Fossil

Epilogue

More than a hundred kilometers below the nearest sunlight, a river of ice worked its way slowly toward the Liquid Ocean. Where it met the water its fate differed from year to year and from hour to hour; sometimes its face simply melted smoothly away; sometime a tongue of glassy solid projected a kilometer or two into the liquid before cracking gently off; sometimes stranger things happened.

For some Common Years now the river had borne more than its usual load of sediment blown from the warm hemisphere. The ice was denser than usual and the river was not only traveling sunward but trying to sink a little deeper into its surroundings. This had several results.

Some of the sediment was fairly soluble, and dropped the melting point of the ice. Just a little. As the river sank, the pressure increased. Just a little. However, the river was flowing along the pressure/ temperature boundary between two of ice’s solid phases, and that little was enough.

As the mass of ice and impurities groped into the Liquid Ocean, one of the much faster random currents sweeping along the nearly vertical face between Solid and Liquid chanced to be just a trifle colder than the solid, and began to absorb heat from it.

For perhaps a year or two, this merely cooled the ice and moved it more definitely across the phase boundary. Nothing impressive occurred until, with no warning, the shift started at a point just where the tongue of river emerged from the Solid. Perhaps some living creature exploded against it; perhaps some still colder jet of water played briefly at it; many things could have been the cause.

A crack started in the river, and a second later the several cubic kilometers of ice were drifting free. The part of the river still surrounded by solid was shrinking, yielding to the pressure of ice around it.

Growing smaller.

A shock wave spread from the interface as the two kinds of solid hunted for a new equilibrium. The speed of waves in ice is slow by seismic standards, but not by humans ones. It was less than a minute before Hugh Cedar felt the wave.

An Erthuma-high pile of ice shavings a hundred meters from the cliff face marked where the Ice Badger V had clawed its way out of sight. Barrar was learning, Hugh reflected; this tunnel went down at a very modest slope, and spikes on one’s soles made it easy to follow without much danger.

The Badger, of course, traveled much faster than a walk, even here. He could make a running slide every minute or two and probably keep it in sight, but had no intention of taking such chances with his armor. Besides, there was too much to check along the walls of the tunnel. This mole, at least, was leaving walls smooth enough to see through, though there was nothing in the ice so far to attract attention. Even the Samian was losing some of his fossil hunting hopes; Five and her predecessors had collectively bored over twenty kilometers of tunnel without sighting a specimen worth keeping.

Ged was not giving up, of course. To the amusement of the Erthumoi and fascination of S’Nash, he had developed a deep interest in the mechanical problems which had afflicted each of the present machine’s predecessors, and contributed more and better ideas for modification as each model developed. Unfortunately, in spite of several frightening experiences, he remained casual by Hugh’s standards about safety procedures.

“I don’t really take chances,” the Samian insisted after being melted out of the cliff face with Badger II. “Exploration and research have certain built-in dangers, which I recognize, of course; but if one postpones action until these are all evaluated and countered, how will anything ever be done?”

“I’m not suggesting we foresee them all,” Hugh had answered with some annoyance, “but carrying spare parts for a few of the mechanical items under really heavy strain, like your scraper blades, isn’t being overcautious.”

“I had the spare blades. I thought of that possibility. There was no way, though, to get outside to install them; the port could not be opened against the ice. Obviously we will have to move the entrance to the rear of the mole, so we can escape into the tunnel if necessary.” Hugh had agreed, and forborne to ask why this had only now become obvious.

Five, however, seemed to be doing well. Barrar had promised not to descend more than fifty meters until he had bored an untroubled hundred kilometers with the same mole, and Hugh consoled himself with the reflection that he could be rescued from that depth by conventional equipment.

All the testing had so far been done near the mass-kill site they had examined earlier. The cause of this prehistoric disaster was not yet clear, but the terrain was unusual enough to encourage the hope that it might have shared some of the responsibility; and even that small chance had kept in the Samian’s mind the hope that what had happened once might happen again.

The mole was out of sight ahead, now; its driver was testing the steering equipment, the main purpose of the present run. Hugh rounded a fairly tight lefthand bend in the tunnel, but failed to see the machine; another turn, this time to the right, started only a dozen meters further on. He followed, without considering particularly in which direction he and the mole were now heading.

An hour later, after a dozen more turns both horizontal and vertical — once the Erthuma had had to use the radio to warn Ged’s copilot about descending too far — he finally caught sight of the polymer shell. Barrar and his crew had stopped. There had been no call by the Habra on board, so presumably there was nothing wrong; Hugh did not increase his pace. It took him a minute or so to reach the machine, but rather than open the hatch leading inside he brought the microphone to his face. There was no reason to go in; the place was cramped enough already. A meter from the white hull, he started to speak.

Before a word emerged, the tunnel floor suddenly struck his feet. Then the ceiling two meters above struck his head — no, he decided moments later when his head cleared, the ceiling simply hadn’t moved fast enough to get out of his way. Something had hurled him violently upward, and even through his helmet his skull must have come close to major damage. His head hurt, but after a moment that claimed very little of his attention.

Where the Badger had been, a meter from where he stood, there was a smooth wall of ice. Like that surrounding the tunnel, this was very clear, and it took Hugh only a few seconds to see the mole, now some ten meters to his right and six below. At almost the same moment Miriam’s voice came from his translator.

“Hugh, can you hear me? Do you know what happened?”

“I hear you, all right. I can guess what happened. The cliff just got a bit higher, or maybe lower. I hope higher.”

“Why does it make any difference?”

“If the Badger is all right, it won’t. If the shock crippled you, maybe a lot. If the cliff went up, I went with it, and the fault will have cut the tunnel somewhere behind me. I wasn’t keeping track of where we went, and I don’t know which way I’m facing, but I hope very much it’s northwest. That puts you inside the cliff, but leaves me a way to walk out — unless there were more twists and turns in your path than I remember. Is the mole working?”

“Ged’s testing it. Power is on.” Hugh felt a steady vibration, hoped that it wasn’t an aftershock, and relaxed as the mole moved slowly away from him through the ice.

“We’ll come around and pick you up, Ged says,” came the Habra’s voice. “You needn’t worry about which way we’re facing.”

Hugh was not completely reassured, but watched as the vehicle drew away from him and became progressively harder to see. It was managing to turn, slowly, so steering as well as drive seemed to be working.

For several minutes it was almost out of sight and changing direction; its radius of turn was at least fifty meters. At last it seemed to be heading back toward him, and he called Miriam. She acknowledged, and the mole grew clearer until he could see the motion of its diggers.

“Up a bit. Either you went down or I went up.” He held his breath until he could see that vertical steering was also still working.

“You’re coming right at me now. Stand by a moment- I’ll have to back down my tunnel a bit. I don’t want you to go through me. You should have put a hatch on the front of that thing, too.”

“Ged says he doesn’t see how that’s possible. We’ll go on past, and you can get to the hatch all right.”

Cedar watched the moving blades slash free in emptiness as the mole cut back into its earlier path, and rode on across with the aid of the track-mounted spikes. Hugh had never seen an earthworm, but Falga had creatures which used their setae in the same fashion. The stern of the machine appeared and crossed the tunnel, and the vibrations ceased. A moment later the hatch opened.

“Going to ride, or try the tunnel?” came Barrar’s voice.

“I’ll come with you, if you’re sure there’s room.”

“But the whole idea of your following was for safety,” Miriam objected. “It was so you wouldn’t be trapped in here if anything went wrong.”

“You’re right,” admitted the Erthuma. “And don’t say anything about lightning not striking twice; I know it does. Start on out, if you know which way is out; I’ll come along behind. Ged, have you an emergency procedure to use if that fault plane had cut through your machine instead of a few centimeters behind it?”

“I’m afraid not. Can you think of anything?”

“Sure. Have two moles traveling together. What are the chances of the same plane slicing both of them?”

Barrar made no answer, and the trip was resumed. An hour later the machine emerged, within ten meters of the cliff’s foot, and crawled forward to clear the tunnel opening. Hugh Cedar emerged after it, and moments later Erthuma, Samian, and Habra were looking consideringly at the cliff.

“Do you really think we should have a second, just on the chance of something like that’s happening again?” Barrar asked at length. “After all, what are the chances?”

“What were the chances of the plane’s cutting between your machine and my face?” asked Hugh. “The reason I was tempted to ride with you afterward was that I wasn’t sure my knees would hold me up even in this gravity. I wonder how Rek would have reacted?”

“He’ll never go underground. The thought’s too much for him,” replied Miriam. “I know how he feels, of course, and I’m a bit the same way, but I’ve had practice. I’ve spent a lot of time with Liquid Ocean around me; Solid isn’t that different.”

“You could still get him to try it,” Hugh assured her. “He has a brain, and it would override his emotions if he thought the job were important enough.”

“What would make it important for him, as long as there were crawlers to do it?”

Cedar grinned. “You might use his feelings, too. If he won’t admit to the possibility of such a wild coincidence, tell him he’s thinking like an Erthuma.”

The logic backfired, but not from Rekchellet. Hugh found himself using it on his wife after she heard of the test, and Janice was an Erthuma.

The End