Page:EB1911 - Volume 21.djvu/990

 rocks including beds of lignite and plant fossils of Miocene age also occur, and they are interstratified and overspread with basalts and other eruptive rocks as in Greenland. In Grant Land Tertiary coal occurs in Lady Franklin Bay (81° 45′ N.), the most northerly deposit of fossil fuel known. Arctic Canada consists of Archaean and Palaeozoic rocks worn down into plateaux or plains and bearing marks of glacial action, the absence of which is the most remarkable feature of the tundra region of Siberia. The Siberian coast is superficially formed to a large extent of frozen soil and gravel sometimes interbedded with clear ice, and in this soil the frozen bodies of mammoths and other Quaternary animals have been found preserved in a fresh condition by the low temperature. The absence of a glacial period in northern Siberia is probably indirectly due to the very low temperature which prevailed there, preventing the access of water vapour from without and so stopping the supply required to produce sufficient precipitation to form glaciers or ice-caps. On the New Siberia Islands Silurian and Tertiary rocks have been recognized, the latter with abundant deposits of fossil wood.

The geological evidence is complete as to the existence of a genial climate in Tertiary times as far north as the present land extends, and of a climate less severe than that of to-day in the Quaternary period. The existence of raised sea margins in many Arctic lands and especially in the American Arctic archipelago bears evidence to a recent elevation of the land, or a withdrawal of the sea, which has been influential in forming some of the most prominent features of the present configuration. It is noteworthy that no great mountain range runs into the Arctic region. The Rocky Mountains on the west and the Ural range on the east die down to insignificant elevations before reaching the Arctic Circle. The plateau of Greenland forms the loftiest mass of Arctic land, but the thickness of the ice cap is unknown. The one active volcano within the Arctic Circle is on the little island of Jan Mayen.

The Arctic Climate.—As the water of the Arctic Sea is free from ice around the margin only for a few months in summer, and is covered at all times over its great expanse with thick ice in slow uneasy motion. there is less contrast in climate between land and sea, especially in winter, than in other parts of the world. The climate of the polar area may be described as the most characteristic of all the natural features, and observations of temperature and pressure are more numerous and systematic than any other scientific observations. The Russian meteorological system includes Siberia, and long series of observations exist from stations up to and within the Arctic Circle. The Canadian Meteorological Service has secured like observations for the extreme north of North America, though the records are more fragmentary and of shorter duration. Norway and Iceland also yield many records on the margin of the Arctic Circle. The international circum-polar stations maintained during 1882 connected the Siberian, Norwegian and Canadian land stations with the more fragmentary work of the various polar expeditions which have wintered from time to time in high latitudes The most valuable records and practically the only data available for the climate north of 84° are those of the first expedition of the “Fram” in her three years' drift across the polar basin. Later expeditions beyond the 84th parallel were merely dashes of a few weeks' duration, the records from which, however accurate, are of an altogether different order of importance. The data collected by the “Fram” were discussed in great detail by Professor H. Mohn in 1904, and that eminent authority combined them with all that had been known previously, and all that was ascertained by later explorers up to the return of Captain Sverdrup from the second “Fram” expedition, so as to give the completest account ever attempted of the climate of the North Polar regions, and on this we rely mainly for the following summary

Temperature.—From Professor Mohn’s maps of the isotherms north of 60° N it is evident that the temperature reduced to sea-level is lowest in the winter months within an area stretching across the pole from the interior of Greenland to the middle of

Siberia, the long axis of this very cold area being in the meridian of 40° W. and 140° E. For every month from October to April the mean temperature of this cold area is below 0° F., and in the two coldest months there are three very cold areas or poles of cold with temperatures below −40° arranged along the axis. These are the interior of Greenland, an area around the North Pole and the centre of Northern Siberia. Professor Mohn is satisfied that these three poles of cold are separated by somewhat warmer belts, as observations on the north coast of Greenland show a temperature higher both than the temperature of the interior reduced to sea-level and the temperature on the frozen sea farther north. As summer advances the temperature rises to the freezing point most rapidly in North America, the mean temperature for June, July and August for the American coast and the Arctic archipelago being above the freezing point. In July and August the Arctic shores in America, Asia and Europe have a mean air-temperature of about 40° F., but the interior of Greenland and the area round the North Pole remain below 32°, those two poles of cold persisting throughout the year while the winter cold pole in Asia disappears in summer. There is no reason to doubt that in winter the Asiatic area is the coldest part of the Arctic region, and as it is permanently inhabited it is plain that low temperature alone is no bar to the wintering of expeditions in any part of the North Polar region. The lowest temperature experienced during the drift of the “Fram” was −62° F., on the 12th of March 1894 in lat. 79° 41′, long. 134° 17′ E. The minimum temperatures recorded on Sir George Nares’s expedition were −73·8° F. on the “Alert” in 82° 27′ N. and −70·8° on the “Discovery” in 81° 44′ N., both in March 1876, and the minimum on Sverdrup’s expedition in Tones Sound in 76° 50′ N. was −60° F. in January 1901. In February 1882 Greely recorded −66·2° at Fort Conger, 81° 44′ N, and at Fort Constance in Canada (66° 40′ N. 119° W.) a temperature of −72° F. was noted in January 1851. The lowest temperature ever recorded on the earth’s surface was probably that experienced at Verkhoyansk in Siberia (67° 34′ N.) where the absolute minimum in the month of February was −93·6°, and minima of −70° or more have been recorded in every winter month from November to March inclusive, and as the absolute maximum in July was +92·7° F. the total range experienced is no less than 186·3°, far exceeding that known in any other part of the world.

The normal monthly mean temperatures for various parallels of latitude are given as follows by Professor Mohn, the last column showing the calculated conditions at the North Pole itself expressed to the nearest degree.

The interior of Greenland is believed to be below the normal temperature for the latitude in all months and so is the region between Bering Strait and the Pole; the Norwegian Sea, and the region north of it as far as the Pole, has a temperature above the normal for the latitude in all months; while the temperature