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Social Science : Geography
LITHOSPHERE – II
IV. Answer in brief
1. Define weathering.
Weathering is the disintegration and decomposition of materials of the earth's crust by their exposure to atmosphere.
2. What do you mean by biological weathering?
Biological weathering occurs due to the penetration and expansion of plant roots, earthworms, burrowing animals (rabbits, rats) and some human activities.
3. Mention the three courses of a river with any two land forms associated to each course.
• The Upper Course - V - shaped valleys, canyons
• The Middle Course - meanders, flood plains
• The Lower Course - delta, estuary
4. What are ox - bow lakes?
• Meanders in due course of time become almost a complete circle with narrow necks.
• This inturn gets abandoned and forms a lake. This is called an ox - bow lake.
5. How does a sea cave differ from a sea arch?
• Prolonged wave attack on the base of cliff erodes rock materials, which result in the formation of caves.
• When two caves approach one another from either side of a head land and unite, they form an arch. (eg) Neil Island, Andaman and Nicobar.
6. List out any four Karst topographical areas found in India
• Guptadham caves - Western Bihar
• Robert cave - Uttarakhand
• Pandav caves - Madhya Pradesh
• Borra caves - Andhra Pradesh
7. What do you mean by a hanging valley?
A hanging Valley is a valley eroded by tributary glacier and that hangs over the main valley.
8. Define a) Moraine b) Drumlin c) Esker
• Land forms formed by the glacial deposits of valley or continental glaciers are moraines.
• Drumlins are deposits of glacial moraines that resemble giant inverted tea spoons or half cut eggs.
• Long narrow ridges composed of boulders gravel and sand deposited by streams of melting water which run parallel to a glacier are called eskers.
9. Mention the various features formed by wind erosion.
• Mushroom rocks
10. What are wave cut platform?
• Flat surface found at the foot of sea cliffs are called wave cut platforms.
• Wave cut platform is also referred as beach, shelf, terrace and plain.
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