428 NEW YORK STATE MUSEUM 



much so that no sign of concordance of level is to be noted among 

 the hill summits. 



This main axis of elevation is everywhere so pronounced that it 

 would seem that it could hardly be a feature which had outlasted 

 the long period of Cretaceous base leveling, but that its present 

 prominence must be owing to unequal uplifting at the close of 

 this erosion cycle. The considerable deepening of the valleys in 

 passing toward the heart of the region (the broad valleys cut in 

 the succeeding erosion cycle are the ones here concerned) points 

 clearly to greater uplifting along this line. It also seems likely 

 that, in a region of abundant faults such as this is, such an uplift 

 could not fail to cause additional adjustment along the fault 

 planes. Such movements would give varying altitudes to such 

 portion of the area as had been graded during the long erosion 

 period. That many of the tops of the high Adirondacks are true 

 monadnocks, is highly probable. But that the area is entirely 

 composed of monadnocks, and never had any recognizable develop- 

 ment of the Cretaceous peneplain on it, is thought to be exceed- 

 ingly improbable, ' much more so than the alternative view here 

 presented. And this is emphasized when the rapid drop in alti- 

 tude to the Champlain valley is taken into account, both its 

 rapidity and its ch^acter suggesting rather recent faulting. 



On the prolongation northward of this main axis, the same 

 features are illustrated in the Paleozoic rocks, these being found 

 at the highest altitudes along that line, dropping rapidly east- 

 ward down the faults and less rapidly, and more regularly west- 

 ward. This represents the total amount of tipping which they 

 have received in all the movements of the region, but the present 

 prominence of the axis as a topographic feature seems too great 

 to be accounted for otherwise than by a not too remote date for 

 the last differential movement along it. In addition, certain 

 prominent eastward facing cliffs which appear to be fault scarps, 

 are found in the Potsdam counttry, just as they are in the Pre- 

 cambrian areas, fault scarps which seem to require actual faulting 

 of comparative recency to account for their presence. The evi- 

 dence, then, seems to point to actual warping of considerable 



