MOUNTAINS 2

MOUNTAINS

HOW MOUNTAINS ARE FORMED

How Are Mountains Formed

• ( Oxford Int. Geo. Pg. 22 to 23) Mountains on land make up about one fifth of the earth surface. A few mountains stand alone such as Fujiyama in Japan, Mount Taranaki in New Zealand and Mount Kenya in Africa.

There are Three main ways by which mountains are formed.

• Some mountains are produced when Volcanoes Erupts. They are known as Volcanic Mountains.

• Some mountains are formed when the earth layers fold over each other. They are known as Fold Mountains.

• Others are formed when blocks of rocks squeeze against each other as a result of faults in the earth crust. These are known as Block Mountains.

Open Ended

There are three main ways by which mountains are formed. These are ..., ..., and ...

Volcanic Mountains

• When a volcanoes erupt many times it builds up a tall cone-shaped mountain. In order to understand how volcanic mountains are formed, we need to know what the inside of the earth looks like.

• Note that the earth is made up of layers of rock. The outside layer of rocks is known as the Earths Crust. Beneath the crust is the mantle. Near the top of the mantle some of the rocks are so hot that they have melted to form a thick liquid, like sticky tar.

• The molten rocks are under great pressure because all the rocks around it press down on it. If there is a weak point in the earth crust, the molten rocks burst through it out onto the earth surface forming a Volcanic Mountain.

Examples of Volcanic Mountains

• Volcanic mountains are mostly stand alone mountains.

• Mount Fuji in Japan is a Volcanic Mountain

• Mount Egmont in New Zealand Mount

• Erebus in Antarctica Mount Vesuvius in Italy

• Some Volcanoes are either Active, Dormant or Extinct

Open Ended

The Earth is made up of layers of rocks. The solid outside layer of rock is called ...

Fold Mountains

• The earths greatest mountain ranges such as the Alps, the Andes, the Rocky Mountains and the Himalayas are called fold mountains.

• They are built of rocks that were slowly forced up from the surface of the earth when two tectonic plates that makes up the Earth's crust pushed up against each other.

• The Earth's crust is made up of large pieces called plates which fit together like a jigsaw puzzle. Some of the plates have continents on them others carry oceans.

• The plates move slowly, floating on the molten rock of mantle below them

• Where two plates push against each other, the Earth's Crust is slowly pushed up in folds or ridges, which form Fold Mountains.

Fold Mountain

• India used to be a long way from Asia, but slowly the plates with India on it moved closer to the plates with Asia on it.

• The rocks in the sea between India and Asia were gradually pushed up into folds that now form the Himalayas mountain range.

• Many Fold Mountain range include the Alps, Andes, Rockies and Urals.

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Faults and Block Mountains

• While some plates are pushing together, others are moving apart. Europe and North America are slowly moving further apart. Each year the Atlantic Ocean is a few centimeters wider.

• As the rocks move apart they often crack and create breaks called faults.

• Sometimes large blocks of rocks are pushed up between two faults. These blocks may be so large that they form block mountains

Block Mountain

• Block Mountains often have flat tops

• A flat top highland is called a plateau. Examples of block mountains found include:

• Benbulben in Ireland, the Vosges Mountains in France, the Black Forest Area of Germany and some highlands in East Africa

Multiple Choice

The Alps, Andes and Himalayas are examples of block mountains.

• True

• False

Multiple Choice

As the rocks of the Earth’s crust move, the cracks or breaks that form are called faults.

• True

• False

Multiple Choice

Which of the following is a Volcanic Mountain

• Andes Mountain

• Mount Kenya

• Mountain Benbulben