Question 1

Question 10Assertion (A): River meanders are bends of longitudinal courses.Reason (R): Meanders are the result of both erosion and deposition under conditions of a gentle slope and sufficient water in rivers.Both A and R are true and R is the correct explanation of A.Both A and R are true but R does not explain A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.Explanation — Meanders are the result of both erosion and deposition work of rivers. Meanders generally form under conditions of a gentle slope and sufficient water in rivers. The river flow is diverted by an obstruction allowing the river to do lateral erosion work.

Question 2

Question 13............... are moon-shaped dunes.DunesSand DunesBarchansSeifs

Accepted Answer

Barchans

Question 3

Question 14Stationary, long and narrow sand-ridges which grow parallel to the direction of the prevailing wind and remain in a fixed position.DunesSand DunesBarchanSeifs

Accepted Answer

Seifs

Question 4

Question 15The lowering of land, rounding of exposed rock surfaces and levelling of the peaks:DenudationErosionMass wastingDeposition

Accepted Answer

Denudation

Question 5

Question 16Assertion (A): In the lower course of the river all the ideal conditions for depositional landforms exist.Reason (R): The load-transporting capacity is drastically reduced due to sluggish flow as well as division of a river into many distributaries.Both A and R are true and R is the correct explanation of A.Both A and R are true but R does not explain A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.Explanation — The load-transporting capacity is drastically reduced due to sluggish flow as well as division of a river into many distributaries. This is why deposition becomes dominant in the lower course of the river.

Question 6

Question 17Which amongst the following is not a factor affecting work of a river?Velocity of waterQuality of waterVolume of waterLoad of water

Accepted Answer

Quality of water

Question 7

Question 18How do migratory dunes damage towns and villages?They cover all surfaces with thick layers of sand.The large mass of sand shifts further.They can be checked by building walls.All of the above.

Accepted Answer

They cover all surfaces with thick layers of sand.

Question 8

Question 19Assertion (A): Barchan are moon-shaped live dunes.Reason (R): The migration of the barchans is a threat to desert life.Both A and R are true and R is the correct explanation of A.Both A and R are true but R does not explain A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true but R does not explain A.Explanation — Barchans are moon-shaped live dunes which advance steadily before winds that blow from a particular direction. The migration of the barchans is a threat to desert life as they sometimes encroach on an oasis, burying palm trees or houses.

Question 9

Question 20Name the landform that is formed as a result of the action of wind wherein loose materials are lifted and blown off to be deposited outside the desert margins.Sand DunesBarchansDeflation HallowsSeifs

Accepted Answer

Deflation Hallows

Question 10

Question 21See the below figure of a barchan and identify the direction of the wind.ABBoth A and BNeither A nor B.

Accepted Answer

A

Question 11

Question 11Name two chief types of sand dunes.

Accepted Answer

Two chief types of sand dunes are-BarchanLongitudinal dunes or Seifs

Question 12

Question 12State any two characteristics of barchans.

Accepted Answer

Two characteristics of barchans are-They occur transversely to the wind, so that their horns thin out and become lower in the direction of the wind.The windward side is convex and gentle-sloping while the leeward side is concave and steep.

Question 13

Question 1(b)Name the various processes involved in denudation. What are the results of denudation?

Accepted Answer

The various processes involved in denudation are-WeatheringErosionMass movement or mass wastingTransportationDepositionThe results of denudation are the formation of erosional or depositional landforms on the surface of the earth.

Question 14

Question 1(c)Give a geographical reason for each of the following:(i) Erosion is the dominant activity of a river in its upper course.(ii) Landforms of deposition are more prominent in the middle course of a river.(iii) All the rivers do not form deltas.

Accepted Answer

(i) Erosion is the dominant activity of a river in its upper course because at this stage, the river flows swiftly, for the gradients are steep. Under the impact of rush of water and the load the river carries, erosion action is swift and effective.(ii) Landforms of deposition are more prominent in the middle course of a river because at this stage, the gradient is reduced and the river flows more slowly. The energy required to transport the materials is just enough to drag large particles and the lateral cutting is more active than down cutting.(iii) All the rivers do not form deltas because there are certain conditions for the formation of deltas, which include nearly calm sheltered sea, large amount of sediment supply and a reasonable size of the river.

Question 15

Question 1(d)Describe the work of wind erosion and state two important landforms of wind erosion.

Accepted Answer

Wind picks up loose debris like sand and pebbles and transports as well as deposits them in another location. Wind can lift and carry sand grains away. When the speed of wind slows down, the sediments brought by the wind begin to drop on the ground. This process continues and forms various landforms on the surface of the earth.Two important landforms of wind erosion are deflation hollows and sand dunes.

Question 16

Question 2(a)Briefly describe the factors which affect the work of a river.

Accepted Answer

The factors which affect the work of a river are-1. Velocity of water — Erosion and transportation are both maximum when the velocity of water is high. Deposition takes place when the velocity of water is low.2. Volume of water — The larger the volume of water, the greater is the power of erosion and transportation. Deposition takes place better when there is reduced volume of water and when the load is greater.3. Load — The load of the river does all the work of erosion and deposition. Mass wasting, deepening of river valleys and formation of landforms depend on the load a river carries.

Question 17

Question 2(b)Describe the three stages of a river.

Accepted Answer

The three stages of a river are-Upper course — At this stage, the river flows swiftly, for the gradients are steep. This course generally lies in a hilly area and the river flows a considerable distance over a steep slope.Along its course, it erodes its bed and banks, and carries large boulders of rock with it. The erosion action is swift and effective. V-shaped valleys and waterfalls are formed in the upper course of the rivers.Middle course — At this stage, the gradient is reduced, and the river flows more slowly. In the middle course of the river, the energy required to transport the materials is just enough to drag large particles.The lateral cutting is more active and the volume of water in the river increases due to many tributaries joining it. Meanders and oxbow lakes are formed in the middle course of the rivers.Lower course — In this stage, the river flows sluggishly and makes many landforms. All the ideal conditions for depositional landforms exist but the load-transporting capacity is drastically reduced due to the sluggish flow as well as division of a river into many distributaries.Deltas are formed in the lower course of rivers.

Question 18

Question 2(c)Give a geographical reason for each of the following:(i) The effects of wind erosion are more pronounced in desert areas.(ii) Migratory sand dunes are uncertain and dangerous.(iii) Long rooted trees and sand holding grasses are grown bordering fields near deserts.

Accepted Answer

(i) The effects of wind erosion are more pronounced in desert areas since there is little vegetation or moisture to bind the loose surface materials.(ii) Migratory sand dunes are uncertain and dangerous because when they migrate with the wind, they damage towns and villages.(iii) Long rooted trees and sand holding grasses are grown bordering fields near deserts to halt the advance of the dunes in order to prevent the fertile land from being devastated.

Question 19

Question 2(d)State the factors on which the shape and size of dunes depend?

Accepted Answer

The factors on which the shape and size of dunes depend are:The direction and force of wind.The speed of wind, carrying the dust and sand particles.The nature and amount of sand brought by the wind.Water features like lakes, streams etc., in the close-by area.The nature of vegetation on the land.The nature of the surface, where the formation of a sand dune takes place.

Question 20

Question 3Given below is a photograph of Purwa Waterfall on the River Tamsa in Madhya Pradesh. Answer the following questions:(a) What stage is the River Tamsa to cause formation of this waterfall? Give reasons to support your answer.(b) What other landforms would a river make in this stage?(c) What landforms would the River Tamsa make in the next stage of its flow?(d) Besides being a tourist attraction waterfalls are important sources of energy. Elucidate.

Accepted Answer

The River Tamsa in Madhya Pradesh is in its youthful stage (also called the upper course). This is due to following reasons:Presence of Waterfalls (like Purva Falls): Waterfalls are classic features of a youthful river stage, where the river flows over a steep slope or escarpment. The Purva Falls are formed as the River Tamsa descends over the Rewa Plateau, which is an elevated region.Steep Gradient: In the upper course, rivers have a high gradient, causing rapid flow and vertical erosion, which leads to the formation of waterfalls and gorges.Vertical Erosion Dominates: The river cuts downwards more than sideways, creating sharp features like rapids and waterfalls.Therefore, the formation of Purva Falls by Tamsa river is a characteristic of its youthful stage, marked by steep gradients, vertical erosion, and the presence of waterfalls.(b) Other landforms (apart from Waterfalls) formed during the youthful stage are —RapidsV-shaped valleys and I-shaped valleysGorgesCanyons(c) River Tamsa would form the following landforms in the next stage, i.e., mature stage (or middle course) —MeandersOxbow lakesFloodplainsWider V-shaped valleys(d) Waterfalls are important sources of energy because the falling water possesses great potential and kinetic energy, which can be harnessed to generate hydroelectric power (HEP). When water falls from a height, it drives turbines connected to generators, producing clean and renewable electricity. This makes waterfalls valuable for sustainable energy production, especially in hilly and mountainous regions.

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