Dangers peculiar to the Arctic Sea.—Ice-fields.—Hummocks.—Collision of Ice-fields.—Icebergs.—Their Origin.—Their Size.—The Glaciers which give them Birth.—Their Beauty.—Sometimes useful Auxiliaries to the Mariner.—Dangers of anchoring to a Berg.—A crumbling Berg.—The Ice-blink.—Fogs.—Transparency of the Atmosphere.—Phenomena of Reflection and Refraction.—Causes which prevent the Accumulation of Polar Ice.—Tides.—Currents.—Ice a bad Conductor of Heat.—Wise Provisions of Nature.
The heart of the first navigator, says Horace, must have been shielded with threefold brass—and yet the poet knew but the sunny Mediterranean, with its tepid floods and smiling shores: how, then, would he have found words to express his astonishment at the intrepid seamen who, to open new vistas to science or new roads to commerce, first ventured to face the unknown terrors of the Arctic main?
In every part of the ocean the mariner has to guard against the perils of hidden shoals and sunken cliffs, but the high northern waters are doubly and trebly dangerous; for here, besides those rocks which are firmly rooted to the ground, there are others which, freely floating about, threaten to crush his vessel to pieces, or to force it along with them in helpless bondage.
The Arctic navigators have given various names to these movable shoals,46 which are the cause of so much delay and danger. They are icebergs when they tower to a considerable height above the waters, and ice-fields when they have a vast horizontal extension. A floe is a detached portion of a field; pack-ice, a large area of floes or smaller fragments closely driven together so as to oppose a firm barrier to the progress of a ship; and drift-ice, loose ice in motion, but not so firmly packed as to prevent a vessel from making her way through its yielding masses.
22. AMONG HUMMOCKS.
The large ice-fields which the whaler encounters in Baffin’s Bay, or on the seas between Spitzbergen and Greenland, constitute one of the marvels of the deep. There is a solemn grandeur in the slow majestic motion with which they are drifted by the currents to the south; and their enormous masses, as mile after mile comes floating by, impress the spectator with the idea of a boundless extent and an irresistible power. But, vast and mighty as they are, they are unable to withstand the elements combined for their destruction, and their apparently triumphal march leads them only to their ruin.
23. DRIFTING IN THE ICE.
When they first descend from their northern strongholds, the ice of which they are composed is of the average thickness of from ten to fifteen feet, and their surface is sometimes tolerably smooth and even, but in general it is covered with numberless ice-blocks or hummocks piled upon each other in wild confusion to a height of forty or fifty feet, the result of repeated collisions before flakes and floes were soldered into fields. Before the end of June they are covered with snow, sometimes six feet deep, which melting during the summer forms small ponds or lakes upon their surface.
47
24. FORMS OF ICEBERGS.
Not seldom ice-fields are whirled about in rotatory motion, which causes their circumference to gyrate with a velocity of several miles per hour. When a field thus sweeping through the waters comes into collision with another48 which may possibly be revolving with equal rapidity in an opposite direction—when masses not seldom twenty or thirty miles in diameter, and each weighing many millions of tons, clash together, imagination can hardly conceive a more appalling scene. The whalers at all times require unremitting vigilance to secure their safety, but scarcely in any situation so much as when navigating amidst these fields, which are more particularly dangerous in foggy weather, as their motions can not then be distinctly observed. No wonder that since the establishment of the fishery numbers of vessels have been crushed to pieces between two fields in motion, for the strongest ship ever built must needs be utterly unable to resist their power. Some have been uplifted and thrown upon the ice; some have had their hulls completely torn open; and others have been overrun by the ice, and buried beneath the fragments piled upon their wreck.
25. FORMS OF ICEBERGS.
26. FORMS OF ICEBERGS.
The icebergs, which, as their name indicates, rise above the water to a much more considerable height than the ice-fields, have a very different origin, as they are not formed in the sea itself, but by the glaciers of the northern highlands. As our rivers are continually pouring their streams into the ocean, so many of the glaciers or ice-rivers of the Arctic zone, descending to the water-edge, are slowly but constantly forcing themselves farther and farther into the sea. In the summer season, when the ice is particularly fragile, the force of cohesion is often overcome by the weight of the prodigious masses that overhang the sea or have been undermined by its waters; and in the winter, when the air is probably 40° or 50° below zero and the sea from 28° to 30° above, the unequal expansion of those parts of the mass exposed to so great a difference of temperature can not fail to produce the separation of large portions.
49 Most of these swimming glacier-fragments, or icebergs, which are met with by the whaler in the Northern Atlantic, are formed on the mountainous west coast of Greenland by the large glaciers which discharge themselves into the fiords from Smith’s Sound to Disco Bay, as here the sea is sufficiently deep to float them away, in spite of the enormous magnitude they frequently attain. As they drift along down Baffin’s Bay and Davis’s Strait, they not seldom run aground on some shallow shore, where, bidding defiance to the short summer, they frequently remain for many a year.
27. ICEBERGS AGROUND.
Dr. Hayes measured an immense iceberg which had stranded off the little harbor of Tessuissak, to the north of Melville Bay. The square wall which faced toward his base of measurement was 315 feet high, and a fraction over three-quarters of a mile long. Being almost square-sided above the sea, the same shape must have extended beneath it; and since, by measurements made two days before, Hayes had discovered that fresh-water ice floating in salt water has above the surface to below it the proportion of one to seven, this crystallized mountain must have gone aground in a depth of nearly half a mile. A50 rude estimate of its size, made on the spot, gave in cubical contents about 27,000 millions of feet, and in weight something like 2000 millions of tons!
Captain Ross in his first voyage mentions another of these wrecked bergs, which was found to be 4169 yards long, 3689 yards broad, and 51 feet high above the level of the sea. It was aground in 61 fathoms, and its weight was estimated by an officer of the “Alexander” at 1,292,397,673 tons. On ascending the flat top of this iceberg, it was found occupied by a huge white bear, who justly deeming “discretion the best part of valor,” sprang into the sea before he could be fired at.
The vast dimensions of the icebergs appear less astonishing when we consider that many of the glaciers or ice-rivers from which they are dislodged are equal in size or volume to the largest streams of continental Europe.
Thus one of the eight glaciers existing in the district of Omenak, in Greenland, is no less than an English mile broad, and forms an ice-wall rising 160 feet above the sea. Further to the north, Melville Bay and Whale Sound are the seat of vast ice-rivers. Here Tyndall glacier forms a coast-line of ice over two miles long, almost burying its face in the sea, and carrying the eye along a broad and winding valley, up steps of ice of giant height, until at length the slope loses itself in the unknown ice-desert beyond. But grand above all is the magnificent Humboldt glacier, which, connecting Greenland and Washington Land, forms a solid glassy wall 300 feet above the water-level, with an unknown depth below it, while its curved face extends full sixty miles in length from Cape Agassiz to Cape Forbes. In the temperate zone it would be one of the mightiest rivers of the earth; here, in the frozen solitudes of the North, it slowly drops its vast fragments into the waters, making the solitudes around re-echo with their fall.
As the Polar shores of continental America and Siberia are generally flat, and below the snow-line, they are consequently deprived both of glaciers and of the huge floating masses to which these give birth.
In a high sea the waves beat against an iceberg as against a rock; and in calm weather where there is a swell, the noise made by their rising and falling is tremendous. Their usual form is that of a high vertical wall, gradually sloping down to the opposite side, which is very low; but frequently they exhibit the most fantastic shapes, particularly after they have been a long time exposed to the corroding power of the waves, or of warm rains pelting them from above.
A number of icebergs floating in the sea is one of the most magnificent spectacles of nature, but the wonderful beauty of these crystal cliffs never appears to greater advantage than when clothed by the midnight sun with all the splendid colors of twilight.
28. ICEBERGS AND GLACIER, FROBISHER BAY.
“The bergs,” says Dr. Hayes, describing one of these enchanting nights, “had wholly lost their chilly aspect, and glittering in the blaze of the brilliant heavens, seemed in the distance like masses of burnished metal or solid flame. Nearer at hand they were huge blocks of Parian marble inlaid with mammoth gems of pearl and opal. One in particular exhibited the perfection of the grand. Its form was not unlike that of the Colosseum, and it lay so far away51 that half its height was buried beneath the line of blood-red waters. The sun, slowly rolling along the horizon, passed behind it, and it seemed as if the old Roman ruins had suddenly taken fire. In the shadow of the bergs the water was a rich green, and nothing could be more soft and tender than the gradations of color made by the sea shoaling on the sloping tongue of a berg52 close beside us. The tint increased in intensity where the ice overhung the water, and a deep cavern near by exhibited the solid color of the malachite mingled with the transparency of the emerald, while in strange contrast a broad streak of cobalt blue ran diagonally through its body. The bewitching character of the scene was heightened by a thousand little cascades which leaped into the sea from these floating masses, the water being discharged from lakes of melted snow and ice which reposed in quietude far up in the valleys separating the high icy hills of their upper surface. From other bergs large pieces were now and then detached, plunging down into the water with deafening noise, while the slow moving swell of the ocean resounded through their broken archways.”
29. GLACIER, BUTE INLET.
A similar gorgeous spectacle was witnessed by Dr. Kane in Melville Bay. The midnight sun came out over a great berg, kindling variously-colored fires on every part of its surface, and making the ice around the ship one great resplendency of gemwork, blazing carbuncles and rubies, and molten gold.
In the night the icebergs are readily distinguished even at a distance by their natural effulgence, and in foggy weather by a peculiar blackness in the atmosphere. As they are not unfrequently drifted by the Greenland stream considerably to the south of Newfoundland, sometimes even as far as the fortieth or thirty-ninth degree of latitude (May, 1841, June, 1842), ships sailing through the north-western Atlantic require to be always on their guard against them. The ill-fated “President,” one of our first ocean-steamers, which was lost on its way to New York, without leaving a trace behind, is supposed to have been sunk by a collision with an iceberg, and no doubt many a gallant bark has either foundered in the night, or been hurled by the storm against these floating rocks.
53 But though often dangerous neighbors, the bergs occasionally prove useful auxiliaries to the mariner. From their greater bulk lying below the water-line, they are either drifted along by the under-current against the wind, or, from their vast dimensions, are not perceptibly influenced even by the strongest gale, but, on the contrary, have the appearance of moving to windward, because every other kind of ice is drifted rapidly past them. Thus in strong adverse winds, their broad masses, fronting the storm like bulwarks, not seldom afford protection to ships mooring under their lee.
Anchoring to a berg is, however, not always unattended with danger, particularly when the summer is far advanced, or in a lower latitude, as all ice becomes exceedingly fragile when acted on by the sun or by a temperate atmosphere. The blow of an axe then sometimes suffices to rend an iceberg asunder, and to bury the careless seaman beneath its ruins, or to hurl him into the yawning chasm.
30. SCALING AN ICEBERG.
Thus Scoresby relates the adventure of two sailors who were attempting to fix an anchor to a berg. They began to hew a hole into the ice, but scarcely had the first blow been struck, when suddenly the immense mass split from top to bottom and fell asunder, the two halves falling in contrary directions with a prodigious crash. One of the sailors, who was possessed of great presence of mind, immediately scaled the huge fragment on which he was standing, and remained rocking to and fro on its summit until its equilibrium was restored; but his companion, falling between the masses, would most likely have been crushed to pieces if the current caused by their motion had not swept him within reach of the boat that was waiting for them.
Frequently large pieces detach themselves spontaneously from an iceberg54 and fall into the sea with a tremendous noise. When this circumstance, called “calving,” takes place, the iceberg loses its equilibrium, sometimes turns on one side, and is occasionally inverted.
Dr. Hayes witnessed the crumbling of an immense berg, resembling in its general appearance the British House of Parliament. First one lofty tower came tumbling into the water, starting from its surface an immense flock of gulls; then another followed; and at length, after five hours of rolling and crashing, there remained of this splendid mass of congelation not a fragment that rose fifty feet above the water.
One of the most remarkable phenomena of the Polar Sea is the ice-blink, or reflection of the ice against the sky. A stripe of light, similar to the early dawn of morning, but without its redness, appears above the horizon, and traces a complete aërial map of the ice to a distance of many miles beyond the ordinary reach of vision. To the experienced navigator the “blink” is frequently of the greatest use, as it not only points out the vicinity of the drift-ice, but indicates its nature, whether compact or loose, continuous or open. Thus Scoresby relates that on the 7th of June, 1821, he saw so distinct an ice-blink, that as far as twenty or thirty miles all round the horizon he was able to ascertain the figure and probable extent of each ice-field. The packed ice was distinguished from the larger fields by a more obscure and yellow color; while each water-lane or open passage was indicated by a deep blue stripe or patch. By this means he was enabled to find his way out of the vast masses of ice in which he had been detained for several days, and to emerge into the open sea.
The tendency of the pack-ice to separate in calm weather, so that one might almost be tempted to believe in a mutual repulsive power of the individual blocks, is likewise favorable to the Arctic navigator. The perpetual daylight of summer is another advantage, but unfortunately the sun is too often veiled by dense mists, which frequently obscure the air for weeks together, particularly in July. These fogs, which are a great impediment to the whaler’s operations, have a very depressing influence upon the spirits; and as they are attended with a low temperature, which even at noon does not rise much above freezing-point, the damp cold is also physically extremely unpleasant.
At other times the sun sweeps two or three times round the pole without being for a moment obscured by a cloud, and then the transparency of the air is such that objects the most remote may be seen perfectly distinct and clear. A ship’s top-gallant mast, at the distance of five or six leagues, may be discerned when just appearing above the horizon with a common perspective-glass, and the summits of mountains are visible at the distance of from sixty to a hundred miles.
On such sunny days, the strong contrasts of light and shade between the glistening snow and the dark protruding rocks produce a remarkable deception in the apparent distance of the land, along a steep mountainous coast. When at the distance of twenty miles from Spitzbergen, for instance, it would be easy to induce even a judicious stranger to undertake a passage in a boat to the shore, from a belief that he was within a league of the land. At this distance the portions of rock and patches of snow, as well as the contour of the different55 hills, are as distinctly marked as similar objects in many other countries, not having snow about them, would be at a fourth or a fifth part of the distance.
Nothing can be more wonderful than the phenomena of the atmosphere dependent on reflection and refraction, which are frequently observed in the Arctic seas, particularly at the commencement or approach of easterly winds. They are probably occasioned by the commixture, near the surface of the land or sea, of two streams of air of different temperatures, so as to occasion an irregular deposition of imperfectly condensed vapor, which when passing the verge of the horizon apparently raises the objects there situated to a considerable distance above it, or extends their height beyond their natural dimensions. Ice, land, ships, boats, and other objects, when thus enlarged and elevated, are said to loom. The lower part of looming objects are sometimes connected with the horizon by an apparent fibrous or columnar extension of their parts; at other times they appear to be quite lifted into the air, a void space being seen between them and the horizon.
A most remarkable delusion of this kind was observed by Scoresby while sailing through the open ice, far from land. Suddenly an immense amphitheatre inclosed by high walls of basaltic ice, so like natural rock as to deceive one of his most experienced officers, rose around the ship. Sometimes the refraction produced on all sides a similar effect, but still more frequently remarkable contrasts. Single ice-blocks expanded into architectural figures of an extraordinary height, and sometimes the distant, deeply indented ice-border looked like a number of towers or minarets, or like a dense forest of naked trees. Scarcely had an object acquired a distinct form, when it began to dissolve into another.
It is well known that similar causes produce similar effects in the warmer regions of the earth. In the midst of the tropical ocean, the mariner sees verdant islands rise from the waters, and in the treeless desert fantastic palm-groves wave their fronds, as if in mockery of the thirsty caravan.
When we consider the intense cold which reigns during the greatest part of the year in the Arctic regions, we might naturally, expect to find the whole of the Polar Sea covered, during the winter at least, with one solid unbroken sheet of ice. But experience teaches us that this is by no means the case; for the currents, the tides, the winds, and the swell of a turbulent ocean are mighty causes of disruption, or strong impediments to congelation. Both Lieutenant de Haven and Sir Francis M’Clintock1 were helplessly carried along, in the depth of winter, by the pack-ice in Lancaster Sound and Baffin’s Bay. A berg impelled by a strong under-current rips open an ice-field as if it were a thin sheet of glass; and in channels, or on coasts where the tides rise to a considerable height, their flux and reflux is continually opening crevices and lanes in the ice which covers the waters. That even in the highest latitudes the sea does not close except when at rest, was fully experienced by Dr. Hayes during his wintering at Port Foulke; for at all times, even when the temperature of the air was below the freezing-point of mercury, he could hear from the deck of his schooner the roar of the beating waves. From all these causes there has at no point within the Arctic Circle been found a firm ice-belt extending,56 either in winter or in summer, more than from fifty to a hundred miles from land. And even in the narrow channels separating the islands of the Parry Archipelago, or at the mouth of Smith Sound, the waters will not freeze over, except when sheltered by the land, or when an ice-pack, accumulated by long continuance of winds from one quarter, affords the same protection.
31. AN ARCTIC CHANNEL.
But the constant motion of the Polar Sea, wherever it expands to a considerable57 breadth, would be insufficient to prevent its total congelation, if it were not assisted by other physical causes. A magnificent system of currents is continually displacing the waters of the ocean, and forcing the warm floods of the tropical regions to wander to the pole, while the cold streams of the frigid zone are as constantly migrating toward the Equator. Thus we see the Gulf Stream flowing through the broad gateway east of Spitzbergen, and forcing out a return current of cold water to the west of Spitzbergen, and through Davis’s Strait.
32. OPEN WATER.
The comparatively warm floods which, in consequence of this great law of circulation, come pouring into the Arctic seas, naturally require some time before they are sufficiently chilled to be converted into ice; and as sea-water has its maximum of density, or, in other words, is heaviest a few degrees above the freezing-point of water, and then necessarily sinks, the whole depth of the sea must of course be cooled down to that temperature before freezing can take place. Ice being a bad conductor of heat, likewise limits the process of congelation; for after attaining a thickness of ten or fifteen feet, its growth is very slow, and probably even ceases altogether; for when floating fields, or floes, are found of a greater thickness, this increase is due to the snow that falls upon their surface, or to the accumulation of hummocks caused by their collision.
Thus, by the combined influence of these various physical agencies, bounds have been set to the congelation of the Polar waters. Were it otherwise, the Arctic lands would have been mere uninhabitable wastes; for the existence of the seals, the walrus, and the whale depends upon their finding some open water at every season of the year; and deprived of this resource, all the Esquimaux, whose various tribes fringe the coasts in the highest latitudes hitherto discovered, would perish in a single winter.
If the Arctic glaciers did not discharge their bergs into the sea, or if no currents conveyed the ice-floes of the north into lower latitudes, ice would be58 constantly accumulating in the Polar world, and, destroying the balance of nature, would ultimately endanger the existence of man over the whole surface of the globe.
33. GLACIER DISCHARGING.