Stratton whistled, a soft, peremptory note, and the thoroughbred sprang, moving swiftly down a short incline, and up towards the buttress. The passage grew difficult. The trail, which took the edge of a precipitous slope, was obstructed by fallen rock. Presently these loose accumulations increased to a slide. Sir Donald dropped to a walk, picking his way lightly. Finally, under the cliff, he halted, balanced nicely on a huge rocking slab, and inspected with suspicion the pitfalls before him. His master waited, motionless; the bridle hung loosely, but in a firm, alert hand. "It’s all right, old fellow," he said, "It’s all right, but take your own time." The chestnut shook his mane in remonstrance and put one forefoot out cautiously, trying for hold. Then he withdrew, backing carefully, swiftly, off the slab, and with hoofs set, head high, whole body quivering, waited. The next instant the solid earth shook, and like a sprung mine, clang, clash, roar, a terrific cannonading filled the gorge. Stratton understood. Smith had seen him at the lower curve, and, bent on deferring a meeting until the return of the sorrel was impossible, had pressed hurriedly on. The autumn frosts, thawing by day, continually split and loosened rock on the face of the cliff, and this incautious passing of the horses, a false step, a stumble, had been the slight jar necessary to start a fresh avalanche. The final echo died far off; the profound silence which had followed him all day settled again like an intangible presence over the gorge. It was a stillness to challenge the very breathing of a man, if he lived, and Stratton waited, listening, for any slight disturbance beyond the buttress. None reached him. But the sorrel was fleet. She would have sprung like the wind at the first crack of the catastrophe; and if there had been space to pass the pack-animals, it was possible she had carried Smith out of the track of the slide. But clearly this portion of the trail was now impassable. He backed Sir Donald slowly away from the bastion, and when he was able to turn him, rode down to a point where a rivulet, cascading from a hidden snow field high up, formed a gully in the slope. He took this rocky stairway, dismounting where he must, swinging into the saddle again, making détours through crumbling earth, on over slippery stone, doubling back, pressing up once more, and so gained the summit of the cliff. He left his horse and crept to the eastern edge and looked down on the slide. It was terrible. For half a mile, obliterating the trail to the next curve, stretched ruin. Midway a crag, like a broken mainmast, dismantled, toppled out of the wreckage, and at the same time a warning and a menace, held the Pass. It was also a monument. There was no longer room for doubt; somewhere down there in the bottom of the gorge, under tons of rock, the unfortunate sorrel was buried with Smith.