GEOLOGY OF THE NORTHERN ADIRONDACK REGION 423 



faults in the Mohawk valley was a block of this sort. Appar- 

 ently the Paleozoic inlier at Wells, Hamilton co., is preserved 

 in a similar trough. In the Precambric areas to the north, 

 specially in the high Adirondacks, the topography often sug- 

 gests faulting of this sort. And, as has been shown, cases of 

 this kind are not infrequent between the minor cross faults in the 

 Champlain region. 



In addition to the modification in the topography produced 

 by the erection of the fault scarps, the faulting must obviously 

 have affected the drainage. Stream courses would be obstructed 

 by the scarps and the streams turned into parallelism with 

 them, tending to flow along at their bases; and the crushing 

 of the rocks along the fault plane would produce a line of weak- 

 ness there, which, even after the disappearance of the scarp 

 through wear, would tend to hold the streams there. 



Mesozoic base-leveling 



This uplift, which terminated the Paleozoic history 'of the 

 region, obviously renewed the activity of the erosive processes, 

 and the task of cutting down the region toward the new base 

 level thus given it w r as begun. Though the evidence is not as 

 clear as could be wished, it point si to the region having remained 

 at this newly given level for a long time, long enough to per- 

 mit the wearing down of the major portion to a comparatively 

 even surface at this new stream grade. In other words, it was 

 worn down to a peneplain, above whose general level certain 

 hills of various altitudes arose, none of which exceeded 1000 feet 

 in elevation, which had resisted somewhat the general wearing 

 tendency, mainly because of advantageous situation. The in- 

 facing escarpments of the Paleozoic rocks retreated well away 

 toward the margins of the region, till the weak belts reached 

 grade, after which the escarpments would disappear as the 

 stronger rocks slowly came down to the same level; the fault 

 scarps also disappeared, both sides coming down to the general 

 level; the streams which were flowing parallel to the sides of the 

 region, adjusted to the weak rock belts, would accompany these 

 belts in their movement away from the heart of the region; 

 they would also increase in size by the capture of many of the 



