South America’s physical structure is dominated by three major regions:

1. The Andes Mountains (west).
2. The Central Highlands – Guiana Highlands (north), Brazilian Highlands (east), Patagonian Plateau (south).
3. The Plains & River Basins (Amazon, Orinoco, La Plata).

This chapter focuses on the mountains & plateaus.

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🌎 3.1 Andes Mountains – The Backbone of South America

• Length: ~7,200 km (world’s longest continental mountain chain).
• Width: ~200–700 km.
• Countries Covered: Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile, Argentina.
• Formation: Result of the Nazca Plate subducting under the South American Plate (convergent boundary).
• Importance:
  • Influences climate (rain shadow → Atacama Desert).
  • Source of major rivers (Amazon, Orinoco tributaries).
  • Rich in minerals (copper, silver, tin, lithium).
  • Habitat of ancient civilizations (Incas).
  • Active part of the Pacific Ring of Fire → volcanoes & earthquakes.

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🔹 Divisions of Andes

1. Northern Andes (Venezuela, Colombia, Ecuador):
   • Narrow, volcanic mountains.
   • Peaks: Cotopaxi, Chimborazo.
   • Features: Coffee-growing highlands, Quito (capital of Ecuador).
2. Central Andes (Peru, Bolivia):
   • Altiplano Plateau (Bolivia–Peru).
   • Lake Titicaca → world’s highest navigable lake (3,812 m).
   • Rich in silver (Potosí mines, Bolivia).
3. Southern Andes (Chile, Argentina):
   • Tallest peak: Aconcagua (6,961 m, Argentina) → highest outside Asia.
   • Features: Glaciers, fjords, Patagonia region.

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🔹 Important Peaks of the Andes

Peak	Country	Height (m)	Significance
Aconcagua	Argentina	6,961	Highest in South America
Huascarán	Peru	6,768	Highest peak in Peru
Ojos del Salado	Chile/Argentina	6,893	World’s highest active volcano
Chimborazo	Ecuador	6,263	Farthest point from Earth’s center
Cotopaxi	Ecuador	5,897	One of the highest active volcanoes
Illimani	Bolivia	6,438	Symbolic mountain of La Paz

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🌎 3.2 Guiana Highlands

• Location: Northern South America (Venezuela, Guyana, Suriname, French Guiana, north Brazil).
• Famous Peak: Mount Roraima (~2,810 m).
• Importance:
  • Source of rivers → Orinoco, Amazon tributaries.
  • Angel Falls (Venezuela): Tallest waterfall in the world (979 m).
  • Rich in bauxite, gold, and iron ore.

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🌎 3.3 Brazilian Highlands

• Location: Eastern & southern Brazil.
• Elevation: 300–900 m.
• Importance:
  • Divides Amazon Basin (north) from coastal plains (east).
  • Minerals: Iron ore, manganese (Minas Gerais).
  • Agriculture: Coffee, sugarcane (São Paulo region).
  • Source of São Francisco & Paraná Rivers.

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🌎 3.4 Patagonian Plateau

• Location: Southern Argentina, bounded by Andes (west) & Atlantic Ocean (east).
• Climate: Cold desert/steppe.
• Importance:
  • Sheep grazing → wool production.
  • Oil & natural gas.
  • Southern glaciers and fjords in Chile.

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🌎 3.5 Altiplano Plateau

• Location: Between two ranges of the Andes (Peru & Bolivia).
• Height: ~3,600–4,000 m.
• Famous For:
  • Lake Titicaca (shared by Bolivia & Peru).
  • Rich in lithium & salt (Salar de Uyuni → largest salt flat on Earth).
  • Ancient Inca & Aymara civilizations.

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📌 UPSC Key Pointers

1. Andes → world’s longest mountain chain; Aconcagua → highest peak outside Asia.
2. Chimborazo (Ecuador) → farthest point from Earth’s center due to equatorial bulge.
3. Altiplano Plateau → Lake Titicaca & Salar de Uyuni (lithium).
4. Guiana Highlands → Angel Falls (world’s tallest waterfall).
5. Brazilian Highlands → Iron ore & coffee.
6. Patagonian Plateau → Cold desert, sheep grazing.
7. Andes = “Backbone of South America” → climate, rivers, biodiversity, resources.