Introduction
There are many elevated parts on our Earth’s crust. They are called Mountains. Do you know how many types of mountains are there?
Friends, here in this chapter we will learn more about mountains, which are the different types, how are they formed, and other facts.
- Mountains are generally an elevated part of the earth’s crust.
- About one-fifth of our world’s landscape is contributed by the mountains.
- They provide shelter to about one-tenth of the people in the world.
- They are mainly formed through volcanism, tectonic forces, and erosion.
- Tectonic plates are parts of the uppermost mantle and crust of the earth.
- They are known as lithosphere together.
- Mountains are also formed by the smashing of two slabs of the earth’s crust or by the collision of continents.
- Mountains are having a limited summit area which makes them different from that of a plateau.
- Typically, mountains rise higher than hills as they rise at least 300 meters above the land surface.
- Mountains are not only present on the land, but they are also found under the surface of the sea.
- The height of a mountain is measured from the height that is above sea level.
- About 80% of our earth’s freshwater has originated from the mountains.
Formation of Mountains
- Apart from the tectonic forces mentioned above, there are other two processes that lead to the formation of mountains.
- The process by which magma or molten rock from the earth’s mantle rise to the surface of the earth is called volcanism.
- Here, the magma reaching the surface is known as Lava.
- It is through the volcano that magma and other gases are released.
- Erosion is the process that removes rock, dissolved materials, or soil from one portion of the earth’s crust to another by the action of flowing water, wind, etc.
- Water, air, gravity, and ice are called agents of erosion.
- During uplifting of the mountains, these agents have the tendency to wear the uplifted areas down.
- Due to the process of erosion, the surfaces of the mountains look much younger than the other rocks which helped in the formation of the mountain itself.
Types of Mountains
- Volcanic Mountains
- Fold Mountains
- Block Mountains
Volcanic mountains
- The molten rock within our earth called magma erupts and a pile is formed on the surface.
- This magma breaks through the crust of the earth and it’s known as lava.
- Cooling down of this lava and ash leads to the formation of a cone-shaped rock.
- Gradually, the lava and rock pile up layer by layer, and volcanic mountains are formed.
- Mount St. Helens in North America and Mount Pinatubo in the Philippines are examples of Volcanic mountains.
Fold Mountains
- When there is a collision between two plates head-on, their edges get crumbled.
- This process leads to the formation of fold mountains.
- Most of the world’s largest mountain ranges are fold mountains.
- Himalayan mountains in Asia, the Alps in Europe are examples of fold mountains.
Block mountains
- Due to the cracks and faults in the earth’s crust, certain materials are brought up and some are placed down.
- When this occurs, the crust of the earth pulls apart rather than folding over.
- These broken rocks and chunks keep moving up and down.
- Eventually, they get stacked on one another, and hence, block mountains are formed.
- The Sierra Nevada mountains in North America and The Harz Mountains in Germany are examples of block mountains.
Mount Everest is the world's highest peak on the land. It is in the Himalayas. The height is measured as 8,850.1728m.
In the Himalayas, there are about 14 highest mountains.
- Depending upon the altitude levels, there are variations in the climate of the mountains.
- There is tropical weather on the bottom or foothill side.
- The top of the mountains or peaks will be covered in ice.
- It is found to be snow or bare rock on the uppermost level of the mountains.
- As the altitude increases, the climate on the mountains becomes much colder.
- It is said that the mountains make their own climate.
- When the wind blows towards a mountain, it has to move upwards in order to pass over the obstruction.
- The moisture content in the warm air is more than that in cool air.
- When the air moves upwards, there is a decrease in air pressure as the altitude increases.
- The decrease in pressure cools the air that has come up.
- This will eventually cause rain or snow as the progression of water vapor stops here.
- The upwind side or the windward side of the mountains will be mostly lush green due to the presence of rain.
- On the downwind side or the leeward side, the moisture that is left from rain may heat up again as they reach the bottom.
- The side of the mountain facing the direction of that of the wind is the windward side.
- The side of the mountain which is opposite to the direction of the wind or the wind-protected side is called the leeward side.
- The climate in these regions is dry and desert-like.
- This process is often called the rain shadow effect.
The highest mountain ranges in the world are the Himalayas.
The longest mountain ranges in the world are formed by the Andes mountains.
Vegetation and mountains
- Depending on the difference in temperature and rainfall, the vegetations are also different in the mountains.
- At the foothills, there is the presence of broadleaved forests.
- At the uppermost sides, needle leaf trees like pine and spruce can be found.
- As the altitude increases, the trees may thin out and they eventually disappear.
- Due to this, the top portion of the mountains is basically bare or snow-capped.
Wildlife and mountains
- The life of animals in the mountains is comparatively very harsh.
- They have to adapt to the bitterly cold climate and the availability of food is less.
Key points to be noted:
- Elevated part of the earth’s crust are called mountains.
- Mountains are mainly formed through volcanism, tectonic forces, and erosion.
- The process by which magma or molten rock from the earth’s mantle rise to the surface of the earth is called volcanism.
- Three types of mountains are volcanic mountains, fold mountains, block mountains.
- Erosion is the process that removes rock, dissolved materials, or soil from one portion of the earth’s crust to another by the action of flowing water, wind, etc.
- Cooling down of the lava and ash due to volcanic eruption leads to the formation of a cone-shaped rock. These lay over one another to form volcanic mounatins.
- Fold mountains are formed by the collision between two plates head-on, their edges get crumbled.
- Mountains create their own climate.
- Depending on the difference in temperature and rainfall, the vegetations are also different in the mountains.
- The life of animals in the mountains is comparatively very harsh.
Questions for practice:
- What are mountains and name the different types of mountains?
- Name the processes by which mountains are formed?
- What is erosion?
- How are volcanic mountains formed?
- What is the difference between block mountains and fold mountains?
- Give some examples for volcanic mountains, block mountains and fold mountains.
- Do mountains make their own climate?
- Can you explain the climate in the mountains?
- How do you know about the vegetation and wildlife in the mountains?
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