A sort of crypt or deep recess was hollowed out beneath the arch, the full extent of which Freeman was unable to discern. The floor of it descended in ridges, like a rough staircase. He stood for a few moments peering into the gloom, tempted by curiosity to advance, but restrained partly by the gathering darkness, and partly by the oppressiveness of the atmosphere, which produced a sensation of giddiness. Something white gleamed on the threshold of the crypt. He picked it up. It was a human skull; but even as he lifted it it came apart in his hands and crumbled into fragments. Freeman’s nerves were strong, but he shuddered slightly. The loneliness, the silence, the mystery, and the strange light-headedness that was coming over him combined to make him hesitate. “I’ll come back to-morrow morning early,” he said to himself. As if in answer, a deep, appalling roar broke forth apparently under his feet, and went rolling and reverberating up and down the canon. It died away, but was immediately followed by another yet more loud, and the ground shook and swayed beneath his feet. A gigantic boulder, poised high up on the other side of the canon, was unseated, and fell with a terrific crash. A hot wind swept sighing through the valley, and the air rapidly became dark. Again came the sigh, rising to a shriek, with roarings and thunderings that seemed to proceed both from the heavens and from the earth. A dazzling flash of lightning split the air, bathing it for an instant in the brightness of day: in that instant Freeman saw the bolt strike the great white pyramid and splinter its crest into fragments, while the whole surface of the gorge heaved and undulated like a stormy sea. He had been staggering as best he might to a higher part of the ravine; but now he felt a stunning blow on his head: he fell, and knew no more. CHAPTER VII. Two horsemen, one of whom led a third horse, carrying a pack-saddle, had reached the borders of the desert just as the earthquake began. When the first shock came, they were riding past a grove of live-oaks: they immediately dismounted, made fast their horses, and lay down beside some bushes that skirted the grove. Neither the earthquake nor the storm was so severe as was the case farther eastward. In an hour all was over, and they remounted and continued their journey, guiding their course by the stars. “It was thus that we rode before, Kamaiakan,” remarked the younger of the two travellers. “Yonder bright star stood as it does now, and the hour of the night was the same. But this shaking of the earth makes me fear for the safety of that youth. The sands of the desert may have swept over him; or he may have perished in the hills.”