Mountains are huge landforms that rise steeply far above the land around them. Most are made when Earth's giant tectonic plates push together and squeeze rock upwards, and others are volcanoes built from layers of lava and ash. The tallest mountain above sea level is Mount Everest in the Himalayas of Asia, at 8,849 m, but Mauna Kea in Hawaii is taller if you measure from its base on the ocean floor. Mountains cover about a quarter of Earth's land. The higher you climb, the colder it gets, which is why snow can sit on top of Mount Kilimanjaro in Africa even though it is close to the equator.
How Did the Himalayas Get So High?
Imagine pushing a rug across the floor until it bumps into a wall. The rug crumples and folds up into ridges. That is what happens to rock when two tectonic plates crash into each other, only it happens very slowly, over millions of years.
The Himalayas are the best example. About 70 million years ago, the land that is now India broke away from an old southern supercontinent called Gondwana and started moving north across the ocean. When India finally reached Asia, neither piece of land would sink, so the rock between them was squeezed, folded and pushed upwards. That crash built the Himalayas, the highest mountains on Earth. Every mountain on our planet that is taller than 7,200 m is in central or southern Asia, and there are at least 100 of them.
Scientists call mountains made by squeezing fold mountains. The Jura Mountains between France and Switzerland and the Balkan Mountains in Bulgaria formed this way too. A second kind, block mountains, forms when the ground cracks along faults and big blocks of rock are pushed up or drop down. The plates are still moving today. You can read more about them in our guide to plate tectonics for kids.
Is Mount Everest Really the Tallest?
It depends on how you measure. Mount Everest has the highest summit above sea level. In 2020, survey teams from Nepal and China measured it together and got 8,848.86 m, which most people round to 8,849 m. Its top sits right on the border between Nepal and China. The nearest sea, the Bay of Bengal, is almost 700 km away. Everest also has older local names. In Nepali it is Sagarmāthā, and in Tibetan it is Chomolangma.
Now think about Mauna Kea, a volcano on the island of Hawaii. Its top is 4,207 m above sea level, so it looks much smaller than Everest. But most of Mauna Kea is hidden under the Pacific Ocean. Measured from its base on the sea floor, it rises more than 9,300 m, and some measurements give about 10,200 m. That makes it taller than Everest from bottom to top.
There is one more way to win. Earth bulges a little at the equator, so places near it are farther from the centre of the planet. Chimborazo, a volcano in Ecuador, is usually counted as the mountain whose summit is farthest from Earth's centre, even though it is more than 2 km lower than Everest. Want the full story of the world's highest peak? Try how tall Mount Everest is.
Which Mountain Is Highest on Each Continent?
Every continent has a highest mountain. Climbers call the list the Seven Summits, and some try to stand on top of all seven. Here they are, from tallest to shortest.
Look at the bottom of the chart. Vinson in Antarctica and Puncak Jaya on the island of New Guinea are only 8 m apart! Some lists use Mount Kosciuszko, at 2,228 m, as Australia's entry instead, because it is the highest point on the Australian mainland.
How Does a Volcano Like Mount Fuji Build Itself?
Not every mountain is squeezed up. Some grow from the inside out. When one plate slides underneath another, rock deep below melts into hot, runny magma. The magma pushes up and bursts out as lava and ash. Each eruption adds a new layer, and over thousands of years the layers pile up into a cone.
Mount Fuji in Japan grew this way. It is 3,776 m tall, about 100 km southwest of Tokyo, and its almost perfect cone is covered in snow for about five months of the year. Fuji is still an active volcano, although its last eruption was in 1707 and 1708. Mount Kilimanjaro in Tanzania is a volcano too, but it is dormant, which means sleeping. Hawaii's Mauna Loa is the biggest mountain on Earth by volume, with a base covering about 5,200 km². To see how eruptions work, read volcanoes for kids.
Why Is There Snow on Kilimanjaro, So Close to the Equator?
Kilimanjaro stands only about 340 km south of the equator, where the lowlands are hot all year. Yet its summit has an ice cap and the largest glaciers in Africa. How can that be?
The answer is that air gets colder as you go up. The Sun mostly heats the ground, and the ground heats the air just above it. Warm air rises, and as it rises it spreads out, because there is less air pressing down on it from above. Air that spreads out cools down. Scientists have measured this. Dry rising air cools by about 9.8 °C for every kilometre it climbs, and damp air cools by about 5.5 °C per kilometre. So the top of a mountain 5 km high can be 25 to 50 degrees colder than the plains at its feet.
That is why mountains often look like layer cakes. Near the bottom of Kilimanjaro, farmers grow maize and beans, and between 1,000 and 1,800 m coffee grows in family gardens. Higher up is a thick forest belt, where in places more than 3,000 mm of rain can fall in a year between about 2,000 and 2,300 m. Above the forest is the alpine zone, which gets only about 200 mm of rain a year, and at the very top is the ice. Sadly, that ice is shrinking fast: almost 85% of Kilimanjaro's ice cover disappeared between 1912 and 2011.
What Animals Live on the Alps and the Himalayas?
Living on a mountain is hard. It is cold and windy, the air is thin, and there is not much food. The animals that live there have special tricks.
The snow leopard lives in the mountains of Asia, from the Himalayas to Mongolia, usually between 3,000 and 4,500 m. It has thick whitish-grey fur, small round ears that lose less heat, broad paws for walking on snow, and a thick, bushy tail. All of these help it survive the cold.
The Alpine ibex is a wild goat from the Alps of Europe. It is an amazing climber, with sharp hooves that grip steep slopes and cliffs as high as 3,300 m. Both males and females have curved horns, but the males' are much larger and longer.
Birds go even higher. In 1953, George Lowe, a member of the first team to climb Everest, said he saw bar-headed geese flying over the summit. Choughs, black birds in the crow family, have been seen at Everest's South Col, a pass at 7,906 m.
People live on mountains too. About 7% of Earth's land is higher than 2,500 m, and around 140 million people live above that height. About half of all mountain dwellers live in the Andes of South America, in Central Asia and in Africa.
Who First Climbed the Matterhorn and Everest?
The Matterhorn, the pointed peak pictured above the first paragraph, is a giant rock pyramid, 4,478 m high, on the border between Switzerland and Italy, with the Swiss village of Zermatt at its foot. It has four steep faces that point roughly north, south, east and west. For years nobody could reach its top, even after most other big peaks in the Alps had been climbed. In 1865, a team led by the English climber Edward Whymper finally made it from Zermatt, but four of the climbers died on the way down.
Everest waited much longer. On 29 May 1953, at 11:30 in the morning, Edmund Hillary from New Zealand and Tenzing Norgay, a Sherpa mountaineer who grew up in Nepal's Khumbu region, stood on the summit for the first time. Their expedition, the ninth British attempt on Everest, was led by John Hunt.
Where Is the Longest Mountain Range on Earth?
The longest mountain range on land is the Andes, which runs 8,900 km down the west side of South America through seven countries, from Venezuela to Argentina and Chile. It is 200 to 700 km wide, and its average height is about 4,000 m. But the longest mountain range of all is hidden under the sea. The mid-ocean ridge winds through every ocean for about 65,000 km, several times longer than the Andes. It forms where plates pull apart and new sea floor is made.
Mountains do not last forever. Once they stop being pushed up, rain, rivers, ice and wind slowly wear them down. Rain freezes in cracks, glaciers grind the rock, and rivers carry the pieces away to the sea. So when you look at a mountain, you are looking at one moment in a story that lasts tens of millions of years.