280 Remarks on the Taconio System. 



covered in many places with a coating of from 2 to 150 feet of 

 transparent material. Miles in extent of their strata, and hun- 

 dreds of feet in thickness, had been abraded and removed, — 

 the overlying cap of Silurian had mostly been carried away, 

 leaving only isolated patches in protected positions, and widely 

 separated localities, for the geologist to infer their former pre- 

 sence in full force. Add to all, the metamorphism of being 

 heated and cooled, — of large masses sliding by each other, thus 

 producing electric and magnetic action, — remember also the 

 chemical action and reaction that must have been present, and 

 you will understand the magnitude of the task any investiga- 

 tor assumes when he attempts to decypher all the problems of 

 the Taconic sytem. 



Our second argument is from its structural geology. 



Viewed comprehensively, and not descending to the minutiae, 

 the geology of this system is very simple. The main bulk of 

 the mountains is composed of laminated or massive slates of 

 various grades and varieties. One range on the east is capped 

 with hornstone or massive silex. The valleys of the eastern 

 portion are tilled with calcareous deposits, with intercalated 

 beds of slates and sandstone, and these beds also flank the 

 eastern slope of the mountains. The western valleys are 

 floored with the same slates as the mountains are composed of, 

 while the mountains on the west are, or have been, capped 

 with unconformable limestones or sandstones of a diiferent age. 

 The calcareous, slaty, or siliceous masses, whether rising into 

 mountain heights or reposing in the valleys, have unmistak- 

 able appearances of having been sediments in their normal and 

 primal condition. Their stratification, always regular, — the 

 ripple marks still remaining upon the surface, — the water-worn 

 rounded or brecciated character of the material composing some 

 of the deposits, as well as their fossil contents, all give evidence 

 of sedimentary origin. 



We may suppose these sediments to have been originally depo- 

 sited upon the floor of the primal ocean, which had primitive 



