side, and by the sinuosities of its channel. The Alpine glaciers, therefore, being supported by the shoulders of the rocky ridges along their sides, may be said (if one may be allowed the expression) to hang down from the gorges through which they flow, into the valleys beneath; and as their weight is thus materially reduced, their erosive power is lessened; and they do not afford a fair criterion of the amount of pressure which a continental mass of ice, thousands of feet in thickness, would exercise upon the rocky ledges of the region over which it might pass. Prof. Tyndall's estimate of the weight of column of ice, would make this pressure more than 7000 lbs. to the square inch beneath a glacier 2000 feet thick. Nevertheless the glacier which may once have covered Acadia, has accomplished little in moulding the general features of the surface. At many points around the New Brunswick coal-fields, in the valleys among the Southern hills and on the coast, tongues and islands of Carboniferous sediment, yet remaining, shew that the more prominent ridges and depressions ante-date the glacial epoch. Prof. Bailey draws attention to an instance of this in the walls of a rather narrow depression through which the river St. John flows near Indian village, a few milcg above Fredericton. Patches of Lower Carboniferous conglomerate may there be seen, plastered against the walls of slate, out of which the gorge was originally cut. Similar instances occur in the southern counties. Nor can the fiord-like bays of the southern coast of New Brunswick be adduced as instances of glacial erosion. Both the St. Croix and Digdeguash estuaries are Pre-Carboniferous. That of the Magaguadavic is crossed by the drift striæ at a wide angle, and the same may be said of other indentations along the coast as far east as Beaver harbour. Lepreau harbour and Basin, and Dipper harbour, are all transverse to the glacial furrows, and Musquash and St. John harbours are too wide and open to be regarded as fiords. Glaciers of the drift period may have enlarged, but they certainly did not excavate the rocky beds. of these indentations to any appreciable extent. Their form though partly due to faults and folds of the older (Pre-Carboniferous) formations, is chiefly the result of erosion accomplished in early Paleozoic times. Although these larger indentations of the coast line cannot be attributed to glaciers, the Boulder-clay betrays the action of ice on the softer rocks of the country, as will be hereafter shown. It is probable that ice assisted in enlarging and deepening the small lakes and ponds, so numerous in tracts where VOL. VI. No. 1. metamorphic and granitic rocks occur. These sheets of water are usually to be found along the course of limestone bands, or at the junction of gneissic and granitic rocks with the softer Palæozoic strata. The rapidity with which hard limestone beds will waste away, even when covered by soil, is well exemplified at the manganese mine at Markhamville, King's County, N.B. At this place beds of gravelly earth, varying from three to eight feet in depth, have been removed from the limestone ledges in which the ore occurs, in the process of mining. The rock thus exposed slopes to the northward, and in its rounded outlines gives evidences of glacial erosion. In places it is filled with pockets of the ore, which being softer than the enclosing rock, must have been planed off to a level with the limestone during the glacial period; yet they now stand out above the surface of the ledge to a height of from eight to ten inches. From this it would appear that the surface of the limestone bed has wasted away to a depth equal to the height of these bosses of manganese, since the drift epoch. DRIFT STRIE. In common with New England, Quebec and Ontario, the rock surfaces in New Brunswick are in most places covered with numerous parallel grooves. In the valley of the St. Lawrence these furrows have a general south-westerly course, and in New England tend to the south-east. The latter course is maintained along the Maine border in New Brunswick, but in the central and eastern part of the Province the striæ run nearly due south. The easterly tendency of the glacial grooves along the Atlantic coast seems to be owing to the general slope of the country from the summit of the Appalachian chain to the deepwater margin of the continent. The Gulf of St. Lawrence and the New Brunswick coal-field forming an extensive plain at the eastern end of this slope, appear to have governed the course of the striæ in the central and eastern part of the province named, giving them a more direct southerly course. As far east as the river Magaguadavic the descent from the table-land of northern Maine towards the Bay of Fundy is comparatively regular, being interrupted only by a group of hills around the Chepetne ticook Lakes on the river St. Croix, but eastward of this stream, in the southern part of the province, inequalities of the surface cause great variations in the course of the striæ. These varia tions seem to have been influenced by the contour of three dis tricts in the Southern counties. 1st. The tract occupied by the group of granite hills extending from the Magaguadavic river to the Nerepis river. These hills vary from 700 to 1000 feet in height, and are without longitudinal valleys, but have transverse valleys of no great depth. 2nd. The area occupied by the valley of the St. John and its tributaries. This tract is characterized by a number of longitudinal ridges and valleys having a S. W. course. The ridges are broken by several transverse valleys, many of which are eroded nearly to the sea level. The third tract is the broad unbroken ridge of the Quaco hills and the slope to the Bay of Fundy on its southern side. It extends from Black river (twelve miles east of St. John) to Shepody mountain in Albert County, and rises to a height of from 900 to 1200 feet above the sea. The wide Carboniferous plain to which allusion has already been made, lying to the north of these districts, is in most parts not more than two hundred feet above the sea-level. The table of striae given below relates chiefly to Charlotte County and the western parts of St. John and King's counties. In it the scattered observations of several years are combined, and although brief and imperfect, it will, I think, serve to show, to how great an extent the peculiarities of the several tracts above named have influenced the direction of the glacial grooves. Numbers 1 to 14 give an average of S. 45° E., and pertain to the district west of the Magaguadavic. The course of the rivers in this part of the Province mark its south-easterly slope. Numbers 15 to 21, which gives an average of S. 10° E., were taken in the granite hills and in the low country north and south of them. They probably exhibit the normal course of the glacier (?) in the middle and eastern part of New Brunswick. Numbers 22 to 33 give the course of the striæ on the eastern side of these hills as far as the St. John river. Here the average is S. 35° E. Eastward of this the influence of the ridges and intervening valleys descending south-westwardly to the St. John River, is clearly seen in the average of S. 25° W., yielded by numbers 34 to 36, 40 to 44, and 51. Numbers 46 and 47, which are on a low S.W. prolongation of the Quaco hills, by their average of S. 10° W., exhibit an approximation to the next set of striæ, which are on the ridge overlooking the Bay of Fundy and on the slope towards it. Here there is no obstacle to a direct descent to the depres sion, occupied by the Bay, and numbers 45, 48 to 50, and 52, in the average of S. 35° E., show a tendency to return to the strong easterly set of the striations in the western part of Charlotte county. TABLE OF DRIFT STRIÆ IN SOUTHERN NEW BRUNSWICK. [These notes are arranged according to the longitude of the places mentioned, from west to east. In general those described as "other striæ," are older than the grooves recorded in the margin. I am indebted to Prof. Bailey for permission to include those marked with an asterisk.] 17 678 23 24 25 do. 26 66 ⚫ 27 28 29 (6 do. north side. Magaguadavic R. Falls of S. 80° E. Lake Utopia, west side. 15 Pennfield, point between Deadman's and 16 Clarendon, Bear Brook (broad valley). Sand Brook (narrow valley). 18 66 19 แ McLeod Road, 14 miles from Douglas Falls Brook (an open valley). 20 Lepreau Harbour, north side. 21 Lepreau Basin, Black Duck Hole. 22 Lancaster, West Branch Musquash River, at Mill, course of valley east. "Musquash Village, McGowan Inn. do. Frenchman's Creek, at bridge 30 Westfield on R.R. 8 miles from Fairville. 31 Lancaster on R.R, 4 miles from Fairville. Also on a ledge sloping 70° striæ N. 70° E. curving to 32 Lancaster, on R.R. 3 miles from Fairville. • 33 South Bay Mills. Other striæ, S. 40° E. 34 Westfield, Kennebeckasis Island, N. side of, south of a ridge running N. E. On sandstone. N.E. S. 30° E. S. 20° E. S. 10° E. N. S. N. S. 10° E. N.W.(flat) S. 10° E. N. S. 20° E. S. S. 10° E. W. S. 20° E. N.N.W. S. 50 E. S.E. S. 20° E. 42 35 Westfield, Kennebeckasis Island, N.E. end, hills to N.W. and E. enclosing valley opening S.S.W. 36 Lancaster, west end of Suspension Bridge. Sand Cove road, striæ on a steep ledge deflected to S. 80° E. from 37 38 Carleton, Queen's Square, on ledge sloping 39 Same place on top of ridge. 40 Portland, summit of valley at Lawlor's L., S. 2° W. N. S. 15°W. S. 4° E. S. 35°W. W. S. 2° W. S. S. 15°W. Next stream southward (course of S. 40° W. S. 20°W. S. 50° E. "L Same road, 1 mile N. of last. S. 5° W. Other striæ S. S. 15°W. Black River Road, east of Grassy L. flat. S. 30° E. " Mountain Road to Black River settle ment, on flank of Bloomsbury Mt. S.W. It is not easy to account for the strong tendency of these grooves to run down the southerly slopes of the land in this systematic way, upon the theory that they are due to icebergs alone; nor does it seem possible that ocean currents could urge the bergs onward with sufficient force to lift them over hills 700 to 1000 feet in height, and drop them down the southern slopes to groove ledges only a few feet above the sea. If the table be examined in detail, objections to the iceberg theory as the sole means of explaining surface striation, quite as weighty as those already spoken of, will be found. Others of a different kind may be adduced; as for instance the striæ on the over-hanging, as well as the exposed side, of a narrow cleft in hard felspar-porphyry rock at the head of Chamcook lake on the St. Andrew railroad. |