SCIENTIFIC SURVEY, 277 



for so great a distance. It runs towards the mass of granite in 

 Enfield, which most probably was forced up along the anticlinal 

 line, as the rock would naturally be weakest there. Very likely 

 the anticlinal described last year in Weston, (page 384,) is the 

 Continuation of this anticlinal line. 



.The next basin is very narrow, and the rock is more argillaceous 

 than in the previous basin. The synclinal line runs along the val- 

 ley of the Piscataquis river, even as far up as Parkman, and then 

 it must run on the west side of Penobscot river a great distance. 

 We think that its position is indicated near the Five Islands in Winn, 

 by the change in the dip. Of course these lines must extend further 

 in both directions than we have indicated, but we point out the 

 lines only so far as we have knowledge of them. 



Next we come to another change in the dip, with clay slates 

 prevailing on one side and argillo-mica schists upon the other. 

 Hence we do not regard it an anticlinal, but a change in the dip 

 incident to different formations, the slates overlying the schists, 

 perhaps unconformably. This line, which upon our large map we 

 have for the present established as the boundary line between the 

 two formations, is first recognized in the north-east, in No. 1, R. 

 5, in Aroostook County, on the Aroostook road. It can be traced 

 through Molunkus, the south-east corner of Medway, (formerly 

 called Nickatou,) thence in a straight line to Medford, when it takes 

 somewhat of a westerly course through Milo, Sebec, Foxcroft, 

 Guilford and Abbot. Here it resumes the south-westerly direction, 

 and we have traced it through Kingsbury, Brighton and Bingham, 

 to the Kennebec river.' The axes on the various radiating sections 

 correspond with one another no further than to this boundary, 

 but the rock on the north-west side of this line is almost entirely 

 clay slate, and is the only belt in Maine from which roofing slate 

 is now obtained. The variations in dip in this clay slate formation 

 we conceive to be due to various causes more or less local, and 

 not to be treated of here. Scarcely anything has been discovered 

 during the Survey which has given us greater pleasure than these 

 axial lines. It is a very important onward step in the progress of 

 our knowledge of Maine rocks, and a faint shadow of what would 

 be developed by a series of comprehensive parallel sections. 



Returning to the details upon our principal section, we find the 

 dip to vary somewhat over the first half of the first synclinal basin. 

 We had just said good-bye to the quartz rock of Holden ; and on 



