ROCKS OLDER THAN THE TACONIC SYSTEM. 
53 
general term, and often covers both ranges. But keeping up the distinction denoted by 
the subordinate portions of the most easterly range, as Hoosic and Mansfield mountains, 
and the 'laconic range upon the west, wc shall find that the geological character of the 
two are quite dissimilar, and well worthy of observation on that account. The former 
are the great primary or schist ranges, the subordinate members of which are gneiss, mica 
and talcose slate, and hornblende, among which are many beds and veins of granite, 
limestone, serpentine and trap. There is no clear line of distinction between the schistose 
rocks : mica slate is the predominant rock, in connection with which we find gneiss and 
talcose slate and hornblende, and with the two last are the serpentine and steatite beds, 
which in some instances are beds of passage; for instance, the great beds of steatite in 
Middlefield and Chester pass into talcose slate and serpentine. 
The principal object in speaking of the schists, is to bring into mind their position and 
character. Situated to the east, running in parallel ridges with the Taconic range, and 
being composed in their entire length of schistose masses, we are furnished thereby with 
the probable reason why the lower masses of the Taconic system are so perfectly schistose 
also : the latter are derived from the former the abraded materials of the one make up and 
constitute the consolidated masses of the other ; they are the first products from the primary 
rocks; the sea in which these materials were deposited was the most ancient, with little 
carbonaceous matter, and probably with a temperature rather above the present seas ; the 
masses are less changed in color and aspect; and being crystalline, also, the lower slates 
of the Taconic system appear like those of the older schists of the Primary system: they 
are regenerated rocks, possessing the characters belonging to the parent beds from which 
they are derived. The fact is notorious that the talcose slates of Berkshire are like the 
talcose slates of the Hoosic or Green mountains; and yet a close inspection of the two 
ranges of schistose rocks will satisfy most geologists that they are not of the same age, or 
of the same system. 
That it is possible for a sedimentary rock to retain or assume the characters of the parent 
rock, is rendered highly probable by the characters of the rocks or slates connected with the 
Rliode-Island coal beds. Here, in connection with the conglomerate probably of the Old 
Red sandstone, there is much material which is a talcose slate, differing but slightly from the 
talcose slate of the Taconic system ; or, in other words, it is like that of Berkshire county. 
I conceive that the slate of the Old Red, and which I believe Prof. Hitchcock calls wacke 
slate in his Massachusetts Report, is one derived directly from the magnesian slate of the 
Taconic system lying in proximity thereto: the quartz pebbles are evidently of that kind 
of quartz in the same rocks. The beds of conglomerate, with which these slate beds are 
in connection, do not appear to be metamorphic: the whole seems to be merely indurated 
or hardened slate, the original particles being talc and mica, with some fine quartz. The 
rock, when complete, is merely an ordinary talcose slate. 
I do not, however, deem it essential to prove the origin of the rocks which happen to 
lie in the ranges belonging to the Taconic system. It is of little consequence what the 
