The sun wheeled and the steep wall of dolerite overhead now cast them in the shade, and it got markedly colder. They were truly much younger-looking mountains than any other eighty-million-year-old range, still as steep and jagged as the Himalayas or the Alps, both only a fourth as old; saved by the cold from the ravages of water erosion, and so aged by the winds only, and rising so fast that the rise more than compensated for that abrasion. Cryopreserved, so to speak.
To keep warm Graham went to work taking some samples from the disconformity just above head level. The diamictite would rub away with a gloved fingertip, but hacking out a good sample was work to warm one up. Certainly water had been here, and seafloor diatoms, the paleobotanists told him, benthic genera that indicated brackish to near-normal marine conditions. A shallow seabottom, a fjord probably, perhaps later a lake that slowly dried out. Shoreline of a fjord. Above the shore, a low hardy beech forest. The Pliocene had without a doubt had temperatures high enough to support Nothofagus; this was agreed upon by everyone, having been an earlier case that some other group had already black-boxed: warm Pliocene, no questions asked. And now a fact basic to the dynamicist case; that was the crux of their whole argument, really—that if you got global temperatures as high as the Pliocene, the Antarctic ice sheets melted both east and west, leaving glaciated archipelagoes and an embayed craton, in a sea covered every winter by substantial amounts of sea ice. That would account for the clear varving here, now that he thought of it; it need not be just the tidal marks on a seashore, but annual sediment fall on a seafloor that in winters was covered by a roof of sea ice. “Hmmm …” Graham said, glancing at Michelson.
Beech trees had not evolved greatly, and any fossil fragments of them found here could have been much older than the Pliocene. Indeed when they had first found beech wood in the Sirius they had assumed it was Triassic wood picked up by a glacier much later. Only when they had come on thousands of beech leaves as well did they realize the wood had been alive when Sirius was laid down. And beech forests supported an array of smaller life as part of their ecology, of course, mostly mosses and lichens, but also weevils and other beetles, freshwater snails, and perhaps even some amphibians. Some of these would be specifically Pliocene species, or could be dated by chemical tests that worked specifically for them. So that looking into the rock of this ancient seafloor (granting for the moment that that was what it was), it was quite possible that one might find fossils larger than the microscopic foraminifera and diatoms. Michelson often mentioned the possibility at the beginning of the day when they set out, or when the helos arrived to carry part of the team to a distant site; cheerily and with no expectations he would call out in farewell, “Keep an eye out for scallop shells!” A kind of joke. Actually the foraminifera and diatoms, although too small to be seen by the naked eye, were enough to prove their contention that the Sirius group was the remnant of a seafloor, and date it as well. But certainly a fossil clam shell would be welcome.
And so when Graham’s finger took a big flake of the diamictite off, revealing a band of yellow-red rusty clayey material, he said “What have we here!”
It was not a clam shell, of course. But it was unusual.
He climbed up the strata to have a closer look at it. He pulled a lens from his pocket and took a glance at 30x power. Crushed plant material.
He called out to Harry, who was worrying at a round block of tillite up the slope. Harry heard him, and called back, “I think I’m in an old estuary here!”
“Very like!” Graham said. “Come here and look at this!”
Harry came around the corner and saw the rusty strata in the gray sandstone. “Hey!”
“Yes. Look at where it is, too. Rudimentary paleosol, at the upper surface of a fluvial diamicton, and see here, root structures going down here vertically, and then spreading out farther laterally.”
“Beech forest,” Harry said, his eyes round. “Oh, my God—this looks like it’ll be as big as Oliver Bluffs or Bennett Platform.”
“Yes.” Carefully they worked the diamictite off the yellow-rust leaf litter mat. “Look, it’s especially well-preserved where it’s compressed under these boulders.” Graham tapped away some more. Harry got on his wrist phone and called Michelson. “Geoff, it looks like we’ve found another beech leaf mat, a good one. Moss cushions too, but mostly beech. Preservation looks good.”
“I’ll be right up. I’m downvalley from you still, right?”
“That’s right. We’re up against the cliff wall, site 3.”
“I’ll be right there.”
Harry was their paleobotanist, and so now grinning ecstatically. At that moment it was like a treasure hunt, Graham realized; or like prospecting for gold. A find like this would result in a paper that would help make a case that would help make a career that would help pay the bills. Gold nuggets right there in the ground, if you wanted to think of it that way. The philosopher’s stone. Or another brick in the wall.
Although Harry was not thinking in such prosaic terms. “Look at that, oh my God. Can you imagine a beech forest growing down here, what it would have looked like! So beautiful. This is a beautiful fjord shoreline, Graham, it’s like a holy place. Really fine mineralization too.”
Another flake of diamictite came off. The yellowy stuff was bowed under the boulders resting on the disconformity. A tiny oil-bearing deposit in the making.
“Leaves up to six or seven centimeters, it looks like. That’s big.”
“So mild temperatures.”
“And maybe cloudy a lot. Check this out, veins in the leaf. Incredible venation.”
“Very nice.”
Of course this would only be another case of disputed age of biological material. Still, it seemed very clear that at the times when the Sirius group was being deposited, this region had been much more than lifeless sand occasionally catching windblown diatoms from afar; if nothing else, this helped to make that very clear, so the main counter-explanation given by the stabilists for the presence of the diatoms was obviously wrong. And if it was clear that there were beech forests here during Sirius, on a cold coast that looked more like the coast of southern Chile than like the current inhospitable icy shore, then one had to admit that Antarctica had certainly had some mild times. And then the diatoms that absolutely permeated the Sirius sandstones, to the point where some diamictites were simply pulverized diatoms and foraminifera and nothing else, could be quite definitively dated to the Pliocene by solid biostratification dating; and so where was the flaw? How could the interpretation of a liquid marine era be faulted at that point? You would have to simply ignore evidence to do it; pretend certain papers didn’t exist; pretend that certain rocks in the field didn’t exist either. And unbiased scientists, without their careers committed to one view or the other, would not do that.