Suiting his action to his words the active lad started with a run that carried him a few yards up the steep ascent. It was so abrupt that he was on the point of sliding back, and dug his heel sharply into the snow to secure a hold. At the same instant he uttered a cry, threw up his arms, and dropped from the sight of his astonished companions as though he had fallen down a well. Before they could make a move toward his rescue they were more astounded than ever to hear his voice, somewhat muffled, but apparently close beside them. "I'm all right!" he cried, cheerily. "That is, I think I am, and I believe I can cut my way out. Don't try to climb the bank. Just wait a minute." Then the bank began to tremble as though shaken by a gentle earthquake, and suddenly a hand clutching a knife shot out from it so close to Jalap Coombs that the startled sailor leaped back to avoid it, stumbled over a sledge, and plunged headlong among his own team of dogs, who were lying in the snow beyond, patiently waiting to be unharnessed. By the time the yelling, howling mass of man and dogs was disentangled and separated, Serge had emerged from the mysterious bank, and stood looking as though he did not quite understand what had happened. Behind him was a black opening into which Phil was peering with the liveliest curiosity. "Of all the miracles I ever heard of this is the strangest!" he cried. "What does it mean, old man?" "I don't exactly know," answered Serge: "but I rather think it is a moss blanket. Anyhow, that's an elegant place to crawl into out of the cold. Seems to be plenty of wood too." Serge was right in his conjecture. What appeared to be the river-bank was merely a curtain of tough, closely compacted Alaskan moss, closely resembling peat in its structure, one foot thick, and reaching from the crest of an overhanging bank to the edge of the river. It had thus held together, and fallen to its present position when the river undermined and swept away the earth from beneath it. That it presented a sloping surface instead of hanging perpendicular was owing to a great number of timbers, the ends of which projected from the excavated bank behind it. Serge had broken through the moss curtain, fallen between these timbers to the beach, and then cut his way out. Now, as he suggested, what better camping-place could they ask than the warm, dry, moss-enclosed space from which he had just emerged.