Nature of Antarctic Regions

NATURE OF ANTARCTIC REGIONS The Antarctic region is roughly that part of the globe encircled by the 6oth south parallel, which for reference purposes is cus tomarily divided into quadrants, reckoned eastward from Green wich meridian under the names Enderby, Victoria, Ross and Wendell. More useful to the reader, if less precise, is the divi sion into African, Australian and American sectors respectively according to the continents below which each sector lies.

Contrast Between Northern and Southern Regions.–, Considering the both parallel as a boundary we are at once impressed with a marked contrast between the amenities of . the northern and southern polar regions. Within the area poleward of 6o° north latitude live more than 1,000,000 human inhabi tants and countless land animals. Some of the largest and most valuable timber forests are north of and not a few indus tries connected with lumber, mining and fishing flourish. In the similar area in the southern hemisphere, there is not a single permanent human inhabitant, nor a single land animal larger than an insect. There are no trees and very few plants of any kind at all. The sole industry which can be said to exist in the antarc tic regions is that of whaling, which is now carried on during a few months in each year in the American and Australian sectors. These contrasts naturally depend largely upon temperature. The explorations of the 2oth century have shown us that the south polar region, again in complete contrast to the north, is largely occupied by a continent of more than 5,000,000 sq.m. in extent, that is to say, equivalent in size to Australia and Europe without Russia. The South Pole is placed centrally in this continent, which, though far from being symmetrical, may for general pur poses be considered as bounded by the loth parallel.

Characteristics of Antarctica.

The most noticeable feature about the continent is its unique isolation. It is possible to traverse all the other continents without crossing more than about 6om. of shallow sea, but to reach the antarctic continent one must voyage over at least 600m. of practically oceanic depths and that across the roughest seas exposed to the fiercest winds in the world. Between 55° and 65° S. lat. there is no land to interfere with the west to east circulation of sea and air, and that zone is therefore the home of the permanent west winds, the westerly drift and the wandering albatross, all of which encircle the antarctic continent ceaselessly. There are, in short, none of the interchanges of warm and cold air and water between temperate and polar regions which in the northern hemisphere lead to such curious anomalies as an almost ice free Spitsbergen in 79° N. and an almost ice-bound Labrador coast 2o° farther south.

In this fact we have an explanation of the contrasts in cli mate, and consequently in habitability, between the opposite polar regions, and the remainder of the explanation is forthcom ing when we consider the relief of this vast deserted continent. The South Pole itself is situated on a plateau nearly i o,000f t. in height, and there is every reason to suspect that the greater part of the continent is continuous plateau. Allowing for the incomplete nature of the data we can with some fairness com pute the average height of the continent as of the order of 6,000 feet, which is just twice as high as Asia, the next in order of magnitude. When we add to this conception of a high and isolated continent the fact that, of its 5,000,000 sq.m. probably less than zoo sq.m. is free from a permanent covering of ice we can well understand that here there is no attraction for man or beast or plant. The continent is thus in the grip of an ice age, more rigorous than that which has left its marks upon Europe and North America, and naturally the study of such a region resolves itself largely into a study of its manifold ice forms.

Of these the least known and the most impressive is the ice cap, whose lateral dimensions are those of the continent itself and which supplies the myriad glaciers which everywhere fringe the coast, sometimes in ice-worn valleys, but more often as a con tinuous glacier-front running down into the sea for hundreds of miles along the coasts. The thickness of the inland ice is proba bly not so great as its extent would suggest. No direct measure ments have been made, but from an examination of the outlet glaciers it appears unlikely that the sheet is ever more than 2,000f t. thick except in basins, and in general is much thinner, a conclusion which is confirmed by the fact that many hundreds of miles inland from the coast the ice sheet appears to follow close ly the form of the underlying ground.

The Barrier.—The general features of the antarctic ice-cap are reproduced on a smaller scale in Greenland, but the floating ice sheets which are to some extent derivatives of the ice-cap are met with nowhere else in the world. When Ross in 1841 first penetrated the pack ice into the ice-free Ross sea he sailed due south until he was brought up in about 77° S. by an ice wall from 5o to aoof t. high, barring his way to the south. He sailed along the greater part of its doom. seaward face. The Ross bar rier, as it is now called, is the greatest of these floating ice sheets, but is typical of many others to be met with in the antarctic. It is roughly the size of France awl consists of a sheet of ice varying from soo to I,5ooft. in thickness, the outer end being open to the ocean and the inner end held fast to the continent by the gla ciers which act as feeders and by being aground close to the actual coast. Its surface is smooth, and it forms the easiest approach to the Pole itself, since it reaches to within 3oom. of that spot. The tabular icebergs so typical of the southern hemisphere, with their flat tops and stratified appearance, are obviously derived from this and similar barriers, and their immense size, up to 3om. in length of side, is only natural considering the size of the parent masses. Each summer, when the break up of the winter sea ice has allowed the full force of the ocean swell to reach the face of the barriers, large fragments are broken off, or "calved," and these float away to the northward until they reach warmer and stormier waters where they disintegrate.

Sea Ice.—The sea ice itself is comparatively temporary. It begins to form in sheltered bays as early as the end of January and by the beginning of March any ship is liable to be frozen in unless its harbour is a windy one. There are large variations from year to year in the area of sea solidly frozen over, since strong winds, and such are very frequent, will prevent sea ice from forming, or will blow out any which is not of considerable thickness, but in sheltered bays the ice will continue to increase in thickness until October or November, by which time it will be anything up to 7ft. through. This will begin to break up and float northward from the beginning of December onwards, but the innermost bays may not lose their ice until late in February, or occasionally not at all for two years in succession. The belt of drifting pack ice which rings the continent is made up of the ice from this summer break-up.

The

continent, thus hidden or protected, is formed for the most part of old rocks amongst which the most prominent are of Permo-Carboniferous age and bear coal, which is found in the Australian sector up to within 3oom. of the Pole. In this sector the rocks have been above sea level since Palaeo zoic times, except where the Ross sea area has broken and sunk below it, giving rise to a series of volcanic centres, of which the largest, the Ross island group, still has an active volcano, Mt. Erebus, i3,000ft. high. Palaeozoic rocks have not been discovered so far in this region, although a graptolite fossil, probably of Ordovician age, shows that they occur in the South Orkneys. Mesozoic rocks have been found in various parts of the archi pelago, a very rich Jurassic fossil flora of ferns, conifers and cycads having been studied by Nordenskjold, some of the genera found being represented also in the rocks of South America, South Africa, India and Australia. Cretaceous ammonites have also been found, and Tertiary fossils, both of land and of marine forms, bring the geological record down probably to Miocene times, the fauna including five genera of extinct penguins. Raised beaches show an emergence of the land in Quaternary times, and there is evidence of a recent glacial period when the inland ice on Graham Land was i,000ft. higher than it is now. The most prominent features of the scenery are due to eruptive rocks, which have been identified as belonging to the eruptive system of the Andes, sug gesting a geologically recent connection between South America and the antarctic lands. Volcanic activity is not yet extinct in the region. As regards Kaiser Wilhelm II. Land, the Gaussberg is a volcanic cone mainly composed of leucite-basalt, but its slopes are strewn with erratics presumably transported from the south and these include gneiss, mica-schist and quartzite, apparently Archaean.

Much more is known as to the geology of Victoria Land, which has been visited by four well-equipped expeditions. From Cape North (7 I ° S.) to 86° S. a grand mountain range runs south curving to south-eastward, where it vanishes into the unknown in lat. 86° S.; it is built up of gneiss and granite, and of hori zontal beds of sandstone and limestone capped with eruptive rock, the peaks rising to heights of 8,000, io,000 and even i5,000ft., the total length of the range so far as known being at least i,ioo miles. This range rises abruptly from the sea, or from the ice of the Great Barrier, and forms a slightly higher edge to the vast snow plateau. About 78° S. the archipelago of volcanic islands, of which Ross island, with the active Mt. Erebus is the largest, rise from the sea in front of the range, and at the northern extremity the volcanic peaks of the Balleny islands match them in height. The composition of the volcanic rocks is similar to that of the volcanic rocks of the southern part of New Zealand. The oldest rocks of Victoria Land are apparently banded gneiss and gneissic granite, which may be taken as Archaean. Older Palaeozoic rocks are represented by greenish-grey slates from the sides of the Beardmore glacier and by radiolarian cherts; but the most widespread of the sedimentary rocks occurring in vast beds in the mountain faces is that which Ferrar named the Beacon sandstones, which are of Permo-Carboniferous age. The coast line appears to be of the Atlantic, not the Pacific type, and may owe its position and trend to a great fault, or series of faults, in the line of which the range of volcanoes, Mt. Melbourne, Mt. Erebus and Mt. Discovery, stands. Boulders of gneiss, quartzite and sandstone have been dredged at so many points between the Balleny islands and the Weddell sea that there can be no doubt of the existence of similar continental land along the whole of that side, at least within the Antarctic Circle.

Climate.

A vast mass of meteorological observations has now been accumulated so that for the parts of the continent most visited, that is to say, the South American and the Australian sectors, it is possible to summarize the climate with some degree of certainty. The mean temperature appears to be about 5°F. lower in the southern latitudes than in the corresponding northern ones, and the phenomenon of rain is practically unknown within the Antarctic Circle. The lowest temperature yet recorded is that of —77°F., but since this was experienced within a few miles of the sea it is probable that the inland plateau tempera tures in the winter are considerably lower. Later expeditions have confirmed the indications of earlier ones that the pressure of the atmosphere increases from the polar circle to the Pole itself, though it is clear that this is due in some part to the form of the continent itself. It has also been made clear by the work of Dr. G. C. Simpson that the weather experienced on the out skirts of the continent is the result of the passage of pressure waves and the turbulent motion due to them.

Such pressure distribution, together with the shape of the land, produces the most prominent feature of the antarctic cli mate, excessively strong winds, which when accompanied by snow or thick drift are known as blizzards. The most windy spots appear to be on the coast near the circle itself. Phenomenal records of wind velocity were recorded at Mawson's headquarters in Adelie Land, where not only was the mean annual velocity the surprising figure of 5om. an hour, but on occasions there were prolonged winds of considerably over loom. per hour. The winds experienced in Graham Land and in the Ross were less extra ordinary but still excessive. The frequency and strength of these winds has the effect of preventing the formation close to the coast of permanent ice, which is continually being blown off shore, and besides being responsible for the perilous drifts of the "Endurance," "Aurora" and other ships, they cause the dense belt of pack ice which circumscribes the continent in the spring and early summer. There are no reliable figures for the amount of precipitation in the form of snow, but it appears probable that even in favoured parts the net precipitation on a surface at sea level is little more than a foot of snow per annum. A small calcu lation shows further that the net addition of snow to the ice-cap must be very much less than that.

Flora and Fauna.

Recent expeditions have discovered that, despite the low temperature of the summer, in which no month has a mean temperature appreciably above the freezing point, there are on the exposed antarctic land patches of ground with a sparse growth of cryptogamic vegetation consisting of mosses, lichens, fungi and fresh-water algae. No flowering plants occur within the Antarctic Circle or in the immediately adjacent lands.

The marine fauna is very rich and abundant. All the expeditions obtained many new species, and the resemblance which occurs between many of the forms and those which inhabit the arctic seas has given rise to the hypothesis that certain species have been able to pass from one frigid zone to the other. Bird life on sea and land is fairly abundant, the most common forms being the skua gull, snow petrels and the various species of penguins. The penguins are specially adapted for an aquatic life, and depend for their food entirely on marine animals. The largest species, the emperor penguin, inhabits the most southerly coast known on the edge of the Great Barrier, and there it breeds at mid-winter, very interesting specializations of structure and habit making this apparently impossible feat practicable. The social organization and habits of the various species of penguins have been carefully studied, and show that these birds have arrived at a stage of what might almost be called civilization worthy of the most intelligent beings native to their continent. The only mammalian life in the antarctic is marine, in the form of various species of whales (but not the "right whale"), and a few species of seals which live through the winter by keeping open blow-holes in the sea ice. There is no trace of any land animal except a few species of minute wingless insects of a degenerate type.

Products of the Continent.

Since there are no land animals or flowering plants the resources of the region are limited to the products of the sea. Of these the most striking are the various species of penguins, which inhabit all zones of the region. For tunately for the eservation of such harmless and delightful birds their blubber-coated skins do not possess a marketable value. The seals also, not being of the fur-bearing kind, are more or less immune from human exploitation. There remain the whales which in large numbers frequent antarctic seas to feed on the minute animals there to be found which in their turn ultimately depend for their food upon diatoms, the typical marine plants of the region, microscopic in size but so countless in num ber as to colour the sea ice. The rorqual, the humpback and the huge blue whale are now all hunted in these seas by modern methods and the annual value of the products obtained exceeds £3,000,000 sterling. (See WHALES AND WHALING.) Until the rise of the whaling industry the antarctic can be said to have had no political significance, but since the beginning of the century the territorial waters of the continent, if not the land itself, have acquired a value and, as will be seen from the map, two sectors are now portions of the British empire and are known as the Ross dependency, administered by New Zealand, and the Falk land islands dependency, administered by the Falkland islands.

BIBLIOGRAPHY.

H. R. Mill, The Siege of the South Pole, a history Bibliography.—H. R. Mill, The Siege of the South Pole, a history of Antarctic exploration with complete bibliography (London, 1905) ; K. Fricker, Antarktis (Berlin, 1898) ; trans. as The Antarctic Regions (London, 1900) ; A. Rainaud, Le Continent austral (Paris, 1893, historical) ; E. S. Balch, Antarctica (New York, 5902, historical) ; James Cook, A Voyage Towards the South Pole and Round the World (3 vols., London, 1777) ; H. Gravelius, F. von Bellingshausens Forschungsfahrten im siidlichen Eismeer 1819-1821 (Leipzig, 1902) ; James Weddell, A Voyage Towards the South Pole (London, 1825) ; J. S. C. Dumont D'Urville, Voyage au Pole Sud et dans l'Oceanie (29 vols., Paris, 1841-45) ; Charles Wilkes, Narrative of the Exploring Expedition during 1838-1842 (6 vols., Philadelphia, 1845) ; J. C. Ross, A Voyage of Discovery and Research in the Southern and Antarctic Regions (2 vols., London, 1847) ; W. G. Burn-Murdoch, From Edin burgh to the Antarctic, an account of the voyage of the "Balaena," (London, 1894) ; H. J. Bull, The Cruise of the "Antarctic" to the South Polar Regions, the voyage to Victoria Land in (London, 1896) ; F. A. Cook, Through the First Antarctic Night; The Collections of the "Southern Cross" (British Museum, London, 1900) ; A. de Gerlache, Quinze mois dans l'Antarctique (Paris, 1902) ; Georges Lecointe, Au Pays des Manchots ("Belgica," Brussels, 1904) ; Resultats du voyage du S.Y. "Belgica," Rapports scientifiques (many vols., Brussels, v.d.) ; C. E. Borchgrevink, First on the Antarctic Continent (London, 1901) ; L. Bernacchi, To the South Polar Regions, the expedition of the "Southern Cross" (London, 1901) ; Report on the Collections of the "Southern Cross" (British Museum, London, 1902) ; G. Murray (editor), The Antarctic Manual (London, 19o1) ; R. F. Scott, The Voyage of the "Discovery" (2 vols., London, 1905) ; A. B. Armitage, Two Years in the Antarctic (London, 1905) ; National Antarctic Expedition 1901-1904 (scientific results published by the Royal Society, London, several vols., v.d.) ; G. von Neumayer, Auf zum Sudpol (Berlin, 1901) ; E. von Drygalski, Zum Kontinent des eisigen Siidens, scientific results of "Gauss" expedition (Berlin, 1904) ; Otto Nordenskjold and J. G. Andersson, Antarctica (London, 1905) ; R. N. R. Brown, R. C. Mossman and J. H. H. Pirie, The Voyage of the "Scotia" (London, 1906) ; Report on the Scientific Results of the Voyage of the "Scotia" (several vols., Edinburgh, v.d.) ; J. B. Charcot, Le Francais au Pole Sud (Paris, 1906) ; E. H. Shackle ton, The Heart of the Antarctic (2 vols., London, 1909) ; British Antarctic Expedition 1907-1909, Reports on the Scientific Investiga tions (several vols., London, v.d.) ; Scott's Last Expedition (1913) ; Sir D. Mawson, The Home of the Blizzard (1915) ; C. R. Markham, The Lands of Silence (1921) ; Sir E. H. Shackleton, South (1922), British Antarctic ("Terra Nova") Expedition, scientific reports (many vols., London) ; F. Hurley, Argonauts of the South (192 5) ; Dr. Rudmose Brown, Polar Regions (1927) ; Nordenskjold and Mecking, The Geography of the Polar Regions (1928) . (F. DE.)