INTERGLACIAL GORGES 75 



main valley may have been occupied by a stream which in some 

 way, perhaps by uplift, was suddenly rejuvenated; (c) a glacial 

 invasion may have altered the base level in the main valley. In 

 regard to these possible explanations, we believe it not only 

 possible, but very probable that a lake, similar to the present 

 Cayuga, existed in the valley previous to the last ice invasion. It 

 is conceivable, also, that such a lake might be drained compara- 

 tively suddenly. For instance, a hard rock stratum might be so 

 disposed as to form a barrier which would yield rather suddenly and 

 expose weaker rocks beneath. It is evident, therefore, that we 

 cannot at once dispose of hypothesis {a) . On the other hand, we 

 have in Six Mile Creek alone no means of proving that a river 

 in the main valley may not have been suddenly rejuvenated, • 

 It will be apparent, however, that if such a trunk river, by its 

 rejuvenation, led to the formation of a gorge in Six Mile Creek 

 valley, it should, in a similar manner, have led to the forma- 

 ton of similar gorges, corresponding to the 200-foot gorge of Six 

 Mile Creek, in all the other tributaries. We should expect to find, 

 then, that the wide buried gorge of Buttermilk Creek, which appar- 

 ently corresponds to our 600-foot gorge, should have a narrower 

 gorge, corresponding to our 200-foot gorge, sunk in its bottom. 

 Such is not the case, however. We must conclude from this, we 

 believe, that hypotheses (a) and (b) are both untenable, for the 

 argument stated above would apply equally well in the case of a 

 lake whose level was suddenly lowered. The third hypothesis sug- 

 gested—the lowering of the base level of the tributaries by the 

 intervention of a period of glacial erosion — ^does not meet with this 

 objection, for it might well happen that the Six Mile stream, after 

 the disappearance of the ice, would find itself still in its old channel, 

 while the Buttermilk stream, happening to find its old channel 

 blocked by drift or delta deposits, cut a new gorge elsewhere, as, 

 in fact, it has done. 



A careful study of the buried gorges of Butternut Creek, New- 

 field Creek, and others should be made in order to settle the question 

 beyond possibility of dispute.^ 



' In this connection it may not be out of place to call the attention of any whose 

 lot it may be to make a further study of these buried gorges to a remarkably fine buried 



