EEOSION IN SOUTHERN AND CENTRAL NEW BRUNSWICK. 93 



would imply an amount of erosion which, considering the nature of the material compos- 

 ing the felsitic group and the vast bulk which it exhibits even at a very limited distance, 

 seems altogether improbable. It may be added that while pebbles, derived alike fi-om the 

 felsitic and schistose beds, occur abundantly and in great variety in the basal conglomerates 

 of the Primordial, no such pebbles from either member of the calcareous group have been 

 identified in such a position as they naturally would be in, were the latter group imme- 

 diately subjacent. All that can at present be positively asserted is : (1) the super-position 

 of the limestoue-quartzite series upon the granitoid gneiss, though perhaps distinct from 

 the latter, and (2) the interposition of a vast body of schistose strata, quite unlike those of 

 the first named group, between the felsitic rocks and the basal beds of the Primordial. It 

 may be added that between the felsitic group and the overlying schists and conglomerates 

 the contacts are abundant and easily observed, showing not only distinct unconfor- 

 mity of dip, but at least a partial breaking up of the lower beds, accompanied by the 

 extensive extravasation of igneous rocks and the formation of coarse tv\ffs and agglomer- 

 ates, filled with blocks derived from the horizons beneath. Adopting this view of the 

 succession, it will be found to accord very nearly with that described by Dr. Hicks and 

 others as characterizing the district of St. DaAÙd's in Wales, where fossiliferous Cambrian 

 strata, containing a fauna similar to that of St. John, are in like manner underlaid in down- 

 ward succession by slaty and comparatively little altered rocks (Pebidian), a middle 

 group (Arvonian), comprising contemporaneous volcanic rocks, felsites, breccias and tuffs, 

 and having a thickness of 15,000 feet, and a lower group (Dimetian) consisting of grani- 

 toid and quartzose rocks with coarse gneiss and bands of limestone and dolomite, The 

 Coastal, Coldbrook and Portland groups of the New Brunswick local reports present appa- 

 rently identical features both of origin and arrangement. We may now pass to the con- 

 sideration of some more recent horizons. 



In connection with the Primordial or Cambrian rocks of St. John, no remains of 

 younger formations are to be met with, except it be those of the Lower Carboniferous 

 series, and although in the more northerly belt of such rocks, found in the valley of the 

 St. John Eiver in King's County, these are approached somewhat nearly by fbssiliferorrs 

 beds of Upper Silurian age, no actual contact of the two has been observed. It is, how- 

 ever, to be remarked that while beneath the Primordial rocks of this region there are, as in 

 St. John County, felspathic and schistose beds, succeeding in turn a well defined felsite- 

 petrosilex group, the latter is also directly and unconformably covered by the Upper Silu- 

 rian strata, thus indicating the extensive erosion to which the surface had been subjected 

 prior to the deposition of these later sediments, — a circumstance made still more conspicuous 

 by the occurrence of numerous hills, some of them several hundred feet in height, which 

 rise like islands through the nearly horizontal Upper Silurian beds, being evidently 

 fragments of a formation at one time much more widely distributed. The nature of these 

 beds and the fossils they contain show that the waters in which they were deposited were 

 but of moderate depth. 



It has long been known that rocks of Upper Silurian age are widely spread over the 

 northern counties of New Brunswick, and that these are bordered along their southern edge 

 by wide belts of much harder rock, flanking one or more belts of granite, and in the vicinity 

 of the latter often presenting the aspect of highly crystalline schists, this second group 

 being variously described by Gesuer, Robb, Hitchcock, Hind and others as Silurian, Cam- 



