of the Red Beds which underlie 

 them. Nothing would seem to be more certain than that the greater 

 portion of these Red Beds and the great Carboniferous series of strata 

 extending thousands of feet under them, as exposed by the Grand 

 Canon of the Colorado, only seventy miles distant, are undisturbed 

 In other words, the series of strata at Coon Mountain have not been 

 disturbed, at least to the extent of being thrown out, for a greater 

 depth than the upper portion of the Red Beds, geologically speaking, 

 or about 1,200 feet more or less — perhaps as much as 1,300 feet — below 

 the present surface of the plain. 



Seventh: A steam explosion I assume could not have pulverized the 

 individual sand grains, as they have been pulverized here, and produced 

 as a result the miUions of tons of ' ' silica ' ' which exists on the inside of 

 the crater and on the outside of the rim as already described. It is not 



