Page:Encyclopædia Britannica, Ninth Edition, v. 17.djvu/649

Rh on the west of this line a sea covered with ice during the whole of the year, throughout nearly its entire extent. It is only rarely that the east coast of Greenland can be approached through the lanes and openings formed in the ice. An arctic current passes southward along the coast of Greenland, carrying with it vast fields of hummocky ice, and enters the North Atlantic through the straits which separate Iceland from the coast of Greenland. To the eastward of this line we have a sea free from ice throughout the year. A warm current—the so-called extension of the Gulf Stream—passes between the coasts of Scotland and Iceland, and carries a large amount of heat to the shores of Norway and Lapland, rendering them relatively mild and habitable. The prevailing wind over the western part of the Norwegian Sea is from the north east, while that over the eastern is from the south-west, in each case corresponding with the direction of the ocean currents. With respect to the relations of the barometric minimum to the prevailing winds and currents see , vol. xvi. p. 139.

In March and April a very extensive seal fishery is carried on to the north and east of Jan Mayen along the edge of the ice-fields,—as many as 300,000 young seals having been captured in one season. Large numbers of polar bears are at this time noticed in the neighbourhood of the seal rookeries, and are captured on the ice at great distances from land. Later in the season there is a right whale fishery to the north and west of the island of Jan Mayen. A large number of small vessels from Hammerfest and Lapland ports visit the coasts of Spitzbergen each season to collect eider-down, and to engage in the walrus and shark fisheries. Narwhals (Monodon) are also captured along the edge of the ice-floes. Guillemots, little auks, gulls, and other sea-birds are found in vast numbers near the coast of Spitzbergen and along the edge of the pack-ice. Along the coast of Norway there are valuable cod, mackerel, herring, and lobster fisheries. The Norwegian Sea has a depth almost rivalling that of the great Atlantic and Pacific Oceans, that of the whole of the central parts exceeding 1000 fathoms, while to the south-east of Jan Mayen there is a depth of 2000 fathoms, and off Spitzbergen of 2500 fathoms.

The bottom in the western portion is composed of a mixture of mud and stones formed from the detrital matter carried from the land by floating ice, and containing not more than 5 or 6 per cent. of carbonate of lime. In the deeper parts of the eastern portion we have a fine mud or clay containing sometimes 50 per cent. of carbonate of lime, and a total absence of the ice-borne stones and gravel so abundant in the western portion. The carbonate of lime consists chiefly of the shells of Globigerina which have fallen from the surface, and some other species of Foraminifera (the most frequent of which is Biloculina) which live on the bottom. In some places this deposit approaches in character the Globigerina ooze or mud of the Atlantic, but is very poor in pelagic shells when compared with the deposits in lower latitudes. The pelagic Foraminifera and Pteropod shells so abundant in tropical parts of the Gulf Stream are killed off and fall to the bottom as they are carried into the colder areas of the North Atlantic. The upper layer of this deposit is of a brownish colour, and is less compact and contains more lime than the deeper layers, which have a blue or greyish colour. In this respect it agrees with the deposits found at similar depths around all continental shores. The deposits along the Norwegian coast, in depths less than 1000 fathoms, consist chiefly of detrital matter from the shores, the mineral particles consisting of quartz, felspars, mica, hornblende, magnetite, and fragments of rocks. Around Jan Mayen and Iceland the deposits consist largely of volcanic sand. In all the deposits there are many Diatom frustules.

XVII. — 75