136 



CHAMPLAIN DIVISION. 



Another E^rcat line of fault exists upon the eastern side of the Hudson and Champlain 

 vallies : it in fact has elevated the country in such a manner that the line of fracture 

 bounds the valley. The most conspicuous eminences arc near this line, and the rocks are 

 the slates of the Taconic system, surmounted by one or more varieties of the Calciferous 

 sandstone. Grcenbush, Baldmountain, Granville, Whitehall, Addison, Burlington, Mil- 

 ton, are upon this line of fracture, and I might mention many other intermediate points 

 where all the phenomena I have stated may be witnessed. 



Tlie agent which determined the existence and direction of this great longitudinal dis- 

 placement of the strata, gave origin also to the vallies of the Hudson river and Lake 

 Champlain ; or, it may be more properly said, that the boundaries were first determined by 

 it, and that then the vallies themselves were formed by denudation. The entire series of 

 sedimentary rocks, which have been elevated and thrown into an inclined position, lie 

 between the base of the Helderberg and the Hoosic mountains. But in taking so wide 

 an area as this, we undoubtedly embrace fractures more ancient than the one which forms 

 the valley of the Hudson. Tliis, though it disturbs the Hudson-river rocks mostly, yet in 

 one section of country it passes through a prolongation of the Helderberg division ; showing, 

 in this fact, that it was really of a date as late as the Onondaga limestone. But the Taconic 

 rocks were elevated, and made to assume an inclined position, before the deposition of the 

 oldest member of the New- York system : this follows from the unconformability of the 

 two systems ; but it is impossible to fix upon the era. The Taconic rocks rarely occur su- 

 perimposed upon one another, as we see in the arrangement of the Helderberg division, 

 and in the slates and shales above ; and hence, it is, that though they may have been 

 fractured many times between the deposition of the granular quartz and the taconic slate, 

 still the relative position of the masses is such that no rational conclusions can be formed 

 in regard to the era in which they took place, whether in the earliest or latest period of 

 the system. 



Another limited fracture appears on the soutlieastcrn side of Becraft's mountain, about 

 three miles southeast of Hudson. On one side the Taconic slate appears supporting a 

 fragmentary mass of the Calciferous sandstone ; on the other, the inferior members of the 

 Helderberg division, the thin-bedded watcrlimes and pentamerus, beneath which are the 

 gray sandstones of the Hudson river. The relation of the latter mass is illustrated in 

 fig. 20. 



Fig. 20. 



o. Pentamerus limestone. e. Talus. b. Thin-bedded wate; limes. c, c. Hudson-river scries. 



