DIASTROPHISM AND THE FORMATIVE PROCESSES 687 



with meteoritic matter, lies below the floor of the crater to a depth 

 of about 660 feet. Below this, disrupted rock seems to grade into 

 undisturbed sandstone at points between 1,100 and 1,200 feet 

 beneath the general plain. Rock masses and clastic material, 

 coarse and fine, were thrown from the pit and strewn over the 

 adjacent plain for distances of one to two miles on all sides, while 

 meteoritic matter, distributed subconcentrically, reaches out to an 

 extreme distance of 5^ miles. The rim and pit, while subsymmetri- 

 cal, have sufficient asymmetry to indicate an iniall from a northerly 

 direction, perhaps N. NW. to S. SE. The chief mechanical effects 

 were the formation of the crater by the breaking up of perhaps 

 8X10^ tons of rock, and the hurling out of perhaps half of it, the 

 turning up to high angles of the previously horizontal limestone 

 and sandstone beds of the crater-border, the crushing of large 

 quantities of sandstone to silicious rock flour, and the develop- 

 ment of some schistosity in connection with it. The chief thermal 

 effects were the partial metamorphism of some of the rock flour 

 and the development of incipient fusion in other portions of it, 

 some of this portion becoming vesicular. The crushing and heating 

 were obviously the direct effects of the impact, the upturning of 

 the rim and projection of the debris as obviously the effects of the 

 attending lateral thrust and the quasi-explosive reaction that 

 followed. 



The energy involved in the mechanical effects must be sub- 

 tracted from the total energy of the impact before the heating 

 effects can be theoretically deduced. The very large sum total of 

 these mechanical effects shows how great would be the error of 

 computing the energy of infall in terms of heat and using that as 



(Feb., 1895), pp. loi-io; D. M. Barringer and B. C. Tilghman, "First Mention of 

 the Discovery that the Crater Is an Impact Crater and Not a Crater Produced by 

 a Steam Explosion" (President's Statement), Proc. of Acad. Nat. Sci. (Philadelphia, 

 Dec. 5, 1905); D. M. Barringer, "Coon Mountain and Its Crater," Proc. Acad. Nat. 

 Sci. (Philadelphia, Dec, 1905), pp. 861-86 (issued March i, 1906); B. C. Tilghman, 

 "Coon Butte, Arizona," ihid., pp. 887-914; J. W. Mallet, Amer. Jour, of Sci., Vol. 

 XXI (May, 1906), pp. 347-55; J- C. Branner, Science, Vol. XXIV (Sept. 21, 1906), 

 pp. 370-71 ; H. L. Fairchild, at Tenth Session of the International Geological Congress, 

 in Mexico, September 14, 1906, Compte Rendu, X Session, Congres Geol. Inter. (Mexico, 

 1906), p. 147; O. C. Farrington, "Analysis of Siderite Oxides or Iron Shale," Amer. 

 Jour, of Sci., Vol. XXII (Oct., 1906), pp. 303-9. 



