When you walk around on land, you are walking on top of Earth’s rocky crust. Below the crust is another thick layer of rock. These layers form Earth’s tectonic plates and when those plates collide with each other, they often form mountains.
To find out more about how mountains form, I visited my friend Julie Menard, a professor at Washington State University who is very curious about geology.
“When the collision happens, one plate will not simply go on top of another,” she said. “The plates will just push against each other and over a long period of time a mountain will form.”
Menard told me that these tectonic plates are huge. The plates are about 77 miles thick, and they move very slowly—just about 2 to 3 inches a year. When the two plates come together, they push the rock upwards. It can take ten millions of years for the mountain to rise up.
The plates move slowly, yet when they collide, they may not just help build a mountain but also shake things up. The movement from the plates can cause earthquakes, too.
Menard reminded me that a lot of mountain ranges on our planet are forming at this very moment. The Himalayas, which are some of the youngest mountains on Earth, are growing about one centimeter a year. Mount Everest is part of the Himalayas and is the tallest summit on Earth.
Meanwhile, the Appalachian Mountains are some of the oldest mountains in North America, but they aren’t very tall compared to some of the younger mountains on the continent. As wind, water and other elements in nature interact with the mountain, the rock goes through a process called erosion and wears down over time.
As mountains form, they create ecosystems for all kinds of life—from ants to alpacas to mountain goats to gorillas. Water is also an important part of our mountain ecosystems. When snow melts off the mountains and flows down into streams and rivers, it helps provide lots of living things with water.
Menard said that one of her favorite mountain ranges to explore is the Rockies, a range that stretches more than 3,000 miles. Perhaps you can do some mountain investigation of your own. Find out which mountain is the tallest in your state, region or even possibly underwater near where you live. Then, investigate how and when it formed.
Maybe you even have a volcano in your neighborhood. Volcanoes are a kind of mountain, but they don’t form in exactly the same ways as mountains that are not volcanic. See if you can find out more about the difference between the two. When we ask big questions about the landscape around us, we are bound to discover something new and exciting about this planet we call home.