Mountains of the World

A mountain is a large, steep piece of land that rises high above the ground around it. Mountains are formed over millions of years as huge pieces of rock are pushed upwards by forces deep inside the Earth. A mountain is taller and steeper than a hill, though there is no exact height where a hill suddenly becomes a mountain — it depends on the country you are in.

Mountains rarely stand alone. They usually rise together in long lines called mountain ranges. A range forms because the forces that push up one mountain push up its neighbours at the same time. Famous ranges include the Himalayas in Asia, the Alps in Europe, the Rockies in North America, and the Andes in South America.

The higher you climb a mountain, the colder and windier it gets. This is because the air gets thinner as you go up, so it holds less warmth from the Sun. That is why many mountain tops are permanently covered in snow and ice even in summer. Climbers heading up the very highest peaks must carry bottled oxygen to breathe, because the air becomes so thin.

Mountains form in more than one way. Some, called fold mountains, form when two of Earth's giant rocky plates crash into each other and the rock crumples upward — just like pushing a tablecloth into a pile. Others are volcanic mountains, which form above volcanoes where lava builds up layer by layer until a tall cone has grown.

Mountains matter to people too. Their snow melts in spring to feed great rivers that millions of people rely on for drinking water and growing food. People visit mountains to ski, climb, and hike, and many of the world's cultures tell special stories about the peaks that tower over their homes.