"And that’s where we’re going," said Owlheart firmly. "We’re going beyond the Mountains at the End of the World, where no mammoth has ventured before—"

"And for good reason." Foxeye rocked to and fro, stamping on the hard ground. "Because it’s impossible, no matter what that rogue calf said. If he ever existed. We don’t even know what’s there, land or sea or ice."

For a heartbeat Owlheart’s resolve seemed to waver. She seemed to slump, as if she were aging through decades in an instant.

Silverhair laid her trunk on Foxeye’s head. "Enough," she said gently. "We must follow the Matriarch, Foxeye."

Foxeye subsided. But her unhappiness was obvious.

Owlheart nodded to Silverhair. Her unspoken command was clear: Silverhair was to lead the way.

Heart pumping, Silverhair turned, and stepped onto the ice.

Mammoths do not spend much time on the bare ice, because no food is to be had there; their habitat is the tundra. But Silverhair understood the glacier, from experience and lore.

At first she walked over cracked-off fragments of ice scattered over the rock. But soon, as she worked her way steadily forward, she found herself walking on a continuous sheet of ice. It was hard and cold under the pads of her feet, but she had little difficulty maintaining her footing.

But it was cold. The sun was warm on one side of her body, but the immense mass of ice seemed to suck the heat from the other side of her body and her belly, and she could feel a wide and uncomfortable temperature difference from one side to the other.

She was climbing a steepening blue-white hillside, which rose above her. She enjoyed the crunchy texture of the snow underfoot. Lumps of blue ice pushed out of the snow around her, carved by the wind into fantastic shapes. Here and there, shattered ice lay in fans across the white surface she was climbing. The glacier was a river of ice, seemingly motionless around her, though its downhill flow was obvious nonetheless. Lines of scoured-off rock in the ice surface marked the glacier’s millennial course. The glacier’s shuddering under her feet was continuous, and Silverhair could feel its agonizingly sluggish progress through its valley, and she could hear the low-pitched grind and crack of the compressed ice as it forced its way through the rock, and the high-pitched scream of the rock itself being shattered and torn away.

She came to a place where the thickening ice was split by crevasses. When it flowed out of the mountains onto the tundra the glacier was able to spread out, like a stream splashing over a plain, and so it cracked open. Most of the crevasses followed the line of the glacier as it poured down its gouged-out channel in the rock. But some of them, more treacherous, cut across the line of the flow.

Most of the crevasses were narrow enough to step across. Some were bridged by tongues of ice, but Silverhair tested these carefully before leading the mammoths onto them. If a crevasse was too wide she would lead the mammoths along its length until it was narrow enough to cross in safety.

She looked into one deep crevasse. The walls were sheer blue ice, broken here and there only by a small ledge or a few frost crystals. The crevasse was cluttered by the remains of collapsed snow bridges, but past them she could see its endless deep, the blue of the ice becoming more and more intense until it deepened to indigo and then to darkness.

In some places, where the glacier had lurched downward, there were icefalls: miniature cliffs of ice, like frozen waterfalls. These were difficult to climb, especially where there were crevasses along the icefalls. In other places, where the glacier flowed awkwardly around a rock outcrop, the ice was shattered to blocks and shards by the shear stresses, and was very difficult to cross.

After a time, as the mammoths climbed up from the plain, they encountered fewer crevasses, and the going got easier. In some places the glacier was covered with hard white snow, but in others Silverhair found herself walking on clean blue unbroken ice. The blue ice wasn’t flat, but was dimpled with cups and ridges. There were even frozen ripples here, their edges hard under her feet. It was exactly like walking over the frozen surface of a river.

When she looked back she could see the Family following in a ragged line: Foxeye with her two calves, and Owlheart bringing up the rear. They looked like hairy boulders, uncompromisingly brown against the blinding white of the ice.

She came to a chasm the glacier had cut deep into the mountain’s rock. The mammoths were silent, even the calves, as they threaded through this cold, gloomy passage. Walls of hard blue-black rock towered above Silverhair. She could see scratches etched into the rock, and scattered over the ice were sand, gravel, rocks, even boulders ripped out of place by the scouring ice.

At last the chasm opened out. Silverhair stepped forward cautiously, blinking as she emerged from the shadows.

She was surrounded by mountains.

She was on the lip of a natural bowl in the mountain range, a bowl that brimmed with ice. The mountain peaks, crusted with snow that would never melt, protruded above the ice like the half-buried tusks of some immense giant. The ice was trying to flow down to the plain below, but the mountains got in the way. The glaciers were the places where the ice leaked out. Rings of frozen eddies and ripples, even frozen waves, had formed where the ice pressed against the mountains’ stubborn black rock faces.

The mammoths walked cautiously onto the ice bowl. Nothing moved here but themselves, nothing lay before them but the plain of white ice, black rock, blue sky. But there was noise: the distant cracks and growls and splintering crashes of ice avalanches, as great sheets broke away from the rocky faces all around them, a remote, vast, intimidating clamor. It was a clean, cold, silent place — white, sprinkled with rugged black outcrops, the only smells the sharp tang of ice and the freezing musk of the mammoths themselves.

Silverhair heard her own breathing, and the squeak of the ice as it compressed under her feet. She felt small and insignificant, dwarfed by the majesty of her planet.

Owlheart stood alongside her. She was breathing hard after the climb, and her breath steamed around her face, "Just as the Cycle describes it. From the ice that pools here, the glaciers flow to the tundra."

"And," said Silverhair, "no mammoth has ever gone farther north than this."

"No mammoth before today. Look."

Silverhair followed the Matriarch’s gaze. She saw that on the northern horizon, the mountains were marked by a notch: another valley scoured out by glaciers. And beyond, she could see blue-gray sky.

"That’s our way through," said Owlheart.

Silverhair reached the ravine on the far side of the ice bowl, and found herself standing on the creaking mass of another glacier.

She looked down the way she must climb.

The view was startling. The glacier was a frozen torrent sweeping down its valley, turning around a bluff in the rock before spreading, flattening, and shattering to shards. The rubble lines along the length of the glacier made the flow obvious. They ran in parallel, turning together with each curve of the glacier. They looked like wrinkles in stretched skin.

There were even tributary glaciers running into the main body, like streams joining a river. But where the tributaries merged, the ice had cracked into crevasses or shattered and twisted into fields of chaotic blocks.

Despite its stillness she could see the drama of the great ice river’s gush through the broken mountains, the endless battle between the stubborn rock and irresistible ice. Where the mountains constricted its flow, the ice reared up in great whirlpools of shattered, frozen sheets; and frozen waves lapped at the base of black hills, truncated by millennia of frost-shatter. She heard the roar of massive avalanches, the shriek of splitting rock, the groan of the shifting ice, and the sullen voice of the wind as it moaned through the valleys.