A abampere (aA) The unit of electric current in the CGSeniu system, defined as that current that, if flowing through two parallel conductors of negligible cross section and infinite length, placed 1 cm apart in vacuo, would produce on each conductor a force of 1 dyne per centimeter of length. 1 abampere = 1 abcoulomb/s = r statampere (where c = speed of light in cm/s) = 10 ampere. aberration Imperfect image formation due to geometric imperfections in the optical elements of a system ablation 1 . The wasting of glacier ice by any process (calving, melting, evaporation, etc.). 2. The shedding of molten material from the outer sur- face of a meteorite or tektite during its flight through the atmosphere. absolute age The age of a natural substance, of a fossil or living organism, or of an artifact, obtained by means of an absolute dating method. See absolute dating method. absolute density Density in kg/m' or, more commonly, in g/cm\ both at STP. Cf. density, relative density abso
Landforms class 11 geography MCQ & SAQ
Landforms class 11 geography NCERT SOLUTION
1. Multiple choice questions.
(i) In which of the following stages of landform development, downward cutting is dominated?
(a) Youth stage
(b) Late mature stage
(c) Early mature stage
(d) Old stage
Answer: (a) Youth stage
(ii) A deep valley characterized by steep step-like side slopes is known as
(a) U-shaped valley
(b) Gorge
(c) Blind valley
(d) Canyon
Answer: (d) Canyon
(iii) In which one of the following regions the chemical weathering process is more dominant than the mechanical process.
(a) Humid region
(b) Limestone region
(c) Arid region
(d) Glacier region
Answer: (a) Humid region
(iv) Which one of the following sentences best defines the term ‘Lapies’ ?
(a) A small to medium sized shallow depression
(b) A landform whose opening is more or less circular at the top and funnel shaped towards bottom
(c) A landform formed due to dripping water from surface
(d) An irregular surface with sharp pinnacles, grooves and ridges
Answer: (d) An irregular surface with sharp pinnacles, grooves, and ridges
(v) A deep, long and wide trough or basin with very steep concave high walls at its head as well as in sides is known as:
(a) Cirque
(b) Glacial valley
(c) Lateral Moraine
(d) Esker
Answer: (a) Cirque
2. Answer the following questions in about 30 words
(i) What do incised meanders in rocks and meanders in plains of alluvium indicate?
Answer: Meandering courses are found over floodplains and delta plains indicate that a former floodplain with a widening stream had been uplifted, enabling the stream to cut downward. Incised meanders occur when a river’s base level has fallen, giving the river a large amount of vertical erosion power, allowing it to downcut. They give an indication of the status of original land surfaces over which streams have developed.
(ii) Explain the evolution of valley sinks or uvalas.
Answer: When sinkholes and dolines join together because of slumping of materials along their margins or due to roof collapse of caves, long, narrow to wide trenches called valley sinks or Uvalas form.
(iii) Underground flow of water is more common than surface run-off in limestone areas. Why?
Answer: Underground flow of water is more common than surface run-off in limestone areas because limestone areas have such rocks, which are permeable, thinly bedded and highly jointed and cracked.
(iv) Glacial valleys show up in many linear depositional forms. Give their locations and names.
Answer: Moraines and eskers are important linear depositional forms of a glaciated region. Lateral moraines form along the sides parallel to the glacial valleys. Medial moraines are formed at the confluence of two glaciers. Terminal moraines are found at the end of the valley glacier. When glaciers melt in summer, the water flows on the surface of the ice. Eskers are sinuous ridges formed by the depositional work of a glacier.
(v) How does wind perform its task in desert areas? Is it the only agent responsible for the erosional features in the deserts?
Answer: The work of wind is more prominent in arid and semi arid areas, where soil particles are loose due to lack of moisture and vegetation. Plenty of loose material is provided to be picked up by the blowing wind. Winds cause deflation, abrasion, and impact. The wind action creates a number of interesting erosional and depositional features in the deserts. Rainfall and Stream channels in desert areas are broad, smooth, and indefinite and flow for a brief time after rains.
(i) Running water is by far the most dominating geomorphic agent in shaping the earth’s surface in humid as well as in arid climates. Explain.
Answer: Running water or river water is the most prominent agent of change in humid areas receiving heavy rainfall. As the rainfall occurs, water flows down the slope of the land and removes upper layers of the earth in the direction of water flow. Gradually small and narrow sills are formed which develop into gullies. The gullies further deepen, widen, lengthen, and unite to form a network of valleys. In the upper state of the river, down cutting dominates during which irregularities are removed. In the middle stage, rivers cut their beds slower and lateral erosion becomes dominant. At a later stage, the valley sides are reduced to lower and lower slopes. Similarly, the divides between drainage basins are lowered until they are almost completely flattened. This type of plain forming because of stream erosion is called a peneplain. The work of a river can be divided into three stages- youth, maturity and old. In dry areas, there is more down cutting because sides of the valley are not eroded due to lack of rainfall. In such areas landforms like gorges and canyons are formed. The Valley of Kaveri River near Hogenakkal, Dharmapuri district, Tamilnadu is one such example.
(ii) Limestones behave differently in humid and arid climates. Why? What is the dominant and almost exclusive geomorphic process in limestone areas and what are its results?
Answer: Limestones behave differently in humid and arid climates because there is change in climate. In humid climates, surface water percolates in the limestone rocks. After some time, the underground water flows horizontally through the bedding planes and joints. The downward and horizontal movement of water erodes rocks. The surface water and the groundwater through chemical processes of solution and precipitation deposition develop a variety of landforms. Limestone does not suffer much solution, erosion, and chemical reaction in dry climates due to lack of water. However, in dry areas, much water does not percolate in limestone rocks and the work of underground water is insignificant in such areas.
(iii) How do glaciers accomplish the work of reducing high mountains into low hills and plains?
Answer: A glacier does the work of erosion, transportation, and deposition on the surface of the earth and forms a variety of landforms. The glacier is always loaded with rock material from top to bottom. This material is called a drift or boulder and acts as an erosive tool of the glacier. Much of it is unsorted and angular. It helps the ice in scouring, scratching, or plucking the rocks. Because of this, the rocks get polished and there are grooves and striation marks on their faces. Erosion by glaciers is tremendous because of friction caused by the sheer weight of the ice. The material plucked from the surface by glacier gets dragged along the floors or sides of the valleys and causes great damage through abrasion and plucking. Glaciers can cause significant damage to even un-weathered rocks and can reduce mountains into low hills, plateaus and plains.
Landforms class 11 geography MCQ
1. Erosional landforms are the
(a) levees.
(b) deltas.
(c) braided channels.
(d) river terraces.
► (d) river terraces.
2. Deflation and abrasion activities are associated with
(a) waves.
(b) rivers.
(c) winds.
(d) glaciers.
► (c) winds.
3. A deep valley characterized by steep step-like side slopes is known as?
(a) U-shaped valley
(b) Gorge
(c) Blind valley
(d) Canyon
► (d) Canyon
4. The total number of wings a seif has is
(a) one.
(b) three.
(c) five.
(d) six.
► (a) one.
5. What is a deep, long and wide trough or basin with very steep concave high walls at its head as well as in its sides is known as?
(a) Cirque
(b) Glacial valley
(c) Lateral Moraine
(d) Esker
► (a) Cirque
6. Natural levees and point bars are depositional landform of
(a) glaciers.
(b) waves.
(c) winds.
(d) rivers.
► (d) rivers.
7. In which one of the following regions the chemical weathering process is more dominant than the mechanical process?
(a) Humid region
(b) Limestone region
(c) Arid region
(d) Glacier region
► (b) Limestone region
8. They are deep basins with very steep concaves to vertically dropping high walls at its head as well as sides. What are they?
(a) Cirque
(b) Horne
(c) Esker
(d) Drumlin
► (a) Cirque
9. Outwash plains are formed by what?
(a) Rivers
(b) Glacier
(c) Underground water
(d) Wind
► (a) Rivers
10. In which of the following regions the chemical weathering process is more dominant than the mechanical process?
(a) desert region
(b) arid region
(c) limestone region
(d) glacier region
► (c) limestone region
11. In the mature stage what are the loop-like channel patterns that develop in rivers?
(a) Meanders
(b) Canyon
(c) Delta
(d) Cirque
► (a) Meanders
12. Erosion causes
(a) Changes.
(b) No change.
(c) Upliftment.
(d) Construction of land.
► (a) Changes.
13. What are the most important landforms in desert areas?
(a) Chardong
(b) Interbedded rocks
(c) Sand dunes
(d) Valleys
► (c) Sand dunes
14. In the middle stages, erosion of valley sides is
(a) vertical.
(b) lateral.
(c) gradual.
(d) negligible.
► (b) lateral.
15. Which of the following is created by soil erosion by the rivers?
(a) V- shaped valley
(b) Waterfall
(c) Delta
(d) Sand dunes
► (a) V- shaped valley
16. The erosional land form consists of
(a) valleys.
(b) floodplains.
(c) deltas.
(d) alluvial fans.
► (a) valleys.
17. Which of the following is a type of channel pattern?
(a) Floodplains
(b) Deltas
(c) Meander
(d) Alluvial Fans
► (c) Meander
18. The depositional landform consists of
(a) levees.
(b) gorge.
(c) river terraces.
(d) valley.
► (a) levees.
Question : A deep, long and wide trough or basin with very steep concave high walls at its head as well as in sides is known as:
(a) Cirque
(b) Glacial valley
(c) Lateral Moraine
(d) Esker
Answer : A
Question : Which of the following is not made by erosion, waves and currents?
(a) Bars
(b) Dunes
(c) Barriers
(d) Stacks.
Answer : D
Question : Deflation and abrasion activities are associated with
(a) waves.
(b) rivers.
(c) winds.
(d) glaciers.
Answer : C
Question : Very coarse materials like boulders and blocks along with some minor fractions of rock debris carried into this stream settle in the valley of ice beneath the glacier and after the ice melts can be found as a sinuous ridge called what?
(a) Meanders
(b) Esker
(c) Delta
(d) Cirque.
Answer : B
Question : The erosional land form consists of
(a) valleys.
(b) floodplains.
(c) deltas.
(d) alluvial fans.
Answer : A
Question : Which of the landforms are made by rivers in old age?
(a) V-shaped valley
(b) Waterfall
(c) Delta
(d) Meanders.
Answer : D
Question : In which one of the following regions the chemical weathering process is more dominant than the mechanical process?
(a) Humid region
(b) Limestone region
(c) Arid region
(d) Glacier region
Answer : B
Question : Which of the following is created by soil erosion by the rivers?
(a) V-shaped valley
(b) Waterfall
(c) Delta
(d) Sand dunes.
Answer : A
Question : Which one of the following sentences best defines the term ‘Lapies’ ?
(a) A small to medium sized shallow depression
(b) A landform whose opening is more or less circular at the top and funnel shaped towards bottom
(c) A landform formed due to dripping water from surface
(d) An irregular surface with sharp pinnacles, grooves and ridges
Answer : D
Question : A deep, long and wide trough or basin with very steep concave high walls at its head as well as in sides is known as.
(a) Cirque
(b) Glacial valley
(c) Lateral Moraine
(d) Esker
Answer : A
Question : Outwash plains are formed by what?
(a) Rivers
(b) Glacier
(c) Underground water
(d) Wind
Answer : A
Question : What are most important landforms in desert areas?
(a) Chardong
(b) Interbedded rocks
(c) Sand dunes
(d) Valleys.
Answer : C
Question : In the mature stage what are the loop-like channel patterns that develop in rivers?
(a) Meanders
(b) Canyon
(c) Delta
(d) Cirque
Answer : A
Question : Deflation and abrasion activities are associated with
(a) waves
(b) rivers
(c) winds
(d) glaciers
Answer : C
Question : The depositional landform consists of
(a) levees.
(b) gorge.
(c) river terraces.
(d) valley.
Answer : A
Question : In which of the following stages of landform development, downward cutting is dominated?
(a) Youth stage
(b) Late mature stage
(c) Early mature stage
(d) Old stage
Answer : A
Question : A deep valley characterized by steep step like side slopes is known as-
(a) U-Shaped valley
(b) George
(c) Blind valley
(d) Canyon
Answer : D
Question : The depositional landform consists of
(a) levees
(b) gorge
(c) river terraces
(d) valley
Answer : A
Question : Which type of landforms are formed by rivers in the youth stage?
(a) Desert
(b) Cirque
(c) Lakes
(d) V-shaped valley.
Answer : D
Question : In which of the following stages of landform development, downward cutting is dominated?
(a) Youth stage
(b) Late mature stage
(c) Early mature stage
(d) Old stage.
Answer : A
Landforms class 11 geography SAQ
How would you explain the fact that the areas of permanent snow or ice are in high latitudes and very high altitudes?
Sun always shines perpendicular on the equator. Hence, equatorial regions get intense heat due to straight sun rays. As we go northwards or southwards from the equator, the sun’s rays become oblique and less heat is received in these regions. Hence, poles are always cold.
Temperature decreases with an increase in height at the rate of 1 °C per 165 meters. Hence, as we go above from the equator, fewer temperatures are observed. A height comes when the temperature is below freezing point and snow and ice rules over.
What are snowfields? Where are they generally situated?
The vast areas which are permanently covered with snow and ice are called snowfields.
The snowfields are generally found situated above the snow line.
High latitudes and polar regions,
Near mountain tops.
What is meant by ‘moraines’?
Glaciers carry pieces of rocks, big and small, with them. They deposit them at certain places – at their edges, on the bottom, at the terminals and the central zone of two glaciers. These deposits are called moraines.
Define loess plateau?
Loess is the deposit of sand blown over long distances and deposited over large areas. When the thickness of the loess is hundreds of meters, it assumes the name of the loess plateau.
Write a short note on the formation of sand dunes.
Wind deposits sand brought by it as sand dunes. The major features of these sand dunes are as follows:
A sand dune is a typical hill. It has a crest.
It is generally mobile as it goes on shifting along the direction of the prevailing wind.
Obstructions in the path of the wind lead to the formation of the sand dunes.
Sand dunes vary in size. They vary from a few meters to 300 meters in height.
Distinguish between stalactite and stalagmite.
Answer:
Distinguish between beaches and sandbars.
What is a fiord?
When a glacial trough formed near the sea gets filled up by the seawater, it is called a fiord. Thus a fiord is a deep, steep-sided water inlet near the sea. It is typical of
What is ‘regolith’?
Regolith is a layer of loose or soft material lying above the bedrock. When a regolith is formed by decomposition and disintegration of the bedrock that lies directly beneath it, it is called residual regolith. The regolith transported by steam, ice, water and deposited elsewhere is called a transported regolith.
Define fluvial denudation.
Running water is undoubtedly the most important agent of denudation. It is most conspicuous as a stream or river that transports enormous volumes of surplus precipitation from the land to the ocean. Stream action, in combination with weathering, mass wasting and overland flow, is responsible for the total process called fluvial denudation.
Explain two forms of the flow of running water as the geomorphic agent.
Running water acts as a geomorphic agent in two basic forms, viz., overland flow and channel or streamflow.
Overland flow is the movement of run-off downhill on the ground surface in a more or less broadly distributed sheet or film. Second is channel flow or streamflow in which water moves to lower levels in a long, narrow, trough-like feature called stream-channel, bounded on both sides by rising shapes called banks that contain the flow.
Discuss the features developed due to falling rain on bare surfaces.
Gentle rain falling on bare surfaces loosens the soil and muddies the water. The muddy water flows as the thin, slow-moving surface layer of water called sheet flow. As the slope increases, the water scours additional sediments and erodes small channels, which are called rills. Headward erosion of rills and their subsequent widening leads to gully formation. Gullies dissect the land into a number of isolated hills, giving rise to badland topography.
Discuss the internal and external forces involved in the creation of landforms.
A host of internal and external forces are involved in the creation of landforms. Tectonic forces crumple rocks and push up continents and mountain ranges. Moving water, air and ice erode rocks and transport the eroded debris to depositional sites and thus change the appearance of the landscape with the passage of time. The intensity of these agencies varies from one region to- another depending on climate, vegetation and altitude.
How is a U-shaped valley formed?
A glacier does not make its own valley. When a glacier enters a V-shaped river valley, it modifies it into a U-shaped valley. The valley is deepened as the pressure of ice increases. A wide, flat structure is formed. Due to side cutting the valley is widened, and it is known as a U-shaped valley.
On what factors does the erosion of the river depend?
Answer:
The erosional work of the river depends upon the following factors:
Volume of water
The slope of the river
Load of the river
Velocity of water
The nature of the rocks
Describe the different types of erosion done by a river.
Ans. The river erodes the land in several ways :
(i) Solution : It dissolves the soluble rocks like limestone.
(ii) Side cutting : The river erodes its banks sideways.
(iii) Down cutting : River cuts deep into the valley floor.
(iv) Attrition : The river loads like pebbles, collide into one another and are broken.
How is a ‘V’-Shaped Valley formed ?
Ans. A V-shaped valley is formed by the vertical erosion of the river. Side-cutting and down-cutting of the river-bed go on simultaneously. The valley is deepened as well as widened. In this way, a broad V-shaped valley is developed.
. On what factors does the erosion of the river depend ?
Ans. The erosional work of the river depends upon the following factors :
(i) Volume of water.
(ii) Velocity of water.
(iii) Load of the river.
(iv) Slope of the river.
(v) The nature of the rocks.
Define the term ‘‘Snowline.’’ Why does the height of snowline differ in different parts of the world ?
Ans. Snowline is the height above which the snow never melts. It is as high as 2,000 meters in the Alps. 5,000 meters in the Himalayas, and 5,500 meters in the equatorial regions. It varies due to latitude and the nature of the slope. It is higher in the steep Southern slopes of the Himalayas than in the Northern slopes. Snowline is higher in areas of heavy snowfall.
What are the different types of Moraines ?
Ans. According to the place of deposition, the moraines are of the following four types : (i) Lateral Moraines (ii) Medial Moraines (iii) Terminal Moraines (iv) Ground Moraines.
. Why is a tributary valley called a hanging valley ?
Ans. Many tributary glaciers from the mountains join the main glacier. A tributary valley is formed at a higher level than the main valley. The main glacier valley is deeper than the tributary valley. After the melting of ice, the tributary valley is left at a height much above the main valley. The stream in this valley ‘hangs’ above the main valley and forms a waterfall. Therefore, such tributary valleys are called hanging valleys.
Why does the middle of a glacier move faster than the sides ?
Ans. The velocity of the glacier varies in its different parts. The velocity of a glacier decreases sidewards and with depth. The velocity decreases due to friction with the valley walls and the bottom floor. The load of the glacier also checks its velocity. There is absence of any friction and load in the middle of the glacier. Therefore, the middle of the glacier moves much faster than its sides.
How are ox-bow lakes formed ?
Ans. Ox-bow lakes. Sometimes the meanders take the shape of the letter ‘S’. The river becomes almost a complete circle. A former bend or loop of the river is separated from the flowing river. This horse shoe-shaped strip of water is known as ox-bow lake. These lakes resemble the shape of an ox-bow. These are common on flood plains.
What is a Delta ?
Ans. Deltas. When a river enters the sea, it becomes very slow. It deposits all the load at its mouth. Such deposits of silt are known as Deltas. A delta is a triangular piece of alluvial land formed at the mouth of the river. It resembles the shape of the Greek letter delta, after which it is named. This name was used by the Greeks for the Nile delta.
Describe two types of deltas with examples.
Ans. Types of Deltas :
(a) Regular Deltas. These are triangular, fan shaped deltas like Ganges delta.
(b) Bird’s Foot Deltas. These are irregular deltas which have several branches (distributaries) like the foot of a bird. The Mississippi delta is of this type and is also called a Crow’s nest delta.
Landforms class 11 geography LONG question
Discuss features created by wave action.
At the shoreline, the line along which the water meets the land, the major erosive agent is wave action. Along the coast of hard rock, a gently inclined rock surface is carved out to accommodate the swash and backwash. It is called an abrasion platform. A shoreline rising abruptly from the abrasion platform is called a marine cliff. The stormy waves thrust rock fragments with great violence against the cliff base to develop wave-cut notches or sea-caves. Relatively thick and gently sloping accumulation of sand, gravel or cobbles in the zone of breakers and surf is called beads.
Write an essay on the geomorphic work of rivers,
Rivers are the stream channels organized into a branching channel network. Rivers perform three closely interacted geomorphic works, viz.,
erosion,
transportation,
deposition. River erosion is the progressive removal of minerals from the surface of a stream channel which itself may consist of the bedrock of regolith. River transportation is the movement of eroded particles in a chemical solution, in turbulent suspension or 6y rolling and changing along the bed. River deposition consists of -accumulation of any transported particles on the stream bed on the adjoining flood plain or on the floor of a body of standing water into which the river empties. While the river performs all three functions simultaneously, one may dominate over the other in different parts of the river course.
The nature of river erosion depends upon the materials of which the channel is composed. Erosion is hydraulic action, the pressure and drag of flowing water exerted upon grains projecting from the bed and banks. Weak bedrock and various forms of regolith are easily carved out by hydraulic action. Abrasion occurs when rock particles carried in the current strike against the exposed bedrock of the channel. Small particles are reduced by crushing and grinding when caught between larger cobbles and boulders. The chemical reaction between ions carried in solution and exposed mineral surfaces results in a form of erosion called a solution.
How does wind affect rocks and what kinds of rocks are eroded the fastest? Explain the formation of landforms by winds.
Winds are not strong enough to remove the mineral matter from hard rocks, moist clay or soil rich in vegetation. They can only affect those rocks which are soft, arid and vegetation less. Hence rocks which are soft are eroded the fastest.
Formation of landforms by winds: Winds form landforms both during erosional and depositional work.
Erosional landforms – Winds erode loose particles of soil and take them away. In course of time, a hollow is formed on the desert surface. This is called a wind-eroded basin.
Depositional landforms – When the wind becomes weak and some obstacle lies in its path, deposition of transported loose particles begins to take place. Wind becomes weak due to the decrease in its velocity. As a result of the depositions, sand dunes are formed. They are of different types and shapes.
Which is the most important agent modifying the coastal topography? Describe the various features formed by this agent of gradation.
The most important agent modifying coastal topography is sea waves. Sea waves erode, transport and deposit debris in the coastal regions and form both erosional as well as depositional features,
Erosional Features: Arches and Sea stacks: If the rock formation along the coast differs in resistance, softer rocks are eroded and harder to stand. This results in the formation of arches and stacks.
Depositional Features:
Sea waves deposit sand, gravel and pebbles on the shore. These deposits are called beaches. Marine beach (Triplicane) in Chennai is famous in India.
Sometimes sea waves deposit embankments of sand and gravel on the seafloor not far from the coast. These embankments are termed as bars. Very often ships strike against these bars and cause damage to themselves.
Sometimes sand bars separate a portion of the sea from the main sea, giving birth to a lake lagoon. A lagoon is a saltwater lake. These lakes have a connection with the main sea through sand and gravel along with the narrow outlets. Malabar coast in India abounds in lagoons. On the eastern coast, Chilka (in Orissa) and Pulicat (near Chennai) are two well-known lagoons.
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