Tura and her brother hatched the plan between them. They would never get this chance again; the greening would be gone in a year, perhaps never to return in their lifetimes. No adult would ever have approved. But no adult need know.
And so, very early one morning, they slipped away from the village. Wearing nothing but kilts woven from dried sea grass, their favourite shell necklaces around their necks, they looked very alike. As they ran they laughed, excited by their adventure, and their blue eyes shone against the rusted crimson of the landscape.
Bel and Tura lived on what had once been the western coast of North America – but, just as in Urlu’s dark time of global catastrophe, it didn’t really matter where you lived. For this was the age of a supercontinent.
The slow convergence of the continents had ultimately produced a unity that mirrored a much earlier mammoth assemblage, broken up before the dinosaurs evolved. While vast unending storms roamed the waters of the world-ocean, New Pangaea’s interior collapsed to a desiccated wasteland, and people drifted to the mouths of the great rivers, and to the sea coasts. This grand coalescence had been accompanied by the solemn drumbeat of extinction events; each time the world recovered, though each time a little less vigorously than before.
The supercontinent’s annealing took two hundred million years. And, since then, another two hundred million years had already gone by. But people lived much as they always had.
Tura and Bel, eleven-year-old twins, knew nothing of this. They were young, and so was their world; it was ever thus. And today, especially, was a day of wonder, as all around them plants, gobbling carbon dioxide, fired packets of spores through the air, and insects scrambled in once-in-a-lifetime quests to propagate.
As the sun climbed the children tired, their pace falling, and the arid air sucked the sweat off their bodies. But at last the mountains came looming out of the dusty air. These worn hills were ancient, a relic of the formation of New Pangaea. But to Tura and Bel, standing before their scree-covered lower slopes, they were formidable heights indeed.
Then Tura saw a splash of green and brown, high on a slope. Curiosity sparked. Without thinking about it she began to climb. Bel, always more nervous, would not follow.
Though at first the slope was so gentle it was no more than a walk, Tura was soon higher than she had ever been in her life. On she climbed, until her walk gave way to an instinctive scramble on all fours. Her heart hammering, she kept on. All around her New Pangaea unfolded, a sea of Mars-red dust worn flat by time.
At last she reached the green. It was a clump of trees, shadowed by the mountain from the dust-laden winds and nourished by water from subsurface aquifers. Instinctively Tura rubbed her hand over smooth, sturdy trunks. She had never seen trees before.
As the sun brightened, Earth’s systems compensated by drawing down carbon dioxide from the air. But this was a process with a limit: even in Jaal’s time the remnant carbon dioxide had been a trace. Already the planet had shed many rich ecosystems – tundra, forests, grasslands, meadows, mangrove swamps. Soon the carbon dioxide concentration would drop below a certain critical level after which only a fraction of plants, with a certain kind of metabolism, would be able to photosynthesise. The rest would die off. And the human population, already only a million strung out around the world’s single coastline, would implode to perhaps ten thousand.
People would survive. They always had. But these trees, in whose cool shade Tura stood, were among the last in the world.
She peered up at branches with sparse crowns of spiky leaves, far above her head. There might be fruit up there, or water to be had in the leaves. But it was impossible; she could not climb past the smoothness of the lower trunk.
When she looked down Bel’s upturned face was a white dot. The day was advancing; as the sun rode higher the going across the dry dust would be even more difficult. With regret she began her scrambled descent to the ground.
As she lived out her life on the coast of Pangaea, Tura never forgot her brief adventure. And when she thought of the trees she might have climbed her hands and feet itched, her body recalling ape dreams abandoned half a billion years before.
V
Ruul was bored.
All through the echoing caverns the party was in full swing. By the light of their hearths and rush torches people played and danced, talked and laughed, drank and fought, and the much-evolved descendants of snakes and wasps curled affectionately around the ankles of their owners. It was a Thousand-Day festival. In a world forever cut off from the daylight, subterranean humans pale as worms marked time by how they slept and woke, and counted off the days of their lives on their fingers.
Everyone was having fun – everyone but Ruul. When his mother was too busy to notice, he crept away into the dark.
Some time ago, restlessly exploring the edge of the inhabited cave, where tunnels and boreholes stretched on into the dark, he had found a chimney, a crack in the limestone. It looked as if you could climb up quite a way. And when he shielded his eyes, it looked to him as if there was light up there, light of a strange ruddy hue. There might be another group somewhere in the caverns above, he thought. Or it might be something stranger yet, something beyond his imagination.
Now, in the dim light of the torches, he explored the chimney wall. And, lodging his fingers and toes in crevices, he began to climb.
He was escaping the party. Eleven years old, neither child nor adult, he just didn’t fit, and he petulantly wished the festival would go away. But as he ascended into profound silence the climb itself consumed all his attention, and the why of it faded from his mind.
His people, cavern-bound for uncounted generations, were good at rock-climbing. They lived in caverns in deep limestone karsts, laid down in long-vanished shallow seas. Once these hollows had hosted ecosystems full of the much-evolved descendants of lizards, snakes, scorpions, cockroaches, even sharks and crocodiles. The extreme and unchanging conditions of Pangaea had encouraged intricacy and interdependency. The people, retreating underground, had allowed fragments of these extraordinary biotas to survive.
Soon Ruul climbed up out of the limestone into a softer sandstone, poorly cemented. It was easier to find crevices here. The crimson light from above was bright enough to show him details of the rock through which he was passing. There was layer upon layer of it, he saw, and it had a repetitive pattern, streaks of darkness punctuated by lumpy nodules. When he touched one of the nodules, he found a blade surface so sharp he might have cut his fingers. It was a stone axe – made, used, and dropped long ago, and buried somehow in the sediments that had made this sandstone. Growing more curious he explored the dark traces. They crumbled when he dug into them with a fingernail, and he could smell ash, as fresh as if a fire had just burned here. The dark layers were hearths.
He was climbing through strata of hearths and stone tools, thousands of layers all heaped up on top of one another and squashed down into the rock. People must have lived in this place a very long time. He was oppressed by a huge weight of time, and of changelessness.
But he was distracted by a set of teeth he found, small, triangular, razor-edged. They had holes drilled in them. He carefully prised these out of the rock and put them in a pouch; perhaps he would make a necklace of them later.
With aching fingertips and toes, he continued his climb.
Unexpectedly, he reached the top of the chimney. It opened out into a wider space, a cave perhaps, filled with that ruddy light. He hoisted himself up the last short way, swung his legs out onto the floor above, and stood up.