274 NEW YORK STATE MUSEUM 



which many changes in conditions occurred, as shown by the 

 changes in character of the rocks. 



Closely involved with these rocks are others which would seem 

 to be of igneous origin, so far as may be judged from their com- 

 position. The great changes which they have undergone have 

 destroyed their original characters utterly, and they have been 

 stretched out into bands parallel with the associated sediments, 

 causing them to appear as an integral part of the series. It 

 seem's quite certain that they are, in part at least, igneous, and 

 that they must be somewhat younger than the sediments, except 

 in so far as they may possibly represent subaqueous surface flows, 

 yet they can not be greatly younger, since they have undergone 

 much the same changes, both in kind and in degree, that the 

 sediments have experienced. Wherever the sediments occur, these 

 igneous rocks are sure to be found associated with them, thus 

 indicating widespread and profound igneous activity at the time. 



Rocks of doubtful age. In many parts of the region, and 

 running in a broad belt across Clinton and Franklin counties, 

 is found a group of old rocks, profoundly changed from their 

 original condition, which seem to be wholly of igneous origin, 

 so far as can be judged from their composition ; at least no rocks 

 similar to those of the preceding group and which are judged 

 to be sediments occur with them. They have been equally, if not 

 more changed from their original condition than have the rocks 

 of the preceding group, and all traces of their original structures 

 have been destroyed. It is by no means impossible that they are 

 older and represent the rocks of the floor on which that group 

 was laid down ; indeed, if any remnants of that floor remain, we 

 have them here. But, since similar rocks, in general not to be 

 distinguished from them, occur associated with the sediments, 

 where they are clearly as young, or younger, these may represent 

 great masses of such rocks, massed in such amount as to have 

 wholly displaced the sediments. We are not able to decide these 

 questions as yet. If but one rock group is represented, it is no 

 older than the sediments. If more than one be present, one may 

 be older. But, if so, we as yet lack the means of discriminating 

 between them. 



