"Gracious, if a fellow went through this crust of snow what would happen to him?" said Randy, as he trudged on, with his uncle just ahead of him and Earl behind. "Let us hope that no such fate overtakes any of the party," replied Mr. Portney, gravely. "It is not likely that one can break through here," he added, "for the snow in the trail is pretty well packed down." The blinding glare of the sun had caused all to put on their smoked glasses, or goggles, but now, as the great orb of day was lost to sight behind the mountain tops, these protectors for the eyes were removed, that they might see their way clearer. The Alaskan twilight was creeping on them, causing all their surroundings to turn to a pale blue color. The mists of the mountains were also rising, and on every hand were weird, ghostlike shadows which enhanced this scene of wild desolation. On and on went the white members of the party, doing their best to keep the sturdy Indian pack-carriers well in sight. But the red people, with their hideously painted faces, knew every foot of the way, and made rapid progress, and it was all the others could do at times to keep up. By ten o'clock it began to grow colder, and even the boys could feel the crust of snow on which they were trudging becoming firmer beneath their feet. It was far from dark, a pale glimmer of light hanging on every mountain top. But now the trail became suddenly steeper, and they found themselves going straight up the side of a hill several hundred feet high. "Plant your feet firmly at every step," were Foster Portney's words of caution. "And remember, looking back will do you no good." This last warning was for Randy's benefit, for the lad had just looked back and shivered over the awful descent below him. A fall would mean a long roll, and a broken neck over a cliff below. Captain Zoss had gone on ahead with the Indians and just before midnight he came back with a warning to watch out for several splits, or crevasses, in the glaciers they were now traversing. "Salmon Head says he heard a report of several new ones just before starting, and these are as yet unmarked," he said. "We'll be as careful as we can," said Dr. Barwaithe. "We can do no more." They now passed over a broad plain of snow where the mists hung more thickly than ever. They had almost reached the centre of the plain when a loud cry from the Indians ahead caused them to halt. "What can be the meaning of that?" questioned Earl. "Can they be in trouble?" Presently, from among the mists appeared the form of one of the Indian carriers, without his bundle. He soon explained in broken English that he had been sent back by Salmon Head to warn them of a split in the ice field just ahead. One of the Indian women had slipped in, and it was by mere good fortune that some of the men had rescued her.