POSTGLACIAL FAULTS OF EASTERN NEW YORK 23 



vations. A like zone of displacement parallel in direction but 

 far to the east is found in southeastern New Brunswick. While 

 the observed small fault scarps are postglacial in origin, it can 

 not be said that the faulting is wholly of postglacial date; secular 

 preglacial and interglacial faulting along the same zones would 

 have had the evidence effaced by glacial erosion. Observations 

 have not so far determined whether the movement is in progress 

 or not. 



When we compare these structures on the east of the Hudson 

 in the vicinity of Troy with the faulted structures on the west 

 in the vicinity of Little Falls on the southern border of the 

 Adirondacks, the upper Hudson valley assumes the appearance 

 of a broad graben, bounded by normal faults on the west and 

 overthrusts on the east, an unsymmetrical structure in which 

 the rock movements of unlike character are probably also of 

 dissimilar age. 



Evidence of dislocation in northern New York and Quebec 



Evidence of faulting which appears to be of recent date, 

 though not definitely determined to be postglacial as in the case 

 of the interrupted glaciated surfaces, was observed by the 

 writer at a number of points on the north, of which the two 

 most striking instances were seen on Trembleau mountain, at 

 Port Kent, N. Y., and on Mt St John (or Monnoir) near St 

 Gregoire in the province of Quebec. 



Probable fault on Trembleau mountain. Trembleau mountain 

 is a mass of norite projecting into Lake Champlain at Port 

 Kent. The eastern slope of this mass is benched more or less 

 definitely at an elevation of about loo feet above the lake. 

 Approaching the foot of the hill from the pasture southwest 

 of the railroad station at Port Kent, on the level of the old delta 

 of the Ausable river, the rocky bluff is most easily ascended at 

 a point where the rock is broken down and a shallow gully 

 encumbered with blocks of local derivation leads up to the plat- 

 form mentioned. This depression is traceable southward over 

 the top of the bench along the line where otherwise its surface 

 would join the steeper slope of the mass in its rear. The rocks 

 are massive, and faulting is consequently difiicult to prove ; but 

 the slopes are interrupted with an apparent uplift of the bench 

 on the east, and the zone of displacement, a few feet wide, forms 

 a trench in which large angular blocks have come to rest. This 



