Naskaupi and Hamilton valleys within the limits of the accompanying map (Figure 4) are preglacial valleys and that Grand Lake and Lake Melville basins are parts of the old valleys of these two major rivers and their tributaries. The Naskaupi flows through a broad, mature valley for 18 or 20 miles above its mouth, which is as far as the writer traversed it. This old valley, and the valley formed by the junction of Susan and Beaver rivers at the western end of Grand lake, unite near the upper end of Grand lake, forming Grand Lake valley, which is comparable in width with Naskaupi valley and represents its continuation. The preglacial Naskaupi river joined the Hamilton in late Tertiary time somewhere near Goose bay. These two, combined probably with the Kenamu, whose Pre-Quaternary valley is unknown, formed the preglacial Hamilton. This stream, which was the main trunk river of eastern Labrador, flowed through the wide, deep valley of Lake Melville basin and reached the sea via The Backway valley. The inference that the preglacial Hamilton flowed seawards by The Backway instead of by The Narrows, as it now does, is based on the much greater width and depth of The Backway, and the fact that the land is very low between the seashore and the eastern end of The Backway. The Narrows was probably developed either in late Tertiary time or during some stage of the Glacial period as a through valley connecting Double Mer and Hamilton valleys just as they are connected by a through valley which joins the upper end of Double Mer and Mulligan bay (See Figure 4). When the final retreat of great valley glaciers which marked the late stages of glaciation began it may be presumed that the high mountains southwest of The Backway, together with the mountain ridge immediately north of the western half of it, supplied an abundance of glacial ice to the terminal end of Hamilton valley, which kept it blocked for a long period after the ice-sheet had vanished from much of the adjacent parts of the valley. This situation would have compelled the restored river to seek a new outlet to the sea by any low divide or through any valley which it found free of ice. It is the writer’s opinion that a pre-existing valley, corresponding in position with the present Narrows and the waterways on the northern and southern sides of Henrietta island, was appropriated by Hamilton river while the original terminal section of the stream was ice-dammed. When the ice finally withdrew from The Backway its outlet was blocked with glacial debris, and the new channel had been sufficiently deepened to prevent the river from resuming its old outlet to the sea.
When Hamilton river returned to its old channel after the valley glaciers had finally disappeared it was not the graded channel it had left at the beginning of the Ice age, but a basin irregularly deepened and widened by the scouring work of the ice (See Figures 4 and 5 A and B). Near Henrietta island this basin has a depth of nearly 1,000 feet. It seems most probable that much of this great depth represents glacial overdeepening. If it represented the original depth of the old Preglacial Hamilton valley cut when the land stood 1,000 feet higher than at present, comparable soundings should be found in the broad, shallow sea zone in Hamilton inlet, or south of it. But
no depths approaching this have been found either here or elsewhere between the coast-line and the margin of the continental shelf. The navigation sheet shows that the prevailing depths of the sea within 2 miles of the shore range as a rule between 20 and 50 fathoms. Along the axis of lake Melville and Grand lake, for a distance of 125 miles, soundings are found ranging from 80 to 160 fathoms. Since no comparable depths are known outside the shallow sill of The Narrows, which separates Lake Melville and Grand Lake basins from the sea, the great depths of these waterways appear to be referable mainly to over-deepening by glacial erosion.
This glacial erosion has doubtless been most intense and profound in those parts of the valley where structural features have resulted in valley floors of relatively soft or easily eroded rocks. In Double Mer and Lake Melville basins the Double Mer sandstone and possibly other softer and now completely removed formations have supplied this factor leading to overdeepening. The convergence of valley ice streams at certain angles may have added locally to their erosive power.
The Labrador coast has all the characteristics of a drowned shore-line. The islands forming a belt nearly 50 miles wide at Hamilton inlet and rising from a shallow sea, and the numerous indentations of the coast-line represent the subsidence of an old land surface which left only the higher points projecting as islands. This subsidence truncated the seaward ends of many rivers. The converging trends of Sandwich Bay, The Backway, and the south shore of Hamilton inlet suggest that the streams which these several shore-lines represented previous to the depression of the coast may have united into a single stream somewhere east of Stag islands. The late Pleistocene re-elevation of the coast, amounting to a little more than 300 feet, has caused a retreat of the valley arms of the sea from their earlier extension far up Hamilton and Naskaupi valleys. If there should be a further coastal elevation of 200 feet or more, the mouth of the Hamilton will again approximate its preglacial location somewhere in the eastern part of Hamilton inlet or farther south.
The coastal strip and the interior of Labrador present surprising climatic contrasts, resulting chiefly from the influence of the Labrador current which carries an Arctic climate southward along the entire eastern coast of Labrador. In passing through the strait of Belle Isle in July a stream of floating ice and bergs is met with, which increases in volume as one proceeds up the coast (Plate IV B). Throughout most of July the vast ice fields move steadily southward under the influence of the Labrador current, dispensing a polar temperature over the western side of Davis bay and the adjacent coast. The summer climate on the Labrador coast is notably colder than that of the west coast of Greenland even, according to Professor Tarr.1 This results
1 Tarr, R. S., “ Difference in the Climate of the Greenland and American Sides of Davis and Baffin’s Bay.” Am. Jour. Sci., vol. III, pp. 315–320, 1897.
from a northward-moving current on the Greenland side and a polar current on the Labrador side of Davis bay.
The sub-Arctic climate which the southward-moving ice fields bring as far south as the strait of Belle Isle extends only a short distance inland from the coast. In going inland by way of The Narrows and lake Melville one finds that there are two Labrador climates. One is a sub-Arctic climate which characterizes a narrow coastal zone of islands and sea-facing mainland called “ the Labrador ” by the cod fisherman. This strand and island zone is chilled by ice-floes and is nearly or quite treeless. Inside this seashore strip is the heavily forested interior Labrador, where a summer climate replaces the ice-chilled coastal climate and forests cover the valleys and much of the mountains.
Holme concisely summed up the great contrast between the interior and coastal climate in the statement that “ A journey of 20 or 30 miles in summertime up the country from the sea is like passing from winter to summer.”1
Small berg fragments and ice-cakes were seem in Hamilton inlet, 18 miles west of Indian Harbour, on August 20, 1921, but the floe-ice had all disappeared before that date. No floe-ice was seen during the summer at or near Rigolet.
Around the western end of lake Melville, potatoes, rhubarb, and other hardy vegetables do well. Mr. Leroy Bowes found that potatoes had been killed by frost before September 10 at Mud Lake on lower Hamilton river. Midsummer frosts are reported to occur at Northwest River, about one year in four or five.
In the summer of 1921 there was no snow on the mountains about lake Melville during July and August, except very small patches at elevations above 2,000 feet. On the outer islands near Indian Harbour a few small patches of snow still persisted near sea-level as late as the last week in August. It is reported that some snow is seen in midsummer during exceptional seasons at Rigolet.
Contrasts between the Coastal and Interior Floras. The most conspicuous feature in the plant geography of the region is the sharp contrast between the flora of the interior and the flora of the seashore. The general absence of forest trees from the flora of the seacoast and their abundance in the interior, cannot escape the notice of even the most superficial observer. Randle F. Holme has stated clearly the impression which this contrast makes on the visitor.2 “ The Arctic current, with its icebergs and icy waters, freezes the coast, but has no effect on the inland. At a distance of not more than
1“ A Journey in the Interior of Labrador, July to October, 1887,” Roy. Geog. Soc., vol. X, p. 189, 1888.
2Proc. Roy. Geog. Soc., vol. X, p. 189, 1888.
12 miles from the coast there commences a luxuriant forest- growth, which clothes the whole of the country, with the exception of a few spots, chiefly towards the north, called 'barrens.' These barrens are what we should call moors, and are the homes of vast herds of caribou. The climate a few miles inland is totally different from that on the coast.” The nature of these contrasts is suggested by Plates IV and V.
A great number of plants other than trees which are abundant inland are absent from the seashore flora. The relative poverty of the seacoast flora, as represented by the island flora near Indian Harbour, is clearly illustrated in the following list of the plants of the region in which the species found respectively in the Interior and Island floras are checked in parallel columns.
Provisional List of Plants Found in Lake Melville and Hamilton Inlet District.1
1Nomenclature and numbers are as found in Gray's “ New Manual of Botany,” seventh edition by robinson and Fernald ; names not in this manual are those validated in recent revisions, chiefly by Prof. Fernald.
The plants in this list were collected by R. H. Wetmore. Determinations were made by R. H. Wetmore under directions of Prof. M. L. Fernald of Harvard University.
See also checklist of plants of the region, by R. H. Wetmore “Plants of the Hamilton Inlet and Lake Melville Region, Labrador,” Rhodora, vol. 25, Jan. 1923, pp. 4-12.
Provisional List of Plants Found in Lake Melville and Hamilton Inlet District—Continued