“Okay,” Arthur says, “but why wouldn't that just sink the whole area? I would think that there would be a depression circling the edge of the volcano, rather than this cliff.”
“Exactly!” Stephan cries.
But Hans is shaking his head, a smile on his face. He gestures for the brandy flask again. “The point is, the lava shield of Olympus Mons is a single unit of rock—layered, admittedly, but essentially one big cap of basalt, placed on a slightly soft surface. Now by far the greatest part of the weight of this cap is near the center—the volcano's peak, you know, still so far above us. So—the cap is a unit, a single piece of rock—and basalt has a certain flexibility to it, as all rock does. So the cap itself is somewhat flexible. Now the center of it sinks the farthest, being heaviest—and the outside edge of the shield, being part of a single flexible cap, bends upward.”
“Up twenty thousand feet?” Arthur demands. “You're kidding!”
Hans shrugs. “You must remember that the volcano stands twenty-five kilometers above the surrounding plains. The volume of the volcano is one hundred times the volume of Earth's largest volcano, Mauna Loa, and for three billion years at least it has been pressing down on this spot.”
“But it doesn't make sense that the scarp would be so symmetrical if that was what happened,” Frances objected.
“On the contrary. In fact that is the really telling aspect of it. The outer edge of the lava shield is lifted up, okay? Higher and higher, until the flexibility of the basalt is exceeded. In other words, the shield is just so flexible and no more. At the point where the stress becomes too much, the rock sheers off, and the inner side of the break continues to rise, while what is beyond the break point subsides. So, the plains down below us are still part of the lava shield of Olympus Mons, but they are beyond the break point. And as the lava was everywhere approximately the same thickness, it gave way everywhere at about the same distance from the peak, giving us the roughly circular escarpment that we now climb!”
Hans waves a hand with an architect's pride. Frances sniffs. Arthur says, “It's hard to believe.” He taps the floor. “So the other half of this cave is underneath the talus wash down there?”
“Exactly.” Hans beams. “Though the other half was never a cave. This was probably a small, roughly circular layer of tuff, trapped in much harder basaltic lava. But when the shield broke and the escarpment was formed, the tuff deposit was cut in half, exposing its side to erosion. And a few eons later we have our cozy cave.”
“Hard to believe,” Arthur says again.
Roger sips from the flask and silently agrees with Arthur. It's remarkable how difficult it is to transfer the areologist's theories, in which mountains act like plastic or toothpaste, to the vast hard basalt reality underneath and above them. “It's the amount of time necessary for these transformations that's difficult to imagine,” he says aloud. “It must take . . .” He waves a hand.
“Billions of years,” Hans says. “We cannot properly imagine that amount of time. But we can see the sure signs of its passing.”
And in three centuries we can destroy those signs, Roger says silently. Or most of them. And make a park instead.
Above the cave the cliff face lies back a bit, and the smoothness of the Jasper Band is replaced by a jumbled, complicated slope of ice gullies, buttresses, and shallow horizontal slits that mimic their cave below. These steps, as they call them, are to be avoided like crevasses on level ground, as the overhanging roof of each is a serious obstacle. The ice gullies provide the best routes up, and it becomes a matter of navigating up what appears to be a vertical delta, like the tracing of a lightning bolt burned into the face and then frozen. Every morning as the sun hits the face there is an hour or so of severe ice and rockfall, and in the afternoons in the hour after the sun leaves the face there is another period of rockfall. There are some close calls and one morning Hannah is hit by a chunk of ice in the chest, bruising her badly. “The trick is to stay in the moat between the ice in the gully and the rock wall,” Marie says to Roger as they retreat down a dead-end couloir.
“Or to be where you want to be by the time the sun comes up,” Dougal adds. And on his advice to Eileen, they begin rising long before dawn to make the exposed parts of the climb. In the frigid dark a wristwatch alarm beeps. Roger twists in his bag, trying to turn it off; but it is his tent mate's. With a groan he sits up, reaches over and switches on his stove. Soon the metal rings in the top of the cubical stove are glowing a friendly warm orange, heating the tent's air and giving a little bit of light to see by. Eileen and Stephan are sitting in their bags, beating sleep away. Their hair is tousled, their faces lined, puffy, tired. It is 3:00 A.M. Eileen puts a pot of ice on the stove, dimming their light. She turns on a lamp to its lowest illumination, which is still enough to make Stephan groan. Roger digs in a food pouch for tea and dried milk. Breakfast is wonderfully warming, but suddenly he has to visit the cave's convenient yet cold latrine. Boots on—the worst part of dressing. Like sticking one's feet into ice blocks. Then out of the warm tent into the intense cold of the cave's air. Through the dark to the latrine. The other tents glow dimly—time for another dawn assault on the upper slopes.
By the time Archimedes, the first dawn mirror, appears, they have been on the slopes above the cave for nearly an hour, climbing by the light of their helmet lamps. The mirror dawn is better; there is enough light to see well, and yet the rock and ice have not yet been warmed enough to start falls. Roger climbs the ice gullies using crampons; he enjoys using them, kicking into the plastic ice with the front points of the crampons, and adhering to the slopes as if glued to them. Below him Arthur keeps singing a song in tribute to his crampons: “Spiderman, Spiderman, Spiderman, Spidermannnnn.” But once above the fixed ropes, there is no extra breath for singing; the lead climbing is extremely difficult. Roger finds himself spread-eagled on one pitch, right foot spiked into the icefall, left foot digging into a niche the size of his toenail; left hand holding the shaft of the ice axe, which is firmly planted in the icefall above, and right hand laboriously turning the handle of an ice screw, which will serve as piton in this little couloir: And for a moment he realizes he is ten meters above the nearest belay, hanging there by three tiny points. And gasping for breath.
At the top of that pitch there is a small outcropping to rest on, and when Eileen pulls herself up the fixed rope she finds Roger and Arthur laid out over the rock in the morning sunlight like fish set out to dry. She surveys them as she catches her wind, gasping herself. “Time for oxygen,” she declares. In the midday radio call she tells the next teams up to bring oxygen bottles along with the tents and other equipment for the next camp.
With three camps established above the cave, which serves as a sort of base camp to return to from time to time, they are making fair progress. Each night only a few of them are in any given camp. They are forced to use oxygen for almost all of the climbing, and most of them sleep with a mask on, the regulator turned to its lowest setting. The work of setting up the high camps, which they try to do without oxygen, becomes exhausting and cold. When the camps are set and the day's climbing is done, they spend the shadowed afternoons wheezing around the camps, drinking hot fluids and stamping their feet to keep them warm, waiting for the sunset radio call and the next day's orders. At this point it's a pleasure to leave the thinking to Eileen.
One afternoon climbing above the highest camp with Eileen, Roger stands facing out as he belays Eileen's lead up a difficult pitch. Thunderheads like long-stemmed mushrooms march in lines blown to the northeast. Only the tops of the clouds are higher than they. It is late afternoon and the cliff face is a shadow. The cottony trunks of the thunderheads are dark, shadowed gray—then the thunderheads themselves bulge white and gleaming into the sunny sky above, actually casting some light back onto the cliff. Roger pulls the belay rope taut, looks up at Eileen. She is staring up her line of attack, which has become a crack in two walls meeting at ninety degrees. Her oxygen mask covers her
mouth and nose. Roger tugs once—she looks down—he points out at the immense array of clouds. She nods, pulls her mask to one side. “Like ships!” she calls down. “Ships of the line!"
Roger pulls his mask over a cheek. “Do you think a storm might come?”
“I wouldn't be surprised. We've been lucky so far.” She replaces her mask and begins a layback, shoving the fingers of both hands in the crack, putting the soles of both boots against the wall just below her hands, and pulling herself out to the side so that she can walk sideways up one of the walls. Roger keeps the belay taut.
Mars's prevailing westerlies strike Olympus Mons, and the air rises, but does not flow over the peak; the mountain is so tall it protrudes out of much of the atmosphere, and the winds are therefore pushed around each side. Compressed in that way, the air comes swirling off the eastern flank cold and dry, having dumped its moisture on the western flank, where glaciers form. That is the usual pattern, anyway; but when a cyclonic system sweeps out of the southwest, it strikes the volcano a glancing blow from the south, compresses, lashes the southeast quadrant of the shield, and rebounds to the east intensified.
"What's the barometer say, Hans?"
“Four hundred and ten millibars.”
“You're kidding!”
“That's not too far below normal, actually.”
“You're kidding.”
“It is low, however. I believe we are being overtaken by a low-pressure system.”
The storm begins as katabatic winds: cold air falling over the edge of the escarpment and dropping toward the plain. Sometimes the force of the west wind over the plateau of the shield blows the gusts out beyond the actual cliff face, which will then stand in perfect stillness. But the slight vacuum fills again with a quick downward blast, which makes the tents boom and stretch their frames. Roger grunts as one almost squashes the tent, shakes his head at Eileen. She says, “Get used to it—there are downdrafts hitting the upper face more often than not.” WHAM! “Although this one does seem to be a bit stronger than usual. But it's not snowing, is it?"
Roger looks out the little tent-door window. “Nope.”
“Good.”
“Awful cold, though.” He turns in his sleeping bag.
“That's okay. Snow would be a really bad sign.” She gets on the radio and starts calling around. She and Roger are in Camp Eight (the cave is now called Camp Six); Dougal and Frances are in Camp Nine, the highest and most exposed of the new camps; Arthur, Hans, Hannah, and Ivan are in Camp Seven; and the rest are down in the cave. They are a little overextended, as Eileen has been loath to pull the last tents out of the cave. Now Roger begins to see why. “Everyone stay inside tomorrow morning until they hear from me at mirror dawn. We'll have another conference then.”
The wind rises through the night, and Roger is awakened at 3:00 A.M. by a particularly hard blast to the tent. There is very little sound of the wind against the rock—then a BANG and suddenly the tent is whistling and straining like a tortured thing. It lets off and the rocks hoot softly. Settle down and listen to the airy breathing WHAM, the squealing tent is driven down into the niche they have set it in—then sucked back up. The comforting hiss of an oxygen mask, keeping his nose warm for once—WHAM. Eileen is apparently sleeping, her head buried in her sleeping bag; only her bunting cap and the oxygen hose emerge from the drawn-up opening at the top. Roger can't believe the gunshot slaps of the wind don't wake her. He checks his watch, decides it is futile to try falling back to sleep. New frost condensation on the inside of the tent falls on his face like snow, scaring him for a moment. But a flashlight gleam directed out the small clear panel in the tent door reveals there is no snow. By the dimmest light of the lamp Roger sets their pot of ice on the square bulk of the stove and turns it on. He puts his chilled hands back in the sleeping bag and watches the stove heat up. Quickly the rings under the pot are a bright orange, palpably radiating heat.
An hour later it is considerably warmer in the tent. Roger sips hot tea, tries to predict the wind's hammering. The melted water from the cave's ice apparently has some silt in it; Roger, along with three or four of the others, has had his digestion upset by the silt, and now he feels a touch of the glacial dysentery coming on. Uncomfortably he quells the urge. Some particularly sharp blows to the tent wake Eileen; she sticks her head out of her bag, looking befuddled.
“Wind's up,” Roger says. “Want some tea?”
“Mmmph.” She pulls away her oxygen mask. “Yeah.” She takes a full cup and drinks. “Thirsty.”
“Yeah. The masks seem to do that.”
“What time is it?”
“Four.”
“Ah. My alarm must have woken me. Almost time for the call.”
Although it is cloudy to the east, they still get a distinct increase of light when Archimedes rises. Roger pulls on his cold boots and groans. “Gotta go,” he says to Eileen, and unzips the tent just far enough to get out.
“Stay harnessed up!”
Outside, one of the katabatic blasts shoves him hard. It's very cold, perhaps twenty degrees below Celsius, so that the windchill factor when it is blowing hardest is extreme. Unfortunately, he does have a touch of the runs. Much relieved, and very chilled, he pulls his pants up and steps back into the tent. Eileen is on the radio. People are to stay inside until the winds abate a little, she says. Roger nods vigorously. When she is done she laughs at him. “You know what Dougal would say.”
“Oh, it was very invigorating all right.”
She laughs again.
Time passes. When he warms back up Roger dozes off. It's actually easier to sleep during the day, when the tent is warmer.
He is rudely awakened late in the morning by a shout from outside. Eileen jerks up in her bag and unzips the tent door. Dougal sticks his head in, pulls his oxygen mask onto his chest, frosts them with hard breathing. “Our tent has been smashed by a rock,” he says, almost apologetically. “Frances has got her arm broken. I need some help getting her down.”
“Down where?” Roger says involuntarily.
“Well, I thought to the cave, anyway. Or at least to here—our tent's crushed, she's pretty much out in the open right now—in her bag, you know, but the tent's not doing much.”
Grimly Eileen and Roger begin to pull their climbing clothes on.
Outside the wind rips at them and Roger wonders if he can climb. They clip on to the rope and jumar up rapidly, moving at emergency speed. Sometimes the blasts of wind from above are so strong that they can only hang in against the rock and wait. During one blast Roger becomes frightened—it seems impossible that flesh and bone, harness, jumar, rope, piton, and rock will all hold under the immense pressure of the downdraft. But all he can do is huddle in the crack the fixed rope follows and hope, getting colder every second.
They enter a long snaking ice gully that protects them from the worst of the wind, and make better progress. Several times rocks or chunks of ice fall by them, dropping like bombs or giant hailstones. Dougal and Eileen are climbing so fast that it is difficult to keep up with them. Roger feels weak and cold; even though he is completely covered, his nose and fingers feel frozen. His intestines twist a little as he crawls over a boulder jammed in the gully, and he groans. Better to have stayed in the tent on this particular day.
Suddenly they are at Camp Nine—one big box tent, flattened at one end. It is flapping like a big flag in a gale, cracking and snapping again and again, nearly drowning out their voices. Frances is glad to see them; under her goggles her eyes are red-rimmed. “I think I can sit up in a sling and rappel down if you can help me,” she says over the tent noise.
“How are you?” asks Eileen.
“The left arm's broken just above the elbow. I've made a bit of a splint for it. I'm awfully cold, but other than that I don't feel too bad. I've taken some painkillers, but not enough to make me sleepy.”
They all crowd into what's left of the tent and Eileen turns on a stove. Dougal dashes about outside, vainly trying to se
cure the open end of the tent and end the flapping. They brew tea and sit in sleeping bags to drink it. “What time is it?” “Two.” “We'd better be off then.” “Yeah.”
Getting Frances down to Camp Eight is slow, cold work. The exertion of climbing the fixed ropes at high speed was just enough to keep them warm on the climb up; now they have to hug the rock and hold on, or wait while Frances is belayed down one of the steeper sections. She uses her right arm and steps down everything she can, helping the process as much as possible.
She is stepping over the boulder that gave Roger such distress when a blast of wind hits her like a punch, and over the rock she tumbles, face against it. Roger leaps up from below and grabs her just as she is about to roll helplessly onto her left side. For a moment all he can do is hang there, holding her steady. Dougal and Eileen shout down from above. No room for them. Roger double-sets the jumar on the fixed rope above him, pulls up with one arm, the other around Frances's back. They eye each other through their goggles—she scrambles blindly for a foothold—finds something and takes some of her weight herself. Still, they are stuck there. Roger shows Frances his hand and points at it, trying to convey his plan. She nods. He unclips from the fixed rope, sets the jumar once again right below Frances, descends to a good foothold, and laces his hands together. He reaches up, guides Frances's free foot into his hands. She shifts her weight onto that foot and lowers herself until Roger keeps the hold in place. Then the other foot crosses to join Roger's two feet—a good bit of work by Frances, who is certainly hurting. Mid-move another gust almost wrecks their balance, but they lean into each other and hold. They are below the boulder, and Dougal and Eileen can now climb over it and belay Frances again.