DISPOSITION or THE METEOR 501 



floor of the crater. The association of the meteoric dust with the siderites 

 is an interesting but not unexpected fact which indicates no more associa- 

 tion with the origin of the crater than do the large masses, but the incor- 

 poration of the meteoric material with the wreckage of the crater and 

 deep in the crushed sandstone of the pit is very significant of an associa- 

 tion in time. 



Disposition of the Meteor 



With expert knowledge of projectiles and their effects Mr Tilghman 

 has discussed the problem of the size of the meteorite which could pro- 

 duce the crater (pages 912-913 of his paper). The effect of a projectile 

 is proportionate to weight and velocity, and with the velocity unknown 

 the weight or size is indeterminable. 



The original or planetary velocities of meteors may be very large, many 

 miles per second. Small meteors reach the earth's surface with a low 

 terminal velocity, being checked by the resistance of the atmosphere. 

 A very large meteor with high density would traverse the atmosphere 

 with less loss of energy. It is thought that a siderite with a terminal 

 velocity of only a few miles per second would require a diameter of only 

 a few hundred feet in order to produce the Meteor crater. 



The amount of Canyon Diablo irons thus far collected is estimated at 

 about 15 tons. The oxides will add only a few tons to this weight. If 

 we double this to allow for fragments yet distributed in the wreckage on 

 the crater rim, it would amount to, say, 60 tons, or about the weight of 

 the largest known meteorites. But this is only a small fraction of the 

 required weight even under an assumed high velocity, and the explorers 

 reasonably are expecting to find the bulk of the meteor in the depths of 

 the crater. 



Mr E. E. Howell long ago suggested (see Doctor Gilbert's article) that, 

 as all the Canyon Diablo irons are perfect individuals, none showing 

 either fractiire or friction, they originally were imbedded in some easily 

 decomposed or stony material which has disappeared. It is under- 

 stood that with the low temperature of the celestial visitors even the 

 nickel iron would be as brittle as glass, and the impact would produce 

 subdivision. The explorers have not been unmindful of this suggestion, 

 but thus far their search has not discovered any stony material foreign to 

 the local rocks. Nevertheless this suggestion may give clue to the fate 

 of the bolide. 



A very important factor in the problem of the disposition of the meteor 

 is the behavior of the C. D. 0. irons. Their decomposition and disap- 



XLIV — Bull. Geol. Soc. Am., Vol. 18, 1906 



