A sheer wall of smooth, seamless rock, hundreds of feet in height, bounded one side of the shelf, and a precipice, almost as sheer, the other. For half a mile or so did Glen and his companion follow it, seeking some place at which they might continue their ascent. Finally it narrowed almost to a point, that terminated in an immense field of snow sloping down, smooth and spotless, for a thousand feet below them, to a tiny blue-black lake. Beyond the snow-field the ascent seemed possible; and, by cutting footholes in it with their hatchets, they managed to cross it in safety.