As the Arctic Basin is shut off from the North Atlantic by ridges rising to within 300 fathoms of the surface and from the Pacific by the shallow shelf of the Bering Sea, and as the ice-laden East Greenland and Labrador currents consist of fresh surface water which cannot appreciably influence the underlying mass, the Arctic region has no practical effect upon the bottom temperature of the three great oceans, which is entirely dominated by the influence of the Antarctic. The existence of deep-lying and extensive rises or ridges in high southern latitudes has been indicated by the deep-sea temperature observations of Antarctic expeditions.
The lower division appears on the Newfoundland and Labrador coasts, and is traceable thence, in a great belt southwest of those points, through Maine and the Hudson-Champlain valley into Alabama, a distance of some 2000 m.; and the rocks are brought up again on the western uplift, in Nevada, Idaho, Utah, western Montana and British Columbia.
These branches are separated from one another at the surface by currents moving southwards: one passes east of Iceland; the second, the Greenland current, skirts the east coast of Greenland; and the third, the Labrador current already mentioned, follows the western side of Davis Strait.
The islands and other districts within the Arctic circle became a portion of the Dominion only in 1880, when all British possessions in North America, excepting Newfoundland, with its dependency, the Labrador coast, and the Bermuda islands, were annexed to Canada.
In eastern Canada Ungava and Labrador are very chill and inhospitable, owing largely to the iceberg-laden current sweeping down the coast from Davis Strait, bringing fogs and long snowy winters and a temperature for the year much below the freezing-point.
Such old sea-ice when prevented from escaping forms the palaeocrystic sea of Nares; but, as a rule, it is carried southward in the .East Greenland and Labrador currents, and melted in the warmer seas of lower latitudes.
Marinus, of which the former is circumpolar, and the latter nearly so - not being hitherto found between Labrador and Japan.
Henry Youle Hind, in his work on the Labrador Peninsula (London, 1863) praises the map which the Montagnais and Nasquapee Indians drew upon bark.
There have been great differences in the seas round Iceland and Greenland with regard to the presence of ice: from the 9th to the 12th centuries there is no evidence (in contemporary accounts) of the presence of much ice in the sea off Greenland, nor was much ice carried by the Labrador current, but from the 13th century onwards we do have evidence that there was very troublesome ice off Greenland.
As one advances northward the timber grows smaller and includes fewer species of trees, and finally the timber line is reached, near Churchill on the west coast of Hudson Bay and somewhat farther south on the Labrador side.