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Geomorphic Processes and Landform of the Earth: WBBSE Class 9 Geography
Get textual answers, explanations, solutions, notes, extras, MCQs, PDF of Chapter 4 Geomorphic Processes and Landform of the Earth: WBBSE Class 9 Geography (English medium). However, the educational materials should only be used for reference, and students are encouraged to make necessary changes.
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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
2. Which Greek word means ‘form’?
A. morphe
B. ge
C. logos
D. litho
Answer: A. morphe
3. According to Thornbury, differences in what cause differences in geomorphic processes?
A. climate
B. elevation
C. time
D. lithology
Answer: A. climate
4. What does the term ‘landforms’ refer to?
A. surface configuration
B. climate patterns
C. soil types
D. hydrological cycle
Answer: A. surface configuration
5. Which are first-order landforms?
A. continents and oceans
B. hills and valleys
C. mountain sections and dunes
D. rivers and lakes
Answer: A. continents and oceans
6. Which are second-order landforms?
A. mountain sections
B. continents and oceans
C. mountains, plateaus, plains
D. sand dunes, deltas
Answer: C. mountains, plateaus, plains
7. Which is a third-order landform?
A. mountain sections
B. plateaux
C. continents
D. oceans
Answer: A. mountain sections
8. Which is a third-order landform?
A. hills
B. mountains
C. plains
D. plateaus
Answer: A. hills
9. Which is a third-order landform?
A. valleys
B. shields
C. plateaus
D. block mountains
Answer: A. valleys
10. Which is a third-order landform?
A. sand dunes
B. fold mountains
C. lava plateaus
D. rift valleys
Answer: A. sand dunes
11. Which forces are generated in the earth’s interior?
A. endogenetic forces
B. exogenetic forces
C. gravitational forces
D. atmospheric forces
Answer: A. endogenetic forces
12. Which of the following is a sudden endogenetic force?
A. volcanic action
B. river erosion
C. wind erosion
D. wave action
Answer: A. volcanic action
13. Diastrophic forces include which movement?
A. epeirogenic
B. fluvial
C. chemical
D. mechanical
Answer: A. epeirogenic
14. Epeirogenic movements involve what?
A. vertical crust movement
B. folding of strata
C. horizontal sliding
D. volcanic flows
Answer: A. vertical crust movement
15. Orogenic movements result in the formation of?
A. fold mountains
B. river valleys
C. lava plateaus
D. sand dunes
Answer: A. fold mountains
16. Exogenetic forces are also known as?
A. external processes
B. internal processes
C. geotectonic processes
D. diastrophic forces
Answer: A. external processes
17. Which is an agent of exogenous processes?
A. rivers
B. plates
C. magma
D. faults
Answer: A. rivers
18. Gradation equals which combination?
A. erosion + transportation + deposition
B. weathering + erosion
C. uplift + subsidence
D. folding + faulting
Answer: A. erosion + transportation + deposition
19. What is degradation?
A. land wearing
B. land building
C. folding
D. weathering
Answer: A. land wearing
20. What is aggradation?
A. land building
B. land wearing
C. chemical break
D. transport
Answer: A. land building
21. Denudation includes which processes?
A. weathering, erosion, transport, deposition
B. folding, faulting
C. uplift, subsidence
D. magma flow, lava spread
Answer: A. weathering, erosion, transport, deposition
22. Which is an example of mechanical weathering?
A. frost action
B. oxidation
C. hydrolysis
D. carbonation
Answer: A. frost action
23. Chemical weathering involves?
A. chemical decomposition
B. physical break
C. transport
D. deposition
Answer: A. chemical decomposition
24. A mountain is defined as a steep-sided hill more than how many metres high?
A. 600m
B. 300m
C. 1000m
D. 200m
Answer: A. 600m
25. According to Finch, a mountain must be at least how many metres above sea level?
A. 900m
B. 600m
C. 700m
D. 800m
Answer: A. 900m
26. On the basis of height, low mountains range from?
A. 700–1000m
B. 100–500m
C. 200–600m
D. 1200–1500m
Answer: A. 700–1000m
27. Which type of mountain is coastal?
A. continental
B. oceanic
C. block
D. residual
Answer: A. continental
28. The Ural mountains represent which location type?
A. inland
B. coastal
C. oceanic
D. block
Answer: A. inland
29. Fold mountains form by?
A. folding sedimentary layers
B. volcanic eruptions
C. faulting
D. erosion
Answer: A. folding sedimentary layers
30. Which theory explains fold mountains via geosynclines?
A. geosyncline theory
B. plate tectonic theory
C. erosion theory
D. fault theory
Answer: A. geosyncline theory
31. Plate tectonic theory states the lithosphere is divided into approximately how many plates?
A. 20
B. 5
C. 10
D. 50
Answer: A. 20
32. At divergent boundaries, plates move?
A. apart
B. together
C. past each other
D. beneath one another
Answer: A. apart
33. Convergent boundaries are also called?
A. destructive edges
B. constructive edges
C. conservative edges
D. passive edges
Answer: A. destructive edges
34. An anticline is a(n)?
A. upfold
B. downfold
C. fracture
D. transform fault
Answer: A. upfold
35. A syncline is a(n)?
A. downfold trough
B. upfold arch
C. plateau
D. ridge
Answer: A. downfold trough
36. An overfold occurs due to extreme what?
A. compression
B. tension
C. erosion
D. deposition
Answer: A. compression
37. A nappe is the what in fold mountains?
A. over-riding portion of thrust fold
B. base layer
C. summit peak
D. protective cover
Answer: A. over-riding portion of thrust fold
38. The Himalayas are examples of which fold mountains?
A. young
B. old
C. block
D. volcanic
Answer: A. young
39. The Aravallis are examples of which fold mountains?
A. old
B. young
C. block
D. volcanic
Answer: A. old
40. Which volcano in Ecuador is the highest active volcano?
A. Cotopaxi
B. Fujiyama
C. Vesuvius
D. Stromboli
Answer: A. Cotopaxi
41. Which mountain is a dormant volcano?
A. Fujiyama
B. Cotopaxi
C. Mt Popo
D. Narcondam
Answer: A. Fujiyama
42. Which volcano in the Andaman & Nicobar Islands is extinct?
A. Narcondam
B. Barren
C. Vesuvius
D. Stromboli
Answer: A. Narcondam
43. The Pacific Ring of Fire contains about what percentage of active volcanoes?
A. 80%
B. 50%
C. 30%
D. 10%
Answer: A. 80%
44. Volcanic mountains are primarily composed of which rock type?
A. igneous rocks
B. sedimentary rocks
C. metamorphic rocks
D. limestone
Answer: A. igneous rocks
45. Block mountains are also called?
A. fault block mountains
B. fold mountains
C. dome mountains
D. residual mountains
Answer: A. fault block mountains
46. A horst refers to what?
A. lifted block mountain
B. tilted block mountain
C. volcanic cone
D. glacial valley
Answer: A. lifted block mountain
47. Which is a tilted block mountain example?
A. Satpura
B. Himalayas
C. Appalachians
D. Deccan
Answer: A. Satpura
48. A rift valley is also called a(n)?
A. graben
B. horst
C. mesa
D. butte
Answer: A. graben
49. Which Indian river flows through a rift valley?
A. Narmada
B. Ganga
C. Yamuna
D. Brahmaputra
Answer: A. Narmada
50. A ramp valley is formed by what forces?
A. compression
B. tension
C. erosion
D. deposition
Answer: A. compression
51. Which mountain type remains as resistant rock after erosion?
A. residual mountain
B. fold mountain
C. block mountain
D. volcanic
Answer: A. residual mountain
52. Butte is defined as a?
A. small remnant hill
B. large plateau
C. block mountain
D. volcanic cone
Answer: A. small remnant hill
53. ‘Inselberg’ in German means?
A. island mountain
B. fold mountain
C. block mountain
D. dome mountain
Answer: A. island mountain
54. ‘Monadnock’ refers to?
A. isolated resistant hill
B. river terrace
C. dune field
D. delta plain
Answer: A. isolated resistant hill
55. Mountains typically cause what type of rainfall?
A. orographic
B. convectional
C. cyclonic
D. frontal
Answer: A. orographic
56. Which is a plateau?
A. level upland land
B. steep hill
C. river valley
D. ocean floor
Answer: A. level upland land
57. What is called the ‘roof of the world’?
A. Pamir plateau
B. Deccan plateau
C. Tibetan plateau
D. Colorado plateau
Answer: A. Pamir plateau
58. Which is the highest plateau in India?
A. Ladakh plateau
B. Deccan plateau
C. Malnad plateau
D. Meghalaya plateau
Answer: A. Ladakh plateau
59. Which example is a lava plateau in India?
A. Deccan plateau
B. Tibetan plateau
C. Iranian plateau
D. Anatolian plateau
Answer: A. Deccan plateau
60. An intermontane plateau lies between which mountains?
A. Himalayas and Kunlun
B. Alps and Pyrenees
C. Rockies and Sierra
D. Urals and Caucasus
Answer: A. Himalayas and Kunlun
61. Dissected plateaus are mainly formed by?
A. river erosion
B. tectonic uplift
C. volcanic deposition
D. glacial melting
Answer: A. river erosion
62. Continental plateaus are also known as?
A. shields
B. mesas
C. fans
D. deltas
Answer: A. shields
63. Which is an example of a shield plateau?
A. Canadian
B. Malnad
C. Meghalaya
D. Colorado
Answer: A. Canadian
64. Which plateau in India is a shield plateau?
A. Deccan
B. Tibetan
C. Iranian
D. Anatolian
Answer: A. Deccan
65. Plateaus often resemble what?
A. tables
B. cones
C. domes
D. ridges
Answer: A. tables
66. Plains are characterized by what relief?
A. low relief
B. high relief
C. steep relief
D. variable relief
Answer: A. low relief
67. Which is an example of an uplifted plain?
A. Gulf coast plain
B. Sahara plain
C. Gobi plain
D. Amazon plain
Answer: A. Gulf coast plain
68. Which is a depressed plain example?
A. Caspian coastal plain
B. Ganga plain
C. Great Plains
D. Nile delta
Answer: A. Caspian coastal plain
69. A peneplain is a plain of what relief?
A. faint relief
B. steep relief
C. rugged relief
D. rolling relief
Answer: A. faint relief
70. Karst plains develop on which rock?
A. limestone
B. sandstone
C. basalt
D. granite
Answer: A. limestone
71. Plains formed by glacial erosion are called?
A. glacial plains
B. alluvial plains
C. desert plains
D. karst plains
Answer: A. glacial plains
72. Desert plains result from what agent?
A. wind erosion
B. river deposition
C. volcanic flows
D. tectonic uplift
Answer: A. wind erosion
73. Flood plains form by what process?
A. river deposition
B. wind action
C. glacial erosion
D. tectonic uplift
Answer: A. river deposition
74. Delta plains resemble the shape of which Greek letter?
A. delta
B. alpha
C. gamma
D. theta
Answer: A. delta
75. Drift plains are associated with what?
A. glacial deposits
B. river sediments
C. wind-blown silt
D. lake clays
Answer: A. glacial deposits
76. Lacustrine plains form in?
A. old lake basins
B. river deltas
C. desert depressions
D. coastal margins
Answer: A. old lake basins
77. Loess plains consist of what material?
A. wind-deposited silt
B. glacial till
C. river sand
D. volcanic ash
Answer: A. wind-deposited silt
78. Coastal plains are formed by what?
A. wave deposition
B. glacial erosion
C. volcanic sediment
D. tectonic uplift
Answer: A. wave deposition
79. A pediment is formed by which combined action?
A. wind and water
B. plate tectonics
C. folding and faulting
D. glacial scouring
Answer: A. wind and water
80. A bajada is formed by which deposition?
A. wind and water
B. glacial meltwater
C. river floods
D. volcanic ash
Answer: A. wind and water
81. Plains are especially preferred for what land use?
A. agriculture
B. mining
C. tourism
D. forestry
Answer: A. agriculture
82. Plateaus are known for which resource deposits?
A. bauxite
B. oil
C. diamonds
D. pearls
Answer: A. bauxite
83. Mountains serve as a barrier between which countries?
A. China and India
B. USA and Canada
C. Spain and France
D. Chile and Argentina
Answer: A. China and India
84. Terraced farming is typically practiced on which landform?
A. mountain slopes
B. coastal plains
C. lava plateaus
D. desert plains
Answer: A. mountain slopes
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.
2. Define landforms.
Answer: The term ‘landforms’ may be defined as the surface configuration of the earth. So the different shapes of the land surface and called Landforms. Actually all the variation in height, size, shape, pattern of land and nature of the earth’s surface are known as landforms. It gives a total view of a landscape.
3. Name the Greek words from which ‘geomorphology’ is derived.
Answer: The term ‘geomorphology’ stems from three Greek words i.e. ‘ge’ (meaning earth), ‘morphe’ (form) and ‘logos’ (a discourse).
4. What are first-order landforms?
Answer: First Order Landforms are continents and oceans.
5. Define endogenetic forces.
Answer: Endogenetic Forces are forces generated in the interior of the earth and causes mountains, plateaus, etc. to subside. These endogenetic forces are also called internal processes.
6. What are sudden endogenetic forces?
Answer: Sudden endogenetic forces are forces such as volcanic action or earthquake, which are natural processes of readjustment of the earth’s crust along a weak zone.
7. Give an example of a sudden endogenetic force.
Answer: An example of a sudden endogenetic force is volcanic action or earthquake.
8. What are diastrophic forces?
Answer: Diastrophic forces are forces that act very slowly, with their effects becoming discernible after thousands of years. These forces, resulting from internal processes, are also called Geotectonic Forces or Tectonic movements.
9. What are epeirogenic movements?
Answer: Epeirogenic movements are the vertical movements of the earth’s crust. Named after the Greek word ‘epeiros’ meaning continent, they are also called continent building movements and generally cause rising or sinking of the crust over broad areas without fracturing or folding the rocks.
10. Define orogenic movements.
Answer: Orogenic movements are the horizontal movements of the earth’s crust, which may be caused by compressional or tensional forces. These movements, derived from the Greek word ‘Oros’ meaning mountain, result in the formation of fold mountains through compressional forces.
11. What are exogenetic forces?
Answer: Exogenetic forces are also called the external processes. External processes are those which act on the surface of the land. These are the agents of denudation like rivers, glaciers, winds and waves. These agents wear down the rocks on the surface and the differences in the rate of their denudation processes produces different features, like valleys, lowlands ridges etc. Hence these forces are also called Gradational Forces. Exogenous are those process which act on the surface of the earth and give birth to various landforms. The external or exogenous processes originate with the earth’s atmosphere and are directed by the force of gravity. They are essentially processes of land destruction.
12. Define weathering.
Answer: Weathering is the process that breaks rocks into smaller fragments by static agents of weather. It takes place in situ which means the rock fragments are found where they were formed originally. According to B. Sparks, “Weathering is the mechanical fracturing and chemical decomposition of rocks, in situ, by the natural agents at the surface of the earth.”
13. Define erosion.
Answer: Erosion is the removal or transportation of the weathered rock material from one place to another. It is one of the three main processes involved in gradation, specifically the process of wearing down uplands.
14. What is gradation?
Answer: ‘Gradation’ means the process of bringing the earth’s surface to a uniform level. The process of levelling the earth’s surface is known as gradation. Gradational processes are continuously engaged in removing the vertical irregularities created by endogenous processes through denudational (both weathering and erosion) and depositional activities. The three main processes involved in gradation are erosion, transportation and deposition of the eroded material. This process of erosion, transportation and deposition is known as gradation. Hence Gradation = Erosion + Transportation + Deposition.
15. What do you understand by degradation?
Answer: 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. Degradation or denudation, as it is called, too, is eroded and carried out by different degradational agents like weather, running water, glaciers, winds, sea-waves, underground water and living beings. The agents, i.e. forces of degradation work in a destructive manner. When landforms of high elevation are reduced in height, the process is known as degradation. The word degradation comes from the word ‘degrad’ and ‘degrade’, means to lower.
16. What is aggradation?
Answer: 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 are ever at work to achieve aggradation of depressed areas of the earth. When landforms of low elevation are increased in height, the process is known as aggradation. The term aggradation comes from the word ‘aggregate’ which means to add to. This happens to work by the process of deposition.
17. Define biotic processes.
Answer: Biotic Processes includes the action of animals and insects, vegetation and man. The quarrying, mining, deforestation and indiscriminate cultivation of land are some of the important actions of man. The long and tenacious root fibres of the plants work down into the cracks of rock. There are millions of animals and insects such as dogs, rabbits, rats, jackals, termites etc. which consume large quantities of rock and soil for making their habitats and for extracting food.
18. What is mechanical weathering?
Answer: In mechanical weathering rocks break up without changing their chemical composition. It takes place in various ways : (i) Temperature change, (ii) Frost action, (iii) Penetrating roots of plants and trees, (iv) Burrowing action of animals and mining and other activities of men.
19. What are volcanic mountains?
Answer: The mountains which 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, are Volcanic Mountains. 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. They build up volcanic cone in time. These volcanic cones are called volcanic mountains. If the lava is basic, a flat cone is formed and if the lava is acidic, a steep cone in formed. Volcanic mountains are formed due to volcanic eruptions from the earth’s interior.
20. Define block mountains.
Answer: When a landmass is formed by the upliftment of land between the two parallel faults or by subsidence of land outside the faults it is called Block Mountain. Block mountains are also called fault block mountains since they are formed due to faulting as a result of tensile and compressive forces.
21. What is a fault?
Answer: A fault is a well defined crack along which the rock-masses on either side have suffered relative displacement.
22. What is faulting?
Answer: The movement of a part of the earth’s crust along a fault is known as faulting.
23. Define residual mountains.
Answer: Mountains which 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 are known as Erosional or Residual or Relict or Denudated Mountains.
24. What are fold mountains?
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.
25. What is a 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.
26. Define rift valley.
Answer: When two roughly parallel faults occur side by side, the portion of the crust between these two faults may get depressed by movements along the fault lines to form a long, narrow valley, several kilometres in length; it is called a Rift Valley.
27. What is a graben?
Answer: In German, a rift valley is called a graben. Rift valleys are generally also called “graben,” which is a German word. These two forms are generally synonymously used in various parts of the world, although some scientists believe that a graben is relatively smaller in size than a rift valley.
28. Define ramp valley.
Answer: Sometimes a rift valley may result from the forcing down of a central block along reverse faults. Such valleys formed by compression are called Ramp Valley.
29. What is a butte?
Answer: A butte is a residual hill formed by erosion of a mesa. After additional erosion from all sides, a mesa is further reduced to a smaller remnant flat summit called a butte.
30. Define Inselberg.
Answer: Inselberg is a German word meaning ‘island mountains’. Inselbergs are outstanding rounded steep-sided residual hills, mainly formed of granite and gneiss, and are remnants of an original plateau which has been eroded away by wind action. They have steep slopes and rounded tops.
31. What is a Monadnock?
Answer: Monadnocks are eroded and isolated remains of resistant rock materials appearing like mountains. These eroded and lowered relicts of landforms were called Monadnocks by W. M. Davis. Thus all monadnocks may be called Residual Mountains.
32. Define plateau.
Answer: A plateau is a broad and rather level stretch of land rising sharply from the neighbouring lowland. A plateau can be 90m to 900 ft. high. It has steep sides and deep edges. It often looks like a table standing above the surroundings and that is why plateau is also called Table land. According to A. N. Strahler and A. H. Strahler, “A plateau is an upland surface, more or less flat and horizontal, upheld by resistant beds of sedimentary rock of lava flows and bounded by a steep cliff.”
33. What is an intermontane plateau?
Answer: 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. Thus the plateaus of high land surrounded more or less by fold mountains are called intermontane plateaus.
34. Define volcanic plateau.
Answer: Lava comes out of the surface of the earth through zones of weakness. This lava spreads in the surrounding areas and forms plateau. Such type of plateau is known as Volcanic plateau or Lava plateau. Thus when plateaus are formed by the accumulation or deposition of lava are known as Lava Plateau.
35. What is a dissected plateau?
Answer: Some plateaus are cut by rivers and broken by deep narrow valleys. These are called Dissected plateaus. This occurs when earth movement causes an uplift of a plain; the plateau, so formed will have an extensive flat surface area, and soon rivers develop on the plateau which curve out their valleys by erosion, but the interfluve tracts retain their flatness and equality of height.
36. Define continental plateau.
Answer: Plateaus which are formed abruptly due to rise of land from the Plains or seas are called continental Plateaus or shields or Ancient Plateaus. These plateaus are away from the mountains and rise abruptly from the plains or seas.
37. What are plains?
Answer: The plain is that lowland which has a low relief and levelled surface. Plains do not usually have a height above 160 metres but many plains above 400 metres exist in many places. Some plains are below sea level.
38. What is an alluvial plain?
Answer: The plains formed by the depositional work of rivers are known as alluvial plains. Finch has divided these plains into three categories—(i) Piedmont Alluvial Fans or Bhabar, (ii) Flood plains and (iii) Delta plains.
39. Define flood plain.
Answer: The plain made up of river alluvium is called Alluvial Flood Plain. When the river deposits sediment by meandering through its course, the alluvial flood plains are formed. The flood plain is relatively level part of the valleys bordering river. Layers of silts deposited by a river in times of flood form the floodplain.
40. What are deltaic plains?
Answer: 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. Such deposits build up a triangular-shaped island called ‘delta’ at the mouth of river.
41. What is a drift plain?
Answer: The Plains formed by the depositional work of glaciers are known as drift plains. There are three types of drift plains according to their mode of formation : (i) Till plains: These plains have been formed by the deposition underneath the ice. (ii) Marginal moraines : They were formed by the deposition of moraines at the edge of the glacier and (iii) Outwash plains : These plains are formed by the glaciofluvial depositions starting from the end of the melting ice.
42. Define loess plains.
Answer: Loess Plains are formed by the depositional work of wind.
43. What is a pediment?
Answer: A pediment is an erosional plain formed by the joint erosional action of wind and water in desert areas at the base of surrounding mountain scarps. It is a gentle slope at the foot-hill areas.
44. Define bajada.
Answer: A bajada is 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. These are found at the foot-hill regions of Atlas mountain in Africa.
45. What are the differences between hills and mountains?
Answer: The differences between Hills and Mountains are:
| Feature | Hills | Mountains |
| I. | A natural elevation of the earth’s surface, not so high as mountain, is loosely called hill. | A high landmass on the earth’s surface, attaining a great height above the surroundings with a series of ranges and peaks is called mountains. |
| II. | The height of a hill generally ranges from 600 m to 1000 m. | The height of a mountain is above 1000 m. |
| III. | Hills are not much extensive as mountains. | Mountains are extensively located. |
| IV. | They have gentler slopes. | They have more rugged features like steeper stopes and deeper vallyes. |
| V. | Hills have rounded peaks. | Mountains have sharp peaks. |
| VI. | Rajmahal and Ayodhya are examples of Hills. | Himalayas, Andes are example of Mountains |
46. Explain the classification of mountains based on height.
Answer: Mountains can be classified on the Basis of Height as follows:
(a) Low mountains or Hills [height 700-1000 m].
(b) Rough mountains [Ht-1000 m-1500 m]
(c) Rugged Mountains [height 1500 m – 2000 m],
(d) High Mountains [Height above 2,000 m]
47. Name two types of exogenetic processes.
Answer: Two types of Exogenous Processes are:
(A) Gradational Process
(B) Weathering
48. List the three processes involved in gradation.
Answer: Evidently, gradation involves three different processes—
(i) The process of wearing down (erosion) uplands,
(ii) The process of transporting (transportation) the eroded materials,
(iii) The process of filling up (deposition) lowlands.
49. Give two examples of volcanic mountains.
Answer: Two examples of volcanic mountains are:
(i) The Coto-paxi in Equador [the highest active volcano]
(ii) The Fujiyama in Japan [Dormant volcano]
50. Provide two examples of block mountains.
Answer: Two examples of block mountains are the Vindhyas and Satpuras in India.
51. Give two examples of residual mountains.
Answer: Two examples of residual mountains are the Aravallis and the Nilgiris in India.
52. Name any two depositional landforms.
Answer: Two depositional landforms are Flood plains and Deltas.
53. List the agents of gradational processes.
Answer: The important agents of gradational process are the erosional, transportational and depositional works of running water or rivers, glacier, wind, groundwater and works of ocean waves and shore currents.
54. What is the Pacific Ring of Fire?
Answer: There are about more than 500 active volcanoes concentrated in a belt 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.
55. Classify mountains based on 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.
56. Describe the features of fold mountains.
Answer: The characteristics of Fold Mountains are:
(1) Fold mountains consist of great masses of folded sedimentary rocks whose thickness is often as much as about 12 km.
(2) Various types of folds are present in fold mountains.
(3) Complex folding is more common in fold mountain.
(4) Simple folding gives rise to mountains and valleys. The anticlines become the mountains and the synclines the valleys. Simple fold mountains are rare.
(5) Faults are also common in fold mountains.
(6) Fold mountains are usually made of sedimentary rocks.
(7) Fossils are common as they originate from the seas.
(8) Most of the peaks are conical.
(9) Many of the world’s largest mountain chains exist beneath the sea. Some of these are revealed as island arcs, as in the West Indies, and in the west and south-west Pacific Ocean.
57. Explain the formation of volcanic mountains.
Answer: 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. They build up volcanic cone in time. These volcanic cones are called volcanic mountains. If the lava is basic, a flat cone is formed and if the lava is acidic, a steep cone is formed. Volcanic mountains are formed due to volcanic eruptions from the earth’s interior. The major causes of volcanic eruption are (i) Geologist, Prof. MacDonald states the earth’s interior heat is the primary cause of volcanic eruption. (ii) According to the Plate Tectonic Theory, the volcanic eruption occurs when two plates approach each other and collide.
58. Describe the characteristics of block mountains.
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.
59. What are the main differences between young and old fold mountains?
Answer: The differences between Young Fold Mountains and Old Fold Mountains are:
| Feature | Young Fold Mountains | Old Fold Mountains |
| 1. | These mountains have been formed relatively recently. | They have been formed very ancient time or long ago. |
| 2. | They are usually higher than the old fold mountains. | They are lower than the young fold mountains. |
| 3. | They have several pointed peaks. | They have few rounded peaks. |
| 4. | They are mainly formed of sedimentary rocks. | They are mainly formed of metamorphic rocks. |
| 5. | They have more rugged features like steeper slopes and deeper valleys. | They have gentler slopes and less rugged features. |
| 6. | Andes, Rockies, Alps and the Himalayas are examples of young fold mountains. | The Appalachians, the Urals and the Aravallis are examples of Old fold mountain. |
60. Discuss the formation of residual mountains.
Answer: Various erosive agencies acting through millions of years may reduce mountains and plateau to a low plain, but the harder and more resistant ones, survived against erosion, may be left standing as residual or relict mountains. Mountains which 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 are known as Erosional or Residual or Relict or Denudated Mountains.
61. What is the Pacific Ring of Fire?
Answer: There are about more than 500 active volcanoes concentrated in a belt 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.
62. Classify plateaus based on their origin.
Answer: Based on structure and origin, plateaus may be classified into Tectonic Plateaus, Erosional Plateaus, and Depositional Plateaus. According to the syllabus, the following plateaus are described:
(1) Intermontane Plateau, (2) Volcanic Plateau, (3) Dissected Plateau, (4) Continental Plateau.
63. Describe the formation of intermontane plateaus.
Answer: The intermontane plateaus are formed by the orogenic movement of the earth’s crust. An intermontane plateau is the resultant of the fold mountain building forces over a vast expanse of areas. It is formed when the land in between the fold mountain ranges lift up consequent upon the rising up of the fold mountain ranges due to horizontal pressure or the movement on the rock strata. 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.
64. Explain how volcanic plateaus are formed.
Answer: Lava comes out of the surface of the earth through zones of weakness. This lava spreads in the surrounding areas and forms plateau. Such type of plateau is known as Volcanic plateau or Lava 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. The accumulation of lava erupted from the volcanoes sometimes build up plateaus; e.g. Maharashtra plateau.
65. What are dissected plateaus? Give an example.
Answer: Some plateaus are cut by rivers and broken by deep narrow valleys. These are called Dissected plateaus. 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. This is called a dissected plateau. Sometimes extensive uplands and mountain are worn down by natural agents and low dissected plateaus are formed; e.g. the Meghalaya plateau.
66. How are continental plateaus formed?
Answer: Continental Plateaus are plateaus which 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.
67. Explain the characteristics of continental plateaus.
Answer: The continental plateaus are characterised by some important features, like:
(i) Shields are in fact the broken parts of the ancient continental landmasses.
(ii) They are formed of most ancient rocks of early origin.
(iii) Rocks of these plateaus are very much hard and resistant to erosion.
(iv) They have undulating surface.
(v) These types of plateaus are rich in mineral resources.
(vi) All shields are plateaus but all plateaus are not shields. According to the geomorphological view, “all ancient plateaus are called shields but there are some plateaus which are not ancient in origin hence they are not shields”.
68. Classify plains based on their formation.
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.
(1) Plains which are formed by the geotectonic force of the earth are called Structural plains;
(2) plains which are formed by erosion of different natural agents are called Erosional Plains; and
(3) which are formed by deposition of different materials of different natural agents are called Depositional plains.
69. How are structural plains formed?
Answer: Structural Plains are formed by the action of endogenetic forces. These forces affect land and sea areas. These are of following types:
A. Natural or Plains of Horizontal Layers : The plains which were formed during the formation of the earth’s surface are known as natural plains. Example : (i) The Russian plain (or northern plain of Asia), (ii) The Central West plains of North America are some such plains.
B. 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. Examples : The eastern and gulf coast of the USA, the Western coast of India, the steppes regions of Europe are of this type.
C. Depressed plain : The plains which are formed due to the lowering down of highlands are called depressed plain. Such plains, in fact lie lower than the general sea-level. Example : The coastal plain of the Caspian sea is lower than the sea-level.
70. What are erosional plains? Provide examples.
Answer: Erosional Plains are plains formed by erosional activities. The running water, glaciers, winds and sea waves mainly take part in erosional activities. These are of following types:
A. 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. In fact peneplain is a low land of faint relief. The surface is smooth and forms almost a plain termed peneplain. Residues of hard rock stand above the general level of the land and are known as ‘Monadnocks’. Paris basin, upper part of Mississippi basins are good examples of peneplain.
B. 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. The plain of Yugoslavia in Adriatic coast, plains of Tennessee and Florida in USA are examples of Karst plains.
C. Plains of Glacial Erosion : Vast area of land were covered by ice in the ice age which eroded highlands to form plains. Even today glaciers are eroding uplands on a large scale resulting in the formation of plains of glacial erosion. These plains are found in Canada, Siberia, Sweden and Finland.
D. Desert plains : The plains which are formed by the erosional work of wind in the desert area are called desert plains. Parts of Sahara in Africa are wind-eroded plains.
71. Explain the geomorphic processes that shape landforms.
Answer: Geomorphology is defined as the science of description (discourse) of various forms (morphe) of the earth’s surface. Many physical and chemical processes operate because of which the earth’s surface undergoes alterations. These are known as geomorphic processes. Geomorphic processes leave their distinctive imprint upon landforms and each geomorphic process develops its own characteristic assemblage of landforms. The various landforms on the surface of the earth are produced by the interaction of two processes or forces: Endogenetic Forces and Exogenetic Forces. Endogenetic forces are generated in the interior of the earth and cause mountains, plateaus, etc. to subside or rise. Exogenetic forces, also called external processes or Gradational Forces, act on the surface of the land. These are the agents of denudation like rivers, glaciers, winds and waves, which wear down rocks and produce different features. The external or exogenous processes originate within the earth’s atmosphere and are directed by the force of gravity. They are essentially processes of land destruction involving stages like weathering and erosion (transportation and deposition).
72. Discuss the characteristics and types of endogenetic forces.
Answer: Endogenetic forces are generated in the interior of the earth and cause mountains, plateaus, etc. to subside or rise. These forces are also called internal processes. On the basis of intensity, these forces can be divided into two sub-groups:
(a) Sudden Endogenetic Forces: The main forces in this sub-group are volcanic action or earthquake. Earthquake and volcano are a natural process of readjustment of the earth’s crust along a weak zone.
(b) Diastrophic Forces: These forces act very slowly, and their effect becomes discernible after thousands of years. The diastrophic forces, which are the result of the internal processes, are also called Geotectonic Forces or Tectonic movements. From the point of view of areas distribution, diastrophic forces can be divided into two further sub-groups:
(i) Epeirogenic Movement: These are the vertical movements of the earth’s crust, also called the continent building movements (after the Greek word epeiros meaning a continent). These movements generally cause rising or sinking of the crust over broad areas without fracturing or folding of the rocks and affect ancient stable blocks or shields.
(ii) Orogenic Movements: These are the horizontal movements of the earth’s crust (from the Greek word Oros meaning mountain). These movements may be caused by compressional forces or tensional forces. Compressional forces result in the formation of fold mountains.
73. Explain in detail the gradational processes and their agents.
Answer: ‘Gradation’ means the process of bringing the earth’s surface to a uniform level. The process of levelling the earth’s surface is known as gradation. Gradational processes are continuously engaged in removing the vertical irregularities created by endogenous processes through denudational (both weathering and erosion) and depositional activities.
Agents of Gradational Process: Gravity is the driving force behind the movement of material from high areas to low areas, thus, reducing the height differences between them. Before this can happen, the rocks have to be eroded (broken) into small pieces. They are then transported and deposited. Hence the important agents of gradational process are the erosional, transportational and depositional works of running water or rivers, glacier, wind, groundwater and works of ocean waves and shore currents.
Processes: Evidently, gradation involves three different processes:
(i) The process of wearing down (erosion) uplands,
(ii) The process of transporting (transportation) the eroded materials,
(iii) The process of filling up (deposition) lowlands.
The three main processes involved in gradation are erosion, transportation and deposition of the eroded material. This process of erosion, transportation and deposition is known as gradation. Hence Gradation = Erosion + Transportation + Deposition. Gradation is achieved by simultaneous processes of Degradation, Aggradation and Biotic Processes.
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. |
