Complete Short Fiction, page 302
If this one spread no farther than the other. Neither he nor any of the Flyers had been able to explain what had caused that other fall. A vertical cliff three hundred feet high and of any length at all near a Mesklin pole was unbelievable enough; the now well determined fact that it completely rimmed a continentsized area of the giant planet was worse.
The general layered appearance, which the Flyers claimed to mean sedimentary rock, was hard even for them to reconcile with an unbroken vertical cliff. There should be rock fragments—more reasonably rock powder—at the bottom. All along the bottom. Barlennan had often heard them arguing about whether the perfectly vertical joints in the cliff face implied that the plateau had been lifted or the surroundings lowered, but it had been another of the inconclusive debates which seldom held his attention for long.
No guess at what might have caused that local fall had ever come close to explaining why it had stayed local; it was easy to imagine something like a careless footfall’s (whose?) starting the break—but what could possibly have kept it from dominoing both ways the whole ten- or twelve-thousand-mile circumference of the continent? And for that matter, what had studded so many thousands of square miles of the plateau’s outer edge with boulders up to truck size, most of them lying on the surface rather than even partially buried? No one on Toorey was in the least surprised that Mesklin showed tectonic activity, and no one was too surprised that this differed in detail from anything familiar to human, Drommian, and the other researchers’ experience.
The edges of the plateau which had been seen, only a small fraction of its total circumference, did appear to be sedimentary rock, but this did nothing to make theorizing simpler.
Would the same unknown cause, or any other, operate to stop the spread of this fall? Were his crew members safe? The original Bree was ashore on the far side of the river, a little farther from the base of the cliff than the scarp itself was high. Many of those below would be away from the ship, farther still from the cliff, hunting, and presumably safe. Others, though, might well be fishing, since the river was a major source of food.
There was nothing Barlennan could do. The Flyers were still calling for attention. There was nothing they could possibly do either, but they deserved to watch. Barlennan was a responsible and reasonably fair-minded adult, and never thought of blaming them for what was happening.
The slow swiveling of the balloon finally brought the lens to face the cliff edge, not at the nearest point but well to the right, where the unaffected edge itself could still be seen. The captain stopped the rotation there. The new edge was now much closer to the balloon and—
And its growth was slowing? Surely it was slowing?
Barlennan’s people, after many thousands of days piling dirt and rocks around the alien rocket in the course of business, had a very clear concept of angle of repose. The collapse couldn’t possibly extend much farther back from the original edge than it was now getting, the captain told himself. The whole plateau would never crumble to fragments, obviously. At least, it hadn’t the other time.
But that was not the immediate problem. How far along would the disintegration extend? How safe were his other men? And how would he get his people and the stuff the Flyers wanted to recover physically, such as the inertial tracker, back to the equator if his original ship were lost? Taking the balloon across thousands of miles of ocean was ridiculous; it could carry fuel to heat its air for only a few days, in spite of Karondrasee’s endless research into different juices with maybe more effective enzymes. It could not carry the whole crew, even if the stuff wanted by the Flyers were all left behind.
“We’ve warned Dondragmer.” Jeanette’s voice caught the captains’s attention at this point in his thoughts. “No one is on the cliff side of the river. A dozen are away hunting. The ones still at the ship are getting as far from the river and the cliff as quickly as they can carry the radio.”
“Can they carry it while keeping it pointed so you can see what happens to the cliff, and tell me?” asked Barlennan.
“Don said he’d try.” That was enough for anyone who knew the mate.
“Can you see from it right now?”
“Yes. It’s pointed along the cliff in the direction the fall will come from, but the view isn’t too steady.”
“North” and “South” were not useful words this close to the pole, though the latter had been located very exactly long before.
“I’d suggest there can’t be any danger farther than, say, three times the river’s width away from the cliff foot. When they get that far, maybe they could put the set down occasionally to give us a steadier look and better pictures.”
“Maybe. But leave that decision to Dondragmer.”
“Of course. But you still have two cameras besides that one; maybe he could leave it—”
“We’ve been using all three. Dondragmer decides. I know what I’d do with my present knowledge, but he’s there.”
“All right.” There were beings, most of them non-human, on Toorey who might have argued further, but Jeanette Parkos was not one of them. She was very conscious of who was in charge on the surface, and as chief communicator realized clearly who would be blamed if any major disagreement should develop with the Mesklinites. “We’ll report to you as well as we can when the collapse gets in sight from where Dondragmer is, if it does.”
“Good. I’m still hoping it won’t. That other one we climbed to get up here—”
“The other one is much narrower than this one is already. Whatever caused it can’t have been as energetic.”
Another alien voice cut in. “That’s silly! Practically all the energy involved now is coming from falling rock. You have a chain reaction.”
“But that must have been true for the other fall, too!”
Barlennan turned his attention back to the still spreading collapse. He had learned long ago the futility of listening to Flyers arguing theoretical points when anything was actually going on. They got too far behind real time much too quickly. No doubt it was because they were too far away to feel personally involved. The captain was not; he turned his eyes back to the explosion site.
At least, nothing more was flying through the air. Their own climb had ceased, according to the tracker and his own eyes; the balloon had reached its ceiling, which was low because of the rapid decrease of air density with altitude. Hars’ efforts were now focused on keeping its height constant; altitude control was highly unstable. Even a slight dip caused a decrease in balloon volume, and hence a decrease in lift, which tended to make the dip deeper. It was like the hollow boat’s behavior, so many gravities to the north. Hars had developed a high skill at handling this problem; it had been he who had conceived the deflectors which gave quick control over how much hot air was actually entering the bag, and eliminated much of the control lag involved in merely feeding fuel or sprinkling meat juice on the fire.
“It’s coming.” The human voice sounded less excited than the captain felt was appropriate, but Jeanette was not, of course, in danger herself. One should make allowances.
“How close?”
“It’s just come around the point about three miles upstream.”
“How far is the debris spreading out into the river?”
“I can’t tell very well yet. The set is on the ground, or as near as no matter. The edge view I get for the bend seems to show repose at about forty degrees for the stuff near the top, and maybe twenty near the bottom. That would mean anything that’s more than about one cliff height away from the original bottom should be safe.”
“That does not quite include the ship,” Barlennan pointed out.
Dondragmer cut in. “There wouldn’t be time to get back to the ship, much less to tow it overland any distance, before the fall gets here.”
“All right. Make sure the crew is safe. Head for the site where this balloon was built; that has to be safe, and a lot of our stuff is there anyway.”
“Yes, Captain. We’ll start searching for ship building materials at once, when we get there. Have you further orders?”
“None for now, except when you think you’re far enough out to be safe you should set the Flyers’ eye where they can see what happens. Remember they can see things over again, and could be able to tell us how best to find and recover anything that gets buried.”
Dondragmer was probably the least susceptible of the Bree’s crew to being startled, and had spent many thousands of days burying and then digging out the alien rocket, but the thought of excavating a rockfall jolted him. Several of the crew could tell this. None, however, said anything, and the communicator was set down and pointed as the captain had ordered. The natives stayed where they were afterward, and nervously watched the collapse region as it neared them.
They could see that the falling material was pretty certain not to reach them, but Mesklinites in general are not calm about anything’s falling. Not even Mesklinites with the background of Barlennan’s crew.
The roar of the rocks was loud enough now to drown out even their voices, and there was no conversation as the wave thundered past in front of them.
From Toorey, the view through the lens involved less emotion, though several of the watchers were already, and everyone hoped prematurely, wondering what the loss of the original Bree would do to their plans. More were observing, in as much detail as the optics allowed, the way new vertical joints appeared closer and closer to the watchers, delimiting sections of rock which began to tilt slowly outward—a slow fall was a phenomenon on Mesklin—and then develop horizontal cracks which shot back toward the areas already bared by the downward disappearance of previously loosened material. The rock above each crack tilted slightly outward and vanished in its turn, reappearing as it shattered on the growing slope below. Lower segments of the falling prisms were just as invisible during their falls, but didn’t fragment as completely before coming to rest. The repose angle grew steeper as the eye traveled upward and encountered less and less fine material and more and more large slabs and columns.
On any other world the details would have been mostly hidden by dust—with or without an atmosphere to suspend it.
Not on this one.
The collapse wave thundered past. Dondragmer retained enough presence of mind to turn the vision set to the left, so the Flyers could keep watching its progress. This was just as well, because it let them see its sudden halt.
The wave was fully two miles past by this time; whatever stopped its progress could not have helped the ship still on the river bank. But it did stop.
Within seconds, the debris seemed to have reached equilibrium. The observers, local and offworld, found themselves looking at a new straight-up cliff far to their left extending inward from the former face, roughly toward the grounded rocket. Its lower section was partly hidden by the scree slope so suddenly formed, but what could be seen was as nearly vertical as the original had been.
Several of the Mesklinites, rendered more nearly insane than their fellows by the events of the last thousands of days, promptly started back toward the cliff, slanting downstream to get a look at the end of the fall. Dondragmer was equally curious but ordered them back. Jeanette interrupted his commands.
“It’s probably safe enough, Don. The stuff must have reached repose angle right away.”
“No doubt you are right, Flyer Jeanette, but we will first bring the captain up to date with events. He could not have seen this, unless the balloon has moved remarkably fast in the right direction. You would know better, but I can’t see it from here. Also, you do not mention that the repose angle, if it really is that, is much steeper for the higher, larger fragments than for the much finer material near the bottom.”
“You know,” cut in another alien voice, “this will be the first chance we’ve ever had to get a close look at the rock making up that cliff. We could see it was sedimentary, if horizontal layering means anything, but all we could tell was that the bottom fifty feet or so was light gray in color, the next layer up was a lot darker, and for the rest of the way up there were variously light and dark bands up to the nearly black one at the top. That one’s silicate—mostly amphibole, the gear on the rocket told us years ago right after the landing, but this will be the first time we’ll be able to tell anything about the other layers.”
“What will we be able to tell?” snapped another. “Just what will color tell us, and what else will we be able to see?”
Dondragmer, like the captain, tuned out the argument. He had more important problems to face.
There was no more visible rock motion anywhere along the fall; the stuff must, indeed, have reached some sort of equilibrium. There was no more sound even from the left, where falling material must presumably have taken a little longer to fill space around the new corner.
But something—the “smoke” described a little while before? well, maybe ordinary fog—was rising from the far side of the river, over the newly fallen material. Even after watching balloons, the sight of something flowing upward was startling. Explanation would have to wait, though.
There were fragments of all shades and several colors at the bottom of the fall, but the mate was more concerned with what might be under it. What had happened to the Bree? And for that matter, what might have happened to the river? He didn’t worry about the captain, who had presumably been almost as much out of danger as the Flyers. After a few moments’ thought, he headed toward where the ship had been, ordering a few of the crew to come with him carrying the communicator, and sending off others to examine the edge of the fall both up and down stream.
Almost immediately he had a question to ask the aliens above.
“It’s getting a lot warmer as we get near the fallen stuff. Can you suggest why?”
Even Jeanette could, but one of the scientists undertook the explanation. Not even Dondragmer had really grasped much thermodynamics yet, but many of the natives had a fairly clear idea of energy. Every falling pebble had lost a lot of potential—
Quite a lot. More than enough, for the stuff originally near the top, to bring its temperature above the melting point of water, one of the aliens figured. Not that any of the natives knew what water was, or that there was any reason to believe there was any around.
“Better stay away for a little while,” the alien concluded his or her remarks. “It shouldn’t take long to cool again; your air is a very good conductor of heat. Actually, it must be radiation you’re feeling; there ought to be a pretty strong wind from where you are toward the cliff.”
“There is. It’s still uncomfortable, but we can stand more if we have to.”
“Just wait a while.”
The mate saw nothing else to do.
Barlennan would have done the same, if the choice had been offered. Hars had worked the balloon rather jerkily downward from its ceiling until the basket was only a few yards above the tallest boulders, but at every level the wind was now toward the cliff edge. It was carrying them far too rapidly for a safe landing; hooking the car on a boulder and tipping the crew out was not acceptable. They could easily have fallen several body lengths. The cliff edge—or rather, the nearest point of the new slope—was less than half a mile away; much less, now. It seemed safest as well as unavoidable to go out beyond it and drop below the level of the plateau, a maneuver which should at least provide a wider choice of wind directions.
It didn’t. There still was only one choice, it turned out. A little later, after his quick physics lesson, Dondragmer could have told his captain what the choice would be, but the information would have been of little help.
As Bree Three neared the top of the slope, the temperature rose abruptly, the balloon started upward, and the surroundings faded from sight.
Neither the need nor the possibility of instrument flying had ever occurred to Barlennan or any of his crew. They had felt the upward surge, tiny as the acceleration was compared to the local gravity, and the captain could tell from the tracker readings that the climb was continuing. The instrument had been the first one salvaged from the very top of the rocket; its main purposes had been to help guide the original landing, with the additional hope that if the south pole were not found exactly its distance from the rocket could be determined and, possibly, seismic measurements be secured later.
To Barlennan, the temperature rise plus the upward acceleration suggested an upward air current heated from below and outside the balloon; Hars judged the same and reacted at once, slanting the vanes to waste hot air to the sides. The captain’s first thought was that this was the proper reaction; then he realized that the climb couldn’t possibly last long, but might very well take them above the balloon’s normal ceiling. If the upward impulse ceased at some point, which it could hardly help doing, even full fire might not be enough to keep a catastrophic descent from following.
“Keep it hot! Hot as you can!” he hooted. The fireman reversed the slope of the guides without question, though perhaps not without uneasiness. For several seconds the crew remained without reference points, though the figures on the instrument showed they were still climbing; then the surrounding fog began to thin, and sun and sky could once again be seen.
The ground directly below could not, nor that along the former line of the cliff edge; they were still in fog. Toward the plateau, however, boulders were visible once more. In the opposite direction the less rugged area of the lowland showed fuzzily at first, but quickly cleared. Evidently they were still traveling in the same direction. A glance at the inertial reading confirmed this.
The readout was reliable to fourteen places, even here; it had been made visible on the surface of the baseball-sized sphere to permit initial calibration, and Barlennan was not the only member of his crew to have learned to interpret the characters. Hexadecimal readings weren’t too difficult for people who normally used base eight. The tracker was completely solid, with no moving parts larger than electrons, and the gravity had produced no readable change in its behavior, the Flyers had reported. It had, after all, been designed for such a field.
