DIASTROPHISM AND THE FORMATIVE PROCESSES 689 



case lies in its clear evidence that the energy of impact was chiefly 

 transformed into lateral thrust and resilience of quasi-explosive type. 

 Confessedly the most outstanding problem left is to find a source 

 of energy adequate to the mechanical effects so impressively 

 forced on attention. The case still remains something of a puzzle 

 on that account. Meteoric matter has been found so widely dis- 

 seminated through the debris, both within and without the crater, 

 that the origin of the crater is no longer in doubt, but yet the 

 amount of meteoric matter thus far brought into evidence seems 

 clearly too small to be adequate. The suggestion of Barringer 

 that the infalling mass was a cluster of meteorites or a comet's 

 head is plausible in itself — and the orbits of comets are such as to 

 make a bump into the earth a recognized contingency — but these 

 suggestions give little help in the matter of adequacy. A larger 

 mass than has been found seems to be required to satisfy the 

 effects realized. For such computations as I have made, a siderite 

 sphere 400 to 500 feet in diameter was taken, but it is scarcely 

 worth while to give the results here. They are of the same import 

 as those of the next case. 



We ought not to overlook the fact that this is the only known 

 case of such an infall in the history of the earth. This is an embar- 

 rassment in postulating a rapid series of infalls. Nor is its negative 

 bearing merely a surface matter. If such a crater had been formed 

 and buried in a natural way in any geologic formation, however 

 old, there would be a fair chance of its detection. There is there- 

 fore a complete absence of geological warrant for supposing that 

 infalls of this kind were ever anything but very sporadic affairs. 

 If Meteor Crater was formed by the impact of the nucleus of a 

 comet, theory would make its repetition an extremely rare event. 

 The concept of an enormous meteorite, or close cluster of meteorites, 

 other than cometic, has no observational basis. If the views 

 respecting the origin of meteorites, later expressed in this article, 

 have any cogency, the infall of such bodies would be governed by 

 the same order of chances as those of comets. From no point of 

 view, therefore, does Meteor Crater offer substantial ground for 

 supposing that the earth was once molten because of the impacts 

 of meteoritic bodies. 



