In a previous chapter we have alluded to the manner in which icebergs are formed by the detachment from the seaward extremity of the glacier of huge masses of ice, which the current carries out into the open sea. To the description already given, we may here add that which Charles Martins furnishes in his valuable and interesting record of persevering scientific enterprise, “Du Spitzberg au Sahara”:—In Spitzbergen, he says, the glacier, after a traject of more or less considerable duration, reaches the sea. If the shore be rectilineal, it advances no further; but, in the recess of a bay, where the shore is curved, it continues its progression, supporting its bulk on the sides of the bay, and advancing above the water, which it overhangs. This is easily understood. In summer the sea-water at the bottom of the bays is always at a temperature a little above 32°; on coming in contact with this comparatively warm water the glacier melts, and, at low tide, an interval is perceptible between the ice and the surface of the water. The glacier being no longer supported, partially crumbles and gives way; immense blocks detach themselves, fall into the sea, disappear beneath the water, reappear revolving on their own axes, and oscillate for a few moments until they have taken up their position of equilibrium. The blocks thus detached from the floating masses, of all sizes and shapes, are called icebergs.
STEAMER “CHARGING” AN ICEBERG, UPERNAVIK, GREENLAND.
Our traveller records that twice a day, in Magdalena Bay and Bell Sound, he was an eye-witness of this partial ruin of the extremity of the glaciers. Their fall was accompanied by a noise like that of thunder; the swollen sea rushed upon the shore in a succession of gigantic waves; the gulf was covered with icebergs, which, caught in the swirl and eddy, issued out of the bay, like immense fleets, to gain the sea beyond, or were stranded here and there at points where the water was shallow. The icebergs seen by M. Martins were not, however, of any surprising magnitude; he estimates their average height at thirteen to sixteen feet. We have seen that those of Baffin Bay are tenfold more considerable and imposing; but then, in that bay the temperature of the sea is below 32°; the glacier does not melt when it enters the water; it sinks to the bottom of the sea; and the portions detached from it are all of greater height than even the submerged part of the icebergs which drift to and fro in the bays and gulfs of Spitzbergen.
We may follow up this description with some observations by Lieutenant Bellot, the chivalrous young Frenchman who perished in one of the expeditions despatched in search of Sir John Franklin and his companions. He is speaking of the masses of ice his ship encountered soon after doubling Cape Farewell, the south point of Greenland, and he remarks, that as Baffin Bay narrows towards the south, the icebergs, first set in motion higher up the bay by the northern gales, necessarily tend to accumulate in the gorge thus formed, and so to impede and block up Davis Strait, even when the higher waters are quite free. It is only through a series of alternate movements of advance and recession that the bergs finally pass beyond the barrier, and float out into the Atlantic, to undergo a slow process of dissolution.
The mobility of the bergs, though necessary to navigation, forms at the same time its peculiar danger, since a vessel is often placed between the shore and the colossal masses driven forward by the wind, or between these and the solid ice which as yet has not broken up. It is useless to dwell upon the immense force possessed by masses which are frequently several square leagues in extent, and which, once in movement, cannot be stayed by any human resistance. A sailing-vessel finds herself placed in conditions all the more unfavourable, because the winds blow from the very direction which she is bound to take in order to open up a way through the floes. Now, if the gale is violent, it is perilous indeed to push forward in the midst of a labyrinth of bergs, which form so many floating rocks; if a calm prevails, a ship can move forward only by laborious hauling or towed by the boats. The application of the screw-propeller to steam-ships has given to them a great superiority, because they are not liable to any accident to paddle-wheels, exposed as such must be to collision with the floating ice. It is recorded that, on one occasion, a screw-steamer, near Upernavik, on the coast of Greenland, actually charged an iceberg, and drove right through it, as a railway-engine might crash through a fence or hurdle. Of course, the berg was of no great elevation; but its solid mass yielded to the immense force of the steamship, and split into large fragments.
In the convulsions caused by furious tempests, which are far from being so rare within the Arctic Circle as is popularly supposed, the shape of the bergs becomes very irregular, and the configuration of the ice-fields is constantly undergoing modification. Hence it often happens that the voyager sees before him an open basin of water of greater or less extent, from which he is separated only by a narrow strip of ice. In such a case he endeavours to effect an opening, either by driving his ship at full speed against the weakest part of the ice, or with the help of immense saws, twenty feet in length, which are worked with a rope and pulley placed at the top of a triangle formed of long poles; or, finally, by exploding a mine. When the ice is not very solid, the ship is forced into the opening, against the sides of which it acts like a wedge. It will sometimes occur, in the course of the operation, that the ice-fields, set in motion by the wind or the currents, close in together, after having treacherously separated for a moment, and the vessel is then subjected to a dangerous pressure. Unhappy the mariner who does not foresee or sufficiently note the warning signs of this accident, which is almost always accompanied by fatal consequences. The ice, which nothing can check, passing underneath the ship, capsizes it,—or, if it resists, crushes it.
We have alluded to the colossal bergs of Baffin Bay. These are thrown off from the northern glaciers, and particularly from the enormous ice-river named after Humboldt, which cumbers the declivities of the Greenland Alps, beyond the 79th parallel. It has been a frequent source of surprise to navigators that these mighty masses should float in a contrary direction to that of the ice-fields which descend with the Polar current towards the Atlantic. They reascend with such rapidity that they shatter the so-called “ice-foot,” or belt of ice, still adhering to the shore. Captain Maury has collected numerous observations on this important subject, and he quotes the case of a ship which was being laboriously hauled against the current, when an enormous floating mountain coming up from the south steered against it, but fortunately did not come into collision with it, and forging ahead, very quickly disappeared. How is such an incident to be explained? By the existence of a submarine counter-current, acting on the lower extremity of the submerged portion of the berg, which, as we have stated, is always seven or eight times larger than the bulk above the surface of the waves.