The Plains of Passage - Jean M. Auel [489]
She added alfalfa and clover to her diet, and welcomed the starchy, slightly sweet groundnuts, finding the roots by tracing rambling surface vines. Milk-vetch pods were swelling with rows of oval green vegetables in addition to edible roots, and she had no trouble distinguishing between them and their poisonous cousins. When the season for the buds of day lilies passed, the roots were still tender. A few early-ripening varieties of low-crawling currants had begun to turn color, and there were always a few new leaves of pigweed, mustard, or nettles for greens.
Her sling did not lack for targets. Steppe pikas, souslik marmots, great jerboas, varying hares—gray brown now instead of winter white—and an occasional, omnivorous, mouse-hunting giant hamster abounded on the plains. Low-flying willow grouse and ptarmigan were a special treat, though Ayla could never eat ptarmigan without remembering that the fat birds with the feathered feet had always been Creb’s favorite.
But those were only the smaller creatures feasting on the plain’s summer bounty. She saw herds of deer—reindeer, red deer, and enormous antlered giant deer; compact steppe horses, asses, and onagers, which resembled both; huge bison or a family of saiga antelope occasionally crossed her path. The herd of reddish brown wild cattle, with bulls six feet at the withers, had spring calves nursing at the ample udders of cows. Ayla’s mouth watered for the taste of milk-fed veal, but her sling was not an adequate weapon to hunt aurochs. She glimpsed migrating woolly mammoths, saw musk oxen in a phalanx with their young at their backs facing down a pack of wolves, and carefully avoided a family of evil-tempered woolly rhinoceroses. Broud’s totem, she recalled, and suitable, too.
As she continued northward, the young woman began to notice a change in the terrain. It was becoming drier and more desolate. She had reached the ill-defined northern limit of the wet, snowy continental steppes. Beyond, all the way to the sheer walls of the immense northern glacier, lay the arid loess steppes, an environment that existed only when glaciers were on the land, during the Ice Age.
Glaciers, massive frozen sheets of ice that spanned the continent, mantled the Northern Hemisphere. Nearly a quarter of the earth’s surface was buried under their unmeasurable crushing tons. The water locked within their confines caused the level of the oceans to drop, extending the coastlines and changing the shape of the land. No portion of the globe was exempt from their influence, rains flooded equatorial regions and deserts shrunk, but near the borders of the ice the effect was profound.
The vast ice field chilled the air above it, causing moisture in the atmosphere to condense and fall as snow. But nearer the center high pressure stabilized, creating extreme dry cold and pushing the snowfall out toward the edges. The huge glaciers grew at their margins; the ice was nearly uniform across its full sweeping dimensions, a sheet of ice more than a mile thick.
With most of the snow falling on the ice and nourishing the glacier, the land just south of it was dry—and frozen. The constant high pressure over the center caused an atmospheric chute funneling the cold dry air toward lower pressures; wind, blowing from the north, never stopped on the steppes. It only varied in intensity. Along the way it picked up rock that had been pulverized to flour at the shifting border of the grinding glacier. The airborne particles were sifted to a texture only slightly coarser than clay—loess—and deposited over hundreds of miles to depths of many feet, and became soil.
In winter, howling winds whipped the scant snowfall across the bleak frozen land. But the earth still spun on its tilted axis, and seasons still changed. Average yearly temperatures only a few degrees lower trigger the formation of a glacier; a few hot days have little effect if they don’t alter the average.
In spring the meager snow that fell on the land melted, and the crust of the