GEOLOGY OF THE NORTHERN ADIRONDACK REGION 419 



greater smoothness is owing principally to this added length of 

 time during which it was undergoing wear. Its irregularities are 

 comparatively few and small; it seems a quite typical peneplain. 

 On the north the irregularities are many and often considerable; 

 are the rule rather than the exception. The surface is quite 

 hummocky and hilly, and the contact line an irregular one. The 

 supposed evidence is perhaps exaggerated in importance, owing 

 to the possibility of undetected faults in certain localities, but is 

 abundant even should all doubtful evidence be eliminated. It 

 does however seem to be true that the irregularities are mostly 

 of a minor order of magnitude, so that, when the tremendous 

 thickness of rock material which was removed in this Pre- 

 cambric interval is taken into account, with the several up- 

 lifts, and the quite respectable altitude at times which are thus 

 indicated, the surprise is not that the surface is so rough, but that 

 it is not vastly rougher. Maximum differences of level of but 

 a few hundred feet are all that are involved, and these compara- 

 tively seldom. Whether the surface were not sufficiently smooth 

 to be worthy of the name peneplain, is merely a matter of the 

 personal conception of such a surface which different individuals 

 may hold. 



The writer has shown that, in the Little Falls region, the present 

 inclination of this old surface is about 100 feet per mile toward 

 the south. The Beekmantown and Trenton rocks which rest on 

 it have a present dip in the same direction of about 70 feet to the 

 mile; whence, if we assume that they were deposited in a horizon- 

 tal attitude, we obtain a slope of 30 feet to the mile as that 

 which the old surface possessed at the time when the Paleozoic 

 rocks were deposited on it. While this is a gentle slope, it is too 

 steep for one graded by stream action and suggests that the move- 

 ment of depression itself resulted in some further tilting of the 

 surface. Little or no direct evidence has been obtained in other 

 districts as to its amount of slope. 



Paleozoic topography 



If the Utica sea overswept the entire region, and all the available 

 evidence seems to indicate that it did, then the region arose from 

 beneath sea level with a smooth, constructive surface whose slopes 

 depended mainly on the character of the uplift. But of this we 



