•• ► 



. It 



ROCKS COMPOSING THE TACONIC SYSTEM. 



145 



46. 



1. Gneiss. 



2. Firet bed of limestone. 



3. Magnesian slate. 



2. Second bed or Stockbridge limestone. 5. Second mass of magnesian slate. 

 4. Granular quartz. 6. Sparry limestone. 



2. Third bed of limestone. ' 8. Taconic slate. 



7. Shales of the Champlain group. 



The preceding section is intended to exhibit not only the rocks and their relative position, 

 but also to illustrate my views in regard to their dip, and other phenomena vvhich are brought 

 to light in this system of rocks. While it is admitted that there are many obscurities which 

 cannot be fully removed, and which with our present knowledge must remain, still it appears 

 that the simplest illustration leaves fewer objections than those which suppose a complicated 

 series of movements. With this view of the subject, I have adopted a mode of exjilanation 

 which is as far removed from complexity as possible, and to which there could be no objec- 

 tion, were it not assumed that the rocks of the western edge of the Taconic belt are newer 

 than those of the eastern, or in other words, at the time of their deposition rested upon the 

 eastern ; but if dip is an indication of age and superposition, the fact is direcdy the reverse. 

 Leaving the further consideration of this subject for another place, I will barely remark, that 

 my object in presenting these views, is to elicit facts from other observers ; that by careful 

 study in the field, we may be enabled soon to clear up all those points which are now so per- 

 plexing. 



Turning once more to the preceding section, it is apparent, if the section is true to nature, 

 that an easterly dip may have been given by several successive uplifts, or by the force which 

 occasioned those uplifts. This force, if regarded as general, and as operating beneath the 

 primary, we may consider that it might have upheaved the Hoosic mountain range, giving 

 its masses the easterly dip ; and as it was applied or exerted beneath those of the Taconic 

 system, gave to its rocks also a similar inclination ; and still passing onwards to the west, 

 produced derangements of the strata of the same kind in the masses composing the Cham- 

 plain group, the effects of which are more particularly seen in the Hudson river slates and 

 shales. That this force acted beneath the primary, is rendered probable by the exposure of 

 the gneiss, bearing up this series of rocks on one side without deranging them ; while on the 

 other, the same rocks are thrown down, leaning against the gneiss at a high angle. But we 

 have, besides the dip, other phenomena to explain ; the occasional folding of the strata, or 

 double contortions. We can conceive of but two methods by which changes of this nature, 

 or folding of the strata, can be produced ; one of which is, a force applied beneath, whose 

 general effect is to uplift the strata, but which at the same time exerts a lateral force, which 

 bends or flexes them upon each other at the moment the masses are under movement ; the 



Geol. 2d Dist. 19 



