EROSION IN SOUTHERN AND CENTRAL NEW BRUNSWiClt. 9 S 



guishable from true segregated veius which accompany them, penetrate the schists in all 

 directions to a distance of several hundred feet. 



•7. Large detached blocks, of various sizes up to two or three feet, but usually angu- 

 lar and sometimes rectangular, are enclosed in the granite, and produce the appearance of 

 a coarse granitic breccia. 



To the above it may be added that small patches, sometimes not more than a few 

 yards or feet in extent, of gneissic or schistose rock, are occasionally met with resting 

 vipou, but inseparable from, the granite, at very considerable distances from the nearest 

 exposures of such schistose rock, while smaller masses, which are evidently detached frag- 

 ments, occur in all parts of the granite area, often retaining the same features of texture, 

 foliation, and even of colour, presented by the main body of such rocks. 



From a consideration of the above and other facts, the conclusion seems to be fairly 

 established that the gi-anites in question are intrusive or exotic, and that the alteration of 

 the associated rocks was an accompaniment, if not an effect, of such intrusion. It may be 

 added that while the several belts of slates and schists, north and south of, or central to, 

 the granite, have been variously described as wholly or partly of different age or origin, 

 recent minute examinations of the region show beyond question their essential identity, — 

 the same crystalline and semi-crystalline rocks always appearing where the granite is 

 approached, whether from the southern, northern or eastern side, while in the opposite 

 directions these as invariably graduate into the upper and comparatively unaltered argil- 

 lites and greywackes. At what period the extravasation of the granite occurred is less 

 certain. As far as yet observed in Carleton County, no veins of the latter are to be found 

 penetrating the Upper Silurian, although veins of syenite and diorite are common ; but 

 the fact observed in the southern counties, that the conglomerates older than the Lower 

 Carboniferous are destitute of granitic pebbles, while those of the latter formation abound 

 with them, taken in connection with the evident similarity of the granites in the two 

 regions, and the precisely similar effects accompanying them, appears to indicate that both 

 are of synchronous origin and both Devonian. In either case the amount of erosion which 

 has since occurred is sufficiently indicated by the facts already stated, the whole granitic 

 area, with a superficies of several hundred square miles, having been evidently laid bare 

 by the denudation of beds (schists, slates and sandstones,) which, though now miles ajjart, 

 were at one time continuous over it, and which, to judge from their highly inclined atti- 

 tude and vast thickness, must have buried it to a very considerable depth. The fact that 

 the granite areas are visually lower than those of the bordering schists would also seem to 

 indicate that erosion has been more extensive and complete along these areas than in 

 the regions adjacent to the latter ; while the much greater breadth of the region of meta- 

 morphism and foliation on the northern side of the granite, than on the southern, would 

 appear to indicate a much more abrupt descent in the junction line of the granitic mass on 

 this latter side than upon the opposite. It is to the contrasts thus produced that the different 

 views, which have been advanced by different observers as to the relations of the strata in 

 the district, are to be ascribed. 



I pass now to the contacts of the Devonian. In the southern counties the rocks of 

 this age, so far as they have been certainly identified, are of very limited distribution, and 

 rest only upon rocks of Cambrian or pre-Cambrian age, a portion of these latter, by an 

 overturn and fault, being also brought to rest, in a position of comparative conformity, 



