Vicki looked at him dubiously. “So why are you asking me about them? It sounds like you pretty much know the problem already.”
“It was something I came across when I got interested in evidence for catastrophes,” Keene said. “I was curious to hear Robin’s take on it. What else did he come up with?”
“Do you know about varves?”
“No. What are varves?”
“Layers of sediment that are deposited in lakes and so on, which change color from summer to winter and can be counted like tree rings. They contain pollen grains, which tell you what vegetation grew in the area over the years. And in the Arctic during the Ice Age, which is when standard thinking says the mammoths and all those other animals were supposed to have been around, there simply wasn’t anything growing there that they could have lived on. It was all just frozen desert.”
Keene nodded, at the same time looking puzzled. “Well . . . okay. What else would anyone expect to find in the Arctic in an Ice Age? Am I missing something?”
“I sometimes wonder if I am,” Vicki said. “Do they really make people professors for coming up with ideas that it could have been different?”
Sid looked from one of them to the other. “So what it sounds like you’re saying is, when the mammoths and all those other animals did live there, it couldn’t have been an Ice Age.”
Vicki nodded. “Exactly.
“So when was that? Do we know?”
“It has to have been during a much warmer period that came later,” Vicki said. “They couldn’t have been buried eleven thousand years ago under Arctic conditions. The soil below a few feet down is permanently frozen. So how could all those bodies and bones and trunks of trees have been buried under it? A few might have been caught by things like slides and collapsing crevasses, maybe, but nothing on the scale that’s found. And even if they did, nonfossilized bones and body tissue would never have survived degradation through thousands of years when the warming occurred. So they must have been wiped out and quick-frozen much more recently, in some event that marked the end of that warm period.”
Keene and Sid looked as if each was waiting for the other to fault it. It seemed that neither of them readily could. “What about carbon-14 dating?” Sid asked finally. “I thought that supports the Ice-Age extinction theory.”
“The data that have been published over the years do,” Vicki conceded. “But now it’s beginning to look as if maybe the indicated dates were too high.”
“How’s that?” Keene asked.
“The Arctic has huge natural carbon reservoirs—permafrost soil, peat deposits, methane hydrate in the oceans—that would release lots of carbon dioxide into the atmosphere if a mild warming occurred for any reason. We’re talking about billions of tons a year. . . . And that `old’ carbon would be breathed and ingested and find its way into plant and animal tissues, making all the dates too high if today’s levels with a cooler climate are assumed as the reference.”
“How do you know the climate’s cooler today?” Keene challenged.
“We don’t have big herds of large animals inhabiting the Arctic today.”
Keene stared at her. There it was again. If the conventionally accepted dates were high by a significant factor, then once again they were led to the conclusion of tremendous and destructive happenings worldwide around that same mysterious time, several thousand years ago.
* * *
Sid drifted away across the cabin to listen to Clowes telling Alice and Jenny some anecdotes from Amspace’s history. Keene and Vicki remained buckled into the restraint harnesses in one of the corners, watching the screen. They talked about the time when she had left Harvard after he and Fey split up, and the support they’d found in each other that had led her to follow him south when he set up the consulting deal that had grown into Protonix. They talked about Karen’s succession of cowboy boyfriends, Judith’s odd mix of talents and even odder-seeming engagement, about David Salio and his case for Venus, and Celia’s cat. Keene was glad to have a chance for once to ramble on with Vicki about whatever took their fancy, free from the pressures that never seemed to let up when they were in or anywhere near the firm. The loyalty that she had always shown to everything he did and the things he believed in had played a big part in enabling him to keep going through the rough parts, but he had never found a way of expressing adequately how much it had meant. Hence, it was gratifying that he had been able to keep his word to get her up on one of the missions one day, even if whenever he mentioned it he had made it sound like a joke. Flippancy came naturally as part of his armor for dealing with the world, and sometimes, he feared, brought the risk of having things like promises not taken seriously. It was nice, even if over so small a thing, to be able to feel that it wasn’t so.