This was desperately slow work, and beyond that ridge of rock they discovered no other evidence. An hour passed, and not the slightest sign gave encouragement. Could the wagon have turned in some other direction? In the shadow of a sand-dune they halted finally to discuss the situation. Should they go on? Or explore further to the east and west? Might it not even be better to retrace their way to the springs, and wait the coming of Lacy? All in front of them the vast sand plain stretched out, almost as level as a floor. So far as the eye would carry there was no visible sign of any depression or change in conformity. Certainly there was no valley in that direction. Beyond this dune, in whose shelter they stood, there was nothing on which the gaze could rest; all was utter desolation, apparently endless. Brennan was for turning back, arguing the uselessness of going further, and the necessity of water for the ponies. "Come on, Jim," he urged. "Be sensible; we've lost the trail, and that's no fault o' ours. An Apache Indian couldn't trace a herd o' steers through this sand. And look ahead thar! It's worse, an' more of it. I'm for stalking Lacy at the springs." He stopped suddenly, staring southward as though he had seen a vision. "Holy smoke! What's that? By God! It's a wagon, Jim; an' it come right up out of the earth. There wasn't no wagon there a second ago." CHAPTER XXX: ON THE EDGE OF THE CLIFF For a moment both men suspected that what they looked upon was a mirage--its actual existence there in that place seemed impossible. Yet there was no disputing the fact, that yonder in the very midst of that desolation of sand, a wagon drawn by straining horses was slowly moving directly toward them. Westcott was first to grasp the truth, hastily jerking the marshal back to where the tired ponies stood with drooping heads behind the protection of the dune. "It's the same outfit coming back," he explained. "The Sunken Valley must be out there--just a hole in the surface of the desert--and that's how that wagon popped up out of the earth the way it did. I couldn't believe my eyes." "Nor me neither," and the marshal drew one of his guns, and held it dangling in his hand. "I'm a bit flustered yet, but I reckon that's about the truth. Get them ponies round a bit more, an' we'll wait and see what's behind that canvas." The distance must have been farther than it seemed, or else the travelling difficult, for it was some time before the heavy wagon and straining team drew near enough for the two watchers to determine definitely the character of the outfit. Westcott lay outstretched on the far side of the dune, his hat beside him, and his eyes barely able to peer over the summit, ready to report observations to the marshal crouched below. "It's Moore's team, all right," he whispered back, "and Matt is driving them. There isn't any one else on the seat, so I guess he must be alone."