Folded Mountains

This mountain is an example of how the Rocky Mountains were formed.

All the land on the earth is in a bunch of pieces of land that ‘float’ around on a deep layer of melted rock deep in the ground. These pieces are called ‘tectonic plates’. They move slowly, but over thousands of years, their movement causes huge changes to the surface of the earth.

Originally, all the rock in the Rockies lay flat on a shallow seabed of the western continental shelf – one of the tectonic plates that make up the surface of the earth. It took many millions of years for all the layers of rock to form.

About 175 million years ago, two tectonic plates moved toward each other and caught the continental shelf in the squeeze. As the plate was squeezed from both sides, the flat-lying layers of rock slowly buckled into folds.

It took about 50 million years for the Rockies to fold and buckle enough to show above the sea.

The Rocky Mountains continued to grow for 75 million years, and were (at one time) higher than the Himalayas. About 45 million years ago, they stopped growing and have now eroded away to a small fraction of their original size.

Folded Mountain in British Columbia is a great example, showing all the twists and folds of the layers of rock. All those layers were flat and lying on the bottom of an ocean about 175 million years ago!