Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 6 Geomorphic Processes Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.
Geomorphic Processes NCERT Solutions for Class 11 Geography Chapter 6
Geomorphic Processes Questions and Answers Class 11 Geography Chapter 6
Question 1.
Multiple choice questions :
(i) Which one of the following processes is a gradational process?
(a) Deposition
(b) Diastrophism
(c) Volcanism
(d) Erosion
Answer:
(d) Erosion.
(ii) Which one of the following materials is affected by hydration process?
(a) Granite
(b) Clay
(c) Quartz
(d) Salts
Answer:
(d) Salts.
(iii) Debris avalanche can be included in the category of:
(а) Landslide
(b) Slow flow mass movements
(c) Rapid flow mass movements
(d) Subsidence
Answer:
(c) Rapid flow mass movements.
Question 2.
Answer the following questions in about 30 words :
(i) It is weathering that is responsible for bio-diversity on earth. How?
Answer:
Weathering is an important exogenetic geomorphic process. It is the mechanical disintegration and chemical decomposition of rocks through the actions of various elements of weather and climate. Weathering processes are conditioned by many complex geological, climatic, topographic and vegetative factors.
Biological weathering is contribution to or removal of minerals and ions from the weathering environment. Burrowing and wedging by organisms help in exposing the new surfaces to chemical attack and assist in the penetration of moisture and air. Decaying plant and animal matter helps in the production of humic matter.
(ii) What are mass movements thsU are real rapid and *” perceptible? List.
Answer:
Mass movements involve the transfer of mass of rock debris down the slopes under the direct influence of gravity. The mass movements may range from slow to rapid, affecting shallow to deep column of materials and include creep, flow, slide and fall.
(iii) What are the various mobile and mighty exogenic geomorphic agents and what is the prime job they perform?
Answer:
Water, ice, wind, etc. are capable of acquiring and transporting earth materials. They are known as exogenetic geomorphic agents. When these natural agents become mobile due to gradients, they remove the materials and transport them over the, slopes. An agent is a mobile medium (like running water, moving ice masses, wind, etc.) which removes, transports and deposits earth materials. Running water, ground water, glaciers, wind waves and currents, etc. can be called geomorphic agents.
(iv) Is weathering essential as a pre-requisite in the formation of soils? Why?
Answer:
When rocks undergo weathering, some materials are removed through chemical or physical leaching by ground water and thereby the concentration of- remaining materials increases. Without such a weathering taking place, the concentration of the same valuable material may not be sufficient and economically viable to exploit, process and refine. Thus, weathering is essential.
Question 3.
Answer the following questions in about 150 words each :
(i) “Our earth is a playfield for two opposing groups of geomorphic processes.” Discuss.
Answer:
The endogenic and exogenic forces causing physical stresses and chemical actions on earth materials and bringing about changes in the configuration of the surface of the earth are known as geomorphic processes.
Diastrophism and volcanism are endogenetic geomorphic processes. Weathering, mass wasting, erosion and deposition are exogenetie processes.
The earth’s surface is being continuously subjected to the external forces originating within the earth’s atmosphere and the internal forces from within the earth, an it is ever-changing. The action of exogenetie ; forces result in wearing down (degradation) of relief/elevations and filling up (aggradation) of basins/depressions on the earth’s surface.
The endogenetic forces continuously elevate or build up parts of the earth’s surface and ‘hence’ the exogenetie processes fail to even out l the relief variations of the surface of the earth. The building up and wearing down of the earth’s surface by endogenetic and exogenetie forces respectively is going on from the time the earth’s crust was 1 developed and enveloped by the atmosphere. Hence, our earth is a playfield of two opposing forces.
(ii) Exogenic gemorphic processes derive their ultimate energy from sun’s heat. Explain.
Answer:
Exogenic geomorphic processes vary from region to region. Temperature and precipitation are the two important climatic elements S that control various processes. All the exogenetie processes are covered under a general term denudation, which means to strip off or to uncover. Weathering, mass wasting/movements, erosion and transportation are the type of denudation processes.
Climatic factors being equal, the intensity of action of exogenetie geomorphic processes depends upon the type and structure of rocks.The density, type and distribution of vegetation, which largely depends upon precipitation and temperature, exert an indirect influence – on exogenetie geomorphic processes. Within different climatic regions, there may be local variations of the effects of different climatic elements due to altitudinal differences. For all exogenetie processes, the energy/ heat is received from the sun. Hence, sun is the ultimate source of energy.
(iii) Are physical and chemical weathering processes independent of each other? ]f not, why? Explain with examples.
Answer:
Chemical weathering processes: The weathering processes, viz, hydration reduction, oxidation, carbonation, solution act on the rocks to decompose, dissolve or reduce them to a fine clastic state through chemical reactions. Water and air. along with heat, must be present to speed up all chemical reactions.
Physical weathering : Physical weathering depends on some applied forces:
- Gravitational forces,
- Expansion forces due to temperature changes,
- Water pressures controlled by wetting and drying cycles.
Physical weathering and chemical weathering are not independent, Both are dependent on each other. The hydration and dehydration both physically and chemically affect the weathering processes. Under certain moisture and temperature conditions, calcium sulphate takes in water and turns to gypsum causing a volume change in material. During this process, both physical and chemical weathering occurs. All weathering processes take place physically as well as chemically. Hence, both processes are dependent on each other.
(iv) How do you distinguish between the process of soil formation and soil forming factors? Wliat is the role of climate and biological activity as two important control factors in the formation of soils?
Answer:
Several processes like eluviation, illuviation, cheluviation, and leaching are involved in soil formation. Soil forming factors: All soil forming processes involve weathering. There are several other factors that influence the end product of weathering. Five of them are primary factors. They are responsible for the development of various types of soils. These factors are: parent material, climate, biota, topography and time.
Role of climatic factor: Climate affects soil formation in the following ways:
- Seasonal distribution of temperature.
- Amount of rainfall.
- The quality of water seeping into rock materials.
- Type and effectiveness of weathering.of parent-rock material.
- Different types of micro-organisms present in the soil.
- Climate affects the vegetation which helps in the soil formation.
Microflora or bacterial activity is quite a significant controlling factor in soil formation: With undecomposed organic matter, because of low bacterial activity, layers of peat develop in sub-arctic and tundra climates. Bacteria and other soil organisms take gaseous nitrogen from the air and convert it into a chemical form that can be used by plants. This process is known as nitrogen fixation.
Earthworms are important in humid regions. They change the texture and chemistry of the soil as it passes through their digestive systems. Large quantities of soil are L brought up to the surface by ants and termites from the lower horizons.Burrowing animals like rodents disturb and rearrange the soil. In this way, biological activities play an important role in soil formation.