A 5,000-mile (8,000-km) long mountain range in
western South America, running generally parallel to the
coast, between the Caribbean coast of Venezuela in the north
and Tierra del Fuego in the south. The mountains merge with
ranges in Central America and the West Indies in the north,
and with ranges in the Falklands and Antarctica in the south.
Many snow-covered peaks rise more than 22,000 feet (6,000
m), making the Andes the second largest mountain belt in the
world, after the Himalayan chain. The highest range in the
Andes is the Aconcagua on the central and northern Argentine-
Chile border. The high cold Atacama desert is located in
the northern Chile sub-Andean range, and the high Altiplano
Plateau is situated along the great bend in the Andes in
Bolivia and Peru.
The southern part of South America consists of a series of
different terranes added to the margin of Gondwana in the
late Proterozoic and early Proterozoic. Subduction and the
accretion of oceanic terranes continued through the Paleozoic,
forming a 155-mile (250-km) wide accretionary wedge. The
Andes formed as a continental margin volcanic arc system on
the older accreted terranes, formed above a complex system of
subducting plates from the Pacific Ocean. They are geologically
young, having been uplifted mainly in the Cretaceous and
Tertiary, with active volcanism, uplift, and earthquakes. The
specific nature of volcanism, plutonism, earthquakes, and
uplift is found to be strongly segmented in the Andes, and
related to the nature of the subducting part of the plate,
including its dip and age. Regions above places where the subducting
plate dips more than 30 degrees have active volcanism,
whereas regions above places where the subduction zone
is sub-horizontal do not have active volcanoes.
See also CONVERGENT PLATE MARGIN PROCESSES; PLATE
TECTONICS.
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