442 



THE AZOIC SYSTEM AND ITS SUBDIVISIONS. 



are eviacntly Upper Silurian and referable to tlie Niagara limestones ; a simi- 

 lar formation has been met with at Gaspe and traced one hundred and fifty 

 miles S. W. ; and from the similarity of the Notre Dame to the Green Moun- 

 tains and the fact that the Hudson Kivcr rocks are continuous along the St. 

 Lawrence to Cape Rosier, we may conclude that the Upper Silurian rocks will 

 be found continuous, or nearly so, throughout. They constitute the calcareo- 

 micaceous formation of Prof. Adams, which he has traced nearly to the souths 

 eru lin(i of Vermont. Besting upon this formation in Gaspe is a body of are- 

 naceous rocks, seven thousand feet thick, which apparently correspond to the 

 Chemung aud Portage group of New York, with the old red sandstones. As 

 this formation is found extending quite to the Mississippi, it is probable that it 

 will accompany the Silurian rocks through New England and surround the 

 coal helds of New Brunswick, of Eastern Massachusetts and Ehode Island. 

 To this may perhaps be referred in part the rocks of the White Mountains, 

 which may s^Yeep around the Western border of the Massachusetts anthracite 

 formation until lost under the super-carboniferous rocks of the Connecticut 

 Eiver. The limestones of Western New England seem to be no other than the 

 metamorphic' Trenton limestones of Phillipsburg, while the chlorito-epidotic 

 rocks and serpentines of Sutton valley appear again in the rocks of Southern 

 Connecticut between these limestones and the new red sandstone. With such 

 a key to the structure of the metamorphic rocks of New England and of the 

 great Appalachian chain of wlach these form a part, we may regard the dilii- 

 culties that have long environed the subject as in a great degree removed, and 

 the bold conjectures as to their metamorphic origin which have been from time 

 to time put forth, fully vindicated." (Am. Jour. Sci., 1850, (2) IX., p. 19; 

 Proc. Am. Assoc. Adv. Sci., 1849, IL, pp. 333, 334.) 



In 1850 Dr. Hunt again expressed similar views with regard to the 

 age of the Green Mountain rocks. (Proc. Am. Assoc. Adv. Sci., 1850, IV., 

 pp. 202-204.) Ho declared that the view of Professor Emmons, that the 

 Taconic system was older than the Silurian formation, was at variance 

 with the structure of the region, as deduced both from stratigraphical 

 and geographical analogies. After summing up the observations which, 

 according to him, were in absolute contradiction with the theory of the 

 pre^Silurian age of the so-called Taconic rocks, he remarks : 



*' Such are the facts that lead to the conclusion that between the crystalline 

 rocks of the East side of Lake Champlain and the North shore of the St. Law- 

 rence, on the one hand, and the Upper Silurian limestones at the eastern base 

 of the Green Mountain range on the other, there are no rocks more ancient 

 than the Silurian/' 



Again, in 1854, Dr. Hunt referred the crystalline limestones of West- 

 ern New England, and their continuation through Northeastern New 

 York and the adjacent parts of New Jersey and Pennsylvania, to the 



