no ABSTRACTS 



It was found also that when the water first fell to the level of the 

 Niagara escarpment, so as to cascade over its edge, there were five 

 points of discharge. Three of these were short-lived, but Lockport 

 for a considerable period divided the water with Niagara. 



The Physical Nature of the Problem of General Geological Correlation. 

 By Charles R. Keyes. 



The main object of this communication has been to formulate 

 briefly certain suggestions which have arisen in the course of recent 

 attempts to parallel some of the geological formations in the Missis- 

 sippi valley. They appear to have a much more than local bearing, 

 and to affect the whole problem of general geological correlation, and 

 perhaps also even our present system of geological classification. 



Regarding as the principal function of correlation the establish- 

 ment of a practical scale of geological succession to which may be 

 referred the strata of all parts of the globe, the critical criteria adopted 

 became essentially the real basis of geological classification or historical 

 geology. A rational classification of geological phenomena reflects 

 the genesis of the events recorded, and this is manifestly the ultimate 

 aim of all methods of paralleling strata. In the correlation, or com- 

 parison of geological formations, experience has shown that the sub- 

 ject may be viewed from at least four very different points of vantage. 

 The aspects presented are: local, provincial, regional, or general. 

 With the various methods which have been followed from time to time 

 in correlative inquiry the almost universal practice has been to attempt 

 to base the broader generalizations upon criteria that are in reality 

 applicable only to limited areas. 



Passing by a review of the various methods of correlation which 

 have been used, a little consideration shows that all are necessarily 

 local in application and not general. This distinction between the 

 two sorts of correlation which is usually entirely overlooked should be 

 clearly borne in mind. When widely applied the almost total failure 

 of the several methods that have been tried is only too apparent. The 

 inherent weakness of the most common criteria — the fossils — is readily 

 gleaned from the writings of Huxley, Irving, Van Hise, McGee, Wal- 

 cott. Brooks and others. The problem is manifestly a physical and 

 not a biological one. We must look therefore to physical criteria for 

 its solution. The nearest approach to an absolute foundation for a 

 system of geological synchrony is to be found in the work of Irving, 



