Mountains, Valleys, and Plains

Core Idea

Earth's surface is not flat -- it has many different shapes called landforms. Mountains are tall, high areas of land with steep sides and peaks. Valleys are low areas between mountains or hills, often with rivers running through them. Plains are large, flat areas of land that stretch out over wide distances. These landforms were shaped by forces inside and on top of the Earth over millions of years.

How It's Best Learned

Use a sandbox, clay, or play dough to build model mountains, valleys, and plains. Show photographs of real landforms from around the world. Look at topographic maps or satellite images. Take a nature walk and identify any landforms visible in the local area. Compare how different landforms affect how people live -- farming on plains, skiing in mountains, building towns in valleys.

Common Misconceptions

• Mountains are permanent and never change. Mountains are slowly being pushed up by forces inside the Earth and worn down by wind and rain. They are constantly changing, just very slowly.
• The ground has always looked the way it does now. Earth's surface has changed dramatically over millions of years.
• Plains are boring or empty. Plains support much of the world's agriculture and are home to unique ecosystems like grasslands and prairies.

Explainer

Look around at the land near you. Is it flat? Hilly? Are there mountains in the distance? The shape of the land around you has a name: landform. Earth's surface has many different landforms, and three of the most important ones are mountains, valleys, and plains.

Mountains are the tallest landforms. They rise high above the land around them, often with steep rocky sides and pointed or rounded tops called peaks. Some mountains are so tall that snow covers their tops all year long. Mountains exist on every continent and even under the ocean. They form when enormous forces deep inside the Earth push rock upward over millions of years, or when volcanoes build up cones of lava and ash.

Valleys are the low areas between mountains or hills. If you stand on a mountain and look down, the dip between your mountain and the next one is a valley. Rivers often flow through the bottoms of valleys because water always flows to the lowest point it can find. Some valleys are narrow and steep-sided (canyons), while others are wide and gentle. Many towns and farms are located in valleys because the flat land and available water make them good places to live.

Plains are large, flat stretches of land. They can extend for hundreds or thousands of kilometers without a single mountain in sight. Plains are some of the most important land on Earth for growing food -- the flat, fertile soil of the Great Plains in North America and the Pampas in South America are major agricultural regions. Grasslands, prairies, and farmland are all found on plains. Plains may look simple compared to mountains, but they support billions of people by providing the flat, rich land needed for farming.