MAINE AND NEW BEUNSWICK. 61 



vey, ISTO-Tl), but as there was reason to believe that much of the grauite fouud in this 

 region was of intrusive origin, and of much later date, while the separation of the two 

 was extremely difficult, it was thought best to represent them upon the maps simply with 

 reference to their lithological aspects. It is the belief of those who have studied the 

 geology of Charlotte County, New Brunswick, that in the great axis of crystalline rocks 

 intervening between the Bay of Fuudy and the central coal basin of the Province, both 

 Laurentiau and Huronian rocks exist, the former being represented not only among the 

 syenitic and gneissic rocks which cross St. Croix Eiver at and below Calais, but also 

 in the limestones and associated beds which directly skirt the Bay at Frye's Island and 

 L'Etang ; while the Huronian, besides including the rocks of Deer Island and Campo 

 Bello (with the southern half of Grand Manan), is also represented by bands of dioritic 

 and serpentinous rock, flanking the granites and syenites on their northern edge in the 

 vicinity of St. Stephen. The existence of these old and firm ridges and platforms of 

 Pre-Cambrian rock in southern New Brunswick and Maine, during the deposition of the 

 Silurian and Devonian ages, goes far to explain the contrast which these latter here 

 exhibit, both in character, attitude and organic remains, as compared with those of the 

 regions farther north, to be presently noticed. 



We have now to consider the rocks which either cross or are nearly adjacent to the 

 international boundary, along that portion of the latter which lies north of Calais and 

 St. Stephen, extending thence to the frontier of Quebec. Through this extensive tract, 

 including a distance of two hundred and fifty miles, the rocks which actually cross the 

 border are, so far as merely lithological characters are concerned, mainly reducible to two 

 principal kinds, viz., granite and slate, the first named forming a belt some twenty miles 

 in breadth, which crosses St. Croix River just north of Vanceboro, while the slaty 

 rocks occupy the areas respectively south and north of the latter. The general structure 

 also would, when viewed as a whole, appear to be quite simple, the granite constituting 

 an axis on either side of which the sedimentary beds are repeated in corresponding order, 

 rising to and including the beds of the Carboniferous system. Nevertheless, great diver- 

 sity of opinion has existed, and still exists, as to the precise age of different portions of 

 these slaty rocks, which, both in Maine and New Brunswick, have been severally referred 

 to very different horizons. This uncertainty arises from various causes, but mainly from 

 the fact that, the rocks being of very uniform character over extensive areas and through 

 considerable thicknesses, the recognition of definite horizons through lithological differ- 

 ences is very diffi(îult, while the fossils are but few and obscure, the slaty cleavage by 

 which the beds have been everywhere affected having tended to obliterate them, as they 

 have also largely the planes of sedimentation. The whole area has also been subjected to 

 extensive plication and probably abounds with faults, the position and effects of which 

 are not always easily ascertainable. 



We may now consider somewhat further the different views which have been 

 advanced as to the precise equivalency of different portions of these slaty rocks, beginning 

 with those which, in New Brunswick, occupy the interval between the southern and the 

 northern granite belts. 



All observers, at least since 1862, have recognized here a division of the slates into 

 two groups. These, in the Eeport and Map of Prof. Hitchcock were separated solely on 

 .lithological grounds — the one adjacent to the granite and presumably the older being 



