THOMSON. — THE FALL OF A METEORITE. 729 



its velocity. A large iron meteorite or a cluster of them has therefore 

 a considerable chance of survival in spite of the rapid waste by burning, 

 while the smaller ones may disappear by combustion while still in the 

 air, especially if the initial velocity be high. But, entering air at a 

 comparatively low velocity such as five to ten miles per second, an iron 

 meteor of more than a few ounces in weight will probably survive in 

 part. I have been particular to lay stress on these actions, as they en- 

 tirely negative an idea which has been advanced to account for the fail- 

 ure to find large masses of embedded iron at the Arizona Crater. It 

 has been claimed that the mass was vaporized on striking, a possibility 

 which is impossible, as I am compelled to regard the matter. 



The age of Coon Butte, the great Meteor Crater, is of course uncertain. 

 How long a time has elapsed since the fall 1 In the absence of definite 

 data for computation we can only guess. However, from the apparent 

 absence of much erosion it must be comparatively recent. While the 

 country is dry, it does rain at times and there are high winds. The 

 climate may have been more moist in times past as is rendered probable 

 by the evidences of water in the crater formerly. The age of certain 

 cedar trees on the slope tend to place the date back perhaps of 500 to 1000 

 years. A mere surmise would be 2000 to 3000 years ago as the possi- 

 ble time of the meteoric fall. 



It is stated that the Indian tribes inhabiting the region in a reserva- 

 tion just north of the railroad have an ancient tradition of the fall of a 

 large body of fire from the sky which killed a number of their tribe. It 

 is also stated that they now hold the spot in some superstitious awe fi:oni 

 the fact that they send to the crater slopes for the white silica, which is 

 sprinkled about during their ghost dances. I cannot, however, person- 

 ally vouch for these statements without further investigation. 



Such craters as this meteor crater if formed many thousands of years 

 ago would probably be obliterated by erosive influences, and even in 

 the desert the shifting sands would finally cover them. The water, 

 the frost, vegetation, the atmosphere are against their indefinite pres- 

 ervation as features of the landscape. Let us imagine, however, a large 

 body such as our moon, in a vacuum, with no atmosphere, no water, 

 no winds, no frost, no vegetation, then, if any such impact took place 

 the record must be left for all time ; not quite unimpaired perhaps, for 

 a subsequent impact may superpose its effect tending to obliteration of 

 the first effect. Moreover, in the lapse of millions of years there may 

 be accumulations of cosmic dust or small particles gathered up from 

 space which will partly cloud over or cover the lower portions. But 

 even in this case the higher ridges will remain. It is indeed no new 

 idea that the lunar craters, instead of being the result of volcanic 



