798 
MR J. M. WORDIE ON THE NATURAL HISTORY OF PACK-ICE 
employ a special name for fast-ice when it breaks adrift, “ land-floes ” is the most 
suitable ; but generally it can be simply spoken of as heavy floes. 
Floe. — An area of ice, other than fast-ice, whose limits are within sight. The 
surface of a floe may be level or hummocked, and in size it may vary from “ pan- 
cakes” on the one hand to “ fields” on the other. “Light floes” are. between 1 and 
2 feet in thickness ; floes thicker than this are termed “ heavy.” The latter, however, 
often owe their thickness to hummocking, and in the Antarctic at any rate are usually 
covered with fairly deep snow. 
Field. — An area of ice of such extent that its limits cannot be seen from the 
masthead. 
Crack. — Any fracture or rift in sea-ice. 
Lead or Lane. — A navigable passage through pack-ice. Leads may form either 
by the widening of a crack or by a general loosening of the floes. (On the Endurance 
voyage it was customary to speak of the former as leads even when covered with 
young-ice.) 
Pool. — Any enclosed water-area in the pack other than a lead or lane. Pools 
may be of any size: those called “polynia” by Admiral Wrangel were so large 
as to give rise to the belief in an open polar sea. 
Frost-smoke . — The fog-like clouds which appear over newly formed leads and 
pools, owing to the contact of the colder air with the relatively warm sea-water. 
Water-sky. — The dark streak on the sky due to the reflection of leads 'or pools 
or the open sea. 
Ice-blink. — The white or yellowish-white glare on the sky produced by the 
reflection of large areas of sea-ice. The antithesis of water-sky. 
Hummocking. — The processes of pressure formation whereby level young-ice 
becomes broken and built up into hummocky-pack. “ Tenting,” “ rafting,” and 
“ raftering ” are terms in use to describe different phases of the process. 
Hummocky-jloes. — Floes composed wholly or partly of recemented pressure-ice. 
They have also been described as “ old pack,” “ screwed pack ” (David), “ Scholleneis” 
(German writers), and sometimes simply “pack-ice.” In contrast to young-ice, the 
structure is no longer invariably platy or fibrous, but is generally spotted and 
granular. There is less salt present, and the ice may appear almost translucent. 
The Pack. — Term used in a wide sense to include any area of sea-ice, other than 
fast-ice, no matter what form it takes or how disposed. The French term is 
“ banquise de derive.” 
Close-pack-ice. — Pack composed of floes mostly in contact.* 
Open-pack-ice. — The floes for the most part do not touch.* 
Drift-ice. — Loose, very open pack, where water preponderates over ice.* The 
* Drift-ice is so open that ships can go full speed through it, and hardly ever need to change direction. In open- 
pack, on the contrary, the speed is slow and changes of course continually necessary. In close-pack a sailing-ship’s 
course is generally completely checked, while steamers can only progress by repeatedly charging the ice. 
