In more fertile spots the observer would have come to the conclusion that one of those great herds of bisons which graze upon the prairie land was approaching him.

This was obviously impossible in these arid wilds.

As the whirl of dust drew nearer to the solitary bluff upon which the two castaways were reposing, the canvas-covered tilts of waggons and the figures of armed horsemen began to show up through the haze, and the apparition revealed itself as being a great caravan upon its journey for the West.

But what a caravan! When the head of it had reached the base of the mountains, the rear was not yet visible on the horizon.

Right across the enormous plain stretched the straggling array, waggons and carts, men on horseback, and men on foot.