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T321 Atlas Pg. 33 Central Andes Mountains, Argentina, Bolivia, Chile Volcanoes, folded rocks, active faults, salars and wind streaks Significance: The six major zones of the Central Andes are arranged parallel to the coast and are highly visible from orbit. 1) A range of mountains occurs on or near the coast, rising out of the sea at some points. Next, 2) a major, narrow valley follows, in which sediments have been fractured by presently active faults. The next major zones are consist of two massive mountain chains (3) High and 5) Eastern Cordilleras) with 4) an intervening, high plateau (altiplano). The mountain chains are composed of highly folded and faulted rocks, covered by great outpourings of younger lavas from hundreds of volcanoes. The highest volcanic cones in the region reach altitudes of 5,500-6,250 meters (18-20,000 feet) and many cones display snow caps. A distinctive feature of the dry altiplano landscape is the light-colored, salt-encrusted depressions (playas or salars) which are more visible than the dark-toned volcanic rocks. Some depressions are water filled (including Lake Titicaca further to the north) and contain algae which change color with the seasons. The loose, silty floors of the dry salars respond to the dominant winds of these high altitudes (3,800 meters of 12,000 feet) and provide particles for dust storms which make wind streaks: lines of alternating lighter and darker tones elongated parallel to the dominant wind direction. A final landscape zone 6) consists of separated, upfaulted mountains at low altitudes on the east flank of the Eastern Cordillera. Valleys separating these mountains are relatively well watered and therefore well populated. Physical Characteristics: The Central Andes is 600 km (350 miles) wide, and includes some of the highest mountains in the Americas. The region varies climatically from the hyperarid Atacama Desert in Chile (the driest desert in the world), to the semiarid foothills in western Argentina. The whole area is one of the most desolate regions in the world and is still being explored for its mineral riches after hundreds of years of metal production. Observation Techniques: Photographs using the 100 mm lens to improve the broad views of this region are of interest especially in identifying and mapping volcanoes and documenting dust storms. Use of the 250 mm lens to photograph small features such as lava flows, debris flows (less viscous, muddy masses), salar surface features and wind streaks are also of interest to Earth scientists. Near-vertical views using the 250 mm lens of coastal features and the dry Atacama Desert are also requested. Center Point: 24[[degree symbol]]S, 67.5[[degree symbol]]W 172
