EEPORT OF THE SECEETAKY. 9 



to a science and an art which bid fair to engage the attention of man- 

 kind for many years to come. 



METEOR CBATER OF CANYON DIABLO, ARIZONA. 



An investigation of the remarkable crater-like depression at Coon 

 Butte, near Canyon Diablo, Arizona, made in 1907 by Dr. G. P. 

 Merrill, head curator of geology in the National Museum, aided by 

 a grant from the Smithsonian Institution, was briefly mentioned in 

 my last year's report and a full account appeared in the Smithsonian 

 Miscellaneous Collections (quarterly issue) under date of January 

 27, 1908. The " crater " is some three-fourths of a mile in diameter 

 and 500 feet in depth in a region of undisturbed sedimentary rocks 

 and remote from volcanoes. The object of the study was to deter- 

 mine, if possible, whether the crater was caused by volcanic action, 

 as assumed by some investigators, or due to the impact of a mass of 

 meteoric iron as asserted by others. 



From the available evidence Doctor Merrill concluded that the 

 crater could not have been formed by volcanic action, all the observed 

 phenomena being of a superficial nature. Some 300 feet of over- 

 lying liinestone and 600 feet of sandstone have been shattered as 

 by some powerful blow, and the quartz particles in the sandstone 

 in part fused, indicating a very high degree of heat. The deeper- 

 lying sandstone, however, is entirely unchanged. These facts abso- 

 lutely preclude the formation of the crater by any deep-seated 

 agency, and forces the conclusion that it resulted from the impact 

 of a stellar body. 



No record has been found of a meteoric fall comparable with this, 

 the largest known meteorites, such as that from Cape York, Green- 

 land, and the enormous irons from Oregon, having fallen under such 

 conditions as to scarcely bury themselves. The nearest approach to the 

 Canyon Diablo occurrence was that at Knyahinya, Hungary, where 

 a 660-pound stone penetrated the ground to a depth of 11 feet. 

 No meteoric mass of sufficient size to have made this enormous crater 

 has been brought to light, but it is thought there still remains the 

 possibility of its having become dissipated through the heat developed 

 by its impact while traveling at a speed of many miles a second. 



In his report Doctor Merrill goes very thoroughly into details. He 

 has secured many specimens of the meteoric irons and their associa- 

 tions from the locality, which are deposited in the National Museum. 

 The specimens include a hitherto unrecognized type of meteoric iron 

 and a peculiar form of metamorphism in the siliceous sandstone of 

 the region. 



Mining operations carried on in the crater afforded special oppor- 

 tunity for this research. These operations were discontinued during 

 the winter, but their resumption in May, 1908, presented a second 



