136 
CHAMPLAIN DIVISION. 
Another great 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 are near this line, and the rocks are 
the slates of the Taconic system, surmounted by one or more varieties of the Calciferous 
sandstone. Greenbush, 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. 
The 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. This, 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 southeastern 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 waterlimes 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. 
a. Pentamerus limestone. 
e. Talus. b. Thin-bedded wateilimes. 
c, c. Hudson-river series. 
