176 PROCEEDINGS OF THE AMERICAN ACADEMY 



ranges of mountains and the New York system. In these remarks 

 the writer does not expect to be able to give full justice to the subject 

 on which he is about, entering ; the merit, to a certain extent, of re- 

 moving some of the obscurities which envelop this system of rocks, is 

 all that he would claim." A very modest estimate, certainly. 

 . " The Taconic System, as its name is intended to indicate, lies along 

 both sides of Ike Taconic range of mountains, whose direction is neatly 

 north and south, or for a great distance parallel with the boundary line 

 between the States of New York, Connecticut, Massachui^etts, and 

 Vermont. The counties through which the Taconic rocks pass are 

 We:!!tchester, Columbia, Rensselaer, and Washington ; and after pass- 

 ing out of the State they are found stretching through the whole 

 length of Vermont, and into Canada as far north as Quebec. It is, 

 however, in Massachusetts, in the county of Berkshire, that we find 

 the most satisfactory exhibition of these rocks. They form a belt 

 whose width is not far from fifteen miles alonfj the whole western 

 border, and which extends clearly to the western part of the Taconic 

 range." * 



He divides the rocks composing his Taconic system into five 

 groups, in the following ascending order: 1, Stockbridge limestone; 

 2. Granular quartz ; 3. Magnesian slate ; 4. Sparry limestone ; and 

 5. Taconic slate. Insisting more especially on the " liability to mis- 

 take some of the slates and limestones for those which beloncj to other 

 systems." Emmons 'demonstrates that the Taconic system is " not con- 

 nected with or related to the slates and shales of the Champlain group 

 (Utica slate and Lorrain shales)." Finally he says: "These rocks 

 are entirely destitute of fossils"; and "appear to be equivalent to the 

 Lower Cambrian of Prof. Sedgwick." 



In the following passage Dr. Emmons gives the exact time from 

 which dates the Taconic system: " When, in 1836, I determined that 

 in New York the Potsdam sandstone was the base of the Silin-ian 

 system, it seemed that we had at that time the base of the sediments ; 

 but when, two years subsequently, I had observed the same base resting 

 on sediments still older, as those along the eastern side of Champlain 

 and elsewhere, it became evident that there was still a series older 

 than the Silurian. The proof of this has been accumulating ever 

 since ; and the Taconic system is found to rest upon primary rocks 

 without an exception ; and it has now been observed through the 

 whole length of the States, from N. E. to S. W. It is worthy of note, 



Geology of the Second District of New York, p. 13G. 



