NCERT Solution Class 11 Geography Landforms and their Evolution

NCERT Solution Class 11 Geography Landforms and their Evolution

. 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 characterised by steep step-like side slopes is known as

(a) U-shaped valley

(b) Gorge

(c) Blind valley

(d) Canyon

(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

. 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 are 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 on the status of original land surfaces over which streams have developed.

(ii) Explain the evolution of valley sinks or uvalas.

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 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. A 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.

. Answer the following questions in about 150 words

(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 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 river, down cutting dominates during which irregularities are removed. In the middle stage, river 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, mature 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 likes gorges and canyons are formed. The Valley of Kaveri River near Hogenekal, 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 climate, 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 process of solution and precipitation deposition develop a variety of landforms. Limestone does not suffer much solution, erosion, and chemical reaction in dry climate 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 area.

(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 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 glacier is tremendous because of friction caused by sheer weight of the ice. The material plucked from the surface by glacier gets dragged along the floors or sides of the valleys and cause great damage through abrasion and plucking. Glaciers can cause significant damage to even un-weathered rocks and can reduce mountains into low hills, plateau and plains.




Click for more Geography Study Material

Latest NCERT & CBSE News

Read the latest news and announcements from NCERT and CBSE below. Important updates relating to your studies which will help you to keep yourself updated with latest happenings in school level education. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning

Procedure for correction in Name and Date of Birth

Procedure for correction in Name and Date of Birth in CBSE records Name Change: Applications regarding changes in name or surname of candidates will be considered provided the changes have been admitted by the Court of law and notified in the Government Gazette before...

CBSE advisory on student marks

CBSE has issued a public advisory for all students to be careful from unscrupulous persons impersonating themselves as officers/officials of CBSE. These people have been contacting parents and have been telling them that they have access to student marks data for Board...

Board Cancelled Official CBSE Statement

Keeping in view the requests received from various State Governments and the changed circumstances as on date, following has been decided- 1. Examinations for classes X and XII which were scheduled from 1st July to 15th, 2020 stand cancelled. 2. Assessment of the...

Board Exams helpline by CBSE

According to the recent announcement of CBSE, the pending Class 10 and 12 Board exams are going to be held from 01 July to 15 July 2020 in India. Along with this, it has also been decided to resume the free of cost tele-counseling service for students from 9.30 am to 5...

CBSE Online Training for Teachers 2020

It is clear that this pandemic has utterly disrupted an education system that many assert was already losing its relevance. Enhancing professional development digitally is a need in the times of COVID-19, where social distancing and remote interactions is the new...

Class 12 Board Exams Datesheet Announced

CBSE has announced the datesheet of the remaining class 12 board exams, see below:  

Studies Today