Samacheer Kalvi 9th Social Science Geography Solutions Chapter 2 Pdf
Tamilnadu Board Samacheer Kalvi 9th Social Science Geography Solutions Chapter 2: Tamilnadu State Board Solution Class 9 Social Science Geography Chapter 2 – Lithosphere – II Exogenetic Processes.
Samacheer Kalvi 9th Social Science Geography Solutions Chapter 2: Overview
Board |
Samacheer Kalvi |
Class |
9 |
Subject |
Social Science (Geography) |
Chapter |
2 |
Chapter Name |
Lithosphere – II Exogenetic Processes |
Samacheer Kalvi 9th Social Science Geography Solutions Chapter 2 Lithosphere – II Exogenetic Processes
I.) Choose the best Answer:
1.) The disintegration or decomposition ofrocks is generally called as weathering.
a.) weathering
b.) erosion
c.) transportation
d.) deposition
2.) The process of the levelling up of land by means of natural agents is Gradation.
a.) aggradation
b.) degradation
c.) gradation
d.) none
3.) Delta is seen in the lower course of the river.
a.) Rapids
b.) Alluvial fan
c.) Delta
d.) Gorges
4.) Karst topography is formed due to the action of Ground water.
a.) Glacier
b.) Wind
c.) Sea waves
d.) Ground water.
5.) Which one of the following is not adepositional feature of a glacier?
a.) cirque
b.) Moraines
c.) Drumlins
d.) Eskers
Answer: Cirque is not a depositional feature of a glacier.
6.) Deposits of fine silt blown by wind is called as Loess.
a.) Loess
b.) Barchans
c.) Hamada
d.) Ripples
7.) Stacks are formed byWave erosion.
a.) Wave erosion
b.) River erosion
c.) Glacial erosion
d.) Wind deposion
8.) Glacial erosion is responsible forthe formation of cirque.
a.) wind
b.) glacial
c.) river
d.) underground water.
II.) Match the following:
Answer
- Distributaries – Lower course ofriver
- Mushroom rock – Aeolian process
- Eskers – glacial action
- Stalactites – karst topography
- Cliff – action of sea wave
III.) Consider the given statements and choose the right option given below
1.) (i) ‘I’ Shaped valley is an erosionalfeature of the river.
(ii) ‘U’ Shaped valley is an erosionalfeature of the glacier.
(iii) ‘V’ Shaped valley is an erosionalfeature of the glacier.
a.) i, ii & iii are correct
b.) i & ii are correct
c.) i & iii are correct
d.) only (iii) is correct
Answer: Statement i & ii are correct.
2.) Statement I: Running water is animportant agent of gradation
Statement II: The work of the riverdepends on the slop of land on whichif flows
a.) Statement I is false and II is true
b.) Statement I and II are false
c.) Statement I is true and II is false
d.) Statement I and II are true
Answer: Statement I and II are true.
3.) Statement: Limestone regions haveless underground water.
Reason: Water does not percolatethrough limestone
a.) The statement is right reason iswrong.
b.) The statement is wrong reason isright.
c.) The statement and reason are wrong.
d.) The statement and reason areright.
Answer: d) The statement and reason are wrong.
IV.) Answer in brief:
1.) Define weathering.
Answer:When the material of the earth starts breaking, disintegrating and decomposing due to its exposure to the atmosphere is known as weathering.
2.) What do you mean by biological weathering?
Answer: Plant root expands and penetrate any material and earthworms also break the material and burrowing animals like rabbits or rat also cause weathering hence it called biological weathering.
3.) Mention the three courses of a river with any two land forms associated to each course.
Answer:There are three courses of rivers: The Upper Course, The Middle Course, The Lower course.
i) The Upper Course: In the upper course erosion plays very important role. This is the place where river falls down the steep from the mountain. As the steep gradient increase the velocity does its work and performs erosion with force, this force widens valley and make in deeper. The land carved by a river has a feature like V-shaped valleys, canyons, rapids, spurs, pot holes, gorges, and waterfalls at its upper course.
ii) The Middle Course: The river starts flowing and reach in the middle of the plain and the water volume is also increase if other tributaries meets to the river hence transportation also done by using this feature of the river. The water is flowing from upper course with a great velocity and velocity suddenly decreases here and thus deposition is also takes place here, all solids or soil settles down here. The landform at this place are like flood plains, meanders, ox-bow lakes etc.
iii) The Lower Course: The lower course is the last stage of the river we can say. At this stage the plain gets filled with debris which came with the flowing water. Big amounts of solids and sediments are deposited here, we can find many pollutants here. The river gets distributed in many distributaries. The main process takes place at this stage is deposition and delta or estuary landforms formed.
4.) What are ox-bow lakes?
Answer:When the curves of the river almost makes a complete circle and have very narrow necks thus it forms a lake, this lake is known as Ox-Bow Lake. The curves also known as meanders and this process take time and thus Ox-Bow lake came into existence.
5.) How does a sea cave differ from a sea arch?
Answer:In the sea the waves slams on a rock material and erosion of rocks takes place and thus the caves are formed, it called Sea Caves. Sea Arch are different from the Sea Caves. Sea Arch forms when the headline of two caves get united, it forms a shape of an arch hence it is known as Sea Arch. The examples of Sea Arch can be seen at Neil Island, Andaman & Nicobar.
6.) List out any four karst topographical areas found in India.
Answer:In India karst topographical areas found at
i) Western Bihar: In Western Bihar Guptadham Caves are found.
ii) Madhya Pradesh: Pandav cave and Pachmari hills are found in Madhya Pradesh.
iii) Uttarkhand: Robert Cave and Tapakeshwar Temple is found in Uttarkhand.
iv) Chhattisgarh: Kutumsar caves are found in Bastar district of Chhattisgarh.
7.) What do you mean by a hanging valley?
Answer:Hanging Valley forms when the tributary glacier erodes and this eroded glacier hangs over the main valley.
8.) Define: a) Moraine b) Drumlin c) Esker.
Answer: Definitions as follow
a) Moraine: Moraine is the material deposited by the Glaciers. There are three types of moraines according to location; Ground Moraine, Terminal Moraine and Lateral Moraine.
b) Drumlin: Drumlins are nothing but the deposits of glacial moraines. Drumlins looks line big inverted teaspoon of half cut egg.
c) Esker: Esker is a long narrow ridge formed by gravel and sand which deposited by melting streams and parallel to a glacier.
9.) Mention the various features formed by wind erosion.
Answer: There are some features formed by wind erosion as below
i) Mushroom Rock: Rocks are made from many layers, some of them are hard and some of them are soft layers. Soft-laden winds flows from the close of the land i.e. downside of the bottom and the constant friction of sand-laden wind with the rock erodes rock and the forms Mushroom shape hence it called Mushroom Rock, it also called pedestal rock. This kind of rocks are found at sandy areas like Jodhpur in Rajasthan.
ii) Inselberg: Inselberg means Island Mountain in the German. Igneous rocks are some of the rocks resistant to wind. Thus isolated residual hills rises abruptly in the surroundings, these structures are known as Inselberg, they are found in Uluru or Ayers rock in Australia.
iii) Yardang: In the arid regions some rocks are made from soft and hard, both kind of layers. Soft layers get eroded when the air flows and it forms a structure called Yardangs.
10.) What is a wave cut platform?
Answer: At the bottom of sea cliffs flat surface are found, this flat surface known as wave cut platform. Another name for the wave cut is wave cut benches terrace.
V.) Give Reasons:
1.) Chemical weathering is predominant in hot and humid zones.
Answer: Chemical Weathering is basically disintegration and decomposition of rocks due to chemical reaction. Chemical weathering goes through the prosses of oxidation, carbonation, solution and hydration. The main agents of chemical weathering are oxygen, carbon-dioxide, hydrogen and water. For the process like hydration humid conditions are required hence we can see chemical weathering predominant in hot and humid zones.
2.) Silt deposits are less at estuaries than deltas.
Answer: Estuary forms when river meets the sea. At the estuaries like delta where waves erode deposits deposition of silt is not possible. For example, River Narmada and Tapti.
3.) Wind can possibly erode the rocks from all sides.
Answer: Wind can flow from all sides hence it is possible that the wind erodes the rocks from all sides. Soft layers of the rocks are gets eroded and the rocks form a shape. Thus, wind forms landforms like Mushroom Rocks, Inselberg and Yardang.
VI.) Distinguish between:
1.) Physical and chemical weathering.
Answer:
Physical Weathering | Chemical Weathering |
Rocks are breaks down without changing its chemical composition. | Chemical weathering is disintegration and decomposition of rocks due to chemical reaction. |
Physical Weathering takes place through physical forces. | Chemical weathering takes place through chemical reactions. |
Major types of physical weathering are exfoliation, block disintegration, granular disintegration. | Chemical weathering happens through processes of oxidation, carbonation, solution and hydration. |
2.) Delta and Estuary
Answer:
Delta | Estuary |
At the mouth of the river a triangular shaped low-lying area forms known as Delta. | The place where rivers meets the sea known as Estuary. |
Fine deposits sediments, rich with minerals are found at this place. | Deposition is not possible due to eroding waves. |
Examples: Cauvery Delta, Tamil Nadu. | Examples: Narmada River and Tapti River. |
3.) Stalactite and stalagmite.
Answer:
Stalactite | Stalagmite |
Stalactites formed when the calcite dissolved water drips from the ceiling of the cave, water evaporates and calcite hangs to ceiling. | Calcite deposited on the floor by ceiling drippings and this calcite deposits rise upward like a pillar it forms Stalagmites. |
The direction of Stalactite is from up to down. | The direction of Stalagmite is upward, from down to up, like pillar. |
4.) Longitudinal and Transverse sand dunes.
Answer:
Longitudinal Sand Dunes | Transverse Sand Dunes |
Longitudinal sand dunes are the long narrow ridges of sand. | Transverse sand dunes are asymmetrical in shape. |
Longitudinal sand dunes Parallel to prevailing winds and the ridges are extends to one direction. | Transverse sand dunes are formed through fast and slow winds which blow from same direction. |
5.) Inselbergs and yardangs
Answer:
Inselbergs | Yardangs |
Inselbergs forms when friction takes place between wind and hard rock like igneous. | There are some rocks which made from hard and soft layers arranged vertically. |
Isolated residual hills rise abruptly from their surroundings are known as inselbergs. | Yardang forms when the rock which have hard and soft layers arranged vertically and the wind blow and soft layer gets eroded and leaves irregular crests. |
6.) Spit and bar.
Answer:
Spit | Bar |
Spit is ridge or embankment of sediment attached to the land at the ending and terminating the open water at another end. | Bar is a elongated deposit of sand, mud or shingle which found in the sea. |
Spits are common at the mouth of estuaries. | Bar is almost parallel to the shoreline. |
VII.) Answer in Paragraph:
1.) Write a note on weathering classify and explain.
Answer: Material of the earth starts breaking naturally or disintegration and decomposition happens with any material naturally it is known as weathering. The weathering happens due to exposure to the atmosphere. Weathering classified in three types i) physical ii) Chemical and iii) Biological.
i) Physical weathering: The material of the earth breakdown without changing its chemical composition and the breakdown takes place due to physical forces is known as weathering. Frequent freezing and thawing of the rocks lead to the expansion and contraction of rocks. Cracks takes place and finally disintegration happens. The major types of physical weathering are exfoliation, block disintegration and granular disintegration.
a) Exfoliation: Exfoliation happens when the heating and cooling happens alternately. It peels the surface of the rock layer by layer, just like an onion. Other types of exfoliation are sheeting and shattering.
b) Block Disintegration: Continuous expansion and contraction to day and night cause stress to the joints of the rocks, this stress causes block disintegration.
c) Granular Disintegration: In the crystalline rocks the grains become loose and fall out are known as Granular Disintegration. It happens due temperature.
ii) Chemical Weathering: Due to chemical reaction the rock is disintegrated and decomposed and this is how chemical weathering happens. Chemical weathering predominantly takes place in the hot and humid regions like the equatorial, tropical and sub-tropical regions. In chemical weathering oxidation, carbonation, solution and hydration processes takes place.
a) Oxidation: There is an oxygen in the atmosphere which reacts with the iron in the rock and iron oxide forms. It is like rusting of iron, air pressure and water weakens the rock and thus oxidation takes place.
b) Carbonation: When the atmospheric carbon-dioxide mix with water and forms carbonic acid then the process is called carbonation. Caves are formed due to carbonation in limestone region. Rocks get disintegrated when the carbonic acid reacts with the carbonate rocks.
c) Solution: Rocks get dissolved in the water and particles of the rock get loosened thus the rock breaks.
d) Hydration: There are some chemicals in the rock which absorb water from atmosphere and enlarge the size of the rock and this swelling of the rock cause disintegration of the rock. This kind of weathering is known as hydration.
iii) Biological Weathering: When any plant root expands and penetrate to the rock then biological weathering happens. Earthworks, burrowing animals like rabbits, rats and human activities also causes biological weathering.
2.) Explain the erosional landforms formed by underground water.
Answer: The process of solution also causes of erosion. When it rains in limestone region the rain water mix with carbon dioxide and dissolves limestone and forms landforms like Terra rossa, Lappies, sinkholes, swallow holes, dolines, uvalas, poljes, caves and caverns.
i) Terra Rossa: In Italian Terra Rossa means Red Soil. Limestone from the rocks get dissolved due to rain and limestone get dissolved and iron oxide in it gives redness to soil.
ii) Lappies: Joints of limestone rocks get corrugated due to groundwater and long furrows comes into existance are known as Lappies.
iii) Sinkhole: Sinkhole is a funnel shaped depression forms when limestone dissolves. The average depth of sinkhole is three to nine meteres.
iv) Caves and Caverns: Caves and caverns are also forming due to erosion by underground water. Dissolution of limestone rocks casing caves and carbon dioxide in the air makes carbonic acid after reacting with water. Caves with irregular floors are known as Caverns for example Guptadham caves in Western Bihar.
3.) What is a glacier? Explain its types.
Answer: Big slice of ice moves very slowly over the land from the place it accumulated is known as glacier. Another name for glacier is ‘River of ice’. Snowline is the height above the permanent snow cover in the higher altitude or latitude. The snowline gets lower as the latitude gets higher from sea level. Snow slowly turns into granules; these granules are known as ‘firn’ and also known as ‘neve’. These neve turns into solid glacial ice.
Two types of landforms glacier forms: Erosional Landforms and Depositional landforms
i) Erosional Landforms of glacier: Glaciers considered very powerful erosive agents. They make landforms like cirque, aretes, matterhorn, U-shaped valley, hanging valley, fiords etc.
a) Cirque: A bowl-shaped armchair forms due to erosion of glacier to the steep side walls of the mountain known as Cirque.
b) Arete: When two cirque wall joints and form ridges like narrow knife is known as Arete.
c) U-Shaped Valley: Sometimes glacier moves down with river valley and hence valley gets eroded deep and wide and U shape valley takes place.
ii) Depositional Landforms of glacier: When glacier got eroded the fragments of the rocks and boulders forms glacial debris, dirt is also mixed in it. It all gets deposited in the low-lying areas. It forms features like moraines, drumlines, eskers, kames and outwash plains.
4.) Describe the depositional work of winds.
Answer: Wind makes very interesting depositional landforms, some of them are
i) Sand Dune: When sandstorm is there in the desserts, wind carries sand and when storm get settled and slow down it deposits big amount of sand. This deposited sand makes hill of the sand, this hill is known as sand dunes.
There are many types of Sand dunes.
a) Barchan: It is a type of dunes isolated and looks like crescent in shape. Barchan have gentle slope on the windward side and steep slopes on the leeward side.
b) Transverse dunes: These dunes are asymmetrical in shape. These types of dunes form due to slow and fast winds alternately which flows towards same directions.
c) Longitudinal Dunes: Long narrow ridges of sand formed on sand are known as Longitudinal dunes. These dunes are extended in the parallel direction to the prevailing winds. Longitudinal dunes are known as Seifs in Sahara.