The Cordillera Blanca in Ancash dominates Peru’s central Andes. Adriana von
Hagen.The midsection of this South American arc from northern Ecuador to
northwestern Argentina is known as the Central Andes. The expression “Central
Andes” now in common usage refers to not just the highlands, but also to the
coastal region and the eastern slope. In broadest outline, this heart of the Andes
consists of two main parallel-trending cordilleras, or ranges, that merge in a
high-altitude tableland known as a “knot.” Beginning at the Pasto Knot (1°30'N)
in southern Colombia, Ecuador’s two major mountain chains enclose between
them a series of 10 basins. The cordillera to the west has 19 volcanoes; that to
the east has 20 volcanoes, of which the highest is Chimborazo (6,310 meters
[20,701 feet]), once considered to be the world’s highest mountain. These two
chains converge southward in the Loja Knot (3°50’S), out of which extend three
chains covering northern highland Peru. An emblematic mountain landscape in
this zone is the Callejón de Huaylas, which forms the upper Santa valley that
separates the Cordillera Negra (to the west) from the higher, snow-capped
Cordillera Blanca in the central chain. Huascarán (6,768 meters [22,205 feet]) is
the highest and most climbed peak there. The rain and melting snow from
westward-draining mountains were unequivocally vital to the development of all
the coastal civilizations.