The birth of the mountain

A mountain is born when two plates of the earth’s crust collide.

Plates found

Mountain ranges form where the plates of the earth’s crust meet. When the two continental plates collide, the collision causes the rocks to ride on top of each other. The result is that they rise slowly. Thus the Alps were born.

Sinking plates

If a plate that is at the bottom of an ocean, an oceanic plate, collides with a continental plate, the first one sinks under the second, lifts it and folds it. The Andes were born that way. The sinking plate eventually melts in the depths. The magma thus originating rises to the surface, where it forms volcanoes.

Grow little by little

Some mountains are very old and have been worn down by erosion. Others continue to grow. Thus, Mont Blanc still rises 1 mm every year. It is little, but since the life of a mountain is counted in millions of years, that makes 1km for every million years!


Collision: A collision is a collision, a violent encounter between two objects, for example two cars.

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