{"id":118749,"date":"2022-04-28T14:16:16","date_gmt":"2022-04-28T08:46:16","guid":{"rendered":"https:\/\/www.mapsofindia.com\/my-india\/?p=118749"},"modified":"2022-04-28T14:18:47","modified_gmt":"2022-04-28T08:48:47","slug":"chapter-6-geomorphic-processes-questions-and-answers-ncert-solutions-for-class-11-geographyfundamentals-of-physical-geography","status":"publish","type":"post","link":"https:\/\/www.mapsofindia.com\/my-india\/education\/chapter-6-geomorphic-processes-questions-and-answers-ncert-solutions-for-class-11-geographyfundamentals-of-physical-geography","title":{"rendered":"Chapter 6 – Geomorphic Processes Questions and Answers: NCERT Solutions for Class 11 Geography(Fundamentals of Physical Geography)"},"content":{"rendered":"

1. Multiple choice questions<\/h3>\n

Question 1(i).
\nWhich one of the following processes is a gradational process?
\n(a) Deposition
\n(b) Diastrophism
\n(c) Volcanism
\n(d) Erosion.<\/h2>\n

Answer:
\n(d) Erosion<\/h3>\n

Question 1(ii).
\nWhich one of the following materials is affected by hydration process?
\n(a) Granite
\n(b) Clay
\n(c) Quartz
\n(d) Salts.<\/h2>\n

Answer:
\n(d) Salts<\/h3>\n

Question 1(iii).
\nDebris avalanche can be included in the category of:
\n(\u0430) Landslides
\n(b) Slow flow mass movements\u2019
\n(c) Rapid flow mass movements
\n(d) Subsidence.<\/h2>\n

Answer:
\n(c) Rapid flow mass movements.<\/h3>\n

2. Answer the following questions in about 30 words.
\nQuestion 2(i)
\nIt is weathering that is responsible for bio-diversity on the earth. How?<\/h2>\n

Answer:
\nWeathering processes lead to breaking down the rocks into smaller fragments and preparing the way for formation of not only regolith and soils, but also erosion and mass movements. Bio-diversity is basically a result of forests and vegetation. Forests and vegetation depend upon the depth of weathering mantles. Erosion cannot be significant if the rocks are not weathered. It implies that weathering aids mass wasting, erosion and reduction of relief and changes in landforms are a consequence of erosion.<\/h3>\n

Question 2(ii)
\nWhat are mass movements that are real rapid and perceptible? List<\/h2>\n

Answer:
\nThese movements transfer the mass of rock debris down the slopes under the direct influence of gravity. That means, air, water or ice do not carry debris with them from place to place but on the other hand the debris may carry with it air, water or ice.
\nMass movements can be slow or rapid. Rapid movements are mostly prevalent in humid climatic regions and occur over gentle to steep slopes. When slopes are steeper, even the bedrock especially of soft sedimentary rocks like shale or deeply weathered igneous rock may slide downslope.<\/h3>\n

Question 2(iii)
\nWhat are the various mobile and mighty exogenic geomorphic agents and what is the prime job they perform?<\/h2>\n

Answer:
\nThe exogenic processes derive their energy from atmosphere determined by the ultimate energy from the sun and also the gradients created by tectonic factors. All the exogenic geomorphic processes are covered under a general term, denudation. The word \u2018denude\u2019 means to strip off or to uncover. As there are different climatic regions on the earth\u2019s surface, the exogenic geomorphic processes vary from region to region. Temperature and precipitation are the two important climatic elements that control various processes.
\nTheir prime job includes weathering, mass wasting\/movements, erosion and transportation.<\/h3>\n

Question 2(iv)
\nIs weathering essential as a pre-requisite in the formation of soils? Why?<\/h2>\n

Answer:
\nYes, weathering is an essential pre-requisite in the formation of soils. Weathering is action of elements of weather and climate over earth materials. There are a number of processes within weathering which act either individually or together to affect the earth materials in order to reduce them to fragmental state. Weathering is mechanical disintegration and chemical decomposition of rocks through the actions of various elements of weather and climate.
\nWeathering is an important process in the formation of soils. When rocks undergo weathering, rocks start to break up and take form of soil gradually.<\/h3>\n

3. Answer the following questions in about 150 words.
\nQuestion 3(i).
\n\u201cOur earth is a playfield for two opposing groups of geomorphic processes.\u201d Discuss.<\/h2>\n

Answer:
\nIt is absolutely right to say that our earth is playfield for two opposing groups of forces. These forces are exogenic and endogenic. The external forces are known as exogenic forces and the internal forces are known as endogenic forces. The differences in the internal forces operating from within the earth which built up the crust have been responsible for the variations in the outer surface of the crust. The earth\u2019s surface is being continuously subjected to external forces induced basically by energy (sunlight). Of course, the internal forces are still active though with different intensities. That means, the earth\u2019s surface is being continuously subjected to by external forces originating within the earth\u2019s atmosphere and by internal forces from within the earth.
\nThe actions of exogenic forces result in wearing down (degradation) of relief\/elevations and filling up (aggradation) of basins\/ depressions, on the earth\u2019s surface. The endogenic forces continuously elevate or build up parts of the earth\u2019s surface and hence the exogenic processes fail to even out the relief variations of the surface of the earth. So, variations remain as long as the opposing actions of exogenic and endogenic forces continue. In general terms, the endogenic forces are mainly land building forces and the exogenic processes are mainly land wearing forces.<\/h3>\n

Question 3(ii).
\nExogenic geomorphic processes derive their ultimate energy from the sun\u2019s heat. Explain.<\/h2>\n

Answer:
\nThe exogenic processes derive their energy from atmosphere determined by the ultimate energy from the sun and also the gradients created by tectonic factors. Various minerals in rocks possess their own limits of expansion and contraction. With rise in temperature, every mineral expands and pushes against its neighbour and as temperature falls, a corresponding contraction takes place. Because of diurnal changes is the cause of splitting of individual grains within rocks, which eventually fall off. This process of falling off of individual grains may result in granular disintegration or granular foliation. Salt crystallisation is most effective of all salt-weathering processes. In areas with alternating wetting and drying conditions salt crystal growth is favoured and the neighbouring grains are pushed aside. Sodium chloride and gypsum crystals in desert areas heave up overlying layers of materials and with the result polygonal cracks develop all over the heaved surface. With salt crystal growth, chalk breaks down most readily, followed by limestone, sandstone, shale, gneiss and granite, etc.<\/h3>\n

Question 3(iii).
\nAre physical and chemical weathering processes independent of each other? If not, why? Explain with examples.<\/h2>\n

Answer:
\nNo, physical and chemical weathering are not independent of each other. They are different but still interdependent. Physical or mechanical weathering processes depend on some applied forces. The applied forces could be: (a) gravitational forces such as overburden pressure, load and shearing stress; (b) expansion forces due to temperature changes, crystal growth or animal activity; (c) water pressures controlled by wetting and drying cycles. Chemical weathering depends on a group of weathering processes viz; solution, carbonation, hydration, oxidation and reduction act on the rocks to decompose, dissolve or reduce them to a fine clastic state through chemical reactions by oxygen, surface and\/or soil water and other acids. Water and air (oxygen and carbon dioxide) along with heat must be present to speed up all chemical reactions. Over and above the carbon dioxide present in the air, decomposition of plants and animals increases the quantity of carbon dioxide underground. These chemical reactions on various minerals are very much similar to the chemical reactions in a laboratory.
\nThese forces are interdependent. For example availability of water and heat depends on physical factors while chemical reactions depend on availability of water and heat.<\/h3>\n

Question 3(iv).
\nHow do you distinguish between the process of soil formation and soil- forming factors? What is the role of climate and biological activity as two important control factors in the formation of soils?<\/h2>\n

Answer:
\nProcess refers to step by step procedure or methodical ways in which soil comes into existence while factors causing this formation are called soil forming factors. Soil formation process: Soil formation is called pedogenesis. It depends on weathering the most. It is this weathering mantle which is the basic input for soil to form. The weathered material or transported deposits are colonised by bacteria and other inferior plant bodies like mosses and lichens. Several minor organisms may take shelter within the mantle and deposits. The dead remains of organisms and plants help in humus accumulation. Minor grasses and ferns may grow; later, bushes and trees will start growing through seeds brought in by birds and wind. Plant roots penetrate down, burrowing animals bring up particles, mass of material becomes porous and sponge- like with a capacity to retain water and to permit the passage of air and finally a mature soil, a complex mixture of mineral and organic products forms.
\nSoil-forming factors: Five basic factors control the formation of soils:
\n1. Parent material
\n2. Topography
\n3. Climate
\n4. Biological activity
\n5. Time.
\nIn fact, soil forming factors act in union and affect the action of one another. Climate: Climate is an important active factor in soil formation. The climatic elements involved in soil development are :
\n1. moisture and
\n2. temperature.
\nPrecipitation gives soil its moisture content which makes the chemical and biological activities possible. Excess of water helps in the downward transportation of soil components through the soil (eluviation) and deposits the same down below (illuviation). Temperature acts in two ways \u2014 increasing or reducing chemical and biological activity. Chemical activity is inci\u2019eased in higher temperatures, reduced in cooler temperatures (with an exception of carbonation) and stops in freezing conditions. That is why, tropical soils with higher temperatures show deeper profiles and in the frozen tundra regions soils contain largely mechanically broken materials.
\nBiological Activity: The vegetative cover and organisms that occupy the parent materials from the beginning and also at later stages help in adding organic matter, moisture retention, nitrogen, etc. Dead plants provide humus. Some organic acids which form during humification aid in decomposing the minerals of the soil parent materials. Intensity of bacterial activity shows up differences between soils of cold and warm climates. Humus accumulates in cold climates as bacterial growth is slow.
\nWith undecomposed organic matter because of low bacterial activity, layers of peat develop in sub-arctic and tundra climates. Rhizobium, a type of bacteria, lives in the root nodules of leguminous plants and fixes nitrogen beneficial to the host plant. The influence of large animals like ants, termites, earthworms, rodents etc., is mechanical, but, it is nevertheless important in soil formation as they rework the soil up and down. In case of earthworms, as they feed on soil, the texture and chemistry of the soil that comes out of their body changes.<\/h3>\n

Multiple Choice Questions<\/h3>\n

Question 1.
\nWhich of the following is a type of mass movement?
\n(a) Slow movements
\n(b) Rapid movements
\n(c) Landslides
\n(d) All of the above.<\/h2>\n

Answer:
\n(d) All of the above.<\/h3>\n

Question 2.
\nWhich of the following is not a cause of soil erosion?
\n(a) Rock Material
\n(b) Landform
\n(c) Climate
\n(d) Deposition.<\/h2>\n

Answer:
\n(d) Deposition<\/h3>\n

Question 3.
\nWhich of the following is a form of weathering?
\n(a) Physical
\n(b) Chemical
\n(c) Biological
\n(d) All of the above.<\/h2>\n

Answer:
\n(d) All of the above<\/h3>\n

Question 4.
\nWhat term is used for the reaction of carbonate and bicarbonate with minerals?
\n(a) Carbonate
\n(b) Carbonation
\n(c) Carbolic
\n(d) All of the above.<\/h2>\n

Answer:
\n(b) Carbonation<\/h3>\n

Question 5.
\nWeathering is important for:
\n(a) Air
\n(b) National economy
\n(c) Climate
\n(d) Earth.<\/h2>\n

Answer:
\n(6) National economy<\/h3>\n

Question 6.
\nWhich type of weathering occurs due to growth of ice within pores and cracks of rocks during repeated cycles of freezing and melting?
\n(a) Frost weathering
\n(b) Landslides
\n(c) Water weathering
\n(d) Crystallisation.<\/h2>\n

Answer:
\n(a) Frost weathering<\/h3>\n

Question 7.
\nWhich of the following is an example of endogenic forces?
\n(a) Erosion
\n(b) Volcanism
\n(c) Weathering
\n(d) Balance.<\/h2>\n

Answer:
\n(b) Volcanism<\/h3>\n

Question 8.
\nWhich of the following is not associated with diastrophism?
\n(a) Orogenic processes
\n(b) Epeirogenic processes
\n(c) Plate tectonics
\n(d) Balance.<\/h2>\n

Answer:
\n(d) Balance<\/h3>\n

Question 9.
\nWhich of the following is a systematic process?
\n(a) Weathering
\n(b) Diastrophism
\n(c) Volcanism
\n(d) Balanced erosion.<\/h2>\n

Answer:
\n(d) Balanced erosion<\/h3>\n

Question 10.
\nWhat are geomorphic causes of erosion?
\n(a) Flowing water
\n(b) Underground water
\n(c) Air
\n(d) All of the above.<\/h2>\n

Answer:
\n(d) All of the above<\/h3>\n

Question 11.
\nWhich of the following process is not associated with physical weathering?
\n(a) Frost wedging
\n(b) Expansion
\n(c) Carbonation
\n(d) Thawing.<\/h2>\n

Answer:
\n(c) Carbonation<\/h3>\n

Question 12.
\nAll earth materials having a sloping surface and tend to produce movement of matter in down slope direction. It is called:
\n(a) Soil erosion
\n(b) Landslides
\n(c) Volcanism
\n(d) Slump.<\/h2>\n

Answer:
\n(a) Soil erosion<\/h3>\n

Question 13.
\nWhich of the following is affected by hydration?
\n(a) Granite
\n(b) Soil
\n(c) Quartz
\n(d) Rocks.<\/h2>\n

Answer:
\n(b) Soil<\/h3>\n

Question 14.
\nWhere\u2019does oxidation take place?
\n(a) Where there is ready access to the atmosphere and oxygenated waters.
\n(b) Where there are plants.
\n(c) Where there is moisture in air.
\n(d) In mountainous regions.<\/h2>\n

Answer:
\n(a) where there is ready access to the atmosphere and oxygenated waters.<\/h3>\n

Very Short Answer Type Questions<\/h3>\n

Question 1.
\nWhat kind of changes are brought by internal forces?<\/h2>\n

Answer:
\nInternal forces give birth to new landforms on the earth.<\/h3>\n

Question 2.
\nWhat is done by external forces?<\/h2>\n

Answer:
\nExternal forces bring changes in existing landforms on the earth. Through erosion and deposition, they keep bringing changes in topography of the earth.<\/h3>\n

Question 3.
\nWhat are geomorphic processes?<\/h2>\n

Answer:
\nThe 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.<\/h3>\n

Question 4.
\nWhat is weathering?<\/h2>\n

Answer:
\nWeathering is defined as mechanical disintegration and chemical decomposition of rocks through the actions of various elements of weather and climate.<\/h3>\n

Question 5.
\nWhat is denudation?<\/h2>\n

Answer:
\nThe term \u2018denude\u2019 means to strip off or to uncover. Weathering, mass wasting\/ movements, erosion and transportation are included in denudation.<\/h3>\n

Question 6.
\nHow do weathering activities work?<\/h2>\n

Answer:
\nA group of weathering processes viz; solution, carbonation, hydration, oxidation and reduction act on the rocks to decompose, dissolve or reduce them to a fine clastic state through chemical reactions by oxygen, surface and\/or soil water and other acids.<\/h3>\n

Question 7.
\nWhat are different types of weathering activities?<\/h2>\n

Answer:
\nThere are three major groups of weathering processes :
\n1. chemical;
\n2. physical or mechanical;
\n3. biological weathering processes.<\/h3>\n

Question 8. How can you classify mass movements?<\/h2>\n

Answer:
\nMass movements are of three types:
\n1. slow movement
\n2. rapid movement and
\n3. landslides.<\/h3>\n

Question 9.
\nWhat are different types of movement?<\/h2>\n

Answer:
\nHeave (heaving up of soils due to frost growth and other causes), flow and slide are three important types of movements.<\/h3>\n

Question 10.
\nWhat do you mean by reduction?<\/h2>\n

Answer:
\nWhen oxidised minerals are placed in an environment where oxygen is absent, reduction takes place.<\/h3>\n

Question 11.
\nPhysical weathering depends on some applied forces. What are these?<\/h2>\n

Answer:
\nPhysical or mechanical weathering processes depend on some applied forces. The applied forces could be:
\ngravitational forces such as overburden pressure, load and shearing stress;
\nexpansion forces due to temperature changes, crystal growth or animal activity;
\nwater pressures controlled by wetting and drying cycles.<\/h3>\n

Question 12.
\nWhere does oxidation occur? Which minerals get affected by oxidation?<\/h2>\n

Answer:
\nOxidation occurs where there is ready access to the atmosphere and oxygenated waters. The minerals most commonly involved in this process are iron, manganese, sulphur, etc.<\/h3>\n

Question 13.
\nWhat are the climatic factors involved in the formation of soil?<\/h2>\n

Answer:
\nThe climatic elements involved in soil development are :
\nmoisture in terms of its intensity, frequency and duration of precipitation -evaporation and humidity;
\ntemperature in terms of seasonal and diurnal variations.<\/h3>\n

Question 14.
\nWhat are geomorphic agents?<\/h2>\n

Answer:
\nAn agent is a mobile medium (like running water, moving ice masses, wind, waves and currents, etc.) which removes, transports and deposits earth materials. Running water, groundwater, glaciers, wind, waves and currents, etc., can be called geomorphic agents.<\/h3>\n

Question 15.
\nWhat do you mean by stress?<\/h2>\n

Answer:
\nGravitational force acts upon all earth materials having a sloping surface and tend to produce movement of matter in down slope direction. Force applied per unit area is called stress.<\/h3>\n

Question 16.
\nWhy is weathering of rocks important for economy?<\/h2>\n

Answer:
\nWeathering of rocks and deposits is important for the economy because it helps in the enrichment and concentrations of certain valuable ores of iron, manganese, aluminium, copper etc., which are of great importance for the national economy.<\/h3>\n

Question 17.
\nWhat are tors?<\/h2>\n

Answer:
\nIn rocks like granites, smooth surfaced and rounded small to big boulders form due to such exfoliation. It is called tors.<\/h3>\n

Question 18.
\nWhen does frost weathering takes place?<\/h2>\n

Answer:
\nFrost weathering occurs due to growth of ice within pores and cracks of rocks during repeated cycles of freezing and melting.<\/h3>\n

Question 19.
\nWhat is enrichment?<\/h2>\n

Answer:
\nWhen rocks undergo weathering, some materials are removed through chemical or physical leaching by groundwater and thereby the concentration of valuable materials increases. It makes the concentration of the same valuable material sufficient and economically viable to be exploited, processed and refined. This is called enrichment.<\/h3>\n

Question 20.
\nWhat factors are helpful in mass movement?<\/h2>\n

Answer:
\nWeak unconsolidated materials, thinly bedded rocks, faults, steeply dipping beds, vertical cliffs or steep slopes, abundant precipitation and torrential rains and scarcity of vegetation etc., favour mass movements.<\/h3>\n

Question 21 .
\nWhat do you mean by mudflow?<\/h2>\n

Answer:
\nIn the absence of vegetation cover and with heavy rainfall, thick layers of weathered materials get saturated with water and either slowly or rapidly flow down along definite channels. It looks like a stream of mud within a valley.<\/h3>\n

Question 22.
\nWhat is soil erosion?<\/h2>\n

Answer:
\nErosion involves acquisition and transportation of rock debris. The erosion can be defined as \u201capplication of the kinetic energy associated with the agent to the surface of the land along which it moves\u201d. Kinetic energy is computed as KE = 1\/2 mv2 where \u2018m\u2019 is the mass and \u2018v\u2019 is the velocity. If erosion takes place with soil, it is called soil erosion.<\/h3>\n

Question 23.
\nDefine Gradation?<\/h2>\n

Answer:
\nThe phenomenon of wearing down of relief variation of the surface of the earth through erosion is known as gradation.<\/h3>\n

Question 24.
\nWhat is meant by geomorphic process?<\/h2>\n

Answer:
\nThe endogenic and exogenic forces causing physical stresses and chemical actions on earth material and bringing about changes in the configuration of the surface of the earth is known as geomorphic process.<\/h3>\n

Question 25.
\nWhat are geomorphic agents? Give examples?<\/h2>\n

Answer:
\nAny exogenic elements of nature (like water, ice, wind, etc.) capable of acquiring and transporting earth materials-can be called geomorphic agents. An agent is a mobile medium (like running water, moving ice, etc.) which removes, transports and deposits earth materials. Examples: Running water, glacier, wind waves and currents, etc. can be called geomorphic agents.<\/h3>\n

Question 26.
\nWhat is meant by diastrophism?<\/h2>\n

Answer:
\nAll processes that move elevate or built up portion of the earth\u2019s crust come under diastrophism.<\/h3>\n

Question 27.
\nWhat do the word volcanism and volcano indicate?<\/h2>\n

Answer:
\nVolcanism includes the movement of molten rock onto or towards the earth\u2019s surface and also form formation of many intrusive and extrusive forms.<\/h3>\n

Short Answer Type Questions<\/h3>\n

Question 1.
\nWhat factors have caused diastrophism?<\/h2>\n

Answer:
\nAll processes that move, elevate or build up portions of the earth\u2019s crust come under diastrophism. They include:
\nOrogenic processes: It involves mountain building through severe folding and affecting long and narrow belts of the earth\u2019s crust;
\nEpeirogenic processes: It involves uplift or warping of large parts of the earth\u2019s crust;
\nEarthquakes: It involves local relatively minor movements;
\nPlate tectonics: It involves horizontal movements of crustal plates. All these processes-cause pressure, volume and temperature (PVT) changes which in turn induce metamorphism of rocks.<\/h3>\n

Question 2.
\nWhy is the surface of the earth uneven?<\/h2>\n

Answer:
\nThe difference in the internal forces operation from within the earth which built up the crust have been responsible for the variations in the outer surface of the crust. Due to variations in geothermal gradients and strength, the actions of endogenic forces are not uniform and hence the tectonically controlled original crystal surface is uneven.<\/h3>\n

Question 3.
\nWhat factors activate the process of mass movement?<\/h2>\n

Answer:
\nFollowing factors activate the process of mass movement.
\nRemoval of support from below to materials above through natural or artificial means;
\nIncrease in gradient and height of slopes;
\nOverloading through addition of materials naturally or by artificial filling;
\nOverloading due to heavy rainfall, saturation and lubrication of slope materials;
\nRemoval of material or load from over the original slope surfaces;
\nOccurrence of earthquakes, explosions or machinery;
\nExcessive natural seepage;
\nHeavy drawdown of water from lakes, reservoirs and rivers leading to slow outflow of water from under the slopes or river banks;
\nIndiscriminate removal of natural vegetation.<\/h3>\n

Question 4.
\nHow does biological weathering take place?<\/h2>\n

Answer:
\nBiological weathering takes place by:
\nAnimals: Animals like rabbits, rats, termides, etc. make burrows and holes in the rocks. They consumes large quantity of soils and rocks for making their habitat and destruction of food. This loosens the rock strata and disintegration occurs.
\nVegetation: Long and teanatious roots of plants work down into cracks of rocks. The roots of shrubs and trees reach deep into them and this lodge large blocks.
\nHuman Activities: Mining, deforestation, indiscriminate cultivation of land and construction activities contribute to weathering.<\/h3>\n

Question 5.
\nDeposition is the result of erosion. Explain.<\/h2>\n

Answer:
\nDeposition is a consequence of erosion. The erosional agents loose their velocity and hence energy on gentler slopes and the materials carried by them start to settle themselves. In other words, deposition is not actually the work of any agent. The coarser materials get deposited first and finer ones later. By deposition depressions get filled up. The same erosional agents viz., running water, glaciers, wind, waves and groundwater act as aggradational or depositional agents also.<\/h3>\n

Question 6.
\nWithout gravity and gradient will there be no erosion?<\/h2>\n

Answer:
\nGravity besides being a directional force activates down slope movement of matters and also causes stresses on earth material.
\nWithout gravity and gradients there would be no mobility and hence no erosion, no transportation and no deposits as gravitation stresses are as important as the other geomorphic process.
\nGravity is force that is keeping us in contact with the surface and it is the force that switches on the movement of all surface material on earth.
\nAll the movement either within the earth or on the surface of the earth occurs due to gradients from higher levels to lower levels and from high pressure to low pressure areas.<\/h3>\n

Question 7.
\nWhat is the importance of weathering?<\/h2>\n

Answer:
\nImportance of weathering:
\nWeathering processes are responsible for breaking down the rocks into smaller fragments and preparing the way for formation of not only regolith and soils but also erosion and mass movement. Biomes and bio-diversity is basically a result of forests depend upon the depth of weathering mantles.
\nWeathering aids mass and deposits helps in the enrichment and concentrations of certain valuables ores of iron, manganese, aluminium, etc. which are of great importance for the national economy.
\nWeathering is an important process in the formation of soils.<\/h3>\n

Question 8.
\nMention the factors which results in mass movement.<\/h2>\n

Answer:
\nThe movements of mass may range from slow to rapid, affecting shallow to deep columns of materials and include creep, flow, slide and fall. Gravity exerts its force on all matter, both bedrock and the products of weathering. So, weathering is not a pre- requisite for mass movement though it aids mass movement.
\nWeak unconsolidated materials dipping thinly bedded rocks, faults, steeply, beds, vertical cliffs or steep slopes, abundant precipitation and torrential rains and scarcity of vegetation etc. favour mass movements.<\/h3>\n

Question 9.
\nExplain the mass movements which are slow.<\/h2>\n

Answer:
\nSoil creep: It is one type under this category which can occur on moderately steep, soil covered slope. We may find some of evidence of extremely, slow down slope movement of soil.
\nRock creep: The disintegrated rock material creeps down the slope under the influence of gravity.
\nSolifluction: It takes place in cold areas where there is heavy snowfall in winter. It involves slow downslope flowing soil mass or fine grained rock debris saturated or lubricated with water.<\/h3>\n

Question 10.
\nWhy are parent material and time considered as passive control factors in soil formation?<\/h2>\n

Answer:
\n1. Parent Material: It is a passive factor in soil formation. Parent materials can be any insitu or on-site weathered rock debris or transported deposits. Soil formation depends upon the texture, structure as well as mineral and chemical composition of the rock debris\/ deposits.
\n2. Time: It is the passive controlling factor in soil formation. The length of time the soil-forming processes operate determine maturation of soils and profile development. A soil becomes mature when all soil-forming processes act for a sufficiently long time developing a profile.<\/h3>\n

Question 11.
\nWrite the difference between:
\n(i) Exogenic and endogenic forces
\n(ii) Orogenic movements and epeirogenic movements
\n(iii) Physical weathering and chemical weathering.<\/h2>\n

Answer:
\n(i)
\nS.no.
\nExogenic Forces
\nEndogenic Forces
\n1.
\nThe external forces are known as Exogenic forces.
\nThe internal forces are known as Endogenic forces.
\n2.
\nSolar energy is the sole driving force behind all the Exogenic processes. E.g. Erosion, Flood, Mining, etc.
\nGravity is the sole driving force behind all the Endogenic process. E.g. Earthquake, Volcanic Eruption, etc.
\n(ii)
\nS.no.
\nOrogenie Movements
\nEpeirogenic Movements
\n1.
\nIn the process of Orogenie the crust is severely deformed into folds.
\nDue to Epeirogenic they may be single deformation.
\n2.
\nIt is mountain building process.
\nIt is continental building process.
\n3.
\nIt affects long and narrow belt of earth\u2019s crust.
\nIt involves uplift or wrapping of large parts of earth\u2019s crust.
\n(iii)
\nS.no.
\nPhysical Weathering
\nChemical Weathering
\n1.
\nPhysical force disintegrates the rocks.
\nRocks are decomposed by chemical changes.
\n2.
\nNo chemical change occurs.
\nNot much physical change occurs but chemical change occurs due to air and water.
\n3.
\nMore effective in dry and cold areas.
\nEffective in hot and hum1areas.
\n4.
\nInsulation, frost and pressure are the agents.
\nOxidation and reduction arbonation, hydration and soil are the agents.
\n5.
\nRocks are affected at the greater depth.
\nRocks are affected on the surface only.
\n6.
\nEven the strong minerals are affected by physical weathering.
\nChemical resistance minerals are not affected.<\/h3>\n

Long Answer Type Questions<\/h3>\n

Question 1.
\nWhat are different types of mass movements?<\/h2>\n

Answer:
\nThere are three types of mass movements: Slow Movements: Creep is one type under this category which can occur on moderately steep, soil covered slopes. Movement of materials is extremely slow and imperceptible except through extended observation. Materials involved can be soil or rock debris. Soil creep, talus creep, rock creep, rock- glacier creep etc can be identified. It also includes solifluction which involves slow downslope flowing soil mass or fine grained rock debris saturated or lubricated with water. This process is quite common in moist temperate areas where surface melting of deeply frozen ground and long continued rain respectively, occur frequently. When the upper portions get saturated and when the lower parts are impervious to water percolation, flowing occurs in the upper parts.
\nRapid Movements: These movements are mostly prevalent in humid climate regions and occur over gentle to steep slopes. Movements of water- saturated clayey or silty earth materials down low angle terraces or hill slides is known as earth flow. When slopes are steeper ever the bedrock especially of soft sedimentary rocks like shale or deeply weathering igneous rock may slide downslope. With heavy rainfall, thick layers of weathered
\nmaterials get saturated with water and either slowly or rapidly flow down along definite channels. It looks like a stream of mud within a valley.
\nLandslides: The types of landslides.
\nSlumps: The slipping of one or several units of rock debris with a backward rotation with respect to the slope over which the movement takes place.
\nDebris slide: rapid rolling or sliding of earth debris without backward rotation of mass is known as Debris slide.
\nRockslide: Sliding of individual rock masses down bedding, joint or fault surface is rockslide.
\nRock fall: Rock fall is free falling of rock blocks over any steep slope keeping itself away from the slope. Rock falls occurs from the superficial layers of the rock face.<\/h3>\n

Question 2.
\nExplain different types of chemical weathering.<\/h2>\n

Answer:
\nDifferent types of chemical weathering includes:
\n1. Oxidation and Reduction: Oxidation is the effect of oxygen in air and water on the rocks. The atmospheric oxygen in rainwater unites with minerals in rocks specially with iron compounds. When oxidised minerals are placed in an environment where oxygen is absent, reduction takes place. It exists normally below water table, in area of stagnant water in more hot and humid climates.
\n2. Carbonation: When the carbon dioxide in atmosphere dissolves in water it form carbonic acid that affects the rocks, it is carbonation. It has acidic affect and dissolves calcium carbonates and magnesium carbonates such as gypsum, marble, limestone.
\n3. Hydration: When the hydrogen of water dissolves in rocks hydration occurs. Certain minerals in rocks increase their volume and become heavy when observe water contains hydrogen. They break due to its increased pressure and the colour also changes.
\n4. Solution: Rainwater is able to dissolve certain minerals and leaching of the soil occurs. Normally solids are also removed during leaching. For e.g.: gypsum, rock salt, etc. undergo solution.<\/h3>\n

Question 3.
\nExplain different types of physical weathering.<\/h2>\n

Answer:
\nDifferent types of physical weathering includes:
\nExfoliation: Due to differential heating and resulting expansion and contraction of surface layers and their subsequent exfoliation from the surface results in smooth rounded surfaces in rocks. In rocks like granites, smooth surfaced and rounded small to big boulders called tors form due to such exfoliation.
\nFrost: It is an active agent in cold climatic regions in high altitudes and the cracks are filled with water during the day time, this water is frozen at night when temperature falls below freezing point.
\nPressure: Many igneous and metamorphic rocks crystallize deep in the interior under the combine influence of high pressure and temperature. The salt near surface pores cause splitting of the grains within the rocks which eventually falls off, this result into granules disintegration.<\/h3>\n

Question 4.
\nExplain about erosion and deposition.<\/h2>\n

Answer:
\nErosion involves acquisition and transportation of rock debris. When massive rocks break into smaller fragments through weathering and any other process, erosional geomorphic agents like running water, groundwater, glaciers, wind and waves remove and transport it to other places depending upon the dynamics of each of these agents. Abrasion by rock debris carried by these geomorphic agents also aids greatly in erosion. By erosion, relief degrades, i.e., the landscape is worn down. Weathering aids erosion it is not a pre-condition for erosion to take place. Weathering, mass-wasting and erosion are degradational processes. It erosion that is largely responsible for continuous changes that the earth\u2019s surface is undergoing. The erosion and transportation of earth materials is brought about by wind, running water, glaciers, waves and ground water.
\nDeposition is a consequence of erosion. The erosional agents loose their velocity and hence energy on gentler slopes and the materials carried by them start to settle themselves. In other words, deposition is not actually the work of any agent. The coarser materials get deposited first and finer ones later. By deposition depressions get filled up. The same erosional agents viz., running water, glaciers, wind, waves and groundwater act as aggradational or depositional agents also. What happens to the surface of the earth due to erosion and deposition is elaborated in the next chapter on landforms and their evolution. There is a shift of materials in mass movements as well as in erosion from one place to the other.<\/h3>\n","protected":false},"excerpt":{"rendered":"

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