Slowly he became aware of a low, pervasive rumbling, like the inaudible undertones produced by the deepest pipes of a church organ. He felt more than heard it, in his chest and the pit of his stomach, a sound so deep into the bass that he had to wonder if he were fantasizing it.
“I…hear it, I think. Something. But what is it?”
Lai-tsz shivered in a kind of ecstasy. “Infrasound.”
“What?”
“I didn’t want to say anything before I got independent confirmation that there really is something there. They’re speaking to each other infrasonically—with sound waves of such low frequency that you and I can’t actually hear them.”
“My God,” Leyster said. “You mean they’re communicating with each other?”
“With each other, with oneirosaurs outside the valley—who knows? Infrasound can travel for miles. They could be speaking with kin beyond the horizon. Elephants use infrasound to communicate with each other over huge distances.”
“How did you discover this?”
“It’s Turok’s discovery, actually. The little floater grows very still whenever the oneirosaurs speak. Child- to-be would be bouncing around actively, and then suddenly stop, listening. After a while, I made the connection. Whenever Turok got still like that, there’d be an oneirosaur in sight. Either that, or else a tyrannosaur.”
“Tyrannosaurs, too?”
“Yes, I really do think so.”
Leyster laughed from sheer joy. “This is wonderful! You’ve made an incredible discovery.” He seized her hand and kissed it fervently. If it hadn’t been for young Turok, he would have picked her up and whirled her around in the air. “This is… it’s important!”
“Yes. I know,” Lai-tsz said complacently. Leyster understood that she was every bit as pleased as he was. She just didn’t like to show it.
For a time, they stared after the oneirosaurs determinedly eating their way up the valley, sharing the moment without speaking. The moon shone down hazily through a sky strewn with wisps of cloud. There would be rain in the morning, and re-growth would begin. When the lesser herbivores returned, there would be new food in plenty for them.
“It’s really quite marvelous,” Leyster said at last, “how everything fits together. The oneirosaurs level and fertilize the valley just at the right time to maximize growth. And then they move on, rather than staying and monopolizing the limited resources.”
“The herds should be returning soon.”
“Yes.”
“It’s funny, though, how the first animals to return from the migrations were the tyrannosaurs. Followed so closely by the oneirosaurs. It’s almost as if the one were leading the other.”
Leyster was silent for a moment. Then he said, “You don’t really believe that, though.”
“I don’t know. They both employ infrasound. It’s quite possible there’s interspecific as well as intraspecific communication going on. It’s something we really ought to look into.”
“How could we check? Could you build a device of some kind?”
“Oh, yeah, easily. We’ve got a couple of recorders, and all I’d have to do is speed up the playback to bring the ultrasonics up into audibility.”
“You’d have to take time away from trying to repair the time beacon, though.”
She threw him an odd look. “Oh, Richard,” she said, as if it were a negligible thing. “I thought you knew. I gave up on that a long time ago.”
To his amazement, he discovered that she was right. He knew she’d given up on their ever returning to their own time. He’d known it for months.
Finally, though, it was time to go home. They picked their way gingerly downslope and through the woods, guided by the fitful glimmer of one of their two remaining flashlights. Since Chuck had lost the third, two weeks ago, the flashlights had been put on the proscribed list of equipment that was never to leave the camp. But Lai-tsz’s condition superceded all rules. Leyster held the flashlight for her, walking half a step ahead and to the side, to make sure the way was safe.
“I miss Daljit and Jamal,” Lai-tsz said.
“They call every day.”
“It’s not the same.”
For the end of the rainy season, Daljit and Jamal had determined to go inland to meet the migrating herds partway home, make a count of their numbers, and possibly gain some insight into their behavior. They would have liked to follow the migrating herds out at the beginning of the season and back again in the spring, but everybody agreed there simply weren’t the resources yet to make that plan practical. So they’d compromised.
The Styx was tributary to the Eden River, which flowed through the Faraways (hardly mountains, but more than hills) at Water Gap. There, on an elevated spot above the migration trails Jamal and Daljit had set up their camp.
Two weeks they’d been waiting, while the herds didn’t come. There had been a flurry of excitement as the oneirosaurs passed through—fifty of them; they’d broken into smaller groups since—preceded by swift waves of tyrannosaurs. But since then, nothing.
The trees opened up onto Smoke Hollow. “Odd,” Leyster said. There was a light on in the long house. “People are still up?” They’d slipped away at sundown, explaining only that they’d be back late.
“Daljit and Jamal, remember? The evening satellite window opens late tonight. If they came up with something interesting this afternoon, this would be their first chance to share it.”
“You know, that satellite would be a lot more useful if it weren’t out of range so often. Why isn’t it in a geosynchrous orbit?”
“Well, two reasons, offhand. First, because it would take a lot more fuel to raise it to such a high orbit. Second, because a geosynchrous orbit is a lousy position for a mapping satellite.”
“There’s another thing. Why is a geosynchrous orbit so high? It would be a lot more convenient if it were lower.”
“Because it—oh, you’re teasing me!”
“It took you this long to figure that out?”
Mock-bickering, they entered the long house. Everyone squatted in a circle around Chuck, who was speaking on the phone.
Chuck looked up. His expression was uncharacteristically tense. “It’s Daljit,” he said. “Jamal’s been hurt.”
Luckily, Jamal’s injury was nothing worse than a broken leg. Unluckily, it left Daljit and him in no condition to return home without help. This at a time when their food supplies were running low and the migrating dinosaurs had flushed most of the small game from their immediate neighborhood.
After much discussion, it was decided that the largest rescue party they could manage was three people. After more discussion, it was agreed that those three should be Leyster, for his orienteering skill, Tamara, because she was the best hunter, and Chuck, because the other two wanted him.
“Why me?” Chuck asked cautiously. He’d been feeling a little insecure of late. Losing the flashlight had hit his self-esteem hard.
“Because you’ll keep our spirits up,” Tamara said. Leyster nodded gravely.
A small flush of pleasure spread over Chuck’s face.
