ANCIENT WATER LEVELS OF CHAMPLAIN-HUUSON VALLEYS 229 



Mohawk above Cohoes have been measured and described by 

 Mr Gilbert. Fitch mentions potholes on both sides of Wood creek 

 in the gneiss and sandstone at various bights, one of them lying 

 60 feet above the canal. Some of these potholes are undoubtedly 

 now in process of formation. No attempt has been made in this 

 survey to determine the value of the known potholes in the east- 

 ern part of the State as indications of the relation to sea level 

 during the time the ice was on the country. So far as those which 

 have been described are concerned and are of glacial origin, they 

 would apparently admit of the land being somewhat lower than it 

 now is or indefinitely higher. 



EVIDENCE OF HIGHER ELEVATION OF THE LAND IN THE SOUTHERN HUDSON 



VALLEY 



Distinct evidence of a higher stand of the land in the middle 

 and lower Hudson valley and over the submerged continental 

 shelf is found in several kinds of facts. 



The submarine valley already referred to as extending the 

 Hudson seaward has often been appealed to as evidence of eleva- 

 tion during the glacial period. The channel probably means 

 elevation at so late a time but no one has been able as yet to 

 determine the precise epoch in the glacial period from any evi- 

 dence the channel affords as to when the Hudson coursed through 

 it. The existence of the channel is however permissive of eleva- 

 tion at any time during the Wisconsin epoch, and appears to the 

 writer to be favorable to the view maintained in this paper. 



Of the particular evidences found within the existing land area, 

 the drowned Hudson gorge, the drowned mouths of its tributary 

 streams, and the abundant evidence about the mouth of the river 

 that the coast is now and has been sinking in relation to sea 

 level are much better evidence of a higher stand of the land 

 during the waning Wisconsin epoch than the submerged Hudson 

 channel taken alone. Some of these more definitely timed indi- 

 cations of depression are described in the following notes. 



In the southern Hudson valley the present is a time of relative 

 depression following one of uplift of the land to a higher level 

 than the present. That the land is undergoing or has recently 

 undergone a change of level in the lower Hudson valley is shown 

 by the character of many lateral stream valleys. 



