Right in front of them stood the broad foot of the Umbilical. It touched the surface, but it was not held by a mechanical tether. The coupling was performed electromagnetically, field-bound to Quake's metal-rich mantle. Perry had told him that it was necessary because of the instability of the planetary surface near Summertide. That was plausible, and consistent with Perry's claim about the violence of the event. Why else would the Builders have avoided a real tether? But mere plausibility did not make the statement true.
Beyond the Umbilical, in the dirrection of Mandel's setting disk, stood a brooding range of low mountains, purple-gray in the dusty air. The peaks were uniform in size and strangely regular in their spacing. From their harsh profile and the steep angle of their ascent, they had to be volcanic. But he could see no pall of smoke standing above them, nor any evidence of recent lava flows. He looked closer. The ground beneath his feet was smooth and fissure-free, with no gaps in plant growth to testify to recent fracturing of the surface.
So this was Quake, the great and terrible? Rebka had slept easy in environments ten times as threatening. Without a word he began walking toward the lake.
Perry hurried after him. "Where are you going?" He was nervous, and it was not simulated tension.
"I want to have a look at those animals. If it's safe to do it."
"It should be. But let me go first." Perry's voice was agitated as he moved on in front. "I know the terrain."
Nice and thoughtful of you, Rebka thought. Except that I don't see a thing in the terrain that
needs
knowing. The ground was marked here and there by patches of igneous outcrops and broken basaltic rubble, a sure sign of old volcanic activity, and the footing was sometimes difficult and uneven. But Rebka would have no more trouble traveling across it than Perry.
As they moved toward the water the going actually became easier. Closer to the lake lay a sward of springy dark-green ground cover that had managed to find purchase on the dry rocks. Small animals, all invertebrates, scuttled to hide away in it from the approaching strangers. The herbivores held their ground until the two men were a few meters away, then unhurriedly sidled off toward the lake. They were round-backed creatures with radial symmetry, multilegged and with cropping mouths set all around their periphery.
"You know what's bugging me, don't you?" Rebka asked suddenly.
Perry shook his head.
"All this." Rebka gestured at the plant and animal life around them. "You insist that humans mustn't come to Quake too near to Summertide. You say we can't survive here, and I'm supposed to tell Julius Graves and the others that they are not allowed to visit, and we'll lose the revenue they'd generate for Dobelle. But
they
stay here." He pointed to the animals making their slow way to the water's edge. "They survive, apparently with no trouble. What can they do that we can't do?"
"Two things." They had reached the lakeside, and Perry had for some reason lost his nervousness. "First of all, they avoid the surface of Quake during Summertide. Each one of the animals that you'll find on Quake either dies before Summertide, and its eggs hatch after summer is all over, or else it estivates—hides away for the summer. Those herbivores are all amphibians. In a few more days they'll go down into the lakes, dig deep into the mud at the bottom, and sleep until it's safe to come out again. We can't do that. At least, you and I can't. Maybe the Cecropians can."
"We could do something like that. We could make habitats, domes under the lakes."
"All right. We could, but I doubt if Darya Lang and the others would agree to it. Anyway, that's only half the story. I said they do two things. The other thing they do is, they breed
fast.
A big new litter every season. We can mate all we want to, every day, but we won't match that." Perry's grin had no humor in it. "They have to do it here. The death rate for animals and plants on Quake is over ninety percent per year. Evolution really pushes, so they've adapted as far as they can adapt. Even so, nine out of every ten will die at Summertide. Are you willing to try odds like that? Would you let Darya Lang and Julius Graves risk them?"
It was a powerful argument—
if
Rebka were willing to accept
Perry's claim of Summertide violence. And so far he was not.
A close
approach to Mandel, consistent with Perry's claim about the violence of Summertide, would exert great tidal forces on Quake. No one could doubt that. But it was not clear how much those land tides would damage the surface. Quake's flora and fauna had survived for over forty million years. And that included dozens of Grand Conjunctions, even if there had been no humans to observe them. Why would it not easily survive another?
"Let's go." Hans Rebka had made up his mind. Mandel was close to setting, and he wanted to be off the planet before they
were reduced to depending on Amaranth's dimmer glow. He was convinced that Perry was not telling him everything; that the man had his own reasons for trying to keep people away from Quake. But even if Max Perry were right, Rebka could not justify closing Quake. The evidence that the world was dangerous was just not there to send back to the government of the Phemus Circle.
The arguments all seemed to be the other way round. The native animals might have trouble making it through Summertide, but they did not have human knowledge and resources. Based on what Rebka could see, he would be quite willing to spend Summertide here himself.
"We have a duty to tell people the odds," he went on. "But we are not their guardians. If they choose to come here, knowing the dangers, we shouldn't stop them."
Perry hardly seemed to be listening. He was staring all around, frowning up at the sky and down at the ground and over to the distant line of hills.
"There's no way this can happen, you know," he said. His voice was perplexed. "Where's it all going?"
"Where's what all going?" Rebka was ready to leave.
"The energy
.
The tidal forces are pumping energy in—from Mandel and Amaranth and Gargantua. And none of it is coming out. That means there has to be some monstrous internal storage—"
He was interrupted by a flash of ruddy light from the west. Both men looked that way and saw that between them and the setting sphere of Mandel a line of dark, spreading fountains had appeared, shot with fire and rising from the distant mountains.
Seconds later the sound wave arrived; the ground shock came later yet, but the animals did not wait. At the first bright flash they were heading for the water, moving much faster than Rebka had realized they could ever manage.
"Blow out! We'll get flying rocks!" Perry was shouting, through a rumble like thunder. He pointed to the multiple plumes. "Molten, some of 'em, and we're within easy range. Come on."
He started running back toward the Umbilical, while Rebka hesitated. The line of eruptions was curiously orderly, their spreading darkness bursting precisely from every third peak. He gave one quick look the other way—would water be a safer haven?—and then followed Perry. The ground began to shake, to seesaw back and forth so that he was close to losing his balance. He felt he had to slow down, until a mass of glowing ejecta, a semimolten rock the size of an aircar, plummeted in and lay sizzling within twenty meters of him.
Perry was already in the capsule at the foot of the Umbilical, holding the lower entry port wide open.
Rebka hurled himself through
it headfirst, sacrificing dignity for speed. "All right. I'm in. Move it!"
Perry ran madly up the stairs to the control-and-observation chamber, and the car was starting into upward motion before Rebka had picked himself up and checked for injuries. Instead of securing the hatch and following Perry, he turned to the entry port and left it open a foot or so. He peered out.
Whistling lumps of rock and lava continued to pelt the area they had left. He could see fires as the ejecta seared the brush and the dry ground, and hear occasional fragments smacking into the Umbilical above and below them. They would do no damage, unless one entered the open port. He would have time enough to see it coming and to slam the door closed.
The most vulnerable items were the imported aircars. They sat in a neat line at the foot of the Umbilical, built by humans and brought from Opal for local exploration and use. As Rebka watched, a smoking chunk of rock hurtled toward the top of one of them. When it
bounced away without making
contact, he realized that the cars were sitting beneath a protective sheet of transparent Builder material—cannibalized, probably, from part of Midway Station.
He looked to the horizon. From their present height of two or three hundred meters he could see a long way through Quake's murky air. The surface was aflame with small flash fires, all the way to the distant peaks. Rising smoke brought a pungent
aroma to his nostrils, resinous and
aromatic, and the ground below was shimmering with
heat and
blurred by dust.
It was clear that the source of the disturbance was restricted to the single line of volcanoes that lay between them and Mandel's glowing face, low to the west. Every third peak carried a dusky plume and a pall of smoke above it. But already the force of the eruption was dwindling. The smoke clouds were no longer shot through with crimson and orange, and fewer rocks came sailing through the air toward the car. The herbivores had disappeared long ago, presumably hiding in the protective depths of the lake. They would know when to come out again.
Perry had left the controls and was crouched at Rebka's side. The car's movement up the Umbilical had ceased.
"All right." Rebka prepared to close the port. "I'm persuaded. I wouldn't want to take the responsibility for allowing
people here at Summertide. Let's get out of here and head back to Opal."
But Perry was holding the door open and shaking his
head. "I'd like to go back down."
"Why? Do you want to get killed?"
"Of course not. I want to take a good look at what's happening, and really understand it."
"Quake is approaching Summertide, Commander. That's what's happening. The volcanoes and earthquakes are starting, just the way you said they would."
"No. They're not." Perry was more contemplative than alarrned. "There's a
mystery here.
Remember, I've been on Quake before at this time of year, many times. What we just saw is nothing, just a little local fireworks. We should have found
more
activity than we did,
one hell of a lot more.
The surface was quiet when we arrived;
it should have been shaking all the time. And the eruptions looked impressive, but the ground tremors were nothing. You saw how
quickly they died away." He gestured out of the port. "Look at it now, everything becoming quiet again."
"I'm no planetary geologist, but that's just what you would expect." Rebka could not understand what was going on in Perry's head. Did the man want people there at Summertide, or did he not? Now that there was a good argument against it, Perry seemed to be changing his mind. "You expect stress buildup and stress release. The internal forces build up for a while, until they reach a critical value, and then they let go. Quiet spells, and violent ones.
"Not here." Perry finally closed the port. "Not at Summertide. Think of it, Captain. This isn't normal planetary vulcanism. Opal and Quake revolve around each other every eight hours. Tidal forces from Mandel and Amaranth squeeze and pull their interiors every revolution. At normal Summertide those forces are huge, and the Grand Conjunction makes them even bigger—hundreds of times stronger than they are during the rest of the year."
He sat down in the lower cargo hold and stared at the wall. After a few moments Rebka went up to the control chamber and restarted their ascent himself. When he came down again, Perry had not moved.
"Come on, snap out of it. I believe you; the tidal forces are strong. But that's true for Opal as well as Quake."
"It is." Perry finally roused himself and stood up. "But the effects are damped on Opal. The ocean surface deforms freely and reaches new high and low tides every four hours. Any seabed changes—seaquakes and eruptions—are damped by the depth of water above them. But the land tides on Quake have no oceans to reduce their effects. At this time of year Quake should be active
all the time
. It isn't. So. Where is all that energy going?"
Perry dropped back into his seat and sat there frowning at nothing.
Rebka felt oddly dissatisfied as the upward speed of the car increased and the soft whistle of rapid travel through Quake's atmosphere began. He had been to Quake and seen evidence for himself. The place seemed fully as dangerous as Perry had warned. And yet Perry himself was not
afraid
of Quake. Not at all. He wanted to go back there—while an eruption was still in progress!
Rebka reached a conclusion. If he were to understand Perry, he had to have more data. He sat down facing the younger man.
"All right, Commander Perry. So it doesn't look the way you expected. I can't judge that. Tell me, then, what does Quake
usually
look like at this time of year?"
But that was exactly the wrong question. Perry's look of concentrated thought vanished. An expression of indefinable sadness crept onto his face. Rebka sat waiting for an answer, until he realized after a couple of minutes that he was not going to receive one. Instead of pulling Max Perry out of his reverie, that question had driven him deeper into it. The man was far gone, off in some strange fugue of unhappy memories.
Memories of what? Surely of Quake at Summertide.
Rebka did not speak again. Instead he swore an internal oath, stared up the Umbilical at the distant knot of Midway Station, and admitted an unpleasant truth. He had not wanted this job, a nursemaid task that had interrupted the most challenging project of his career. He had resented being taken away from Paradox, he resented being assigned to Dobelle, he resented Max Perry, and he resented having to worry about the interrupted career of a minor bureaucrat.
But his own pride would not allow him to abandon the job until he knew for certain what had destroyed the man. For Perry
was
destroyed, even if it did not show on the surface.