Page:South - the story of Shackleton's last expedition, 1914-1917.djvu/473

Rh 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.

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.

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

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.

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

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

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

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

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.

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

The meteorological results of the Expedition, when properly worked out and correlated with those from other stations in the southern hemisphere, will be extremely valuable, both for their bearing on the science of meteorology in general, and for their practical and economic applications.