The rover rolled up the last concentric terraces of lava, working less strenuously now as it curved over the asymptotic flattening of the broad circular rim. Only slightly uphill, and less so every meter; and then onto the rim itself. Then to the inner edge of the rim.
Overlooking the caldera. She got out of the car, her thoughts flicking about like skuas.
Ascraeus’s nested caldera complex consisted of eight overlapping craters, the newer ones collapsing down across the circumferences of the older ones. The largest and youngest caldera lay out near the center of the complex, and the older higher-floored calderas embayed its circumference like the petals of a flower design. Each caldera floor was at a slightly different elevation, and marked by a pattern of circular fractures. Walking along the rim changed perspective so that distances shifted, and the floors’ heights seemed to change, as if they were floating in a dream. Taken all in all, a beautiful thing to witness. And eighty kilometers across.
Like a lesson in volcano throat mechanics. Eruptions down on the outer flanks of the volcano had emptied the magma from the active throat of the caldera, and so the caldera floor had slumped; thus all the circular shapes, as the active throat moved around over the eons. Arcing cliffs: few places on Mars exhibited such vertical slopes, they were almost true verticals. Basalt ring worlds. It should have been a climbers’ mecca, but as far as she knew it was not. Someday they would come.
The complexity of Ascraeus was so unlike the single great hole of Pavonis. Why had Pavonis’s caldera collapsed in the same circumference every time? Could its last drop have erased and leveled all the other rings? Had its magma chamber been smaller, or vented to the sides less? Had Ascraeus’s throat wandered more? She picked up loose rocks on the rim’s edge, stared at them. Lava bombs, late meteor ejecta, ventifacts in the ceaseless winds… These were all questions that could still be studied. Nothing they did would ever disturb the vulcanology up here, not enough to impede the study. Indeed the Journal ofAreological Studies published many articles on these topics, as she had seen and still occasionally saw. It was as Michel had said to her; the high places would look like this forever. Climbing the great slopes would be like travel into the prehuman past, into pure areology, into the areophany itself perhaps, with Hi-roko or not. With the lichen or not. People had talked of securing a dome or a tent over these calderas, to keep them completely sterile; but that would only make them zoos, wilderness parks, garden spaces with their walls and their roofs. Empty greenhouses. No. She straightened up, looked out over the vast round landscape, held up and offering itself to space. To the chasmoendolithic life that might be struggling up here, she waved a hand. Live, thing. She said the word and it sounded odd: “Live.”
Mars forever, stony in the sunlight. But then she glimpsed the white bear in the corner of her eye, slipping behind a jagged rim boulder. She jumped; nothing there. She returned to the rover, feeling that she needed its protection. She climbed inside; but then all afternoon on the screen of the rover’s AI, the vague spectacled eyes seemed to be looking out at her, about to call any second. A kind bear of a man, though he would eat her if he could catch her. If he could catch her — but then none of them could catch her, she could hide in these high rock fastnesses forever — free she was and free she would be, to be or not to be if she chose that, for as long as this rock held. But there again, right at the lock door, that white flash in the corner of her eye. Ah so hard.
PART SEVEN
Making Things Work
An ice-choked sea now covered much of the north. Vastitas Borealis had lain a kilometer or two below the datum, in some places three; now with sea level stabilizing at the minus-one contour, most of it was underwater. If an ocean of similar shape had existed on Earth, it would have been a bigger Arctic Ocean, covering most of Russia, Canada, Alaska, Greenland, and Scandinavia, and then making two deeper incursions farther south, narrow seas that extended all the way to the equator; on Earth these would have made for a narrow North Atlantic, and a North Pacific occupied in its center by a big squarish island.
This Oceanus Borealis was dotted by several large icy islands, and a long low peninsula that broke its circumnavigation of the globe, connecting the mainland north ofSyrtis with the tail of a polar island. The north pole was actually on the ice ofOlympia Gulf, some kilometers offshore from this polar island.
And that was it. On Mars there would be no equivalent of the South Pacific or the South Atlantic, or the Indian Ocean, or the Antarctic Ocean. In its south there was only desert, except for the Hellas Sea, a circular body of water about the size of the Caribbean. So while ocean covered seventy percent of the Earth, it covered about twenty-five percent of Mars.
In the year 2130, most of Oceanus Borealis was covered by ice. There were large pods of liquid water under the surface, however, and in the summer, melt lakes scattered on top of the surface; there were also many polynyaps, leads and cracks. Because most of the water had been pumped or otherwise driven out of the permafrost, it had deep groundwater’s purity, meaning it was nearly distilled: the Borealis was a freshwater ocean. It was expected to become salty fairly soon, however, as rivers ran through the very salty regolith and carried their loads into the sea, then evaporated, precipitated, and repeated the process — moving salts from the regolith into the water until a balance was reached — a process which had the oceanographers transfixed with interest, for the saltiness of Earth’s oceans, stable for many millions of years, was not well understood.
The coastlines were wild. The polar island, formally nameless, was called variously the polar peninsula, or the polar island, or the Seahorse, for its shape on maps. In actuality its coastline was still overrun in many places by the ice of the old polar cap, and everywhere it was blanketed by snow, blown into patterns of giant sastrugi. This corrugated white surface extended out over the sea for many kilometers, until underwater currents fractured it and one came on a “coastline” of leads and pressure ridges and the chaotic edges of big tabular bergs, as well as larger and larger stretches of open water. Several large volcanic or meteoric islands rose up out of the shatter of this ice coast, including a few pedestal craters, sticking up out of the whiteness like great black tabular bergs.
The southern shores of the Borealis were much more exposed and various. Where the ice lapped against the foot of the Great Escarpment there were several mensae and colles regions that had become offshore archipelagoes, and these, as well as the mainland coastline proper, sported many beetling sea cliffs, bluffs, crater bays, fossa fjords, and long stretches of low smooth strand. The water in the two big southern gulfs was extensively melted below the surface, and, in the summers, on the surface as well. Chryse Gulf had perhaps the most dramatic coastline of alclass="underline" eight big outbreak channels dropping into Chryse had partly filled with ice, and as it melted they were becoming steep-sided fjords. At the southern end of the gulf four of these fjords braided, weaving together several big cliff-walled islands to make the most spectacular seascapes of all.
Over all this water great flocks of birds flew daily. Clouds bloomed in the air and rushed off on the wind, dappling the white and red with their shadows. Icebergs floated across the melted seas, and crashed against the shore. Storms dropped off the Great Escarpment with terrifying force, dashing hail and lightning onto the rock. There were now approximately forty thousand kilometers of coastline on Mars. And in the rapid freeze and thaw of the days and the seasons, under the brush of the constant wind every part of it was coming alive.