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Summary
The Earth’s surface is not the same everywhere; it has many different shapes like high mountains, flat plains, and raised plateaus. These features are called landforms. The study of these landforms, how they are made, and how they change is called geomorphology. Landforms are always changing due to processes happening both inside the Earth and on its surface. These changes can be very slow, taking millions of years.
Two main kinds of forces shape our Earth. Endogenetic forces come from inside the Earth. Some are sudden, like volcanoes and earthquakes. Others are very slow, like the movements that build continents or create mountains by pushing and squeezing the Earth’s crust. Exogenetic forces work on the Earth’s surface. These include things like rivers, wind, ice, and waves. They wear down high areas and fill up low areas. This wearing down is called erosion, and the filling up is called deposition.
Weathering is a process where rocks are broken down into smaller pieces without being moved. This can happen due to changes in temperature or the actions of plants and animals. Gradation is a larger process that includes weathering, erosion (carrying away broken rock), transportation (moving the material), and deposition (dropping the material in a new place). Degradation makes land lower, while aggradation builds it up.
Mountains are large, high landforms. Fold mountains, like the Himalayas, are formed when layers of rock are squeezed and folded, much like a carpet wrinkles if you push it from the sides. Volcanic mountains are built up by layers of lava and ash from volcanic eruptions. The area around the Pacific Ocean has many volcanoes and is called the “Pacific Ring of Fire.” Block mountains form when large blocks of the Earth’s crust move up or down along cracks called faults. Sometimes, the land between two faults sinks, creating a rift valley. Residual mountains are what’s left when softer rocks around them have been worn away by erosion.
Plateaus are large, flat areas of land that are higher than the land around them. They are often called “table lands” because they are flat on top like a table. Some plateaus, like the Tibetan Plateau, are found between mountain ranges. The Pamir Plateau is so high it is known as the “roof of the world.” Volcanic plateaus are made from layers of hardened lava. Other plateaus are formed when old, high lands are worn down or when large areas of land are lifted up.
Plains are large areas of flat or gently rolling land, usually not very high. Some plains are formed by the uplift of land from under the sea. Erosional plains are created when higher lands are worn down by rivers, glaciers, or wind. Depositional plains are built up by materials like sand, silt, and mud left behind by rivers, glaciers, or wind. For example, rivers deposit rich soil on flood plains and build deltas where they meet the sea.
These different landforms affect how people live. Mountains can be difficult for farming and building, but they are sources of rivers and can influence weather. Plateaus can be good for grazing animals and may contain valuable minerals. Plains are often good for farming and are where most cities are built because it’s easier to build homes and transport goods.
Textual Questions, Answers (Oriental)
Multiple Choice Questions
1. Endogenetic forces are also called— (Earthquakes/Internal processes/Earth move).
Earthquakes/Internal processes/Earth move
Answer: Internal processes
2. Greek word ‘epeiros’ means— (a continent/an Ocean/a mountain).
a continent/an Ocean/a mountain
Answer: a continent
3. The Plate ‘Techtonic ‘ is related to the formation of— (block mountains/rift valleys/fold mountains).
block mountains/rift valleys/fold mountains
Answer: fold mountains
4. Faults are due to— (tensional forces/ contractional forces/compressional forces).
tensional forces/ contractional forces/compressional forces
Answer: tensional forces
5. Faults are related to (fold mountain/volcanic mountain/ block mountain).
fold mountain/volcanic mountain/ block mountain
Answer: block mountain
6. Block mountains are formed by— (folding/faulting/volcanic eruption).
folding/faulting/volcanic eruption
Answer: faulting
7. Aravalli, Pareshnath, Rajmaha hills are examples of— (block mountains/ fold mountains/residual mountains).
block mountains/ fold mountains/residual mountains
Answer: residual mountains
8. Rocky, Alps, Himalayas are examples of— (residual mountains/ block mountains/fold mountains).
residual mountains/ block mountains/fold mountains
Answer: fold mountains
9. The name of the highest volcano in the world is— (Mauna Loa in Hawaii/Fujiyama in Japan/Vesuvius in Italy.)
Mauna Loa in Hawaii/Fujiyama in Japan/Vesuvius in Italy.
Answer: Mauna Loa in Hawaii
10. The Chhotanagpur plateaus are examples of— (intermontane plateaus/dissected plateaus/ lava plateaus).
intermontane plateaus/dissected plateaus/ lava plateaus
Answer: dissected plateaus
True or false
1. Aravalli range is a young fold mountain.
Answer: False
Explanation: The Aravalli range is actually one of the oldest fold mountain systems, not a young one. It belongs to a much earlier period of mountain formation. Young fold mountains, like the Himalayas, are geologically much more recent.
2. Deccan plateau has been formed by the volcanic eruption.
Answer: True
Explanation: Indeed, the Deccan Plateau was formed by extensive volcanic activity. Over time, layers of lava erupted from volcanoes and spread out, building up this vast plateau. The Maharashtra plateau is a good example of this process.
3. The valley between two block mountains is called a rift valley.
Answer: True
Explanation: Yes, that’s correct. When a block of land between two faults subsides, or sinks down, while the adjacent blocks remain elevated as block mountains, the resulting depression is known as a rift valley.
4. The Mississippi Delta takes the shape of the foot of a bird.
Answer: True
Explanation: That’s right. The Mississippi Delta is a classic example of what we call a bird’s-foot delta. This distinctive shape occurs when the river deposits a lot of sediment into relatively calm waters, allowing its distributaries to extend outwards, resembling the talons of a bird’s foot.
5. The river Nile forms the largest delta in the world.
Answer: False
Explanation: While the Nile River does form a very significant and large delta, the information available doesn’t confirm it as the absolute largest in the world. There are other extremely large delta systems globally.
6. The Malnad plateaus are important examples of dissected plateau.
Answer: True
Explanation: Dissected plateaus are those that have been significantly eroded by rivers and streams, creating a landscape of valleys and ridges. If the Malnad plateaus exhibit these characteristics of being extensively cut by water action, then they would indeed be examples of dissected plateaus.
7. The Barren Islands in the Andaman and Nicobar Islands of India are examples of volcanic mountain.
Answer: True
Explanation: Yes, this is correct. The Barren Islands, located in the Andaman and Nicobar group, are indeed examples of volcanic mountains. In fact, Barren Island is known for being an active volcano.
8. In India the Narmada and the Tapti rivers flow through two rift valleys and the Satpuras in between them is a block mountain.
Answer: True
Explanation: This is an accurate description. The Narmada and Tapti rivers in India flow through rift valleys, which are depressions in the land. The Satpura range, situated between these two river valleys, stands as an example of a block mountain, an uplifted block of land.
Answer in very short
1. Where was the ‘Tethys Sea’ located?
Answer: The Tethys Sea was a vast ocean that existed between the ancient supercontinents of Gondwana (to the south) and Laurasia (to the north) during much of the Mesozoic Era, roughly 250 to 66 million years ago.
2. Why is Pamir plateau called the ‘roof of the world’?
Answer: The Pamir is the highest plateau (4,873m.) in the world and that is why it is called the roof of the world.
3. Name the largest deltaic plain in the world.
Answer: The river Nile forms the largest delta in the world.
4. Give an example of block mountain.
Answer: In India the Narmada and the Tapti rivers flow through two rift valleys and the Satpuras in between them is a block mountain.
5. Which is the largest Aggradational Plain in India?
Answer: The largest Aggradational Plain in India is the Ganga Plains or Indus-Ganga-Brahmhaputra plains.
6. Name one lava plateau.
Answer: The Southern Plateau or Maharashtra Plateau of India is an example of extensive lava plateau.
7. Name one bird’s foot type delta.
Answer: The Mississippi Delta takes the shape of the foot of a bird.
8. Which type of mountain is the Andes?
Answer: The Andes are Fold Mountains.
9. Name any Volcanic mountain.
Answer: Examples of volcanic mountains include The Coto-paxi in Equador, The Fujiyama in Japan, The Mt. Popo in Mayanmar, The Stromboli in Italy, The Vesuvius in Italy, and The Barren and Narcondam in Andaman & Nicobar islands of India.
10. What is Orogeny?
Answer: When two plates move towards each other, horizontal pressure originates and it exerts tremendous pressure on the sedimentary rock beds lying on the sea-bottom, pushes and pulls up the sedimentary layers by bending them. A series of folds then formed to build up the fold mountains. This is an Orogenic collision.
11. Give at least two examples of dissected plateau.
Answer: Examples of dissected plateaus include the Meghalaya plateau and the Malnad plateaus.
12. Give at least two examples of Residual mountains.
Answer: Examples of Residual or Relict mountains include the Aravallis, the Nilgiris, and the Paresnath in India.
13. What is the name of highest plateau of India?
Answer: The Ladakh plateau of Kashmir is the highest plateau in India.
14. Name the oldest fold mountain of India.
Answer: The oldest fold mountain of India is The Aravallis.
15. Give two examples of rift valleys of India.
Answer: Two examples of rift valleys of India are the Narmada valley and the Damodar valley.
16. The Himalayas belong to which type of mountain?
Answer: The Himalayas are Fold Mountains, specifically New or Young Fold mountains.
Write Short notes
1. Monadnock
Answer: Monadnocks are eroded and isolated remains of resistant rock materials appearing like mountains, named after Mt. Monadnock in New Hampshire in USA. Thus, all monadnocks may be called Residual Mountains. These eroded and lowered relicts of landforms were called Monadnocks by W. M. Davis. Residues of hard rock that stand above the general level of the land are known as ‘Monadnocks’. Where rocks remain hard and resist erosion, monadnock types of hills are formed.
2. Inselberg
Answer: An Inselberg is a German word that means ‘island mountains’. Inselbergs are outstanding rounded steep-sided residual hills. They are mainly formed of granite and gneiss and are remnants of an original plateau which has been eroded away by wind action. They have a steep slope and rounded top and are found in the Kalahari and West Australian Deserts. Inselbergs are formed in desert areas.
3. Butte
Answer: A butte is a residual hill formed by the erosion of a mesa. After additional erosion from all sides, a mesa is further reduced to a smaller remnant flat summit called a butte. They are found in the Arizona desert of the USA.
4. The Pacific-ring of fire
Answer: The Pacific ring of fire refers to a belt where there are about more than 500 active volcanoes concentrated, which encircles the Pacific Ocean like a ring. This is called the ‘Pacific Ring of Fire’. This belt contains nearly 80% of the total number of active volcanoes. This belt includes the Andes Mountains of South America and the Rockies of North America.
5. Relict Mountains
Answer: Relict Mountains, also known as Erosional, Residual, or Denudated Mountains, are formed by the process of erosion and denudation by which soft rocks are worn down and the resistant rock masses are left standing still. Examples include the Aravallis, the Nilgiris, the Paresnath in India, and the Mesas and Buttes of the USA. Characteristics of these mountains are:
(i) Most of the erosional mountains are of irregular shape.
(ii) In the erosional mountain, the top is generally flat or of rounded shape.
(iii) The erosional mountains are very old in age and are of ancient origin.
(iv) They have a gentle slope.
(v) They are not so lofty.
6. Rift Valley
Answer: A Rift Valley is formed when two roughly parallel faults occur side by side, and the portion of the crust between these two faults may get depressed by movements along the fault lines to form a long (several kilometres in length) narrow valley. In German, a rift valley is called a graben. Examples include:
(i) In India, the Narmada and the Tapti flow through two rift valleys, and the Satpuras in between them is a block mountain.
(ii) The Rhine river flows through the graben between the two horsts, the Vosges (France) and Black Forest (Germany).
(iii) The most well-known rift valley is the Great Rift Valley of Africa, which stretches from Mozambique in the south to Syria in the north, a total length of about 6440 km.
(iv) The upper part of the Damodar river is another example of a river valley.
(v) The Death Valley of California (USA) is a rift valley.
Characteristics of a rift valley are:
(i) Rift valleys are bounded by steep scarps.
(ii) Such valleys have straight wall-like sides which may extend for hundreds of kilometres.
7. Horst
Answer: In Germany, a block mountain is called a horst. Horst or Lifted Block Mountains are mountains which have a flat top and extremely steep slopes on every side. The Western Ghat hills of India and the Great Basin Range of USA are examples of such type of mountain. The Rhine river flows through the graben between the two horsts, the Vosges (France) and Black Forest (Germany).
Answer the following questions briefly
1. Classify mountains according to their mode of origin.
Answer: Mountains are classified into four types according to their structure and mode of origin, viz 1 Fold Mountains, 2 Block Mountains, 3 Volcanic Mountains and 4 Residual Mountains.
2. Classify plateaus according to their mode of origin.
Answer: Based on structure and origin plateaus may be classified into the following main types, viz. 1. Tectonic Plateaus, 2. Erosional Plateaus, and 3. Depositional Plateaus.
3. Name with examples any three types of mountain?
Answer: Three types of mountains with examples are:
(i) Fold Mountains: These are formed by folding of sedimentary rocks strata of the earth’s crust due to forces of compression. Examples include the Himalayas (Asia), Alps (Europe), Rockies (N. America), Andes (S. America), and Atlas (Africa).
(ii) Volcanic Mountains: These are mountains formed in the form of tall conical or dome shaped extrusions at the volcanic site by the accumulation of lava, dust, and liquid mud. Examples include The Coto-paxi in Equador, The Fujiyama in Japan, Mt. Popo in Mayanmar, The Stromboli in Italy, The Visuvius in Italy, and The Barren and Narcondam islands in India.
(iii) Block Mountains: These are formed when a landmass is uplifted between two parallel faults or by the subsidence of land outside the faults. Examples include The Great Basin Ranges (USA), Vosges (France), Black Forest (Germany), and in India, the Vindhyas, Satpuras, and Tura.
4. What is meant by mountain of Accumulation?
Answer: A mountain of accumulation refers to mountains which are formed by the accumulation of materials. For instance, Volcanic Mountains are formed in the form of tall conical or dome shaped extrusions at the volcanic site by the accumulation of lava, as dust and liquid mud, ejected via a vent of the mouth of the volcano in successive layers. These volcanic mountains are formed by the accumulation of volcanic materials, like lava, magma, volcanic ash and dust etc., which are deposited in layers around the vent, building up a volcanic cone in time.
5. How are Block Mountains formed?
Answer: Block mountains, also called fault block mountains, are formed due to faulting as a result of tensile and compressive forces. According to the fault theory, block mountains are formed in the following ways:
(i) Due to upward movement of the block in the middle between two normal faults. The summit of the block is flat.
(ii) Sometimes, the surrounding blocks subside leaving the middle block stationary. Such cases are found in high plateau regions.
(iii) Block mountains may originate when the middle block moves downward and becomes a rift valley while the surrounding blocks stand higher as block mountains.
6. What are Dissected Plateaus ? Give one example.
Answer: Dissected plateaus are plateaus that are cut by rivers and broken by deep narrow valleys. An example of a dissected plateau is the Meghalaya plateau.
7. Describe the characteristics of Block Mountain with examples.
Answer: The characteristics of Block Mountains are:
(i) These mountains are usually very steep-sided and they are flat-topped.
(ii) They are not as lofty as the fold mountains, nor they stretch for vast areas like the fold mountains.
(iii) Block mountains are associated with a graben or rift valley.
Examples of block mountains include The Great Basin Ranges (USA), Vosges (France), Black Forest (Germany), and in India, the Vindhyas, Satpuras, and Tura.
8. State the genesis of Fold Mountains with diagrams.
Answer: The genesis of Fold Mountains, which are formed by the folding of sedimentary rock strata of the earth’s crust due to forces of compression, is explained by two main theories:
(A) Geosyncline Theory: According to this theory, fold mountains originate from an elongated trough or shallow sea, called a geosyncline, which is filled with sediments brought by erosional agents from marginal higher lands. The heavy pressure of the continuous deposit of sediments causes the middle portion of the floor of the geosyncline to subside or sag. This results in consequential compression of the two adjacent landmasses of the geosyncline. The movement of these two landmasses from opposite ends towards each other causes the sedimentary layers in the geosyncline to get folded. These movements are known as the convergence of forelands. The enormous compressive forces produced by these moving forelands produce contraction, squeezing, and folding of sediments deposited on the geosynclinal bed. Due to contraction, the compressive forces raised the folded sedimentary layers of the geosyncline into folded mountains.
(B) Plate Tectonic Theory: This modern theory states that the solid lithosphere is made up of several continental and Oceanic Plates. Fold mountains may emerge at convergent boundaries or destructive edges, where two plates head on. This zone of collision may undergo crumpling and folding, which is an Orogenic collision. When two plates move towards each other, horizontal pressure originates and exerts tremendous pressure on the sedimentary rock beds lying on the sea-bottom, pushing and pulling up the sedimentary layers by bending them. A series of folds then formed to build up the fold mountains. The Great Himalayas formed this way.
9. Name with examples any three types of plateau.
Answer: Three types of plateaus with examples are:
(i) Intermontane Plateaus: These are plateaus of high land surrounded more or less by fold mountains. Examples include The Tibetan Plateau in between the Himalayas and the Kunlun, the Anatolian Plateau in between the Pontics and Tauras, and the Iranian Plateau in between the Zagros and Elburz mountains.
(ii) Volcanic Plateau or Lava Plateau: These are formed by the accumulation or deposition of lava that comes out of the surface of the earth through zones of weakness and spreads in the surrounding areas. Examples include The Southern Plateau or Maharashtra Plateau of India and the plateau of Columbia.
(iii) Continental Plateaus or Shields or Ancient Plateaus: These are plateaus which are formed abruptly due to the rise of land from the Plains or seas and are away from mountains. Examples include The Deccan plateau of India, the Arab Plateau, the Canadian Plateau, the Russian plateau, and the plateaus of Spain and Australia.
Essay Type Questions
1. Discuss the causes of the origin of different types of plateaus.
Answer: Plateaus are formed in various ways:
(i) Tectonic movement sometimes lift the land up and this upliftment of the lowland often forms plateau e.g. the Tibetan plateau.
(ii) Sometimes extensive uplands and mountain are worn down by natural agents and low dissected plateaus are formed; e.g. the Meghalaya plateau.
(iii) The accumulation of lava erupted from the volcanoes sometimes build up plateaus ; e.g. Maharashtra plateau.
Based on structure and origin plateaus may be classified into the following main types, viz. Tectonic Plateaus, Erosional Plateaus, and Depositional Plateaus. These can be further categorized. For example, Tectonic Plateaus include Intermontane (Or Intermont) Plateaus. During mountain building movement when fold mountains rise up due to the horizontal pressure on the layers of rock, the lands in between the mountains also lift up and this lifted up land or plateau is known as the Intermontane Plateau.
Volcanic Plateau Or Lava Plateau are formed when lava comes out of the surface of the earth through zones of weakness. This lava spreads in the surrounding areas and forms plateau. Thus when plateaus are formed by the accumulation or deposition of lava are known as Lava Plateau. Lava plateaus are formed as a result of lava flow in volcanic regions. Sometimes the lavas erupted and flow of variable thickness and bury an uneven surface of the original land areas. They are erupted from many separate fissures rather than from one central orifice. Lava which is acidic in nature spreads over a wide area on the earth’s surface and solidifies to form a volcanic plateau or lava plateau.
Dissected plateaus of Composite Tectonic and Erosional Origin are formed when the earth movement causes an uplift of a plain. The plateau, so formed will have an extensive flat surface area; soon rivers develop on the plateau which curve out their valleys by erosion, but the interfluve tracts retain their flatness and equality of height.
Continental Plateaus in Tectonic Origin are formed abruptly due to rise of land from the Plains or seas. These plateaus are away from the mountains. They rise abruptly from the plains or seas. Some scholars think that these plateaus are originated by the rise of a plain area under endogenetic forces. Sometimes the emission of lava and its spread closeby form these plateaus.
2. Discuss the origin of Fold mountain with the help of a diagram and an example.
Answer: The mountains which are formed by folding of sedimentary rocks strata of the earth’s crust due to the forces of compression are known as Fold Mountains, e.g. the Himalayas (Asia), Alps (Europe), Rockies (N. America), Andes (S. America), Atlas (Africa).
Among the several theories propounded as possible explanation of the cause of fold mountain building forces, the Geosyncline Theory and Plate Tectonics Theory receive special consideration.
According to the Geosyncline Theory, fold mountain originate from elongated trough or shallow sea, called geosyncline and it is filled with sediments brought by the erosional agents (like rivers) from the marginal higher lands. The period in which sediment goes on depositing in a geosyncline is known as period of quiescence. The heavy pressure of the continuous deposit of sediments causes the middle portion of the floor of geosyncline to subside or sag, resulting in consequential compression of the two adjacent landmasses of the geosyncline. Then the movement of these two landmasses from opposite ends towards each other, causes the sedimentary layers in the geosyncline to get folded. These movements are known as the convergence of forelands (landmasses). The enormous compressive forces produced by these moving forelands produce contraction, squeezing and folding of sediments deposited on the geosynclinal bed. Due to contraction, the compressive forces raised the folded sedimentary layers of the geosyncline into folded mountains.
According to the Plate Tectonic Theory, the solid lithosphere is made up to several continental and Oceanic Plates. This movement of the plates is very slow, about 10-20 mm in a year. Convergent boundaries or Destructive edges are formed when two plates head on. The zone of collision may undergo crumpling and folding and folded mountains may emerge. This is an Orogenic collision. When two plates move towards each other, horizontal pressure originates and it exerts tremendous pressure on the sedimentary rock beds lying on the sea-bottom, pushes and pulls up the sedimentary layers by bending them. A series of folds then formed to build up the fold mountains. The Great Himalayas formed this way.
3. Explain in brief the reasons for the origin of any two types of mountains.
Answer: Two types of mountains and the reasons for their origin are:
Fold Mountains: The mountains which are formed by folding of sedimentary rocks strata of the earth’s crust due to the forces of compression are known as Fold Mountains. This can occur through processes described by the Geosyncline Theory, where sediments in a geosyncline are compressed and folded by the movement of adjacent landmasses. Alternatively, the Plate Tectonic Theory explains that when two tectonic plates converge, the collision can cause crumpling and folding of the earth’s crust, leading to the formation of fold mountains. For example, the Great Himalayas formed this way.
Volcanic Mountains: These mountains are formed in the form of tall conical or dome shaped extrusions at the volcanic site by the accumulation of lava, as dust and liquid mud, ejected via a vent of the mouth of the volcano in successive layers. The mechanism of volcanicity and volcanic eruptions which are responsible for the formation of volcanic mountains is closely associated with several interconnected processes such as increase in temperature with increasing depth, origin of magma due to lowering of melting point, origin of gases and vapour, the ascent of magma, and finally the occurrence of volcanic eruptions. Volcanic mountains are formed by the accumulation of volcanic materials, like lava, magma, volcanic ash and dust etc. These materials are deposited in layers around the vent, building up a volcanic cone over time. If the lava is basic, a flat cone is formed, and if the lava is acidic, a steep cone is formed. Volcanic eruptions from the earth’s interior are the primary cause. Prof. MacDonald states the earth’s interior heat is the primary cause of volcanic eruption. According to the Plate Tectonic Theory, volcanic eruption occurs when two plates approach each other and collide.
4. Explain the causes of formation of different types of plains.
Answer: Plains are formed by the following ways: (A) Plains formed by earth’s movement (B) Plains formed by depositions and (C) Plains formed by erosions.
Structural Plains: These plains are formed by the action of endogenetic forces. These forces affect land and sea areas.
- Natural or Plains of Horizontal Layers: The plains which were formed during the formation of the earth’s surface are known as natural plains.
- Plains of Emergence or uplifted plains: These are the plains which are formed due to the upliftment of coastal land as resultant effect of earthquakes and earth movement are called uplifted plains.
- Depressed plain: The plains which are formed due to the lowering down of highlands are called depressed plain.
Erosional Plains: Plains are formed by erosional activities. The running water, glaciers, winds and sea waves mainly take part in erosional activities.
- Peneplains: Over long ages, the higher land is levelled down into a sort of plain. The slope of the plains is so gentle that it can barely transport the debris.
- Karst Plains: The underground water dissolves rocks in a limestone area. This results in the erosion of limestone area and a karst plain is formed.
- Plains of Glacial Erosion: Vast area of land were covered by ice in the ice age which eroded highlands to form plains.
- Desert plains: The plains which are formed by the erosional work of wind in the desert area are called desert plains.
Depositional Plains: The depositional plains are formed as a result of deposition of the material in lowlands such as depressions, lakes and sea floor.
- Plains formed by River Deposition:
- Alluvial Plains: The plains formed by the depositional work of rivers are known as alluvial plains. This includes Alluvial Flood Plains, formed when the river deposits sediment by meandering through its course.
- Deltaic Plains: The plains which are formed by the deposition of the rivers on their deltaic regions, are known as Deltaic Plains. When a river enters the sea, it becomes very slow and deposits all the load on its path, building up a triangular-shaped island called ‘delta’.
- Drift Plains: The Plains formed by the depositional work of glaciers are known as drift plains. This includes Till plains (deposition underneath the ice), Marginal moraines (deposition at the edge of the glacier), and Outwash plains (glaciofluvial depositions).
- Lacustrine Plains: Depositional plain of sediments in a lake basin gives rise to old lake plain or a Lacustrine plain.
- Loess Plains: Loess Plains are formed by the depositional work of wind.
- Coastal Plains: The coastal plains are formed due to depositional work of Sea waves which drive the beach material landwards.
Erosional and Depositional Plains:
- Pediment: An erosional plain formed by the joint erosional action of wind and water in desert areas at the base of surrounding mountain scarps.
- Bajada: A depositional plain formed by the joint depositional work of wind and water in the desert area at the base of the surrounding scarps and made up of alluvial materials laid down by intermittent streams.
Extras
Additional MCQs
1. What is geomorphology defined as?
A. Study of earth forms
B. Study of climate patterns
C. Study of rock formation
D. Study of ocean currents
Answer: A. Study of earth forms
85. Which landform’s undulating surface favours hydroelectric power?
A. plateaus
B. plains
C. deserts
D. valleys
Answer: A. plateaus
Additional Questions, Answers
1. What is geomorphology?
Answer: Geomorphology is a significant branch of physical Geography. Geomorphology is defined as the science of description (discourse) a various forms (morphe) of the earth’s surface. P. G. Worcester (1940) preferred to define geomorphology as the interpretative description of the relief features of the earth’s surface.
74. Discuss the processes involved in degradation and aggradation.
Answer: Degradation and aggradation are two key processes involved in gradation.
(a) Degradation: Degradation is the general wearing away of the land surface by external forces. It is achieved by the break up and carrying of the broken rock material. The agents of degradation work through three successive processes: (i) Erosion of the elevated surface, (ii) Transportation of the eroded rock and (iii) Mass-wasting. Degradation or denudation is carried out by different degradational agents like weather, running water, glaciers, winds, sea-waves, underground water and living beings. These agents work in a destructive manner.
(b) Aggradation: When landforms of low elevation are increased in height, the process is known as aggradation. It is also known as deposition. Actually aggradation is the process of filling up low-lying areas of the earth to give them a levelled up surface. Various forces, which are the very agents that carry out degradation, are ever at work to achieve aggradation of depressed areas of the earth. Important agents of aggradation are (i) depositional work of flowing or running water, (ii) depositional work of winds, (iii) depositional work of glacier, (iv) depositional work of ground water, (v) depositional work of sea waves etc. Associated landforms include flood plains, deltas, moraines, stalactites and stalagmites, and loess.
The difference between Degradation and Aggradation is as follows:
| Feature | Degradation | Aggradation |
| (i) | When landforms of high elevation are reduced in height, the process is known as degradation. | When landforms of low elevation are increased in height, the process is known as aggradation. |
| (ii) | The word degradation comes from the word ‘degrad’ and ‘degrade’, means to lower. | The term aggradation comes from the word ‘aggregate’ which means to add to. |
| (iii) | This happens to work by three processes – erosion, transportation and deposition. | This happens to work by the process of deposition. |
| (iv) | Elevated landform is reduced in height by this process. | Low landform is increased in height by this process. |
Ron’e Dutta is a journalist, teacher, aspiring novelist, and blogger who manages Online Free Notes. An avid reader of Victorian literature, his favourite book is Wuthering Heights by Emily Brontë. He dreams of travelling the world. You can connect with him on social media. He does personal writing on ronism.
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