It was a rough mass of gravel and sand, liberally sprinkled with boulders. There was, however, a zone corresponding to the bench below it, which was relatively level. This zone was the only thing that made passage possible; it was a matter of finding an unobstructed way over a surface like poorly mixed cement, around boulders and past the occasional gaping hole. Michel drove the lead car boldly, with a stubborness verging on the reckless. “Desperate measures,” he declared cheerily. “Can you imagine getting on this kind of ground in the normal course of things? It would be insane.”

“It’s insane now,” Nadia said sourly.

“Well, what can we do? We can’t go back, and we can’t give up. These are the times that try men’s souls.”

“Women, however, do fine.”

“I was quoting. You know what I mean. There’s simply no possibility of going back. The head of Ius will be flooded wall to wall. I suppose it’s this that makes me somehow happy. Have we ever been so free of choices? The past is wiped out, all that matters is now. The present and the future. And the future is this field of stones, and here we are. And, you know, you never really summon all of your strength until you know that there’s no way back, no way to go but onward.”

And so onward they went. But Michel’s sanguinity was sharply reduced when the second car collapsed into a hole that had been concealed by a kind of trapdoor arrangement of boulders. With some work they were able to open the front lock and pull out Kasei, Maya, Frank and Nadia. But there was no chance whatsoever of freeing the second car, they didn’t have the lift or the leverage. So they transferred all the supplies out of it, until the lead car was absolutely stuffed. And they moved on, eight of them and their supplies, all now in a single car.

Beyond the landslide, however, it got easier. They followed the canyon highway down into Melas Chasma, and found that the road had been built close to the south wall, and as Melas was so broad canyon, the flood had had room to spread out, and had bowed off some ways to the north. It still sounded like air miners were running at full capacity right outside their lock, but the road was well above and to the south of the flood, which was releasing veils of frost steam that filled the chasm, and obscured any views farther north.

So they proceeded without difficulty for a couple of nights, until they came to the Geneva Spur, which stuck out from the gigantic south wall nearly to the edge of the flood. Here the official road had swung out into what was now the course of the deluge, and they had to find a higher route. The rocky traverses they made around the lower slopes of the Spur were really difficult for the rover. Once they were nearly hung up on an obtruding rounded rock, and Maya shouted at Michel, accusing him of recklessness. She took over the driving while Michel and Kasei and Nadia went out in walkers. They jacked them off the rock, and then walked ahead to reconnoiter the route of the traverse.

Frank and Simon helped Maya look for obstructions as she drove. Sax continued to spend all his time at his screen. From time to time Frank would turn on the TV and run a search for signals, trying to piece together news from the occasional staticky voices the radio found in the jamming. On the very spine of the Geneva Spur, as they were crossing the absurdly thin concrete thread of the Transcanyon Highway, they were far enough out from the south wall to briefly get some transmissions; something about it not becoming a global dust storm after all. And indeed the days were sometimes only hazy, rather than clotted with the dust. Sax claimed this as proof of the relative success of the dust-fixing strategies pursued since the Great Storm. No one responded to this. The haze that was in the air, Frank observed, seemed actually to help clarify weak radio signals. That was stochastic resonance, Sax said. The phenomenon was counter-intuitive, and Frank questioned Sax closely for an explanation of it. When he understood, the room rang with his mirthless bray: “Maybe all the emigration was stochastic resonance, enhancing the weak signal of the revolution.”

“I don’t think it helps to make analogies between the physical and social worlds,” Sax said primly.

“Shut up, Sax. Go back to your virtual reality.”

Frank was still angry, still filled with bitter bile; it sublimed from him like the frost steam off the flood. He snapped questions at Michel about the hidden colony, his curiosity bursting out two or three times a day. Ann was happy to think she would not be Hiroko when Frank first met her. Michel answered these accusing questions calmly, ignoring the sarcasm and the furious gleam in Frank’s eye. Maya’s attempts to cool Frank only increased his rage, but she kept at it; Ann was impressed at how persistent she was, how insensitive to Frank’s brusque rejections. It was a side of Maya that Ann had never seen before; Maya was usually the most volatile person around. But not now, not when the pressure was really on.

Eventually they rounded the Geneva Spur, and got back on the bench under the southern escarpment. The way east was often interrupted by landslides, but they always had room to veer left around them. Progress was good.

But then they came to the eastern end of Melas. Here the greatest chasm of them all narrowed, and dropped several hundred meters down into the two parallel canyons of Coprates, which were separated by a long narrow plateau. South Coprates dead-ended in a cliffy headwall some two hundred and fifty kilometers away; North Coprates connected with the lower canyons farther east, and therefore was the one they wanted to take. North Coprates was the longest single segment of the Marineris system; Michel called it La Manche, and it, like the English Channel, narrowed as it progressed eastward, until at around 60° longitude it narrowed and reared into a gigantic gorge: sheer cliffs four kilometers high, facing each other across a gap only twenty-five kilometers across. Michel called this gorge the Dover Gate; apparently the cliff walls in this gap were whitish, or had been.

So they made their way down North Coprates, and the cliffs closed in on them more every day. The flood filled almost the whole width of the canyon floor, and its flow was so rapid that the ice on its surface had broken into small bergs, which flew off the lips of standing waves and crashed back into the cascade: a furious whitewater rapid with the flow of a hundred Amazons, topped by icebergs. The canyon floor was being ripped away, torn free of its bed and rushing down in red jolts of water like massive pulses of rusty blood, as if the planet were bleeding to death. The noise was incredible, a roar so continuous and pervasive that it dulled thought, and made talk almost impossible; they had to shout everything at the top of their lungs, which quickly reduced them to communicating only the basic necessities.

But then there was a very basic necessity to shout about, for when they came to the Dover Gate they found that the canyon floor was almost completely covered by the flood; their bench below the southern wall of the gorge was no more than two kilometers wide, and dimishing every minute. It seemed possible the whole bench might be torn away in a flash. Maya cried that it was too dangerous to go on, and argued for a retreat. If they circled around and drove up to the dead end of south Coprates, she shouted, and managed to climb to the plateau above, then they could drive past the pits of Coprates Catena, and proceed onward to Aureum.

Michel shouted his insistence that they press forward, and get through the Gate on the bench. “If we hurry we can make it! We must try!” And when Maya continued to protest, he added forcefully: “The head of south Coprates is steep! The car would never get up it, it’s a cliff like these! And we don’t have the supplies to add so many extra days to our trip! We can’t go back!”