The term floe is applied to pieces which are from half a mile to a mile in diameter. Pieces smaller than a floe are called drift ice. When drift ice is so extensive that its limits cannot be seen, it is called a pack, when the pieces do not touch an open pack, when they are pressed together a close pack. A patch is a collection of drift ice, the limits of which are visible. A stream is a drifting line of drift ice. A tongue is a projecting point of ice, under water. A calf is a mass of loose ice lying under a floe near its margin, and, when disengaged from that position, rising with violence to the surface. Brash ice consists of fragments and nodules, the wreck of other kinds of ice, and sludge is the term applied to smaller pieces, generally saturated by the sea.
A bright white line on the horizon, seen over an ice-field, and denoting more ice, is known as the ice-blink. Over land or large masses of ice it generally has a yellowish tinge. On the other hand a blue streak on the horizon, denoting open water, is called a water sky. A lane or lead is a narrow track of open water between floes or pack ice. Rotten ice is old ice partially melted, and in part honeycombed.
When a ship is forcibly pressed by ice floes on both sides she is said to be nipped, and she is beset when closely surrounded by ice. To bore is to enter the ice under press of sail or steam and to force a way through by separating the masses. Sallying is causing a ship to roll by making the men run in a body from side to side, to relieve her from adhesion of young ice.
An ice foot along a coast line is caused by the accumulation of the autumn snow-fall, as it drifts to the beach, being met by sea-water with a temperature just below the freezing point of fresh water. It is at once converted into ice, forming a solid wall from the bottom of the sea, constantly maintained. The upper surface of an ice foot is level with high water mark. The terrace above this wall, from its edge to the base of the talus, has a width dependent on the land slope. Thus an ice foot will not be found either where there are perpendicular cliffs or low coast lines, but only along sloping high lands under special conditions.
The most striking features in the polar landscape are the icebergs, and they are wholly derived from the land, the large icebergs from Greenland, from Spitsbergen much smaller ones. To understand their origin and movements we must turn to the great continental mass of Greenland. It consists of a vast ice-cap fringed by a strip of mountainous coast, which is penetrated by deep fjords and flanked by numerous off-lying rocks and islands. The area of Greenland is believed to be 512,000 square miles, of which 320,000 form the inland ice, and 192,000 represent the fringing margin of mountains not permanently ice-covered. The widest part is 900 miles across; at Disco in 70° N. it is 480 miles and thence the two coasts converge until they meet in a point at Cape Farewell in 59° 49′ N. The length of Greenland is 1400 miles. The Greenland ice-cap is by far the largest in the northern hemisphere—a continuous covering of snow, névé[1], or ice resting on land, known as the “Inland Ice.” From it descend glaciers or rivers of solid ice, coming from their sources in the ice-cap.
The “Inland Ice” of Greenland rises to a height of 8000 feet, and the deep fjords run for 80 or 100 miles before they end at the foot of walls of ice rising abruptly from the water. These walls are the terminations of glaciers from the inland ice, which, constantly throwing off icebergs, are called discharging glaciers. There are eight principal discharging glaciers on the west coast of Greenland[2]. On the Greenland continent the snow, converted into ice by pressure, has in the course of ages filled all the valleys, covered the mountain tops, and formed a smooth plateau far above them, so that the thickness of the inland ice is measured by thousands of feet. The ice walls at the heads of the discharging glaciers are driven onwards by the force of gravity, the pressure of the superincumbent mass behind them being enormous. In some cases the rate of movement is as much as 28 yards in a day.
A discharging glacier, on reaching the sea, has a thickness of at least a thousand feet. It continues to slide along the bottom until it reaches a point where the depth of the water has sufficient buoyant force to lift it. Still it continues its course. The action of the tides gives rise to fissures in the enormous mass, and at length the foremost part is broken off, and drifts away as an iceberg. The icebergs are discharged from the fjords in vast numbers, and are eventually carried by the current of Baffin’s Bay and Davis Strait into the Atlantic.
The icebergs are alike the grandest and the most beautiful features of the Arctic seas. Only one-seventh of their bulk appears above water, yet they may be hundreds of yards in circumference, and their peaks reach a height of 300 ft. A grander sight can scarcely be conceived than new-born icebergs drifting out from the fjord of their birthplace. When the icebergs drift well out into the open sea the weathering and consequent reduction in size begins. They eventually lose their equilibrium and capsize. The part that has been long under water becomes the upper part, and it is now that the bergs assume their most fantastic shapes. Very often a large piece breaks off from the parent berg, and falls into the sea, churning it up into creamy waves. This is called calving.
The colour of an iceberg is opaque white. Scattered through the mass, and sometimes visible on the surface, are strata of deep blue ice, varying in width from one to several feet. They have an exquisitely lovely effect, contrasting with the deep white of the rest of the berg. These blue stripes may be formed by a filling up of the fissures in the inland ice with water. Such refrigeration of the water in the fissures may be an important agent in setting these great mountains of ice in motion. Sometimes there is a passage right through an iceberg. But it is when a line of icebergs is refracted on the horizon that the polar scenery is converted into a veritable fairy land. Some are raised up into lofty pillars. Again a whole chain of them will assume the appearance of a long bridge or aqueduct, and as quickly change into a succession of beautiful palaces and temples of dazzling whiteness, metamorphosed by the fantastic wand of Nature. When the ice breaks up in summer, the current takes many of the icebergs into the Atlantic.
