9-1 TACONIC SYSTEM IN MAINE. 



V. THE TACONIC SYSTEM IN MAINE. 



Rtimirks en the geology of tht country between Portland and WateroUle. Origin and position qf the granite 

 wed m construction. Slab qf WatervUle: similarity <;/' oil its subordinati beds to those of a; o- York. 

 Breadth qf the taeonic slate. Beferenct to the JVercitet qf WatervxUe. Similarity qf tht Kennebeck valley 

 to tht floosie valley in New-York. General remarks on tin rocks between WateroilU unit 'Belfast, Examina- 

 tion unsatisfactory at Belfast. Rocks qf Camden. Meguntieook mountain. Fox islands. Limestone qf 



Thomoslon. 



Tin- valleys of the Kennebeck ami Penobscot, together with a wide bolt of country upon 

 the Piscataqua, furnish many important fads in support of the Taeonic system. I was 

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

 which was famished me by mj friend Prof. A. Hopkins, of Williams College, from the 

 Kennebeck at Waten ille, upon which I obsen ed peculiar markings, so strongly resembling 

 those of the JYereites figured by Mr. Murchison in his Silurian System, that I could not 

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

 Taeonic 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 tins slate, I will avail myself of the opportunity to say a few words 

 upon the rocks between Portland and Watoi \ ille. 



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

 to the Primarj system. Tiny 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 Bchists in rather narrow veins. I hardly need re- 

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

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

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

 mining several of these hills which bad 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 that remained of those 

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

 State. These \eins are from one or two inches to a foot in thickness. I know that this is 

 not a new fact in geology; but 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 M assachusetts, 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, and of their igneous character, prin- 



