Worksheet Solutions: Geomorphic Processes | Geography Class 11 - Humanities/Arts PDF Download

Fill in the Blanks

Q1: The phenomenon of wearing down of relief variations of the surface of the earth through erosion is known as __________.
Ans: gradation
Gradation refers to the process of wearing down relief variations through erosion, which results in a more even surface.

Q2: The energy emanating from within the earth is the main force behind __________ geomorphic processes.
Ans: endogenic
Endogenic processes are driven by energy originating from within the Earth, such as geothermal heat, which induces processes like diastrophism and volcanism.

Q3: __________ is the force that is keeping us in contact with the surface and is the force that switches on the movement of all surface material on earth.
Ans: Gravity
Gravity is the fundamental force responsible for keeping matter in contact with the Earth's surface, and it plays a crucial role in various geomorphic processes.

Q4: Weathering is defined as mechanical disintegration and chemical decomposition of rocks through the actions of various elements of __________ and climate.
Ans: weather
Weathering is the result of physical and chemical processes driven by elements of weather and climate, which break down rocks into smaller fragments.

Q5: The three major groups of weathering processes are __________, physical or mechanical, and biological.
Ans: chemical
Weathering processes can be broadly categorized into chemical weathering, physical or mechanical weathering, and biological weathering, each with its unique mechanisms.

Q6: __________ is the process of solution, where solids are dissolved in water or weak acids.
Ans: Solution
Solution refers to the dissolution of solid materials in water or weak acids, resulting in their removal from rocks.

Q7: In areas of curved ground surface, arched fractures tend to produce massive sheets or __________ of rock.
Ans: exfoliation
Exfoliation is the process where curved sheets of rock or bedrock flake off, often due to thermal expansion or unloading, resulting in smooth and rounded surfaces.

Q8: Frost weathering occurs due to the growth of __________ within pores and cracks of rocks during repeated cycles of freezing and melting.
Ans: ice
Frost weathering is caused by the expansion of water when it freezes, leading to the widening of pores and cracks in rocks.

Q9: Biological weathering is the contribution to or removal of minerals and ions from the weathering environment and physical changes due to growth or movement of __________.
Ans: organisms
Biological weathering involves the actions of living organisms, such as burrowing, which exposes rocks to chemical attack and contributes to weathering.

Q10: Erosion cannot be significant if the rocks are not __________.
Ans: weathered
Weathering prepares rocks by breaking them into smaller fragments, making them more susceptible to erosion. Without weathering, erosion would be less effective.

Assertion and Reason Based

Q1: Assertion: Exogenic processes derive their energy from the atmosphere.
Reason: Exogenic processes are genetically related to the atmosphere, hydrosphere, and biosphere.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (b)
Exogenic processes are indeed related to the atmosphere, hydrosphere, and biosphere, but their energy source is primarily from these external components, not the atmosphere itself.

Q2: Assertion: Weathering processes are responsible for breaking down rocks into smaller fragments.
Reason: Weathering aids in the enrichment and concentration of valuable ores.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (a)
The assertion correctly states the role of weathering in breaking down rocks, and the reason explains how it contributes to the enrichment of valuable ores by removing less valuable materials.

Q3: Assertion: Expansion due to unloading and pressure release can result in exfoliation.
Reason: Exfoliation is primarily caused by chemical reactions between rocks and water.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (c)
The expansion due to unloading and pressure release can indeed result in exfoliation. However, exfoliation is primarily a result of physical processes, not chemical reactions.

Q4: Assertion: Salt crystallization is most effective in salt-weathering processes.
Reason: Salt crystals cause the expansion of minerals, leading to the disintegration of rocks.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (a)
The assertion correctly states that salt crystallization is effective in salt-weathering processes, and the reason explains how it causes the disintegration of rocks.

Q5: Assertion: Gravitational forces can lead to rock fracture.
Reason: Physical weathering processes depend on applied forces.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (a)
Gravitational forces can indeed lead to rock fracture, and physical weathering processes are dependent on applied forces, including gravitational forces.

Very Short Answer Type Questions

Q1: Define geomorphic processes.
Ans: Geomorphic processes are natural processes that shape the Earth's surface over time.

Q2: Name one endogenic geomorphic process.
Ans: Diastrophism is an endogenic geomorphic process.

Q3: Name one exogenic geomorphic process.
Ans: Erosion is an exogenic geomorphic process.

Q4: What is the role of gravity in geomorphic processes?
Ans: Gravity is essential for the downslope movement of matter, erosion, and transportation in geomorphic processes.

Q5: How do endogenic forces affect the earth's surface?
Ans: Endogenic forces uplift or build up parts of the Earth's surface, leading to changes in its configuration.

Q6: What are the three major groups of weathering processes?
Ans: The three major groups of weathering processes are chemical, physical (or mechanical), and biological.

Q7: Explain the process of solution in weathering.
Ans: Solution involves the dissolution of solid materials in water or weak acids, resulting in their removal from rocks.

Q8: What causes frost weathering?
Ans: Frost weathering occurs due to the growth of ice within pores and cracks of rocks during repeated cycles of freezing and melting.

Q9: How does salt crystallization affect rocks?
Ans: Salt crystallization causes the expansion of minerals within rocks, leading to their disintegration.

Q10: How do biological activities contribute to weathering?
Ans: Biological activities, such as burrowing, expose rocks to chemical attack and assist in the penetration of moisture and air, contributing to weathering.

Short Answer Type Questions

Q1: Explain the concept of exogenic forces and endogenic forces. How do they affect the Earth's surface?
Ans: Exogenic forces are external forces that shape the Earth's surface, while endogenic forces are internal forces. Exogenic forces, like erosion and weathering, result in the wearing down and filling up of relief variations. Endogenic forces, such as diastrophism and volcanism, uplift or build up parts of the Earth's surface. These forces interact to create the Earth's topography.

Q2: Describe the endogenic geomorphic process known as diastrophism. Provide examples.
Ans: Diastrophism involves processes that move, elevate, or build up portions of the Earth's crust. Orogeny, for example, involves mountain building through severe folding, impacting long and narrow belts of the Earth's crust. Epeirogeny involves the uplift or warping of large parts of the Earth's crust. Earthquakes involve relatively minor local movements, while plate tectonics involve horizontal movements of crustal plates.

Q3: What is volcanism, and how does it shape the Earth's surface?
Ans: Volcanism includes the movement of molten rock (magma) onto or toward the Earth's surface and the formation of volcanic features. Intrusive and extrusive volcanic forms, such as volcanoes, volcanic mountains, and lava plateaus, are created by volcanism. The solidification of magma leads to the formation of volcanic landforms, impacting the Earth's topography.

Q4: Discuss the various types of chemical weathering processes and provide examples.
Ans: Chemical weathering processes include solution, carbonation, hydration, oxidation, and reduction. Solution involves the dissolution of minerals in water or weak acids, affecting minerals like nitrates and sulphates. Carbonation results from the reaction of carbonate and bicarbonate with minerals, breaking down feldspars and carbonate minerals. Hydration involves the chemical addition of water, causing minerals to expand, like the conversion of calcium sulphate to gypsum. Oxidation involves the combination of minerals with oxygen, affecting minerals like iron and manganese. Reduction occurs when minerals lose oxygen in environments lacking oxygen. These processes alter rocks, leading to their decomposition.

Q5: Explain the physical weathering processes and the forces responsible for them.
Ans: Physical weathering processes depend on applied forces. These forces include gravitational forces, expansion forces due to temperature changes or crystal growth, and water pressures controlled by wetting and drying cycles. Unloading and expansion, which occurs when overlying rock is removed, leads to the expansion and disintegration of upper rock layers. Temperature changes cause minerals to expand and contract, impacting rocks, particularly in dry climates with drastic temperature changes. Freezing and thawing, known as frost wedging, result from the repeated cycles of freezing and melting, causing the expansion of water and the widening of pores and cracks in rocks. Salt weathering occurs when salts expand due to thermal action and crystallization, affecting various rock types.

Q6: How does unloading and expansion contribute to physical weathering?
Ans: Unloading and expansion in physical weathering occur when overlying rock layers are removed due to erosion or other processes. This leads to a release of vertical pressure on the underlying rocks. As a result, the upper layers of rock expand because they are no longer compressed by the weight of the overlying rock. This expansion causes fractures to develop roughly parallel to the ground surface. In curved terrain, arched fractures can produce massive sheets or exfoliation slabs of rock. This process of expansion due to unloading and pressure release can result in the physical weathering known as exfoliation.

Q7: Describe the role of temperature changes in physical weathering.
Ans: Temperature changes play a significant role in physical weathering, especially in regions with drastic diurnal temperature fluctuations. As temperatures rise, minerals within rocks expand, pushing against neighboring minerals. Conversely, as temperatures fall, contraction occurs. These repetitive cycles of expansion and contraction within the superficial layers of rocks can lead to physical weathering. This process is most effective in dry climates and high elevations where temperature changes are more pronounced. The expansion and contraction of minerals contribute to the disintegration of rocks, particularly in environments with extreme temperature variations.

Q8: How does salt weathering affect rocks, and in what conditions is it most effective?
Ans: Salt weathering occurs when salts, such as calcium, sodium, magnesium, potassium, and barium, expand due to thermal action, hydration, and crystallization. These salts tend to expand at specific temperature ranges, typically between 30 and 50 degrees Celsius. The expansion of salt crystals within near-surface pores exerts pressure on individual grains within rocks. As a result, these grains may separate and eventually fall off. This process of falling off individual grains can lead to granular disintegration or granular foliation. Salt crystallization is most effective in arid regions with high surface temperatures, where salt expansion is more pronounced. Chalk, limestone, sandstone, shale, gneiss, and granite can be affected by salt weathering, with chalk being the most susceptible to this process.

Long Answer Type Questions

Q1: Discuss the significance of weathering in shaping the Earth's surface and its role in the formation of regolith, soils, and erosion.
Ans: Weathering plays a crucial role in shaping the Earth's surface. It breaks down rocks into smaller fragments, contributing to the formation of regolith, which is the unconsolidated layer of fragmented rock and mineral material covering the Earth's bedrock. Regolith is a critical component for the growth of soils, as weathering processes further break down regolith into finer particles, facilitating the development of soil horizons. Erosion, which is the transportation of weathered material, depends on weathering, as eroded particles originate from weathered rocks. Without weathering, there would be limited soil formation, and erosion would be less effective in reshaping the landscape.

Q2: Explain the interrelated weathering processes of hydration, carbonation, and oxidation. Provide examples of each.
Ans: Hydration, carbonation, and oxidation are interrelated chemical weathering processes. Hydration involves the addition of water to minerals, causing them to expand. For example, calcium sulphate takes in water and turns into gypsum, which is more unstable. Carbonation is the reaction of minerals with carbonate and bicarbonate ions, often from carbon dioxide in water, leading to the dissolution of minerals. An example is the dissolution of calcium carbonate in water with carbonic acid, forming caves. Oxidation involves minerals reacting with oxygen to form oxides or hydroxides. For instance, iron minerals oxidize to form iron oxides, resulting in the color change of rocks. These processes can occur together and accelerate weathering.

Q3: Describe the role of biological activity in weathering and how it contributes to the exposure of new surfaces for chemical attack.
Ans: Biological activity contributes significantly to weathering. Burrowing organisms, like earthworms and termites, create tunnels and openings in rocks, exposing new surfaces to chemical attack. This exposure facilitates the penetration of moisture and air into rock crevices, enhancing chemical weathering processes. Additionally, organisms can excrete substances that react with rocks, contributing to their breakdown. Plant roots exert physical pressure on rock surfaces, causing mechanical weathering. Human activities, such as cultivation and vegetation disturbance, also create new contacts between air, water, and minerals in Earth materials, further promoting weathering. The decay of plant and animal matter produces humic, carbonic, and other acids, which increase the solubility of elements and minerals, aiding in their weathering and dissolution.

Q4: Explain the concept of exfoliation in weathering and its various forms, including exfoliation domes and tors.
Ans: Exfoliation in weathering involves the flaking off of curved sheets or shells from rocks or bedrock, resulting in smooth and rounded surfaces. Exfoliation can occur due to various factors, including expansion and contraction induced by temperature changes and unloading. In areas with curved ground surfaces, arched fractures tend to produce massive sheets of rock, known as exfoliation slabs. These slabs can be extensive, measuring hundreds or even thousands of meters horizontally. Exfoliation domes are large, smooth, rounded landforms that result from expansion due to unloading. Tors are exposed outcrops of bedrock formed through exfoliation. These landforms are a product of physical weathering processes, particularly the release of pressure on rock surfaces. Exfoliation can contribute to the gradual reshaping of landscapes by exposing new rock surfaces.