All the ice floating in the sea is generally rough and uneven on the surface, and during the greater part of the year covered with snow. Even newly-formed ice, which is free from snow, is so rough and soft that it cannot be skated upon. Under water the colour of the ice varies with the colour of the sea; in blue water it is blue, in green water it is green, and of deeper shades in proportion to its depth. In the thickest olive-green coloured water, its colour, far beneath the surface, appears brownish.
A description of the process of freezing from its commencement may now be attempted. The first appearance of ice, when in a state of detached crystals, is called by the sailors sludge, and resembles snow when cast into water that is too cold to dissolve it. This smooths the ruffled surface of the sea, and produces an effect like oil in preventing breakers. These crystals soon unite, and would form a continuous sheet, but, by the motion of the waves, they are broken in very small pieces, scarcely three inches in diameter. As they strengthen, many of them coalesce, and form a larger mass. The undulations of the sea still continuing, these enlarged pieces strike each other on every side, whereby they become rounded, and their edges turn up, whence they obtain the name of cakes, or pan-cakes. Several of these again unite, and thereby continue to increase, forming larger flakes, until they become perhaps a foot in thickness, and many yards in circumference. Every larger flake retains on its surface the impression of the smaller flakes of which it is composed, so that when, by the discontinuance of the swell, the whole is permitted to freeze into an extensive sheet, it sometimes assumes the appearance of a pavement. But when the sea is perfectly smooth, the freezing process goes on more regularly, and probably more rapidly. During twenty-four hours’ keen frost, the ice will become an inch or two in thickness, and in less than forty-eight hours’ time capable of sustaining the weight of a man. Both this kind, and cake-ice, are termed bay-ice. In every opening of the main body of ice at a distance from the sea, the water is always as smooth as that of a harbour; and in low temperatures, all that is necessary for the formation of ice is still water. There is no doubt that a large quantity of ice is annually generated in the bays and amidst the islands of Spitzbergen; which bays, towards the end of summer, are commonly emptied of their contents, from the thawing of the snow on the mountains causing a current outwards. But this will not account for the immense fields which are so abundant in Greenland. These evidently come from the northward, and have their origin between Spitzbergen and the Pole.
Ice-fields constitute one of the wonders of the deep. They are often met with of the diameter of twenty or thirty miles, and when in the state of such close combination that no interstice could be seen, they sometimes extend to a length of fifty or a hundred miles. The ice of which they are composed is generally pure and fresh, and in heavy fields it is probably of the average thickness of ten to fifteen feet, and then appears to be flat, low, thin ice; but when high hummocks occur, the thickness is often forty feet and fifty feet. The surface before the month of July is always covered with a bed of snow, from perhaps a foot to a fathom in depth. This snow dissolves in the end of summer, and forms extensive pools and lakes of fresh water. Some of the largest fields are very level and smooth, though generally their surfaces are varied with hummocks. In some, these hummocks form ridges or chains, in others, they consist of insulated heaps. I once saw a field which was so free from either fissure or hummock, that I imagined, had it been free from snow, a coach might have been driven many leagues over it in a direct line, without obstruction or danger. Hummocks somewhat relieve the uniformity of intense light reflected from the surface of fields, by exhibiting shades of delicate blue in all the hollows, where the light is partly intercepted by passing through a portion of ice.
When the surface of snow on fields is frozen, or when the snow is generally dissolved, there is no difficulty in travelling over them, even without snow-skates or sledges. But when the snow is soft and deep, travelling on foot to any distance is a work of labour. The tribe of Esquimaux, discovered by captain Ross, made use of sledges, drawn by dogs, for conveying them across the rough land-ice, lying between the ships and the shore. A journey they performed with such celerity, that captain Ross conjectured they could travel fifty or sixty miles a day. If such a distance were practicable on drift-ice, occurring near shore, it would be much more easy on the smoother ice of fields.
This term, field, was given to the largest sheets of ice by a Dutch whale-fisher. It was not until a period of many years after the Spitzbergen fishery was established, that any navigator attempted to penetrate the ice, or that any of the most extensive sheets of ice were seen. One of the ships resorting to Smeerenberg for fishery, put to sea on one occasion when no whales were seen, persevered westward to a considerable length, and accidentally fell in with some immense flakes of ice, which, on his return to his companions, he described as truly wonderful, and as resembling fields in the extent of their surface. Hence the application of the term field to this kind of ice. The discoverer of it was distinguished by the title of “field-finder.”
Fields commonly make their appearance in the months of May or June, though sometimes earlier; they are frequently the resort of young whales. Strong north and westerly winds expose them to the whalers by driving off the loose ice. The invariable tendency of fields is to drift to the south-westward, even in calms, which is the means of many being yearly destroyed. They have frequently been observed to advance a hundred miles in this direction within the space of one month, notwithstanding the occurrence of winds from every quarter. On emerging from amidst the smaller ice, which before sheltered them, they are soon broken up by the swell, are partly dissolved, and partly converted into drift-ice. The places of such are supplied by others from the north. The power of the swell in breaking the heaviest fields is not a little remarkable. A grown swell, that is so inconsiderable as not to be observed in open water, frequently breaks up the largest fields, and converts them wholly into floes and drift-ice in the space of a few hours; while fields composed of bay-ice, or light-ice, being more flexible, endure the same swell without any destructive effort.
The occasional rapid motion of fields, with the strange effects produced by such immense bodies on any opposing substance, is one of the most striking objects the Polar seas present, and is certainly the most terrific. They not unfrequently acquire a rotatory movement, whereby their circumference attains a velocity of several miles per hour. A field thus in motion, coming in contact with another at rest, or more especially with another having a contrary direction of movement, produces a dreadful shock. A body of more than ten thousand millions of tons in weight, meeting with resistance when in motion, produces consequences which it is scarcely possible to conceive. The weaker field is crushed with an awful noise; sometimes the destruction is mutual; pieces of huge dimensions and weight are not unfrequently piled upon the top, to the height of twenty or thirty feet, while a proportionate quantity is depressed beneath. The view of these stupendous effects in safety exhibits a picture sublimely grand, but where there is danger of being overwhelmed, terror and dismay must be the predominant feelings. The whale-fishers at all times require unremitting vigilance to secure their safety, but scarcely in any situation so much as when navigating amidst these fields; in foggy weather, they are particularly dangerous, as their motions cannot then be distinctly observed. It may easily be imagined, that the strongest ship is but an insignificant impediment between two fields in motion. Numbers of vessels, since the establishment of the fishery, have been thus destroyed; some have been thrown upon the ice, some have had their hulls completely torn open, or divided in two, and others have been overrun by the ice, and buried beneath its heaped fragments. The Dutch have lost as many as twenty-three sail of ships among the ice in one year. In the season of 1684, fourteen of their ships were wrecked, and eleven more remained beset during the winter.
In the month of May, of the year 1814, I witnessed a tremendous scene. While navigating amidst the most ponderous ice which the Greenland Sea presents, in the prospect of making our escape from a state of besetment, our progress was unexpectedly arrested by an isthmus of ice, about a mile in breadth, formed by the coalition of the point of an immense field on the north, with that of an aggregation of floes on the south. To the north field we moored the ship, in the hope of the ice separating in this place. I then quitted the ship, and travelled over the ice to the point of collision, to observe the state of the bar, which now prevented our release. I immediately discovered that the two points had but recently met, that already a prodigious mass of rubbish had been squeezed upon the top, and that the motion had not abated. The fields continued to overlay each other with a majestic motion, producing a noise resembling that of complicated machinery, or distant thunder. The pressure was so immense, that numerous fissures were occasioned, and the ice repeatedly rent beneath my feet. In one of the fissures, I found the snow on the level three and a half feet deep, and the ice upwards of twelve. In one place, hummocks had been thrown up to the height of twenty feet from the surface of the field, and at least twenty-five feet from the level of the water; they extended fifty or sixty yards in length, and fifteen in breadth, forming a mass of about two thousand tons in weight. The majestic, unvaried movement of the ice, the singular noise by which it was accompanied, the tremendous power exerted, and the wonderful effects produced—were calculated to excite in the mind of the most careless spectator admiration of Him with whom “the nations are as a drop of a bucket, and are counted as the small dust of the balance: behold, he taketh up the isles as a very little thing.”
The term icebergs has commonly been applied to the glaciers occurring in Spitzbergen, Greenland, and other arctic countries. It is also as commonly extended to the large peaks, mountains, or islets of ice that are found floating in the sea. It is the latter kind of icebergs we purpose to describe.
Icebergs occur in many places in the arctic and antarctic regions; some of them of astonishing magnitude. In the Spitzbergen Sea, indeed, they are neither numerous nor bulky, compared with those of other regions; the largest I ever met with in this quarter not exceeding a thousand yards in circumference, and two hundred feet in thickness. But in Hudson’s Strait, Davis’s Strait, and Baffin’s Bay, they occur of a prodigious size. Ellis describes them as sometimes occurring of the thickness of five hundred or six hundred yards. Frobisher saw one iceberg which was judged to be “near fourscore fathoms above water.” One berg is described by captain Ross (the dimensions of which were given in by lieutenant Parry[1]) as having nine unequal sides, as being aground in sixty-one fathoms, and as measuring 4,169 yards (paces) long, 3,689 yards broad, and fifty-one feet high. The weight of this iceberg, taken at somewhat smaller dimensions, was estimated, by an officer of the Alexander, at 1,292,397,673 tons. This amount, however, is greater than the truth, the cubical inch of ice being taken at 240 grains, whereas it does not exceed 231·5 grains.