What is a mountain?

Mountains are very big bumps on the ground. Some are small, and some are very tall — taller than houses or even whole cities! You can think of a mountain like a giant cake made of different layers: solid rock, broken rocks and stones, and a top layer of soil.

How do mountains form? (Step by step)

1. Big pieces of Earth are moving: The outside of the Earth is cracked into giant pieces called plates. These plates move very slowly.
2. Plates push together: When plates push or squeeze, the ground can fold up like a wrinkled rug. Those wrinkles become mountains. This is one common way mountains form.
3. Volcanoes make mountains too: Sometimes hot rock from under the Earth pushes up and piles on the surface. That makes a volcano mountain.
4. Sometimes the ground breaks and moves: Parts of the Earth can lift up or drop down along cracks. The lifted parts can make mountains or big cliffs.
5. It takes a very long time: Mountains grow and change over millions of years — much longer than a person lives!

Why mountains look like layers (your cake idea)

• Bottom layer — hard rock: Deep inside, mountains are made of very hard rock. This is like the bottom layer of a cake that holds everything up.
• Middle layer — broken rocks and stones: Over time, pieces of rock break off and pile up on the sides. These are like the crumbs or chunks between cake layers.
• Top layer — soil and plants: Dirt and soil form on top where plants can grow. This is like the frosting and sprinkles on a cake!

Other things about mountains

• Mountains have parts: a peak (the top), slopes (the sides), and valleys between them.
• Wind, rain, snow, and ice slowly wear mountains down. This is called erosion.
• Different heights have different plants and animals. Near the top it can be cold and snowy; lower down it can be warm and full of trees.
• Famous mountains: Mount Everest is the tallest on Earth, Mount Fuji is a famous cone-shaped volcano in Japan, and the Rocky Mountains are a big range in North America.

Easy mountain activity you can try

Try this simple experiment to see how mountains can form:

1. Take two pieces of paper or a towel and put them flat on a table next to each other so there is a seam in the middle.
2. Push the ends of the papers toward each other slowly. The middle will wrinkle and fold up — this shows how mountains can form when plates push together.
3. Or, press two colors of playdough together and squeeze. You will see layers and folds, like a mountain's inside layers.

Fun facts

• Mountains can keep getting taller if the plates keep pushing.
• Glaciers (big slow rivers of ice) can carve deep valleys in mountains.
• Some mountains are still growing today, but they grow so slowly you cannot see them move.

That’s the story of mountains: they are giant bumps that form by pushing, folding, or piling up. They have layers like a cake, and they change slowly over a very long time. Want to try the paper or playdough activity now?