One day Maya crashed her fist against the table and cried, “Couldn’t we wait for the island ridge to get torn away?”

After an awkward pause Kasei said, “It’s a hundred kilometers long.”

“Well, shit-couldn’t we just wait until this flood stops? I mean, how long can it go on like this?”

“A few months,” Ann said.

“Can’t we wait that long?”

“We’re running low on food,” Michel explained.

“We have to keep going,” Frank snapped at Maya. “Don’t be stupid.” She glared at him and turned away, clearly furious. The rover suddenly seemed much too small, as if a bunch of tigers and lions had been thrown together in a dog’s kennel. Simon and Kasei, oppressed by the tension, suited up and went out to scout what lay ahead.

Beyond what they called Island Ridge, Coprates opened up like a funnel, with deep troughs under the diverging canyon walls. The northern trough was Capri Chasma, the southern trough was Eos Chasma, which ran on as a continuation of Coprates; because of the flood they had no choice but to follow Eos, but Michel said it was the way they would have wanted anyway. Here the southern cliff finally lowered a bit, and was cut with deep embayments, and shattered by a couple of good-sized meteor craters. Capri Chasma curved out of their sight to the northeast; between the two trough canyons was a low triangular mesa, now a peninsula dividing the course of the flood in two. Unfortunately the great bulk of the water ran into the somewhat lower Eos, so that even though they were out of the tight constriction of Coprates, they were still pressed against a cliff, and moving slowly, off any road or trail, and with diminishing supplies of food and gases. The cupboards were nearly bare.

And they were tired, very tired. It had been twenty-three days since they had escaped from Cairo, now 2500 kilometers upcanyon; and all that time they had been sleeping in shifts, and driving almost constantly, and living in the aural assault of the flood, the roar of a world falling down in pieces on their heads. They were too old for this, as Maya said more than once, and nerves were frayed; they were fudging things, making little mistakes, falling into little microbursts of sleep.

The bench that was their road between cliff and flood became an immense boulder field, the boulders mostly ejecta from nearby craters, or detritus from really extensive mass wasting. It looked to Ann like the big fluted and scalloped embayments in the southern cliff were sappings that would initiate tributary subsidence canyons; but she didn’t have the time to look very closely. Often it seemed that they were going to have their way blocked entirely by boulders, that after all these days and kilometers, after negotiating most of Marineris in the midst of a most violent cataclysm, they were going to be halted just short of the tremendous washes leading out of its lower end.

But then they found a way; and were stopped; and found a way; and were stopped; and found a way; and so on, for day after day after day. They went to half rations. Ann drove more than anyone else, as she seemed to be fresher than the rest, and was the best driver there anyway with the possible exception of Michel. And she felt she owed it to them after her shameful collapse during the greater part of their journey. She wanted to do everything she could, and when she wasn’t driving, she went out to scout the way. It was still numbingly loud outside, and the ground trembled underfoot. It was impossible to get used to that, though she did her best to ignore it. Sunlight burned through the mist and haze in broad lurid splashes, and in the sunset hour icebows and sundogs appeared in the sky, along with rings of light around the dulled sun; often the whole sky seemed afire, a Turner vision of the apocalypse.

Soon enough Ann too wore down, and the work became exhausting. She understood now why her companions had been so tired, why they had been so short with her and with each other. Michel had been unable to locate the last three caches they had passed; buried or drowned, it didn’t matter. The half rations were 1200 calories a day, much less than they were expending. Lack of food, lack of sleep: and then, for Ann at least, the same old depression, persistent as death, rising in her like a flood, like a black slurry of mud, steam, ice, shit. Doggedly she kept at the work, but her attention kept blinking out and the glossolalia kept returning, washing everything away in the white noise of despair.

The way got harder. One day they made only a kilometer. The following day they seemed completely stopped, the boulders arrayed across the bench like tankstoppers in Big Man’s Maginot Line. It was a perfect fractal plane, Sax remarked, of about 2.7 dimensions. No one bothered to answer him.

Kasei, wandering on foot, found a passage right down on the bank of the flood. For the moment the whole visible expanse of the deluge was frozen, as it had been for the last couple of days. It stretched out to the horizon, a jumbled surface like Earth’s Arctic Sea, only much dirtier, a great mix of black and red and white lumps. The ice just offshore was flat, however, and in many places clear. They could look down into it, and see that it appeared to be only a couple meters deep, and frozen right down to the bottom. So they drove down to this icy shore and ran along it, and when rocks in the way forced her to, Ann put the left wheels of the rover out onto the ice, and then the entire car; and it held like any other surface. Nadia and Maya snorted at the others’ nervousness about this course: “We spent all winter driving on the rivers in Siberia,” Nadia said. “They were the best roads we had.”

So for an entire day Ann drove along the ragged edge of the flood, and out onto its surface, and they made a hundred and sixty kilometers, their best day in two weeks.

Near sunset it began to snow. The west wind poured out of Coprates, driving big gritty clumps of snow past them as if they weren’t moving at all. They came to a fresh slide zone, which spilled right out onto the ice of the flood. Big boulders scattered over the ice gave it the air of an abandoned neighborhood, old houses half demolished. The light was dusky gray. They needed a foot guide through this maze, and in an exhausted conference Frank volunteered, and went out to do the job. At this point he was the only one of them with any strength left, more even than the younger Kasei; still burning with the force of his anger, a breeder fuel that would never give out.

Slowly he walked ahead of the car, testing routes and returning, either shaking his head or waving Ann on. Around them thin veils of frost steam lofted into the falling snow, the two mixing and gusting off together on the powerful evening wind, off into the murk. Watching the dark spectacle of one hard gust, Ann misread the configuration of the ice’s meeting with the ground, which was hard to see in any case; and the rover ran up onto a round rock right at the frozen shoreline, lifting the left rear wheel off the ground. Ann gunned the front wheels to roll them over the rock, but they dug into a patch of sand and snow, and suddenly both rear wheels were barely touching the ground, while the front two merely spun in the holes they had dug. She had run the rover aground.

It had happened before several times, but she was annoyed with herself for getting distracted by the irrelevant spectacle of the sky.

“What the fuck are you doing?” Frank shouted over the intercom. Ann jumped in her chair; she would never get used to Frank’s biting vehemence. “Get going!” he shouted.

“I ran it onto a rock,” she said.

“Damn you! Why don’t you watch where you’re going! Here, stop the wheels, stop them! I’m gonna put the grip cloths under the front wheels and lever you forward, and then you get it off this rock and up the slope as quick as you can, understand? There’s another surge coming!”