94 TACONIC SYSTEM IN MAINE. 



V. THE TACONIC SYSTEM IN MAINE. 



Remarks on the fetology of tht country bettveeii Portland and iVuterville. Origin and position of the granite 

 used in construction. Slate of Waterville: similarity of all its subordinate beds to those of JVtiv-York. 

 Breadth of the laconic slate. Reference to the JVereites of Waterville. Sitmlarity of the Kenncbeck valliy 

 to the Iloosic valley in J\'eiv- York. General remarks on the rocks between Waterville and Belfast. Examina- 

 tion unsati.'factory at Belfast. Rocks of Camden. Megunticook moxmtain. Fox islands. Limestone of 

 Thomaston. 



The valleys of the Kennebeck and Penobscot, together with a wide belt of country upon 

 the Piscataqua, furnish many important facts in support of the Taconic system. I was 

 first convinced of the importance of the rocks in these valleys, from a specimen of slate 

 which was furnished mo l\y my friend Prof. A. Hopkins, of Williams College, from the 

 Kennebeck at Waterville, upon which I observed peculiar markings, so strongly reseml)ling 

 those of the J^'ereites figured by Mr. Murchison in his Silurian System, that I could not 

 doubt tliat they belonged at least to that genus. As this slate appeared identical with the 

 Taconic slate of New-York, I deemed it important to visit the region which furnished the 

 specimen. I accordingly visited Waterville, going by way of Portland, for the purpose 

 of passing over as much of the adjacent territory as possible. Before proceeding to relate 

 the facts concerning this slate, I will avail myself of the opportunity to say a few words 

 upon the rocks between Portland and Waterville. 



The rocks in and about the city of Portland, and onwards through Brunswick, belong 

 to the Primary system. They consist of schists, gneiss and mica slate, mostly of the same 

 character as those of Massachusetts. They are traversed like them with coarse granitic 

 veins, abounding in tourmaline and other minerals peculiar to such veins. Besides the 

 coarse variety of granite, one of a beautiful light grey is associated in beds with the same 

 schists. This variety is almost entirely destitute of the fine minerals so abundant in the 

 coarser kinds, and which traverse the schists in rather narrow veins. I hardly need re- 

 mark tliat it is the grey and uniform rock which has been so much employed in construc- 

 tion. The most interesting fact which I observed in relation to this rock, was, that it 

 occupies usually the summit of the liills, appearing there as the capping stone. On exa- 

 mining several of these iiills wliich had been opened as quarries, I found that the granite 

 was quite limited, and that the entire mass had been removed ; that the bed rested originally 

 upon the edges of the nearly vertical mica slate ; and, in fine, all tliat remained of those 

 beds, were the veins through which the granite seemed to have issued while in a molten 

 slate. These veins arc from one or two inches to a foot in thickness. I know that this is 

 not a new fact in geology ; InU I had not seen any statement to this effect in the publica- 

 tions of the day. Granite of the same kind, but of a coarser grain, forms large beds in 

 some parts of Massachusetts, and has probably a similar origin. In New- York, granite 

 seems also to have overflowed some of the beds of primary limestone. 



I have introduced a notice of the primary rocks, atul of their igneous character, prin- 



