The Andes are formed by the movement of the Nazca plate under the South American plate, and are part of the Pacific Ring of Fire. Located on the western edge of the South American continent, they lie between a very slim coastal plain to the west, and the vast reaches of the
Amazon Rainforest to the east. The runoff from the Andes helps create the
Amazon River. Some of the highest peaks in the world are in the Andes, including Aconcagua in northern
Argentina at 22,841 feet. Lake Titicaca, in the Andes on the border of Peru and Bolivia, is the highest navigable lake in the world. The
Inca Civilization extended over much of the Andes.