SCIENTIFIC SURVEY. 



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ful for our present purposes, in the Preliminary Report, (page 225, 

 etc.) The Taconic rocks recognized in Maine on Penobscot Bay, 

 are the Quartz Rock, Eolian (Stockbridge) Limestone, and the pe- 

 cular Argillo-micaceous and Argillo-talcose schist, erroneously de- 

 nominated " Magnesian Slate." None of them, in this region, are 

 fossiliferous in the slightest degree, so far as is now known. 



The rocks in this district, according to our conclusions, are the 

 following: 1, Granite and Syenite; 2, Gneiss and Mica Schist, 

 older than the Taconic group ; 3, Saccharoid Azoic Limestone ; 

 4, Taconic Quartz Rock ; 5, Eolian Limestone ; 6, Taconic Schists, 

 mostly Argillo-micaceous ; 1, Alluvium. This is the arrangement 

 adopted in the map, only that Alluvium is not there represented. 

 We will now proceed to describe these rocks in order. 



1. Granite and Syenite. 



Five patches of granite and syenite are represented upon the 

 map. The first occupies the greater portion of St. George, with 

 a part of South Thomaston. The second is really a part of the 

 same mass, although separated from it by the St. George river. 

 It is in the central part of Gushing. The third patch is in Warren, 

 forming Congress mountain. The fourth is a small development of 

 granite constituting the backbone of a ridge of hills in the north- 

 west corner of Hope. The fifth patch lies chiefly in Camden, and 

 runs under Megunticook mountain, the highest eminence in this 

 district. 



At Ash Point the granite crops out at the ocean's edge, while 

 the greater part of the point away from the shore line is covered 

 by drift. The island off the point is also granite. Upon Spauld- 

 ing's Point, to the south-west, the granite changes its mica for 

 hornblende, and hence becomes syenite. The rocks on these two 

 points would make an enduring building material. The constituent 

 crystals are often quite large. 



At the village of South Thomaston one may see the boundary 

 line between the poorly characterized mica schist and the granite. 

 This line runs north-westerly for two or three miles towards Thom- 

 aston village, and then continues to the St. George river in a 

 south-westerly direction, crossing over to the middle of Cushing. 

 The westernborder of this granitic mass is composed of hornblende 

 rock and granite. Passing to the middle of the granitic expanse, 

 we find the rock sometimes porphyritic — i. e., containing large 



