Social Science : Geography
LITHOSPHERE – II
EXOGENETIC
PROCESSES
VII. Answer in
paragraph
1. Write a note on weathering
classify and explain.
Weathering:
• Weathering is the
disintegration and decomposition of materials of the earth's crust by their
exposure to atmosphere.
Types :
• Physical weathering
• Biological weathering
• Chemical weathering
Physical
Weathering:
• The breakdown of rocks without changing their chemical
composition, through the action of physical forces is " Physical
Weathering"
• Exfoliation, block disintegration, granular disintegration,
are different types of weathering.
Chemical
weathering:
• Disintegration and decomposition of rocks due to chemical
reactions is called Chemical Weathering.
• Chemical weathering takes place through oxidation,
carbonation, solution and hydration.
Biological
weathering:
• Due to plants, animals and human beings occur.
• Biological weathering, Penetration and expansion of plant
roots.
2. Explain the erosional
landforms formed by underground water.
• As an agent of gradation, underground water creates distinct
landforms in limestone regions
Erosional Landforms
of Underground Water
• When the rain water mixes with carbon - di - oxide and enters
into a limestone region, it dissolves and destroys much of the limestone.
Terra Rossa
• Deposition of red clay soil on the surface of the Earth is due
to the dissolution of limestone content in the rock, (iron oxide is the reason
for redness)
Lappies:
• Lappies are the
long furrows formed when the joints of limestone rocks they are corrugated by
groundwater.
Sinkhole:
• A funnel shaped depressions formed due to dissolution of
limestone is 'sinkholes'.
Caves:
• The hollows that are formed by the dissolution.
• Caves are hollow that are formed by the dissolution of
limestones by carbonic acid are 'caves'.
Caverns:
• Caverns are the caves with irregular floors. Ex. Guptadham
caves in Western Bihar.
3. What is a glacier? Explain its
types.
Glaciers:
• A large mass of ice that moves slowly from its place of
accumulation is a 'Glacier'.
Based on the place
of occurence Glaciers are divided into
• Continental Glacier
• Valley Glacier
Continental Glacier
• Thick Sheets of ice that covers vast areas of a continent is
called 'Continental Glacier'.
Valley Glaciers
• The glacier which takes its origin from a snow covered mountain
range is known as a 'Valley Glacier'
(Like the rivers glaciers also carry out erosion, transportation
and deposition)
4. Describe the depositional work
of winds.
Depositional
Landforms of wind :
• Deposition occurs when the speed of wind is reduced by the
presence of obstacles, (bushes, forests, rock, structures) The sediments
carried by wind get deposited on both the wind ward and leeward sides of these
obstacles.
• Some of the depositional landforms are
• sand dunes
• Barchans
• Loess.
Sand Dune:
• In deserts, during sand storms, wind carries loads of sand.
When the speed of wind decreases, huge amount of sand gets deposited. These
mounds or hills of sand are called 'sand
dunes'.
• There are different types of sand dunes are
• Barchans
• Transverse dunes
• Longitudinal dunes
Loess:
• Loess are the deposits of fine silt and porous sand over a
vast region.
Barchans
• Barchans are isolated, Gescent shaped sand dunes, (windward
side - gentle slope; leeward side - steep slope)
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