GEO - FORMS OF THE EARTH

I.        Define:

            1. Mountains - Mountains are naturally elevated large mass of land forming peaks which occur in long narrow chains called ranges.

            2. Plateaus - Plateaus are uplifted sections of the earth's crust that are almost flat or level; usually descend steeply to the surrounding low lands also known as plain-in-the air or tableland.

            3. Plains - are vast, nearly flat , expanses of land, less than 200 meters above sea level.

II.     Answer the following questions:

1. Which forces cause movement below the ground and how?

Ans -Internal forces ( Endogenic forces) and External forces ( Exogenic forces) cause movement below the ground. The plates in the Earth crust are in constant motion and collide with each other due to internal forces. Slow movement within the earth are either caused by compression or by tension

2. Describe different types of mountains.

Ans - There are four types of mountains:-

            1) Fold mountains - formed when the layers of the earth's crust are folded by compression
which is caused by the forces generated by movements inside the earth. ex- Aravallis, Himalayas, etc.

            2)Volcanic mountains -when a volcano erupts, it gives out hot molten lava, ash, cinder and smoke vent is the opening from which the lava comes to the surface and solidify after cooling. ex - Mt. Fuji Japan.

            3) Block mountains -formed due to the forces of compression or tension, cracks or faults appear in the earth's crust when the land between two faults is pushed upwards above the surrounding level they form block mountain or horsts. ex -the Vosges and the Black Forest

            4) Residual mountains -Continuous erosion of old fold mountains or block mountains over the years forms residual mountains. ex - Mt. Monadnock in USA and Highlands of Scotland

3. How mountains are important for us?

Ans -   1) Rivers originate in mountains.
            2) Home for a variety of flora and fauna.
            3) Affect the climate of an area.

            4) Mountains are a store house of water. Many perennial rivers originate in the
            glaciers.

            5) The river valleys and the gentle slopes of the mountains are used for cultivation
            of crops and fruits.

            6) provide minerals for industries and stones for construction.
            7) provide valuable softwood, medicine, herbs and other products.

            8) Mountains are very important for tourism.

4. Describe types of plateaus.

Ans - 1)  Techtonic Plateaus - Formed due to movements inside the earth, have considerable size and uniform altitude. They are of three types -

            a) Continental plateaus - Formed due to upliftment of a block of land from the adjacent lowland or sea. Ex - Chota Nagpur Plateau,           Plateau of South Africa, Meseta of Spain, etc.

            b) Intermontane Plateau - Surrounded by fold mountains. ex - Bolivian plateau between two ranges in Andes, Snake Plateau in Columbia, etc.

            c) Piedmont Plateau - Lies at the foot of mountains.  E.g. plateau of Patagonia in Argentina

2) Volcanic Plateaus - Molten lava erupts from the cracks on the Earth’s surface , solidifies on its surface in successive layers and forms plateaus. E.g. Deccan Plateau
3) Residual Plateaus -Formed by continuous erosion of an old fold mountain or block mountain by natural agents such as wind, rivers, rain etc.E.g. the Fjeld Plateau in Scandinavia, the Cumberland Plateau in the USA.

5. Explain the importance of plateaus?

Ans -    Plateaus are rich in mineral deposits. The African plateau is rich in gold, diamond, copper, uranium, etc. In India, the Deccan and the Chota Nagpur plateaus have vast reserves of coal, iron-ore, manganese, bauxite, etc.
-Rivers in the plateau regions form waterfalls as they drop abruptly down the steep slopes. These waterfalls are utilised for generation of hydroelectricity. The Victoria Falls in Africa, the Niagara Falls in North America and the Jog Falls in India are some examples.
-Volcanic plateaus are rich in black soil. They are very fertile and good crops like cotton and sugarcane.
-The natural beauty of plateau areas also attracts many tourists.

6. Explain the different types of plains.

Ans - 

1)       Depositional Plain: various agents of erosion (wind, rivers, glaciers etc.) deposit over the years , they form depositional plains. they are three types:
-  Alluvial plains: formed by deposition of water ; e.g. indo- Gangetic Plain(India)
-  Mississippi River Plain: formed by deposition of glaciers; e.g. plains of Indiana (North America)
-  Desert plains: formed by winds; e.g. Sahara desert

2) Structural Plain: Formed by internal forces that result in upliftment of the horizontal layers of the Earth. E.g. Central Lowlands of Australia and Great Plain of USA

3) Erosional Plains: carved when rivers , wind, glaciers etc erode asmoothens the irregularities of the Earth’s surface e.g. Interiors plains of Canada

4) Coastal Plains: Situated near the sea shore E.g. Malabar Coast along the Western Coast of India

7. Explain the importance of plains.

Ans - Most plains have fertile soil and are, thus, ideal for agriculture. River plains have abundant supply of water, which is very useful for human settlements. The flat surface of plains helps in the construction of transport network, buildings, industries, etc.

8. In which landform human beings settle and what changes they make to settle?

Ans - Human settlement are found in all kinds of landforms

            The flat surface of plains helps in the construction of transport network, buildings, industries, etc. Settlement also found in areas prone to natural disasters such as volcanoes, earthquake.Technology has helped in minimising the risk of staying in the such areas.
            To establish settlement people have polluted air and water bodies, caused
deforestation and degradation of land. We should use natural resources carefully.

9. Explain the different types of minor landform.

Ans -

Minor landforms	Details	Examples
Island	piece of land surrounded by water on all sides	the Lakshadweep Islands, The Andaman and Nicobar Islands
Peninsulas	piece of land surrounded by water on three sides and joined to a larger land mass	the peninsular plateau of India, the Malay Peninsula
Isthmuses	an elongated narrow piece of land with water on each side joining two large land masses	Isthmus of Panama, Isthmus of Suez