But in the spring of one hundred and sixty-one, for a little while one day, the gulf was bridged. * * * * * Schroeder was returning from a trip he had taken alone to the east, coming down the long canyon that led from the high face of the plateau to the country near the caves. He hurried, glancing back at the black clouds that had gathered so quickly on the mountain behind him. Thunder rumbled from within them, an almost continuous roll of it as the clouds poured down their deluge of water. A cloudburst was coming and the sheer-walled canyon down which he hurried had suddenly become a death trap, its sunlit quiet soon to be transformed into roaring destruction. There was only one place along its nine-mile length where he might climb out and the time was already short in which to reach it. He had increased his pace to a trot when he came to it, a talus of broken rock that sloped up steeply for thirty feet to a shelf. A ledge eleven feet high stood over the shelf and other, lower, ledges set back from it like climbing steps. At the foot of the talus he stopped to listen, wondering how close behind him the water might be. He heard it coming, a sound like the roaring of a high wind up the canyon, and he scrambled up the talus of loose rock to the shelf at its top. The shelf was not high enough above the canyon's floor--he would be killed there--and he followed it fifty feet around a sharp bend. There it narrowed abruptly, to merge into the sheer wall of the canyon. Blind alley.... He ran back to the top of the talus where the edge of the ledge, ragged with projections of rock, was unreachably far above him. As he did so the roaring was suddenly a crashing, booming thunder and he saw the water coming. It swept around the bend at perhaps a hundred miles an hour, stretching from wall to wall of the canyon, the crest of it seething and slashing and towering forty sheer feet above the canyon's floor. A prowler was running in front of it, running for its life and losing. There was no time to watch. He leaped upward, as high as possible, his crossbow in his hand. He caught the end of the bow over one of the sharp projections of rock on the ledge's rim and began to pull himself up, afraid to hurry lest the rock cut the bowstring in two and drop him back. It held and he stood on the ledge, safe, as the prowler flashed up the talus below. It darted around the blind-alley shelf and was back a moment later. It saw that its only chance would be to leap up on the ledge where he stood and it tried, handicapped by the steep, loose slope it had to jump from. It failed and fell back. It tried again, hurling itself upward with all its strength, and its claws caught fleetingly on the rough rock a foot below the rim. It began to slide back, with no time left it for a third try.