Using the 50,000-year calibrations, they had figured it out. One jump (conceding that the calibration was correct) would have landed them at the end of the Wisconsin glacial period; two jumps, at its beginning. The third would set them down toward the end of the Sangamon Interglacial and apparently it had--give or take ten thousand years or so. They had arrived at a time when the climate did not seem to vary greatly, either hot or cold. The flora was modern enough to give them a homelike feeling. The fauna, modern and Pleistocenic, overlapped. And the surface features were little altered from the twentieth century. The rivers ran along familiar paths, the hills and bluffs looked much the same. In this corner of the Earth, at least, 150,000 years had not changed things greatly. Boyhood dreams, Hudson thought, were wondrous. It was not often that three men who had daydreamed in their youth could follow it out to its end. But they had and here they were. Johnny was on watch, and it was Hudson's turn next, and he'd better get to sleep. He closed his eyes, then opened them again for another look at the unfamiliar stars. The east, he saw, was flushed with silver light. Soon the Moon would rise, which was good. A man could keep a better watch when the Moon was up. He woke suddenly, snatched upright and into full awareness by the marrow-chilling clamor that slashed across the night. The very air seemed curdled by the savage racket and, for a moment, he sat numbed by it. Then, slowly, it seemed--his brain took the noise and separated it into two distinct but intermingled categories, the deadly screaming of a cat and the maddened trumpeting of a mastodon. The Moon was up and the countryside was flooded by its light. Cooper, he saw, was out beyond the watchfires, standing there and watching, with his rifle ready. Adams was scrambling out of his sleeping bag, swearing softly to himself. The cooking fire had burned down to a bed of mottled coals, but the watchfires still were burning and the helicopter, parked within their circle, picked up the glint of flames. "It's Buster," Adams told him angrily. "I'd know that bellowing of his anywhere. He's done nothing but parade up and down and bellow ever since we got here. And now he seems to have gone out and found himself a saber-tooth." Hudson zipped down his sleeping bag, grabbed up his rifle and jumped to his feet, following Adams in a silent rush to where Cooper stood. Cooper motioned at them. "Don't break it up. You'll never see the like of it again." Adams brought his rifle up. Cooper knocked the barrel down. "You fool!" he shouted. "You want them turning on us?" Two hundred yards away stood the mastodon and, on his back, the screeching saber-tooth. The great beast reared into the air and came down with a jolt, bucking to unseat the cat, flailing the air with his massive trunk. And as he bucked, the cat struck and struck again with his gleaming teeth, aiming for the spine.