TACONIC SYSTEM. 149 
reasons already for presuming to dissent; but I may go on and remark farther and more in 
detail, at the expense of some repetition. 
It is not so much the object of these remarks to express doubts in regard to the existence 
of similar plications : they often do exist, sometimes upon a small, at others upon a large scale ; 
but in this arrangement, the relative position of the several masses remains unchanged. The 
granular quartz, for example, if deposited originally beneath limestone, cannot really be placed 
upon it, though the circumstances may favor an apparent dip beneath it. An inspection 
of the real position of the Stockbridge limestone, as shown in a true section, will satisfy 
most observers that the theory of plication is insufficient to explain one or two important 
points, particularly as it regards the position of the granular quartz or limestone with an 
east dip. No force or plication could have placed this limestone in the slate, embraced as 
it is on each side ; and I take the opportunity to remark here, that it cannot correspond to 
either limestone in the New-York system, the Trenton, or Calciferous ; for I hold it to be an 
absurdity, that by any metamorphosis, a sandstone can be changed into a slaty rock. The 
Potsdam sandstone being the lowest rock in the series, and being succeeded also by limestones, 
and these followed by a succession of slates and shales, we are unable to discover in the 
Taconic rocks a series at all analogous to those composing the lower members of the New- 
York system; and the folds and plications, though they may exist, by no means furnish a 
satisfactory answer to the fact of a change in relative position; that is, it does not appear that 
the limestones of one system correspond at all to the limestones of the other — the same re¬ 
mark holding good, too, in regard to the slates and sandstones. 
These remarks are intended to disprove the unity of the Taconic rocks and the inferior 
members of the New-York system, differing from each other principally in condition, and 
which difference arises from metamorphism ; not that the rocks may not be metamorphic in 
one sense of the word, that is, altered in texture since their deposition, but that they are not 
the members of the Champlain group, thus changed by internal heat or by any other agent. 
