Everyone
knows that the Andes Mountains contain rugged, snow-capped peaks. Not everyone
knows that not all the white surfaces in the Andes are ice or snow. Some of the
bright spots in this part of the world get their color from salt.
On
December 1, 2001, the Enhanced Thematic Mapper on NASA’s Landsat 7 satellite
took this picture of part of the Atacama Desert. On the lee side of the Andes,
away from prevailing winds and precipitation-making weather, reside salt
pans—vast expanses of salt-covered soil. This image shows one such salt pan,
Bolton de Pipanaco, tens of kilometers long. Besides the pale color of the salt
pan, other features in this photo give clues to the region’s aridity. The sharp
ridges around the salt pan appear in shades of beige and brown, indicating land
that supports little vegetation. Two small water bodies appear in this image,
one in the northwest and the other in the southwest.
The
salt plains of the Atacama Desert were once underwater, and research at Cornell
University deduced that 15,000 years ago, the salt pans were great salt lakes.
When a lake has no outlet, the minerals carried into it accumulate, increasing
its salinity. If conditions dry out, the lake can evaporate, creating a salt
pan. Harsh as this environment is, some plants and animals have adapted to
living in it. A species of saltbush in this area concentrates salt in its stems
and leaves, crystallizing the excess on its exterior. Rabbit-resembling
viscacha rats, able to eat the saltbush, live nowhere else. Able to tolerate
saline lakes, flamingoes congregate in this area to dance.
Dry
as this area is, it does see the occasional torrent. Summertime monsoons and
mountain runoff can inundate the region, but the water does not soak the area
enough to erase the vast plains of
salt .
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