Arctic and Antarctic Exploration [part i 
water pools on the ice. Generally an ice-field is traversed 
by long ridges of hummocks, often 40 to 50 feet high, 
brought about by the collision of two fields, the irresistible 
pressure causing them to rise up. 
The tvcrafloe is applied to pieces which are from half 
a mile to a mile in diameter. Pieces smaller than a floe 
are called drift ice. When drift ice is so extensive that 
its limits cannot be seen, it is called a pack, when the 
pieces do not touch an open pack, when they are pressed 
together a close pack. A patch is a collection of drift ice, 
the limits of which are visible. A stream is a drifting line 
of drift ice. A tongue is a projecting point of ice, under 
water. A calf is a mass of loose ice lying under a floe 
near its margin, and, when disengaged from that position, 
rising with violence to the surface. Brash ice consists of 
fragments and nodules, the wreck of other kinds of ice, 
and sludge is the term applied to smaller pieces, generally 
saturated by the sea. 
A bright white line on the horizon, seen over an ice- 
field, and denoting more ice, is known as the ice-blink. 
Over land or large masses of ice it generally has a 
yellowish tinge. On the other hand a blue streak on 
the horizon, denoting open water, is called a water sky. 
A lane or lead is a narrow track of open water between 
floes or pack ice. Rotten ice is old ice partially melted, 
and in part honeycombed. 
When a ship is forcibly pressed by ice floes on both 
sides she is said to be nipped, and she is beset when closely 
surrounded by ice. To bore is to enter the ice under 
press of sail or steam and to force a way through by 
separating the masses. Sallying is causing a ship to 
roll by making the men run in a body from side to side, 
to relieve her from adhesion of young ice. 
An ice foot along a coast line is caused by the accumula- 
tion of the autumn snow-fall, as it drifts to the beach, 
being met by sea- water with a temperature just below 
the freezing point of fresh water. It is at once converted 
into ice, forming a solid wall from the bottom of the 
sea, constantly maintained. The upper surface of an ice 
foot is level with high water mark. The terrace above 
this wall, from its edge to the base of the talus, has a 
width dependent on the land slope. Thus an ice foot will 
