Geomorphic Processes Class 11 Important Extra Questions Geography Chapter 6
Geomorphic Processes Important Extra Questions Very Short Answer Type
Question 1.
What are exogenetic forces?
Answer:
The external forces are known as exogenetic forces.
Question 2.
What are endogenetic forces?
Answer:
The internal forces operating from within the earth are known as endogenetic forces.
Question 3.
What is the degradation?
Answer:
The wearing down of relief is known as degradation.
Question 4.
What is the function of endogenetic forces?
Answer:
These forces continuously elevate or build up parts of the earth’s surface.
Question 5.
Name the various exogenetic elements.
Answer:
Water, air wind, ice, etc. are exogenetic elements.
Question 6.
How is energy generated within the earth?
Answer:
The energy within the earth is generated by radioactivity, rotational and tidal friction.
Question 7.
What is the effect of gravitational stresses?
Answer:
They activate wave and tide induced currents and winds.
Question 8.
What is orogeny?
Answer:
Orogeny is a mountain building process.
Question 9.
What causes earthquakes?
Answer:
Orogeny, epeirogeny, plate tectonics cause earthquakes.
Question 10.
Name the denudation processes.
Answer:
Weathering, mass wasting/movements, erosion and transportation are the denudation processes.
Question 11.
Name the different types of weathering.
Answer:
Weathering is of three types:-
Chemical,
Physical,
Biological weathering.
Question 12.
What are the important agents of weathering?
Answer:
Frost, wind, heat, glacier and running water.
Question 13.
Name the two active factors of soil formation.
Answer:
Climate and living organisms.
Question 14.
What do you mean by exfoliation?
Answer:
It is the process of peeling off the outer layers from the main rock.
Question 15.
What is bad land?
Answer:
An area dissected with gullies and ravines.
Question 16.
What is humus?
Answer:
Humus is the organic matter of vegetable or animal organs in the soil.
Question 17.
How do organic soils develop?
Answer:
Organic soils develop from the accumulation of plant residues that are preserved by the low oxygen environment of shallow and stagnant waters.
Question 18.
Name the primary factors responsible for the development of soils.
Answer:
The primary factors responsible for the development of soils are parent material, climate, biota, topography and time.
Question 19.
What is eutrophication?
Answer:
Enrichment of water with nutrients, primarily phosphorous, causing abundant aquatic plant growth is called eutrophication.
Question 20.
Define soil profile.
Answer:
A vertical section of the soil through all its horizons and extending into the parent material is called a soil profile.
Question 21.
What is pedology?
Answer:
The branch of science that deals with the study of soil are called pedology.
Question 22.
What is added to the saline soil to reduce its salinity?
Answer:
Gypsum is added to the saline soil to reduce its salinity and make it useful for crops.
Question 23.
What are the mineral contents of laterites?
Answer:
The mineral contents of laterites include aluminium and iron oxide,
Question 24.
What makes the soil alkaline?
Answer:
Alkaline soils are formed in areas of low rainfall due to the accumulation or retention of lime.
Question 25.
Name the four soil-forming processes.
Answer:
The four soil-forming processes are eluviation, illuviation, Teaching and chelation.
Question 26.
What does ICAR stand for?
Answer:
ICAR stands for Indian Council of Agricultural Research.
Question 27.
Name eight soil groups as classified by ICAR.
Answer:
They are alluvial soils, black soils, red and yellow soils, laterite, arid, saline, peaty, organic and forest soils.
Geomorphic Processes Important Extra Questions Short Answer Type
Question 1.
What are geomorphic processes? Describe briefly.
Answer:
The endogenetic and exogenetic forces causing physical; stresses and chemical actions on earth materials and bringing about changes in the configuration of the earth’s surface are known as geomorphic processes. Diastrophism and volcanism are endogenetic geomorphic processes.
Question 2.
Distinguish between exogenetic and endogenetic forces.
Answer:
Exogenetic forces: The earth’s surface is being continuously subjected to external forces induced basically by the energy (sun). These external forces are known as exogenetic forces.
Endogenetic forces: The forces originating within the earth from its interior are known as endogenic forces. They are responsible for building up and wearing down of the earth’s surface.
Question 3.
What is directional force and what is its role?
Answer:
Gravity is a directional force. It activates the movements of matter and also causes stresses on the earth materials. Indirect gravitational stresses activate wave and tide induced currents and winds. Without gravity and gradients, there would be no mobility and hence no erosion.
Question 4.
What do you understand by oxidation?
Answer:
When atmospheric oxygen combines with minerals of rocks (especially with iron) to form oxides, the process is known as oxidation, v Rocks get rusted due to the presence of air and water. The rocks begin to decay and crumble to a powder mass of brown dust.
Question 5.
What is carbonation?
Answer:
Carbonation is the process in which rainwater gets mixed with carbon dioxide. It dissolves limestone, chalk and marble rock to form carbonates or bicarbonates with minerals. Calcium carbonates and magnesium carbonates are dissolved in carbonic acid.
Question 6.
What is weathering?
Answer:
Weathering means the weakening or wearing down, breaking up, rotting and disintegration of rocks at or over the earth’s surface.
Question 7.
What is chemical weathering?
Answer:
Chemical weathering is the decomposition of rocks by chemical methods. It results from the action of weak acids and gases like oxygen, carbon dioxide and hydrogen. Chemical weathering produces a chemical change in the minerals of rocks. High temperatures and humidity cause the rocks to decompose.
Question 8.
How does mass wasting take place?
Answer:
The force of gravity acts constantly upon the soil and bedrock. At various places, the internal strength of these materials is sufficient to keep them in place. But when the ground surface is sloping, the force of gravity is directed down the slope parallel with the surface. Every particle has least same tendency to roll or slide downhill and will do so whenever the downslope force exceeds the resisting forces of friction and cohesion that tend to bind the particles to the rest of the mass.
Question 9.
How does biota help in soil development?
Answer:
Biota is the collective term for the animal and plant life of a specific area as per the period of time. The decomposition of organic wastes and residues and the activities of living plants and animals have marked influence on soil development. Burrowing animals such as moles, prairie dogs, earthworms, ants and termites help soil development slowly by decomposing organic matter and forming weak acids that dissolve minerals faster. The roots of living plants and decomposed plant material release weak organic acids that help in weathering and soil development.
Question 10.
What is the pH value of soils?
Answer:
‘pH’ value means ‘potential hydrogen’, the standard measure of activity or Alkalimists in the soils. It is based on the activity of hydrogen ions in a litre of a solution, expressed in gram per litre. The pH value range from 0 to 14.0. Neutrality is at 3.0. Numbers lower than neutrality signify increasing acidity and higher numbers increasing salinity. Knowledge of the pH value of the soil under cultivation is most important in agriculture and horticulture.
Question 11.
What is saline soil?
Answer:
Because of the dry climate and poor drainage conditions, this soil acquires more salt. It is widespread in western Gujarat (Rann of Kutch), deltas of the east coast and Sunderban areas of West Bengal. Gypsum diminishes the salinity of soil and makes it useful for drops.
Question 12.
Distinguish between chelation and leaching.
Answer:
Leaching is the downward movement of material from a soil horizon in solution.
Chelation is also the downward movement of material, similar to leaching, but under the influence of organic complex compounds.
Question 13.
Discuss the role of topography in soil formation.
Answer:
The topography influences the soil formation through its relationship with relief, water and temperature. Steep hillsides have thin soil cover because of surface runoff that results in the erosion of the surface. On the other hand, gentle hillside preserves appreciable soil overdue to the luxuriant vegetation and sufficient water passing in vertically to deeper levels. The land-locked depressions receive a high amount of runoff water that favours appreciable vegetation cover but slower decomposition because of oxidation deficiency. This results in the formation of soil that is rich in organic matter.
Question 14.
How many essential elements are required by plants?
Answer:
Plants need at least 16 essential elements. They are carbon, hydrogen, oxygen, phosphorus, potassium, nitrogen, sulphur, calcium, iron, magnesium, boron, manganese, copper, zinc, molybdenum and chlorine.
Question 15.
How are the exogenetic earth processes driven?
Answer:
Exogenetic earth processes are the external processes that are driven by solar energy. They act through the atmosphere and oceans where air and water come in contact with the lithosphere.
Geomorphic Processes Important Extra Questions Long Answer Type
Question 1.
What is the rock weathering? Discuss various ways in which it takes place.
Answer:
Rock weathering is the chemical decomposition and physical disintegration of rocks. Weathering takes place in three ways :
Chemical weathering
Physical or mechanical weathering
Biological action
1. Chemical weathering: Chemical weathering is the decomposition of rocks by chemical methods. It results from the action of weak acids and gases like oxygen, carbon dioxide and hydrogen. Chemical weathering produces a chemical change in the minerals of rocks. High temperatures and humidity cause the rocks to decompose.
2. Physical or Mechanical weathering: The physical wear and tear of rocks is called mechanical weathering. In the middle and high latitude climates, and at high altitudes, alternate freezing and melting of water called frost action provide a powerful mechanism for breaking up of rocks. Water that penetrates joint planes and other natural openings in the rock expands when transformed into ice crystals. The pressure of the growing mass of such crystals causes joint blocks to be heaved up and pried free of the parent mass.
In the dry climates of low and middle latitudes, an important agent of rock disintegration is salt. The dry climates have long droughts in which evaporation can occur continuously causing water deep in the rock to be drawn surfaceward by capillary force. Near the rock surface, the moisture steadily evaporates permitting dissolved salts to be deposited in the opening of the rock. The growing salt crystals in this manner are capable of exerting pressure and disintegrating rocks.
The action of roots of growing plants exerting pressure upon the confining walls of rocks is yet another kind of mechanical weathering.
Biological weathering: When the breakdown of rocks and minerals is due to plants, animals and bacteria, it is called biological weathering. The main contribution of animals to weathering seems to be repeated mixing of soil material, thus bringing fresh material into exposure to the weathering agents. Snails are common in lime-rich ) areas and can wear deep holes in the limestone. Bird droppings may provide ‘ organic matter for the slant of soil formation and weathering.
Grazing by large animals loosens the soil, thus increasing surface runoff and soil erosion. Larger plants affect weathering in a number of ways. Cracks may be widened by root pressure. The accumulation of elements by plants and their return to the surface of the soil affects the nature of the soil and weathering profiles and the course of weathering. , Vegetation litter and decaying vegetation are important in conserving moisture which in turn enhances weathering.
Question 2.
Describe the geomorphic processes and how the gravity force affects the materials.
Answer:
The endogenetic and exogenetic forces causing physical stresses and chemical action on earth materials and bringing about changes in the configuration of the surface of the earth are known as geomorphic processes. The common geomorphic processes are diastrophism, volcanism, weathering, mass wasting, erosion and deposition.
Any exogenetic element of nature (like ice, wind, water, etc.) capable of acquiring and transporting earth materials can be called a geomorphic agent. When these elements become mobile due to gradients, they remove the materials and transport them over slopes. An agent is a mobile medium which removes, transports and deposits ‘ earth materials. Running water, groundwater, glaciers, wind, waves and currents, etc. can be called geomorphic agents.
Gravity is a directional force activating all downslope movements of matter and also causes stresses on the earth materials. Gravitational stresses activate wave and tide induced currents and winds. Without p gravity and gradients, there would be no mobility and hence no erosion, transportation and deposition are possible. So, the gravitational stresses are as important as the other geomorphic processes. Gravity force keeps us in contact with the surface and switches on the movement of all surface earth materials.
Question 3.
Write short notes on:-
1. Diastrophism,
2. Volcanism,
3. Exfoliation.
Answer:
1. Diastrophism: These are endogenetic processes. They include
orogenic processes, involving mountain building through severe folding and affecting long and Harrow belts of earth’s crust,
Epeirogenic processes, involving uplift or warping of large parts of the earth’s crust,
earthquakes, involving local, relatively minor movement, and
plate tectonics, involving horizontal movements of the crustal plates. In the process of orogeny, the crust is severely deformed into folds. Due to Epeirogency, there may be simple deformation. Orogeny is a mountain building process, whereas epeirogeny is a continental building process. Through the processes of orogeny, epeirogeny earthquakes and plate tectonics, there can be faulting and fracturing of the crust. All these processes cause pressure, volume and temperature (PVT) changes which in turn induce metamorphism of rocks.
2. Volcanism: Volcanism includes the movement of molten rocks towards the surface of the earth and also the formation of many intrusive and extrusive volcanic forms. In the process of volcanism, a host of landforms are created, including rock deformation, resulting in Domal folds and metamorphism of surrounding rocks due to intense heat.
3. Exfoliation: This is a type of physical weathering process unloading, thermal contraction and expansion and salt weathering. Exfoliation is a result and not a process. Spalling or flaking off of more or less curved sheets of shells from rocks or bedrocks resalts in smooth and rounded surfaces. Exfoliation can occur due to expansion and contraction induced by unloading and temperature changes. Exfoliation domes and tors result due to unloading and thermal expansion respectively. Granular exfoliation or disintegration, taking place especially due to salt weathering processes, also results in smooth and rounded surfaces.
Question 4.
Define and describe soil horizons.
Answer:
Soil horizons are the soil layers that are approximately parallel to the soil surface. Each horizon is different from the other. Boundaries between horizons range from indistinct to abrupt and clear. Horizons are formed because of differences in the degree of depth, amounts of humus accumulated, translocation of colloids by water and loss of colloids. Capital letters A, B, C, D and E are used to designate these horizons.
Horizons are commonly identified from the surface downwards.

‘A’ horizon is the topsoil containing humus, from which materials are washed downwards by percolating water (leaching) so that it is termed an eluvial (eluviation) horizon.
‘B’ horizon or sub-soil lies beneath ‘A’ horizon. It is a horizon of deposition, of secondary enrichment, an illuvial horizon (illuviation) into which are deposited, the washed-out materials from ‘A’ horizon. Underneath is the ‘C’ horizon, it is the weathered parent material of the existing soil. Some soil scientists also distinguish ‘D’ horizon, the bedrock.
Question 5.
Discuss the factors responsible for soil formation and also the processes involved.
Answer:
Soil forming factors: There are five factors that influence soil formation, viz., parent material, climate, biota, topography and time.
1. Parent material: Parent material in soil science is weathered bedrock or the transported glacial or alluvial material. Soils from weakly cemented sandstone will be sandy and soils from shales will be shallow and fine-textured. Similarly, clay formation is favoured more by a high percentage of decomposable dark mineral and less by quartz.
2. Climate: Climate is an important active factor in soil formation. Several processes are involved in soil formation and may to some extent affect the soil profile.
3. Biota: Biota is the collective term for the animal and plant life of a
a specific area as per the period of time. The decomposition of organic wastes and residues and the activities of living plants and animals have marked influence on soil development. Burrowing animals such as moles, prairie dogs, earthworms, ants and termites help soil development slowly by decomposing organic matter and forming weak acids that dissolve minerals faster. The roots of living plants and decomposed plant material release weak organic acids that help in weathering and soil development.
4. Topography: Topography means relief features. Steep hillsides have thin soil cover because of surface runoff that results in the erosion of the surface. On the other hand, gentle hillside preserves appreciable soil cover due to the luxuriant vegetation and sufficient water passing in vertically to deeper levels. The landlocked depressions receive a high amount of runoff water that favours appreciable vegetation cover but slower decomposition because of oxidation deficiency. This results in the formation of soil that is rich in organic water. Thus, topography influences soil formation through its relationship with water and temperature.
5. Time: Soil formation is a very slow process. It may take a few hundred to a few thousand years. This period of time, however, varies from place to place, depending upon other factors discussed above (plant material, -biota, topography, climate). Under ideal conditions, a recognisable soil profile may develop in 200 years and under less favourable circumstances, it may extend to several thousand years.
Soil, forming processes: Several processes are involved in soil formation. These are:
Eluviation: It is the mechanical translocation of clay or other fine particles down the profile.
Illuviation: ft is the accumulation of the washed down material in the lower horizons of the soil profile.
Leaching: It is the removal and downward movement of material from a horizon in solution.
Cheluviation: It is a downward movement of the material, similar to leaching, but under the influence of complex organic compounds.
