Sea Ice Terminology

By J. M. WORDIE, M.A. (Cantab.), Lieut. R.F.A.

By J. M. Wordie, Master of Arts (Cambridge), Lieutenant, Royal Field Artillery.

During the voyage of the Endurance it was soon noticed that the terms being used to describe different forms of ice were not always in agreement with those given in Markham’s and Mill’s glossary in “The Antarctic Manual,” 1901. It was the custom, of course, to follow implicitly the terminology used by those of the party whose experience of ice dated back to Captain Scott’s first voyage, so that the terms used may be said to be common to all Antarctic voyages of the present century. The principal changes, therefore, in nomenclature must date from the last quarter of the nineteenth century, when there was no one to pass on the traditional usage from the last naval Arctic Expedition in 1875 to the Discovery Expedition of 1901. On the latter ship Markham’s and Mill’s glossary was, of course, used, but apparently not slavishly; founded, as far as sea-ice went, on Scoresby’s, made in 1820, it might well have been adopted in its entirety, for no writer could have carried more weight than Scoresby the younger, combining as he did more than ten years’ whaling experience with high scientific attainments. Above all others he could be accepted both by practical seamen and also by students of ice forms.

During the voyage of the Endurance, we soon noticed differences in the terms used to describe various forms of ice. They did not always agree with those in Markham’s and Mill’s glossary in “The Antarctic Manual,” 1901. Of course, we followed the terminology used by members of the party whose experience of ice went back to Captain Scott’s first voyage. The terms used may therefore be said to be common to all Antarctic voyages of the present century. The main changes in terminology must date from the last quarter of the nineteenth century. No one was then available to pass on traditional usage from the last naval Arctic Expedition in 1875 to the Discovery Expedition of 1901. On the Discovery, Markham’s and Mill’s glossary was, of course, used, but apparently not followed slavishly. Its terms for sea ice were based on Scoresby’s glossary of 1820, and it might well have been adopted in full. No writer could have carried more authority than Scoresby the younger. He combined more than ten years’ whaling experience with high scientific attainments. More than anyone else, he could be accepted by both practical seamen and students of ice forms.

That the old terms of Scoresby did not all survive the period of indifference to Polar work, in spite of Markham and Mill, is an indication either that their usefulness has ceased or that the original usage has changed once and for all. A restatement of terms is therefore now necessary. Where possible the actual phrases of Scoresby and of his successors, Markham and Mill, are still used. The principle adopted, however, is to give preference to the words actually used by the Polar seamen themselves.

Despite the efforts of Markham and Mill, not all of Scoresby’s old terms survived the period of indifference to Polar work. This suggests either that the terms are no longer useful or that their original usage has changed for good. The terms therefore need to be set out again. Where possible, the actual phrases used by Scoresby and his successors, Markham and Mill, are still used. However, preference is given to the words actually used by Polar seamen themselves.

The following authorities have been followed as closely as possible:

The following sources have been followed as closely as possible:

W. Scoresby, Jun., “An Account of the Arctic Regions,” 1820, vol. i, pp. 225–233, 238–241.

W. Scoresby Jr., “An Account of the Arctic Regions,” 1820, volume 1, pages 225 to 233, 238 to 241.

C. R. Markham and H. R. Mill in “The Antarctic Manual,” 1901, pp, xiv–xvi.

C. R. Markham and H. R. Mill in “The Antarctic Manual,” 1901, pages xiv to xvi.

J. Payer, “New Lands within the Arctic Circle,” 1876, vol. i, pp. 3–14.

J. Payer, “New Lands within the Arctic Circle,” 1876, volume 1, pages 3 to 14.

W. S. Bruce, “Polar Exploration” in Home University Library, c. 1911, pp. 54–71.

W. S. Bruce, “Polar Exploration” in Home University Library, around 1911, pages 54 to 71.

Reference should also be made to the annual publication of the Danish Meteorological Institute showing the Arctic ice conditions of the previous summer. This is published in both Danish and English, so that the terms used there are bound to have a very wide acceptance; it is hoped, therefore, that they may be the means of preventing the Antarctic terminology following a different line of evolution; for but seldom is a seaman found nowadays who knows both Polar regions. On the Danish charts six different kinds of sea-ice are marked—namely, unbroken polar ice; land-floe; great ice-fields; tight pack-ice; open ice; bay-ice and brash. With the exception of bay-ice, which is more generally known as young ice, all these terms pass current in the Antarctic.

The Danish Meteorological Institute also publishes an annual report showing Arctic ice conditions during the previous summer. The report appears in both Danish and English, so its terms are bound to gain very wide acceptance. It is therefore hoped that they may prevent Antarctic terminology from developing along different lines. This matters because sailors who know both Polar regions are now rarely found. The Danish charts mark six different kinds of sea-ice: unbroken polar ice, land-floe, great ice-fields, tight pack-ice, open ice, bay-ice and brash. All these terms are used in the Antarctic, except bay-ice, which is more generally known as young ice.

Slush or Sludge. The initial stages in the freezing of sea-water, when its consistency becomes gluey or soupy. The term is also used (but not commonly) for brash-ice still further broken down.

Slush or Sludge. The early stages of freezing seawater, when it becomes sticky or soupy. The term is also sometimes used for brash ice that has broken down even further.

Pancake-ice. Small circular floes with raised rims; due to the break-up in a gently ruffled sea of the newly formed ice into pieces which strike against each other, and so form turned-up edges.

Pancake-ice. Small circular floes with raised rims. They form when newly formed ice breaks into pieces in a gently rippling sea. The pieces strike each other, turning up their edges.

Young Ice. Applied to all unhummocked ice up to about a foot in thickness. Owing to the fibrous or platy structure, the floes crack easily, and where the ice is not over thick a ship under steam cuts a passage without much difficulty. Young ice may originate from the coalescence of “pancakes,” where the water is slightly ruffled or else be a sheet of “black ice,” covered maybe with “ice-flowers,” formed by the freezing of a smooth sheet of sea-water.

Young Ice. This term applies to all ice without hummocks, up to about a foot thick. Because of their fibrous or plate-like structure, the floes crack easily. Where the ice is not too thick, a steam-powered ship can cut a passage without much difficulty. Young ice may form when “pancakes” join together in slightly rippled water. It may also form when a smooth sheet of seawater freezes into a sheet of “black ice,” perhaps covered with “ice-flowers.”

In the Arctic it has been the custom to call this form of ice “bay-ice”; in the Antarctic, however, the latter term is wrongly used for land-floes (fast-ice, etc.), and has been so misapplied consistently for fifteen years. The term bay-ice should possibly, therefore, be dropped altogether, especially since, even in the Arctic, its meaning is not altogether a rigid one, as it may denote firstly the gluey “slush,” which forms when sea-water freezes, and secondly the firm level sheet ultimately produced.

In the Arctic, this form of ice has usually been called “bay-ice”. In the Antarctic, however, the term has been wrongly used for land-floes (fast-ice, etc.) for fifteen years. Perhaps the term bay-ice should therefore be dropped altogether. Even in the Arctic, its meaning is not entirely fixed. It can mean the gluey “slush” that forms when seawater freezes. It can also mean the firm, level sheet that eventually forms.

Land floes. Heavy but not necessarily hummocked ice, with generally a deep snow covering, which has remained held up in the position of growth by the enclosing nature of some feature of the coast, or by grounded bergs throughout the summer season when most of the ice breaks out. Its thickness is, therefore, above the average. Has been called at various times “fast-ice,” “coast-ice,” “land-ice,” “bay-ice” by Shackleton and David and the Charcot Expedition; and possibly what Drygalski calls Schelfeis is not very different.

Land floes. Heavy ice that is not necessarily hummocked and is generally covered by deep snow. It remains where it formed throughout the summer, when most ice breaks out. It is held in place by an enclosing coastal feature or by grounded icebergs. It is therefore thicker than average. Shackleton, David, and the Charcot Expedition have called it “fast-ice,” “coast-ice,” “land-ice,” and “bay-ice” at various times. What Drygalski calls Schelfeis may not be very different.

Floe. An area of ice, level or hummocked, whose limits are within sight. Includes all sizes between brash on the one hand and fields on the other. “Light-floes” are between one and two feet in thickness (anything thinner being “young-ice”). Those exceeding two feet in thickness are termed “heavy floes,” being generally hummocked, and in the Antarctic, at any rate, covered by fairly deep snow.

Floe. An area of ice, flat or hummocked, whose edges are within sight. Floes include all sizes between brash and ice fields. “Light-floes” are between one and two feet thick (anything thinner is “young-ice”). Floes more than two feet thick are called “heavy floes.” They are generally hummocked and, in the Antarctic at least, covered by fairly deep snow.

Field. A sheet of ice of such extent that its limits cannot be seen from the masthead.

Field. A sheet of ice so large that its edges cannot be seen from the masthead.

Hummocking. Includes all the processes of pressure formation whereby level young ice becomes broken up and built up into

Hummocking. Includes all the pressure processes that break up level young ice and build it up into

Hummocky Floes. The most suitable term for what has also been called “old pack” and “screwed pack” by David and Scholleneis by German writers. In contrast to young ice, the structure is no longer fibrous, but becomes spotted or bubbly, a certain percentage of salt drains away, and the ice becomes almost translucent.

Hummocky Floes. This is the most suitable term for what David also called “old pack” and “screwed pack” and German writers called Scholleneis. Unlike young ice, hummocky floes are no longer fibrous. Instead, the ice becomes spotted or bubbly. Some of the salt drains away, and the ice becomes almost translucent.

The Pack is a term very often used in a wide sense to include any area of sea-ice, no matter what form it takes or how disposed. The French term is banquise de derive.

The Pack is very often used broadly to mean any area of sea ice, whatever its form or arrangement. The French term is banquise de derive.

Pack-ice. A more restricted use than the above, to include hummocky floes or close areas of young ice and light floes. Pack-ice is “close” or “tight” if the floes constituting it are in contact; “open” if, for the most part, they do not touch. In both cases it hinders, but does not necessarily check, navigation; the contrary holds for

Pack-ice. A narrower use than the one above, including hummocky floes or dense areas of young ice and light floes. Pack-ice is “close” or “tight” if its floes touch. It is “open” if, for the most part, the floes do not touch. In both cases, pack-ice hinders navigation but does not necessarily stop it. The opposite is true for

Drift-ice. Loose open ice, where the area of water exceeds that of ice. Generally drift-ice is within reach of the swell, and is a stage in the breaking down of pack-ice, the size of the floes being much smaller than in the latter. (Scoresby’s use of the term drift-ice for pieces of ice intermediate in size between floes and brash has, however, quite died out). The Antarctic or Arctic pack usually has a girdle or fringe of drift-ice.

Drift-ice. Loose, open ice where water covers a larger area than ice. Drift-ice is generally within reach of the swell and represents a stage in the breaking down of pack-ice. Its floes are much smaller than those in pack-ice. (Scoresby used the term drift-ice for pieces of ice between floes and brash in size, but that usage has completely died out.) The Antarctic or Arctic pack usually has a fringe of drift-ice around it.

Brash. Small fragments and roundish nodules; the wreck of other kinds of ice.

Brash. Small fragments and rounded pieces left from other kinds of ice.

Bergy Bits. Pieces, about the size of a cottage, of glacier-ice or of hummocky pack washed clear of snow.

Bergy Bits. Pieces of glacier ice or uneven pack ice, about the size of a cottage, washed free of snow.

Growlers. Still smaller pieces of sea-ice than the above, greenish in colour, and barely showing above water-level.

Growlers. Even smaller pieces of sea ice than those above, greenish in color and barely showing above the water.

Crack. Any sort of fracture or rift in the sea-ice covering.

Crack. Any kind of break or split in the sea ice.

Lead or Lane. Where a crack opens out to such a width as to be navigable. In the Antarctic it is customary to speak of these as leads, even when frozen over to constitute areas of young ice.

Lead or Lane. A crack that has opened wide enough for a ship to pass through. In the Antarctic, these are usually called leads, even when they have frozen over and formed areas of young ice.

Pools. Any enclosed water areas in the pack, where length and breadth are about equal.

Pools. Areas of water enclosed by pack ice, with roughly equal length and width.