328 POLAR REGIONS Ice. by heavy falls of snow, as these winds come direct from expanses of open water caused by the current from the Atlantic. Sea water, in the process of congelation, expels the salt, and its freezing point is about 28. The ice first forms in thin, irregular flakes called "sludge," nnd|when this is compact enough to hold snow it is known as " brash." Gathered into rounded masses it becomes extensive that its limits cannot be seen. " Pack ice " consists of broken floes forced together by the wind or currents. When the pack is loosened and scattered by a wind from an opposite direction the pieces are called " sailing ice. " The greatest thickness attainable by ice in one season is about 7 feet. The results of observations made by Sir George Nares in 82 17 N. on the west side of Green land and by Captain Koldewey on the east side in 74 30 N. were identical, namely 6 feet 7 inches. Old ice is believed to become thicker in a second winter, and even to attain a thickness of 10 feet. In the palaeocrystic sea there are floes from 80 to 100 feet thick, but these must be considered rather as sea-glaciers, formed by accumulations of snow on the ice year after year ; and the smaller pieces broken from them have been very appropriately named floebergs. These mighty floes are sea-borne glaciers, perpetually wasted beneath and restored from above. Icebergs. Icebergs are only met with where there are great discharging glaciers on the laud, or in currents leading from them. Greenland is the principal mother of icebergs. This immense mass covers an area of about 512,000 square miles, and has 3400 miles of coast line. It is indented by deep channels or fjords, often extending more than 60 miles, with many islands and rocks along the coast. The whole of the interior is believed to be capped by an enormous glacier always moving towards the coast, and at certain points reaching the sea where masses break off in the shape of icebergs. These icebergs rise to a height of from 60 to 300 feet above the sea, with a circumference from several hundred to several thousand yards ; and from seven to eight times the bulk seen above water is submerged, so that the weight of a large berg is millions of tons When pieces break off from a parent iceberg the process is called " calving," and the pieces are " calf ice." Recent observation of one of the principal discharging glaciers of Greenland shows it to be 920 feet thick, and 18,400 feet wide, and that it advances at a rate of 47 feet a day during the summer season. In Spitzbergen and Nova Zembla there are much smaller glaciers discharging smaller pieces.. The Franz-Josef Lnnd glaciers produce large flat-topped icebergs, which do not, however, float southwards. Currents. The movements of the polar seas are influenced by the current; of seas and rivers which are constantly flowing northwards, and by ice-laden counter-currents which press through every strait and channel in the opposite direction. On the fringe of land forming the northern shores of Asia and America are the mouths of severa great rivers. Of the Siberian rivers the Obi, with its affluent the Irtish, has a basin covering 60,000 square miles, the Yenisei 50,000, and the Lena 40,000; but these areas are almost entireh within the temperate zone. In America the rivers Mackenzie, Coppermine, ami Great Fish (or Back) also pour their waters into the polar sea. The enormous volume of warm water which these rivers send into the ocean drives the heavy ice from the coast and, owing to the influence which the rotatory motion of the earth exercises, receives an easterly direction along the coast. Behring Strait is too narrow and too shallow to admit of any large flow from the Pacific, still there is a warm current which keeps the heavy ice at some distance and also flows easterly, its influence being felt beyond Point Barrow. The Norwegian current, usually considered to be a continuation of the Gulf Stream, conveys s large volume of water northwards along the coasts of Norway anc Lapland, and keeps the ice at a distance from that shore throughou the winter. The polar currents flow southwards in the direction o the two great openings by Davis Strait and the sea on the east coas of Greenland, but the whole body appears eventually to find its wai southwards by the former outlet. The current flowing south alon< the east coast of Greenland brings with it immense quantities o heavy ice, and when it reaches the south point of the land it turn westward and northward round Cape Farewell, until about 64 N. when it unites with the current coining from Baffin s Bay, and th united current, with its enormous quantity of ice and icebergs flows south along the Labrador coast to Newfoundland. The othe polar current flows southwards through all the channels and strait among the Parry Archipelago, and through Fury and Hecla Strait down Baffin s Bay and Davis Strait. The observations of various explorers lead to the conclusion tha these outlets are insufficient to carry off the great harvests of ice and that, in one part of the polar region, it continues to accumulat and form sea-borne glaciers. Collinson observed this formation o: the coast of North America. M Clure found it along the wes coast of Banks Island, while M Clintock and Mecham traced i along the western side of Prince Patrick Island. " The surface o the floes resembles rolling hills, some of them a hundred feet frorr crystic sea. iase to summit, aged sea ice which may be centuries old, and from vant of an outlet likely to increase yet in thickness to an unlimited .egree. The accumulated action of repeated thaws and falls of now on the upper surface gives it a peculiar hill and dale appear- nce." The same ice was found by Nares s expedition along the lorthern coast of Grant Land and Greenland 80 to 100 feet thick. . branch from it flows down M Clure Strait and M Clintock hannel until it impinges upon the north-west coast of King VilliamIsland. This is what Professor Haughton calls "the ice barrier placed in this position by the still waters caused by the meeting of the Atlantic and Pacific tides." The physical aspects of polar lands are much influenced by their Geolog;
- eological formation. The Greenland coast consists mainly of
- neiss, mica schist, hornblende schist, and syenite pierced by
jranite veins. In this formation are found the steatite used by the natives to make lamps, the cryolite of Ivigtut in the south, and the plumbago at Upernivik. North of 69 N. a flow of basalt extends across the Noursoak peninsula and Disco Island, covering an area of about 7000 square miles, and rising to a height of 6000 eet. With these trap rocks are associated the Miocene and "retaceous beds. The Cretaceous rocks have only been found in the Omenak-fjord in 70 N. ; while the Miocene formation is confined to the shores of the Waigat Strait, between Disco and the main land, underlying the trap. Coal beds appear in several places along the shore, and very interesting remains of fossil plants have been discovered. At the termination of Igalliko-fjord in 61 N. a compact red sandstone is found. Pendulum Islands on the east coast are Oolitic. But with these exceptions the whole mass of Greenland is granitic or gneissose. The opposite side of Baffin s Bay is of the same character, as well as both sides of Peel Sound. The Parry Islands are partly Silurian and partly of the Carboniferous period. The eastern part, including North Somerset and Prince of Wales Land (except the shores of Peel Sound) and Cornwallis Island are of Silurian formation, with fossils, equivalents to the Wenlock and Dudley groups. This formation extends westward from Boothia Felix and King William Island over Prince Albert Land and the southern half of Banks Island. The southern halves of Bathurst, Melville, and Prince Patrick Islands, and the northern half of Banks Island consist of Lower Carboniferous sand stones with beds of coal, while Grinnell Land and the northern halves of Bathurst, Melville, and Prince Patrick Islands are Carboniferous limestone. Lias fossils (ammonites) were found at one place on the east side of Prince Patrick Island in 76 20 N. Sherard Osborn also found the vertebra; of a huge saurian (TcJco- saurus) at the north-west extreme of Bathurst Island, probably of the Lower and Middle Oolitic period. Ellesmere Land, on the western side of Smith Sound, consists of gneiss rising to heights of 2000 feet which underlie Miocene rocks at Fort Foulke. Farther north the gneiss continues with stratified black slates having a very high and often vertical dip. In 82 33 N. these slates give place to a series of quartzites and grits rising to elevations of 2000 and 3000 feet. Silurian limestones are found on the shores of Kennedy Channel up to Cape Tyron on the Green land side. Carboniferous limestone occurs on the north coast of Grant Land, as far west as Clements Markharn Inlet, rising to a height of 2000 feet. Near Lady Franklin Bay in 81 45 N. a deposit of coal of the Miocene period was discovered, with a fossil flora including thirty species of plants pines, birch, poplar, elm, and hazel. The whole of this land to the north of Baffin s Bay is slowly rising. Spitzbergen and Nova Zembla are also composed mainly of primitive rocks. In northern Spitzbergen there are also Miocene beds with a fossil flora closely allied to that of Lady Franklin Bay, and some fossils of the Lias period. The geological characters of Franz-Josef Land and Spitzbergen are closely allied. The predomi nant rock is dolerite, a kind of greenstone. The "tundra" of Siberia is a wide belt of land intervening between the line of forest and the polar shores, and intersected by the great rivers. It is frozen for immense depths below the surface, and here the remains of mammoths, generally in great landslips along the river banks, have been found. But their fossil ivory occurs in greatest quantity in the New Siberia group. On these islands also occur the "wood-hills " consisting of horizontal sand stone beds alternating with strata of bituminous tree stems, heaped on each other to the top of the hill. Ammonites of the Lias period are also found there. In the polar regions the line of forest seldom reaches to the Flora Arctic Circle ; low birches and willows and shrubs bearing berries occur in the south of Greenland, but farther north the creeping willow alone forms wood. There are 762 flowering plants, and 925 cryptogams within the Arctic Circle, making s, total of 1687 plants. Lapland contains-by far the richest arctic flora, amounting to three- fourths of the whole, while three-fifths of the species found in Arctic Asia and America also belong to Lapland. In the European arctic district 616 flowering plants have been collected, in Arctic Asia 233, in Arctic America eastward of the Mackenzie 379, and westward of
that river 364, and in Greenland 207. The most arctic plants of
