THOMSON. — THE FALL OF A METEORITE. 725 



I am indebted for the opportunity of conveniently visiting and examin- 

 ing the formation, and also for publications, charts, slides, and other 

 material.^ 



The uncovering of a mass of millions of tons of iron containing about 

 8 per cent nickel would have great commercial value. Add to this the 

 fact that analyses show the iron to contain an average of about 6/10 

 ounce of platino-iridium to the ton and the value is much enhanced. 

 Besides, there is an undetermined amount of diamond present. 



All of the iron examined and even the oxidized shale ball iron shows 

 the characteristic Wiedmanstatten figures regarded as proof of meteoric 

 origin. Such a structure, it may be remarked, is probably the result 

 of slow cooling in the interior of a large body and under compression. 

 This structure is stated to disappear when the iron is heated to about 

 900° C. 



What happened at the Meteor Crater may be briefly outlined as 

 follows : A large mass, or more probably a cluster resembling a small 

 comet, passed so near to the earth as to be deflected sufficiently to 

 cause it to strike. Its velocity, reduced by retardation in the air, may 

 have been not more than two or three miles per second when it struck 

 earth. As it penetrated the dry plain, some of the smaller and still 

 more retarded and slower moving pieces following in the rear of the 

 main cluster were diverged therefrom and so fell at various distances 

 around the crater. As soon as the main body reached the wet rock 

 layers superheated steam was generated at high pressure, pulverizing 

 and metamorphosing the silicious rock, and producing an enormous 

 lateral pressure which the disturbed and uplifted strata together with 

 the horizontal compression as shownjn the structure of adjacent rock 

 masses clearly indicate. As the mass advanced the pulverized mate- 

 rial in its path and around it would be swept backward almost as a 

 fluid and would expand outwardly at the same time, fracturing the 

 adjacent rock layers, up-casting and folding back the strata, and dis- 

 charging the enormous mass of pulverized and mixed rock material 

 which now forms the circular rim. This blast would entangle the 



* Mr. D. M. Barringer, conceiving the impact theory to be the correct one, 

 collected largely at his own expense, and through a period of years, the evi- 

 dences thereof and has published his results in the following papers, to wit, 

 "Coon Mountain and Its Crater," Proceedings of the Academy of Natural 

 Sciences of Philadelphia, December, 1905; " Meteor Crater in Northern Cen- 

 tral xVrizona," read before the National Academy of Sciences at its meeting at 

 Princeton, November 16, 1909. To these papers of Mr. Barringer reference 

 may be made for an abundance of interesting detail with illustrations and 

 maps. 



