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southern California. However, ''California's climate buffered forests from the
extreme cold that lay over most of North America during the Ice Age and forests
of giant redwoods probably grew along the northern California coast at this time
just as they had done for at least the past 5 million years.''
Bonnicksen (2000) also described the fauna of the Ice Age:
''No single plant or animal symbolizes the Ice Age better than the woolly
mammoth. It evolved in Eurasia and migrated across the Bering land bridge into
North America about one-half million years ago. The smaller and more primitive
mastodon, a forest dweller that lived on shrubs and trees, joins the mammoth as a
symbol of the Ice Age. Coarse golden-brown hair covered the animal, but it was
not as shaggy as the hair of the woolly mammoth. It roamed North America and
parts of South America for several million years before the woolly mammoth
arrived. Woolly mammoths plodded through cold steppes and tundra in the far
north and at the southern edge of the glaciers. They also flourished within the
open spruce and pine forests, and the Columbian and Jefferson mammoths lived
as far south as northern Florida, southern California, and Central America.
Mammoths looked something like a modern elephant. However, instead of
rough gray skin, thick brown hairs covered their entire body, even the trunk.
A 6-inch woolly undercoat provided additional protection from the cold. Their
eyes were like protruding saucers, and their dull white tusks stuck out 12 feet and
curled sharply upward. They swung their tusks back and forth to scrape away
snow so that they could eat the underlying grass much like bison use their noses
for the same purpose. Their ears were small and round, and long hair draped over
their dome-shaped heads like a bad toupee. Wide padded feet designed for snow
or marshy ground supported the 8-ton weight of the shaggy beasts as they
lumbered along in search of food.''
He also described other extinct herbivores, such as shrub-ox, stag-moose,
7-foot-long armadillos, and a beaver the size of a black bear, giant ground sloths
weighing several tons, western camel, horse, and long-legged and short-legged
llamas, a giant condor-like vulture with a 15- to 17-foot wingspan, the dire wolf,
saber-toothed cats, the American lion, and the American cheetah. The most
terrifying extinct carnivore of all was the giant short-faced bear. It stood as high
as a moose and it used its long legs to run swiftly after prey across the tundra and
cold steppes. These animals are described further and illustrated by Barton et al.
(2002).
1.4 THE LAST GLACIAL MAXIMUM (LGM)
The Last Glacial Maximum (LGM) refers to the time of maximum extent of the
ice sheets during the last glacial period, roughly 20,000 years ago. According to
Wikipedia:
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