She shuddered. "It is a thing of the Lost."

Yes. There is a great beast, like a beetle, which tends it. The beast wipes away the dust on the floor. My brother challenged the beetle. It turned away.

"Your brother defeated it?"

My brother is brave and strong. But not so brave as me. And he is smaller than me in many ways. Much smaller. For example, his —

"I can guess," Icebones said dryly. She told him she had decided to head for the basin she had called the Footfall of Kilukpuk. "But we face many obstacles." And she told him about the Gouge, and tried to tell him of the mammoths’ confusion and dissent.

You think you have problems, he called back. Imagine how it is for me. All the time I slip up in my own musth dribble, and I trip over my long, erect —

"You cannot still be in musth."

Wait until we meet at the Footfall. You will see my musth flow, and you will be awed at its mighty gush. Are you in oestrus yet?

"No," Icebones said, with a shiver of sadness.

Good, came Boaster’s voice, deep-whispering through the rock. It would be a waste. Wait until we meet at the Footfall. I must go. We have found a dwarf willow and the others are stripping it like wolf cubs, leaving none for me. Be brave, little Icebones. We will meet at the Footfall. Goodbye, goodbye…

Icebones stood alone in the chill, bloody light of dawn, listening to the last of his words wash through the rock.

The Ragged One stepped onto the smooth slope of the bridge. She stamped hard on the cold surface, as if testing it under her weight.

The bridge rang hollowly.

More tentatively Shoot followed, and then, at last, Spiral.

Autumn growled, her voice filled with sadness as she watched her daughters walk out into emptiness.

"This is wrong," Icebones said. "Wrong, wrong. Mammoths are creatures of the steppe, and the open sky. They are not meant to hover like birds high above the ground."

But none of the three rebels was listening.

Soon the mammoths had gone so far that they looked like beetles, crawling over the mighty band of the bridge. The sun was still low in the sky, and the three toiling mammoths cast long shadows across the bridge’s smooth, pink-lit surface.

Icebones could hear the deep thrumming vibrations of the bridge as it bent and bowed in response to the mammoths’ weight.

The Ragged One turned. She trumpeted, her voice dwarfed by the Gouge beneath her. "You are wrong, all of you. The bridge will protect us. See?" And she raised her foot -

Icebones trumpeted, "No!"

— and the Ragged One began to stamp, hard, at the shining surface of the bridge.

Icebones heard the cracking long before she could see it. It sounded like pack ice over a swelling sea, or a fragment of bone beneath a clumsy mammoth foot pad.

A spiderweb of cracks spread over the pale pink surface. The whole bridge was quivering, and already slivers of it were crumbling off its edges and falling, to be lost far below.

Autumn trumpeted, an ancient, wordless cry, and she ran forward to the edge of the bridge.

Shoot turned back and faced her sister. "Go back! We must go back!"

But Spiral, last in line, would not move. She stood on the trembling bridge, feet splayed and trunk dipped, as if frozen in place.

"She is terrified," Breeze said. "And if she does not move, the others cannot."

Thunder tossed his head skittishly. "I will go out there. I will save them." But there was terror in the white rims of his eyes.

"Your place is here," Icebones said firmly. "You must protect these others, and the calf. That is your duty now."

He tried to hide his relief. "Yes," he said. "That is my duty."

And my duty, Icebones thought, is to bring the others back — or die trying.

Without thinking about it she stepped onto the cold surface of the bridge. She could feel the deep, dismal resonance of the bridge as it shuddered and shook. The frequent cracks were sharp detonations, carrying clearly to her ears and belly.

She stepped forward gingerly.

Autumn growled, but did not try to stop her.

Soon Icebones had passed beyond the edge of the land, and she could look down into the depths of the Gouge. The rising sun cast deep pink shadows from the layers of cloud, obscuring the brown-gray ground far beneath. She was standing above the clouds, she thought, and all that kept her from that immense drop was the fragile thinness of the bridge; her stomach clenched, tight as the jaws of a cat.

At last she reached Spiral. Icebones tugged at her tail until she yelped.

"You must turn around. We have to go back."

"I can’t," Spiral said, whimpering. The Cow stood rooted as solid as a tree to the thin bridge floor.

Shoot picked her way back along the shuddering bridge. She slapped Spiral’s head with her trunk, and even clattered her tusks against her sister’s.

At last, under this double assault, Spiral, moaning softly, began to turn. Each footfall was as tentative and nervous as a newborn calf’s. Step by step, Icebones led Spiral back toward the cliff top.

They had almost reached the hard, secure rock when there was a harsh trumpet.

Autumn called, "Shoot!"

A section of the shuddering bridge had crumbled and fallen away. Icebones could see bits of it falling through the air, sparkling as they spun, diminishing to snowflakes.

And there was nothing beneath Shoot’s hind feet.

Shoot fell back, oddly slowly. For a heartbeat she clung to the broken edge of the bridge with her forelegs, and she scrabbled with her trunk. Then she slid back, as smoothly as a drop of water sliding off the tip of a tusk. She wailed, once.

Icebones glimpsed her sprawled in the air, almost absurdly, limbs and trunk and tusks flapping like the wings of a clumsy, misshapen bird. Her fall was agonizingly slow, slow enough for Icebones to hear every whimper and cry, even to smell the urine that gushed into the air around Shoot’s legs.

Then she was lost in cloud, and Icebones was grateful.

She heard the trumpeting cry of Spiral, and Autumn’s answering wail.

Icebones inspected the crack. It was wide, and getting wider as more chunks of bridge structure fell away like sharp-edged snowflakes.

The Ragged One stood on the far side of the crack, backing away slowly. The damaged bridge was like a great tongue lolling from the remote far side of the Gouge. But as the bridge swung up and down beneath her the Ragged One kept her footing easily.

"You cannot return," Icebones called.

"I do not choose to return."

"You will be alone."

The Ragged One snorted, and stepped back again as more of the bridge fell away. "I have always been alone. Don’t you know that yet?"

"We will meet at the Footfall."

"Perhaps." And the Ragged One turned away.

Icebones watched her recede. For all the tragedy and renewed danger her shrunken band would face from now on, a secret part of her was glad that the Ragged One was gone — at least for now.

The bridge trembled and cracked further.

Autumn was still trumpeting, her voice thin and sharp. "The morning is barely begun. But already my daughter is dead. How can this be?"

The sun rose higher, shining brighter as the blue morning clouds dispersed.