Bad as the pressure ridges are for sledge-traveling, however, they are not as dangerous or trying as the lead or lanes of open water caused by the action of wind and tides on the ice. These are in some cases mere cracks running across the floes in almost straight lines. In other cases they take an irregular course across the ice, and are just wide enough to prevent crossing. Again they will be as large as rivers, a mile or two wide and many miles long. For a polar-sea explorer these leads are an omnipresent nightmare. When or where they will occur is impossible to tell. It may be with a loud report directly ahead of a party, cutting off their advance northward or cutting off their return to land on the way back. It may be directly in the midst of camp. With every northward march on my last two sledge journeys fear of impassable leads increased, and I would find myself hurrying toward every pressure ridge, fearing it concealed a lead beyond it. Arriving at the summit and finding no lead ahead, I would catch myself hurrying on in the same way at the next one.
The best way to cross wide leads is learned only by long experience. Sometimes a detour east or west will result in finding a place narrow enough to permit long sledges to be bridged across. In very cold weather it may be found practicable to wait until new ice forms thick enough to allow a sledge to be rushed across, or a lead may show signs of closing, in which case a party can wait until it is quite close together.
Occasionally large pieces of floating ice are to be found in a lead, forming a sort of pontoon-bridge across it. One member of the party goes ahead to pick the way, jumping from one cake to another, and making sure the weight of dogs and sledge will not tilt the cake, then encouraging the dogs to go forward while the driver of the sledge steers it and at the same time balances the cake of ice to keep it from overturning.
To make dogs leap across a widening crack is work which requires an expert dog-driver. Some can do it without any trouble by use of the whip and voice, others have to go ahead of the dogs and coax them to make the jump by holding their hand low and making a pretense of shaking a morsel of food. Leads which are too wide to jump the dogs and sledges across can be ferried by hacking out a cake of ice large enough to bear the weight of dogs and sledges. It sometimes happens that in crossing a narrow lead it will open before the entire party has crossed. This occurred on my last trip north, an Eskimo with his sledge and dogs being left on the other side. An impromptu ferry-boat was cut out of the ice on our side of the lead, two coils of rope were fastened to each other, and slipped around the cake. Two Eskimos boarded it; a line was thrown across the lead to the other Eskimo while one on our side held that end. Then the two men on the ice-cake took hold of the rope and pulled the raft across the lead. The dogs and sledge and other Eskimo were taken upon the ice-cake, and we hauled them across to our side.
Leads which assume the proportions of rivers, such as the one we encountered on the way north in 1906 and on our way back the same season, are a different matter, and the only thing one can do is to wait until young ice forms strong enough to afford a passage.
To know how to travel safely over young newly formed ice is one of the most important items of knowledge and training for a polar explorer. Prof. Marvin of my last expedition was drowned by breaking through young ice while returning in command of one of my supporting parties, and one of Captain Cagni’s supporting parties was totally lost in the same way.
Members of my expedition had frequent narrow escapes in spite of every precaution, and my entire party had a very close call in 1906 while crossing a two-mile wide stretch of extremely thin ice. Only the utilization of every known trick and method brought us through in safety.
That there were not more fatal accidents was due largely to my previously gained experience and the careful and repeated training and cautioning which my men received.
Snowshoes are a most necessary adjunct of such travel. The distribution of a man’s weight effected by a good pair of six-foot snowshoes will enable him to travel safely over ice which would not support him for an instant without them.
The Eskimos of Whale Sound as a result of their seal hunting on newly formed ice in the autumn, and their spring walrus hunting on young ice at Cape Chalon, have the art of traversing thin ice down fine.