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 circimistances 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, diifering 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. 



