Explore how plate tectonics affect our planet.


It may seem like the Rocky Mountains have been there forever, but these mountains are very young compared to the age of Earth . In the history of our planet, mountain chains like the Rockies have risen and worn away many times.

Mountains form where two continental plates collide. Since both plates have a similar thickness and weight, neither one will sink under the other. Instead, they crumple and fold until the rocks are forced up to form a mountain range. As the plates continue to collide, mountains will get taller and taller.

Appalachian mountain range

Old mountain ranges, like the Appalachians in the eastern U.S., are not as high. They stopped forming long ago, and have been worn down over millions of years by the erosive power of water and wind. The Appalachians formed about 400 million years ago.

snowcapped Himalayas

The youngest mountains on Earth, like the Himalayas in Asia, are high. They started forming 60 millions years ago and are still rising. Mount Everest in the Himalayas is the tallest mountain in the world. 

Image Credits:

Appalachian mountains, courtesy of National Park Service (NPS); Himalayas mountains, courtesy of NASA