The Explainer: Why Are Mountains So Formidable?

The explainer

- Alex Franklina-Cheung

HOW DO MOUNTAINS FORM?

Most mountains owe their existence to the movement of tectonic plates, vast sections of the Earth’s crust. Where two tectonic plates converge, they buckle and fold, resulting in the most common type: fold mountains. The Himalayas, for example, result from the Asian and Indian plates slowly colliding. Block mountains are created when the pressures between plates allow cracks (faults) to appear, with huge slabs of rock being thrust upwards.

Volcanic activity can also produce mountains. As a volcano erupts,the buildup of molten rock can form peaks. Sometimes, the rising magma can remain trapped underground, causing the surface to swell in a dome shape.

With tectonic plates typically moving just three to five centimetres per year, mountains slowly take shape over tens or hundreds of millions of years. The oldest mountain range in the world is the Barberton Greenstone Belt in South Africa, with some mountains estimated at 3.5 billion years old.

WHAT’S THE BIGGEST MOUNTAIN IN THE SOLAR SYSTEM?