Gradually other cactus forms showed a harder struggle for existence, and the spaces of sand between were wider. But now the dreaded, glistening choya began to show pale and gray and white upon the rising slope. Round-topped hills, sunset-colored above, blue-black below, intervened to hide the distant spurs and peaks. Mile and mile long tongues of red lava streamed out between the hills and wound down to stop abruptly upon the slope.
The fugitives were entering a desolate, burned-out world. It rose above them in limitless, gradual ascent and spread wide to east and west. Then the waste of sand began to yield to cinders. The horses sank to their fetlocks as they toiled on. A fine, choking dust blew back from the leaders, and men coughed and horses snorted. The huge, round hills rose smooth, symmetrical, colored as if the setting sun was shining on bare, blue-black surfaces.
But the sun was now behind the hills. In between ran the streams of lava. The horsemen skirted the edge between slope of hill and perpendicular ragged wall. This red lava seemed to have flowed and hardened there only yesterday. It was broken sharp, dull rust color, full of cracks and caves and crevices, and everywhere upon its jagged surface gew the white-thorned choya.
Again twilight encompassed the travelers. But there was still light enough for Gale to see the constricted passage open into a wide, deep space where the dull color was relieved by the gray of gnarled and dwarfed mesquite. Blanco Sol, keenest of scent, whistled his welcome herald of water. The other horses answered, quickened their gait. Gale smelled it, too, sweet, cool, damp on the dry air.
Yaqui turned the corner of a pocket in the lava wall. The file of white horses rounded the corner after him. And Gale, coming last, saw the pale, glancing gleam of a pool of water beautiful in the twilight.
Next day the Yaqui's relentless driving demand on the horses was no longer in evidence. He lost no time, but he did not hasten. His course wound between low cinder dunes which limited their view of the surrounding country. These dunes finally sank down to a black floor as hard as flint with tongues of lava to the left, and to the right the slow descent into the cactus plain. Yaqui was now traveling due west. It was Gale's idea that the Indian was skirting the first sharp-toothed slope of a vast volcanic plateau which formed the western half of the Sonora Desert and extended to the Gulf of California. Travel was slow, but not exhausting for rider or beast. A little sand and meager grass gave a grayish tinge to the strip of black ground between lava and plain.
That day, as the manner rather than the purpose of the Yaqui changed, so there seemed to be subtle differences in the others of the party. Gale himself lost a certain sickening dread, which had not been for himself, but for Mercedes and Nell, and Thorne and the rangers. Jim, good-natured again, might have been patrolling the boundary line. Ladd lost his taciturnity and his gloom changed to a cool, careless air. A mood that was almost defiance began to be manifested in Thorne. It was in Mercedes, however, that Gale marked the most significant change. Her collapse the preceding day might never have been. She was lame and sore; she rode her saddle sidewise, and often she had to be rested and helped; but she had found a reserve fund of strength, and her mental condition was not the same that it had been. Her burden of fear had been lifted. Gale saw in her the difference he always felt in himself after a few days in the desert. Already Mercedes and he, and all of them, had begun to respond to the desert spirit.
Moreover, Yaqui's strange influence must have been a call to the primitive.
Thirty miles of easy stages brought the fugitives to another waterhold, a little round pocket under the heaved-up edge of lava.
There was spare, short, bleached grass for the horses, but no wood for a fire. This night there was question and reply, conjecture, doubt, opinion, and conviction expressed by the men of the party.
But the Indian, who alone could have told where they were, where they were going, what chance they had to escape, maintained his stoical silence. Gale took the early watch, Ladd the midnight one, and Lash that of the morning.
They day broke rosy, glorious, cold as ice. Action was necessary to make useful benumbed hands and feet. Mercedes was fed while yet wrapped in blankets. Then, while the packs were being put on and horses saddled, she walked up and down, slapping her hands, warming her ears. The rose color of the dawn was in her cheeks, and the wonderful clearness of desert light in her eyes. Thorne's eyes sought her constantly. The rangers watched her. The Yaqui bent his glance upon her only seldom; but when he did look it seemed that his strange, fixed, and inscrutable face was about to break into a smile. Yet that never happened. Gale himself was surprised to find how often his own glance found the slender, dark, beautiful Spaniard. Was this because of her beauty? he wondered. He thought not altogether. Mercedes was a woman. She represented something in life that men of all races for thousands of years had loved to see and own, to revere and debase, to fight and die for.
It was a significant index to the day's travel that Yaqui should keep a blanket from the pack and tear it into strips to bind the legs of the horses. It meant the dreaded choya and the knife-edged lava. That Yaqui did not mount Diablo was still more significant.
Mercedes must ride; but the others must walk.
The Indian led off into one of the gray notches between the tumbled streams of lava. These streams were about thirty feet high, a rotting mass of splintered lava, rougher than any other kind of roughness in the world. At the apex of the notch, where two streams met, a narrow gully wound and ascended. Gale caught sight of the dim, pale shadow of a one-time trail. Near at hand it was invisible; he had to look far ahead to catch the faint tracery.