The Andes extends along which of the following ?

Question

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Correct — C, West Coast of South America. The Andes run for roughly 7,000 kilometres down the entire Pacific margin of South America — through Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile and Argentina — which makes them the longest continental mountain range on Earth. They exist because of what is happening at the sea floor just offshore: the oceanic Nazca Plate is being subducted eastwards beneath the continental South American Plate, and the crumpling, uplift and melting produced at that convergent boundary have raised a young fold-mountain belt studded with active volcanoes. Aconcagua in Argentina, at 6,961 metres, is the highest peak in the range and the highest anywhere outside Asia, and the belt forms the eastern arc of the Pacific Ring of Fire. The range shapes the continent's climate as decisively as its relief. It blocks moisture from the Amazon on its eastern flank; on the western side, working with the cold Peru current offshore, it produces the Atacama, one of the driest deserts in the world. Between the two main ranges in Peru and Bolivia lies the Altiplano, a high plateau carrying Lake Titicaca, and along the range's length lie the porphyry copper deposits that make Chile the world's leading copper producer and Peru another major one. Every one of those facts is a possible follow-up question, and all of them follow from the single structural fact this question asks for: a subduction-built cordillera on the western edge of South America.

Why the other options are wrong — (a) The correct continent's mirror image, and the most attractive wrong answer because North America genuinely does have a great western mountain system — the Rockies, with the Sierra Nevada and the Cascades nearer the coast. The two cordilleras are continuous in a broad sense as the American Cordillera, but the name Andes belongs to the southern continent alone.  (b) India's west coast carries the Western Ghats, or Sahyadri, running about 1,600 kilometres from the Tapi valley to Kanyakumari — a block-faulted escarpment of the peninsular plateau, geologically ancient and quite unlike a young folded range. It is a biodiversity hotspot and a UNESCO World Heritage site, but it is not the Andes.  (d) Australia's eastern rim carries the Great Dividing Range, running roughly 3,500 kilometres from Queensland to Victoria, with Mount Kosciuszko at 2,228 metres as its highest point. It is old, worn and low by Andean standards, and it separates the coastal strip from the interior — a genuine range on the wrong continent, which is exactly how this distractor is meant to work.

Concept: The world's great mountain ranges divide into two families by age and origin, and knowing which family a range belongs to answers most questions about it. YOUNG FOLD MOUNTAINS were raised in the Cenozoic by plate convergence and are high, sharp, seismically active and often volcanic: the Himalayas, the Alps, the Rockies and the Andes. OLD FOLD or BLOCK MOUNTAINS were raised far earlier and have been worn down: the Appalachians, the Urals, the Aravallis, the Great Dividing Range and, in a different way, the Western Ghats, which are the faulted edge of an ancient plateau rather than a folded belt at all. The Andes belong to the young family and to a specific sub-type — an oceanic-continental convergent margin, where dense oceanic crust dives beneath lighter continental crust. That single mechanism explains the whole package: the deep Peru-Chile trench offshore, the earthquakes, the chain of andesitic volcanoes (andesite is literally named for the range), the porphyry copper mineralisation, and the great height achieved in a relatively narrow belt. The Himalayas, by contrast, come from continental-continental collision, which is why they have no volcanic arc.

State PCS 2024 Q86 — Geography PYQ with Answer

State PCS 2024 Q86 — Geography PYQ with Answer