Category Mountains

How do they measure a mountain?

In 1749 the British ‘Survey of India’ identified a lofty peak in the distant ranges of the Himalayas. It was called Peak XV, but it was not until 1849 that another survey set out to measure its height. When the survey was completed in 1852 it was confirmed that Peak XV was the highest mountain in the world.

Various names were suggested for it, including Devadhunga (Throne of Gods) and Guarishankar (Gleaming White Bride of Shiva). The Tibetans call it Chomolungma (Goddess Mother of the World). But the name approved by the Royal Geographical Society in London was suggested by Andrew Waugh, then Surveyor General of India. He thought it should be named after his predecessor – Sir George Everest.

Classical surveying techniques were used to calculate Everest’s height. First of all a baseline several miles long was measured along the ground at a known elevation above sea level. The top of the mountain could be seen from both ends of the line, and bearings were taken to the peak with theodolites – instruments which accurately measure angles.

From a knowledge of two angles and the length of one side of a triangle, the lengths of the other sides can be worked out – giving the distance of the peak from the baseline. Further calculations can then give the height. The surveyors measured Everest from six different sites – producing six figures ranging between 28,990 and 29,026ft (8836 and 8847m). The average came to exactly 29,000ft (8839m) – but because it sounded like an approximation they added 2ft (0.6m), and produced their authoritative answer – 29,002ft (8840m).

Everest’s position as the world’s highest mountain went unquestioned until 1986, when George Wallerstein, from the University of Washington, using a different method, claimed that another Himalayan mountain, K-2, might be 36ft (11m) higher.

Wallerstein’s claim was so startling that an Italian expedition visiting the Himalayas in 1987 decided to check it. They placed receivers part-way up Everest and K-2, and used Navstar signals to establish their exact height of the baseline on which calculations are based.

The team, led by geologist Ardito Desio, then calculated the heights of the two mountains using theodolites set up on the receivers’ positions. Their conclusion was that Wallerstein was wrong: Everest was measured at 29,108ft (8872m), a full 840ft (256m) higher than K-2.


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What weather conditions are there at mountains?

Weather up high

The main differences in climate of mountains are temperature and moisture. The temperature on mountains becomes colder the higher the altitude gets. Mountains tend to have much wetter climates than the surrounding flat land. Mountain weather conditions can change dramatically from one hour to the next. Mountains can be found in hot and cold countries. But if you go for a walk in the mountains, be prepared for any type of weather. Mountains can be sunny one moment, and cold and windy the next.

There can be snow on mountain peaks in hot weather.

The highest part of a mountain is also the coldest. High up, the air is very thin and cannot hold much heat. Mountains are so tall that they make their own weather. They act as a barrier, forcing air to rise up and over them. The air cools when it passes over     the mountain and this creates more rain and snow.

Mountains can be wet on one side, but dry and sunny on the other!

The side of a mountain facing the wind is the wettest. This is because the wind carries warm, damp air that falls as rain when it reaches the cold mountain. By the time the air has passed over the mountain peak, it is drier and there is no rain left to fall on the other side! The dry side is said to be in a ‘rain shadow’.

The mountains are getting warmer.

The chemicals and fuels that we use each day release harmful gases. This pollution traps hot air around the Earth causing temperatures to rise. As the glaciers melt, plants and animals move up the mountain, taking over from wildlife that used to live in colder part. The land below may also flood.

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How mountain ranges get their shape?

Shaping mountains

Most mountains are very old. But mountains like the Himalayas and the Rockies are young (only about 70 million years old!) These mountains have jagged peaks. Old mountains are smoother because their edges have been worn away.

Over thousands of years, rain, wind and ice wear away the hard rock.

The effect of wind, rain and ice on the rock is called erosion. Rainwater seeps inside the rock and freezes. As it does so, the water expands and eventually cracks and breaks the rock. Fierce winds also blow sand and tiny pieces of rock onto the mountain, slowly wearing it away.

Some mountain rivers are always frozen.

Rivers flow down mountains, carrying rocks and pebbles that cut into the rock. Up high, the rivers are frozen. These massive ice blocks are called glaciers. When glaciers move they crack the rock, and stones tear the mountain-sides.

Water carves out valleys as it flows down mountains to the sea.

Valleys are deep areas of land running between mountains. They are formed by the action of rivers and glaciers. Block mountains also create rift valleys (such as the Great Rift Valley in Africa) when the Earth’s plates move apart. Valleys are very fertile because minerals in the river water are deposited on the flat land.

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Where we can find mountains?

Mountains everywhere

We see Land Mountains in many parts of the world. But mountains can also be found under the sea and even on other planets in space. Scientists and explorers use special equipment to study mountains everywhere.

Mountain ranges can be found in the ocean.

Some ocean mountains are so huge that their tops form islands where people can live — Iceland is one example. Mauna Kea, in Hawaii, rises 10,200 metres from the bottom of the sea. It is the Earth’s largest mountain, even though Mount Everest rises 8,850 metres above land. Sometimes, gaps in the ocean rocks cause gas to escape and the water to boil.


This mountain is found on Mars.

Space scientists have been studying the surface of other planets. They have found enormous volcanic mountains on Mars, like Olympus Mons, its highest mountain. It is 22,860 metres tall — three times higher than Mount Everest.

Special robots and cameras are used to study sea and space mountains.

Remote-controlled machines fitted with cameras travel millions of kilometres to Mars. They take pictures of the planet’s mountainous surface. Underwater robots, called submersibles, look at the ocean floor and find out more about underwater mountains.

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How do mountains form?

Mountains are an outcome of the movements of the Earth’s crust, which is the Earth’s outer layer. The Earth’s crust consists of six massive slabs referred to as tectonic plates, which are always moving a few centimeters annually. Two tectonic plates moving against each other cause the thickening and deformation of the crust and land mass is forced upwards to form mountains. Over time, mountains are subjected to erosion from elements such as the wind, ice, and rain, causing their surfaces to be younger than the rocks which initially formed them. Depending on the tectonic forces at work, different types of mountains are formed.

Mountains take millions of years to form. Huge movements deep in the centre of the Earth slowly push rocks into mountain shapes. Some mountains, like the Urals in Russia, started to form about 250 million years ago.      

The Earth’s surface is like a rocky jigsaw.

The outer layer of the Earth is made from giant pieces of rock called plates which lie on top of boiling hot, runny rock called ‘magma’. The plates move about a thumb’s length each year, but we can’t feel them moving. When the plates push into or pull away from each other, rock is forced upwards forming a mountain. This aerial view shows a fault in Tibet in Asia. The Kunlun fault is 1,500 km long. It can be seen running from left to right. Lines of vegetation are shown in red.

Some mountains are still growing!

Some plates that collided millions of years ago are still pushing together, and causing the land to rise upwards. The Himalayas in Asia grow about six centimetres each year. Soft soil above the Asian plate is rising because it is being pushed by the stronger Indian plate.

Geologists study mountain rocks.

Geologists are scientists. They study rock layers and the ways that rocks form. Bu examining rocks, they are able to work out how a mountain formed and even how old it is! Geologists use a range of tools, from hammers and chisels to drills, satellites and computer technology.

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What is a mountain?

A mountain is a large landform that rises above the surrounding land in a limited area, usually in the form of a peak. A mountain is generally steeper than a hill. Mountains are formed through tectonic forces or volcanism. These forces can locally raise the surface of the earth. Mountains erode slowly through the action of rivers, weather conditions, and glaciers. A few mountains are isolated summits, but most occur in huge mountain ranges.

High elevations on mountains produce colder climate than at sea level. These colder climates strongly affect the ecosystem of mountains: different elevations have different plants and animals. Because of the less hospitable terrain and climate, mountains tend to be used less for agriculture and more for resource extraction and recreation, such as mountain climbing.

The surface of the Earth is full of bumps, hills and valleys. We call the tallest places on Earth ‘mountains’.  Life in the mountains is cold and harsh but many people, plants and animals are able to live there.

Mountains come in all shapes and sizes.

No two mountains look the same! Some are pointed and jagged. Others are rounder and smoother. There is no agreed definition about when a hill becomes a mountain, but generally mountains are more than 700 metres tall. Mount Everest is the tallest mountain on land and is 8,850 metres tall.

The four principal shapes of mountain ranges include: diamond, pyramid, inverted pyramid and hourglass. For all the range shapes except pyramid, land availability can be greater at higher elevations than it is farther down the mountainside. Yet, people’s idea that land area steadily shrinks as a mountain rises is so entrenched that it has come to guide conservation plans and research.

Mountains are made from rock.

There are three main types of mountain rock, depending on where the mountain is found and how it formed. Granite is very hard and looks grainy, like a mixture of salt and pepper. Sandstone is made of squashed up grains of sand. Limestone is mostly made from the remains of dead plants and animals.

Groups of mountains are called ranges.

Most mountains are grouped together in ranges, such as the Alps in Europe and the Atlas mountains in Africa. The highest range of mountains in the world is the Himalayas range in Asia.

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