e earth? The great desert
river was down there, of course, but he knew nothing of it. Would that
turn back Wildfire? Slone thought grimly how he had always claimed
Nagger to be part fish and part bird. Wildfire was not going to escape.

By and by only isolated mescal plants with long, yellow-plumed spears
broke the bare monotony of the plateau. And Slone passed from red sand
and gravel to a red, soft shale, and from that to hard, red rock. Here
Wildfire's tracks were lost, the first time in seven weeks. But Slone
had his direction down that plateau with the cleavage lines of canyons
to right and left. At times Slone found a vestige of the old Indian
trail, and this made him doubly sure of being right. He did not need to
have Wildfire's tracks. He let Nagger pick the way, and the horse made
no mistake in finding the line of least resistance. But that grew harder
and harder. This bare rock, like a file, would soon wear Wildfire's
hoofs thin. And Slone rejoiced. Perhaps somewhere down in this awful
chasm he and Nagger would have if out with the stallion. Slone began to
look far ahead, beginning to believe that he might see Wildfire. Twice
he had seen Wildfire, but only at a distance. Then he had resembled a
running streak of fire, whence his name, which Slone had given him.

This bare region of rock began to be cut up into gullies. It was
necessary to head them or to climb in and out. Miles of travel really
meant little progress straight ahead. But Slone kept on. He was hot and
Nagger was hot, and that made hard work easier. Sometimes on the wind
came a low thunder. Was it a storm or an avalanche slipping or falling
water? He could not tell. The sound was significant and haunting.

Of one thing he was sure--that he could not have found his back trail.
But he divined he was never to retrace his steps on this journey. The
stretch of broken plateau before him grew wilder and bolder of outline,
darker in color, weirder in aspect and progress across it grew slower,
more dangerous. There were many places Nagger should not have been put
to--where a slip meant a broken leg. But Slone could not turn back. And
something besides an indomitable spirit kept him going. Again the sound
resembling thunder assailed his ears, louder this time. The plateau
appeared to be ending in a series of great capes or promontories. Slone
feared he would soon come out upon a promontory from which he might see
the impossibility of further travel. He fel