All three of the searchers, as may be imagined, kept a sharp look-out, not only for trace of Bismark but also for any sign of danger. But they tramped on, while the sun rose higher, without anything alarming making itself manifest.
But of Bismark not a trace was to be found. He had, apparently, vanished completely. The ground was dry and rocky, too, which was bad, so far as trailing was concerned. Nat, although he now and then tumbled on a hoof mark or found a spot where Bismark had stopped to graze, saw nothing further of the horse.
At last he looked at his watch. He gave an exclamation of astonishment as he did so. It was almost noon.
"Got to be starting back," he thought, and drawing his revolver, he fired one shot, the signal agreed upon for the return.
This done, he set off walking at a brisk pace toward what he believed was the valley. But Nat, like many a more experienced mountaineer, had become hopelessly turned around during his wanderings. While it seemed to him he was striking in an easterly direction, he was, as a matter of fact, proceeding almost the opposite way.
After tramping for an hour or more the boy began to look about him.
"That's odd," he thought as he took in the surroundings, "I don't remember seeing anything like this around the valley."
It was, in fact, a very different scene from that surrounding the camp that now lay about him. Instead of a soft, grass-covered valley, all that could be seen from the bare eminence on which he had now climbed, was a rift in some bare, rocky hills. The surroundings were inexpressibly wild and desolate looking. Tall rocks, like the minarets of Eastern castles, shot upward, and the cliffs were split and riven as if by some immense convulsion of nature.
High above the wild scene there circled a big eagle. From time to time it gave a harsh scream, adding a dismal note to the dreary environment.