Half a day's travel beyond, they reached another large tributary whose roiling confluence, tumbling down from higher ground, looked formidable, with icicles extended into frozen curtains and mounds of broken ice lining both banks. No longer were the rivers joining on the north coming from the uplands and foothills of the familiar mountains they were leaving behind. This water came from the unfamiliar terrain to the west. Rather than cross the perilous river, or attempt to follow it upstream, Jondalar decided to backtrack and cross the several branches of the Mother instead.

It turned out to be a good choice. Though some of the channels were wide and choked with ice along the edges, for the most part the frigid water barely reached as high as the horses' flanks. They didn't think much about it until later that evening, but Ayla and Jondalar, the two horses, and the wolf had finally crossed the Great Mother River. After their dangerous and traumatic adventures on other rivers, they accomplished it with so little incident that it seemed an anticlimax, but they were not sorry.

In the deep cold of winter, simply traveling was dangerous enough. Most people were snugly settled in warm lodges, and friends and kin would come looking if anyone was outside for too long. Ayla and Jondalar were entirely on their own. If anything happened, they had only each other, and their animal companions, to depend on.

The land gradually sloped upward, and they began to notice a subtle shift in the vegetation. Fir and larch appeared among the spruce and pine near the river. The temperature on the plains of the river valleys was extremely cold; due to atmospheric inversions, often colder than it was higher in the surrounding mountains. Although snow and ice whitened the highlands that flanked them, snow seldom fell on the river valley. The few light, dry siftings that did produced little buildup on the frozen ground, except in hollows and depressions, and sometimes not even there. When snow was lacking, the only way they could get drinking water for themselves and the animals was to use their stone axes to chop ice from the frozen river and then melt it.

It made Ayla more aware of the animals that roamed the plains along the valley of the Mother. They were the same varieties as those they had seen on the steppes all along the way, but the cold-loving creatures predominated. She knew these animals could subsist on the dry vegetation that was easily available on the subfreezing but essentially snow-less plains, but she wondered how they found water.

She thought that wolves and other carnivores probably derived some of their liquid requirement from the blood of those they hunted for food, and they ranged over a large territory and could find pockets of snow or loose ice to chew. But what about horses and the other grazing and browsing animals? How did they find water in a land that in winter was a frozen desert? There was enough snow in some areas, but others were barren regions of rock and ice. Yet no matter how dry, if there was some kind of fodder, it was inhabited by animals.

Although still rare, Ayla saw more woolly rhinoceroses than she had ever seen in one place, and though they didn't herd together, whenever she saw rhinos, they often saw musk-oxen, too. Both species preferred the open, windy, dry land, but the rhinos liked grass and sedge, and musk-oxen, true to the goatlike creatures they were, browsed on woodier brush. Large reindeer and the gigantic megaceroses with massive antlers also shared the frozen land, and horses with thick winter coats, but if there was one animal that stood out among the populations in the valley of the upper course of the Great Mother River, it was mammoths.

Ayla never grew tired of watching the huge beasts. Though they were occasionally hunted, they were so unafraid that they seemed almost tame. They often allowed the woman and man to come quite close, sensing no danger from them. The danger was, if anything, to the humans. Though woolly mammoths were not the most gigantic examples of their species, they were the most gigantic animals the humans had ever seen – or that most people were ever likely to see – and with their shaggy coats even more filled out for winter, and their immense curved tusks, they looked bigger, up close, than Ayla remembered.

Their enormous tusks began, in calves, with inch-and-a-half-long tushes, enlarged upper incisors. After a year, the baby tushes were lost and replaced by permanent tusks that grew continually from then on. While the tusks of mammoths were social adornments, important in interactions with their own kind, they also had a more practical function. They were used to break up ice, and the ice-breaking abilities of mammoths were phenomenal.

The first time Ayla observed the practice, she had been watching a herd of females approach the frozen river. Several of them used their tusks, somewhat smaller and straighter than the ivory shafts of males, to tear out ice that was caught in the lee of rock crevices. It puzzled her at first, until she noticed a small one pick up a piece with her little trunk and put it in her mouth.

"Water!" Ayla said. "That's how they get water, Jondalar. I was wondering about that."

"You're right. I never thought much about it before, but now that you mention it, I think Dalanar said something about that. But there are lots of sayings about mammoths. The only one I remember is, 'Never go forth when mammoths go north,' though you could say the same for rhinos."

"I don't understand that saying," Ayla said.

"It means a snowstorm is coming," Jondalar said. "They always seem to know. Those big woollies don't like snow much. It covers up their food. They can use their tusks and their trunks to brush away some, but not when it gets really deep, and they get bogged down in it. It's especially bad when it's thawing and freezing. They lie down at night when it's still slushy from the afternoon sun, and by morning their fur is frozen to the ground. They can't move. They are easy to hunt then, but if there are no hunters around and it doesn't thaw, they can slowly starve. Some have been known to freeze to death, especially little ones."

"What does that have to do with going north?"

"The closer you get to the ice, the less snow there is. Remember how it was when we went hunting mammoths with the Mamutoi? The only water around was the stream coming from the glacier itself, and that was summer. In winter, that's all frozen."

"Is that why there's so little snow around here?"

"Yes, this region is always cold and dry, especially in winter. Everyone says it's because the glaciers are so close. They are on the mountains to the south, and the Great Ice is not very far north. Most of the land in between is flathead… I mean Clan country. It starts a little west of here." Jondalar noticed Ayla's expression at his slip of the tongue, and he felt embarrassed. "Anyway, there's another saying about mammoths and water, but I can't remember exactly how it goes. It's something like, 'If you can't find water, look for a mammoth.'"

"I can understand that saying," Ayla said, looking beyond him. Jondalar turned to see.

The female mammoths had moved upstream and joined forces with a few males. Several females were working on a narrow, almost vertical, bank of ice that had built up along the river's edge. The bigger males, including one dignified elder with streaks of gray hair, whose impressive, if less useful, tusks had grown so long that they were crossed in front, were scraping and gouging out huge chunks of ice from the banks. Then, lifting them high with their trunks, the mammoths threw the ice down with a loud crash to shatter into more usable pieces, all accompanied by bellowings, snortings, stompings, and trumpetings. The huge woolly creatures seemed to be making a game of it.

The noisy business of breaking ice was a practice that all mammoths learned. Even young ones only two or three years old, who had barely lost their baby tushes, showed wear on the outside edges at the ends of their tiny two-inch tusks from scraping ice, and the tips of the twenty-inch prongs of ten-year-olds were worn smooth from moving their heads up and down against the vertical surfaces. By the time the young mammoths reached twenty-five, their tusks were beginning to grow forward, upward, and inward, and the way they used them changed. The lower surfaces began to show some of the wear of scraping ice and brushing aside what snow did fall on the dry grass and plants of the steppes. Ice breaking, though, could be a dangerous business, since tusks often broke along with the ice. But even broken ends were often worn smooth again by later scraping and gouging of ice.