Download CL IX Unit-II, Landforms SM-F - CBSE

CLASS
IX
CBSE-i
L
UNIT-2
GEOGRAPHY
ANDFORMS
STUDENTS' MANUAL
Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110 092 India
CBSE-i
GEOGRAPHY
LANDFORMS
STUDENTS' MANUAL
CLASS
IX
UNIT-2
Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110 092 India
The CBSE-International is grateful for permission to reproduce
and/or translate copyright material used in this publication. The
acknowledgements have been included wherever appropriate and
sources from where the material may be taken are duly mentioned. In
case any thing has been missed out, the Board will be pleased to rectify
the error at the earliest possible opportunity.
All Rights of these documents are reserved. No part of this publication
may be reproduced, printed or transmitted in any form without the
prior permission of the CBSE-i. This material is meant for the use of
schools who are a part of the CBSE-International only.
Preface
Education plays the most important role in acquiring professional and social skills and a positive attitude to face thechallenges of
life. Curriculum is a comprehensive plan of any educational programme. It is also one of the means of bringing about qualitative
improvement in an educational system. The Curriculum initiated by Central Board of Secondary Education-International
(CBSE-i) is a progressive step in making the educational content responsive to global needs. It signifies the emergence of a fresh
thought process in imparting a curriculum which would restore the independence of the learner to pursue the learning process
in harmony with the existing personal, social and cultural ethos.
The CBSE introduced the CBSE-i curriculum as a pilot project in few schools situated outside India in 2010 in classes I and IX and
extended the programme to classes II, VI and X in the session 2011-12. It is going to be introduced in classes III, VII and for Senior
Secondary classes with class XI in the session 2012-13.
The Senior Secondary stage of education decides the course of life of any student. At this stage it becomes extremely important
for students to develop the right attitude, a willingness to learn and an understanding of the world around them to be able to
take right decisions for their future. The senior secondary curriculum is expected to provide necessary base for the growth of
knowledge and skills and thereby enhance a student's potential to face the challenges of global competitiveness. The CBSE-i
Senior Secondary Curriculum aims at developing desired professional, managerial and communication skills as per the
requirement of the world of work. CBSE-i is for the current session offering curriculum in ten subjects i.e. Physics Chemistry,
Biology, Accountancy, Business-Studies, Economics, Geography, ICT, English, Mathematics I and Mathematics II. Mathematics
at two levels caters to the differing needs of students of pure sciences or commerce.
The Curriculum has been designed to nurture multiple intelligences like linguistic or verbal intelligence, logical mathematical
intelligence, spatial intelligence, sports intelligence, musical intelligence, inter-personal intelligence and intra-personal
intelligence.
The Core skills are the most significant aspects of a learner's holistic growth and learning curve. The objective of this part of the
core of curriculum is to scaffold the learning experiences and to relate tacit knowledge with formal knowledge. This involves
trans-disciplinary linkages that would form the core of the learning process. Perspectives, SEWA (Social Empowerment through
Work and Action), Life Skills and Research would be the constituents of this 'Core'. The CBSE-i Curriculum evolves by building
on learning experiences inside the classroom over a period of time. The Board while addressing the issues of empowerment with
the help of the schools' administering this system strongly recommends that practicing teachers become skilful and lifelong
learners and also transfer their learning experiences to their peers through the interactive platforms provided by the Board.
The success of this curriculum depends upon its effective implementation and it is expected that the teachers will make efforts to
create better facilities, develop linkages with the world of work and foster conducive environment as per recommendations
made in the curriculum document.
I appreciate the effort of Dr. Sadhana Parashar, Director (Training), CBSE and her team involved in the development of this
document. I specially appreciate the efforts of (Late) Dr. Srijata Das for working tirelessly towards meeting deadlines.
The CBSE-i website enables all stakeholders to participate in this initiative through the discussion forums. Any further
suggestions on improving the portal are always welcome.
Vineet Joshi
Chairman, CBSE
Acknowledgements
Advisory
Conceptual Framework
Shri Vineet Joshi, Chairman, CBSE
Dr. Sadhana Parashar, Director (Training), CBSE
Shri G. Balasubramanian, Former Director (Acad), CBSE
Ms. Abha Adams, Consultant, Step-by-Step School, Noida
Dr. Sadhana Parashar, Director (Training), CBSE
Ideators
Dr. Anju Srivastava
Ms. Varsha Seth
Ms. Sarita Manuja
Prof. Chand Kiran Saluja
Mr. N. K. Sehgal
Ms. Preeti Hans
Ms. Sunita Tanwar
Dr. Usha Sharma
Dr. Uma Chaudhry
Ms. P Rajeshwary
Ms. S. Radha Mahalakshmi
Ms. Renu Anand
Ms. Anita Sharma
Ms. Suganda Vallli
Ms. Neelima Sharma
Dr. Rajesh Hassija
Mr. Mukesh Kumar
Material Production Groups
English :
Ms. Gayatri Khannaa
Ms. Renu Anand
Ms. P. Rajeshwary
Ms. Sarabjit Kaur
Hindi :
Ms. Sunita Joshi
Ms. Babita Singh
Ms. Veena Sharma
Sh. Akshay Kumar Dixit
Core- SEWA
Ms. Vandna
Ms. Nishtha Bharati
Ms. Seema Bhandari
Ms. Seema Chopra
Ms. Madhuchhanda
Ms. Reema Arora
Ms. Neha Sharma
Chemistry
Ms. Charu Maini
Ms. S. Anjum
Physics:
Ms. Novita Chopra
Ms. Meenambika Menon
Biology :
Ms. Pooja Sareen
Ms. Neeta Rastogi
Core- Prespectives
Ms. Madhuchhanda,
RO(Innovation)
Ms. Varsha Seth,
Consultant
Ms. Neha Sharma
Mathematics :
Dr. K.P. Chinda
Dr. Ram Avtar
Mr. Mahendra Shankar
Mr. J.C. Nijhawan
Ms. Rashmi Kathuria
Ms. Reemu Verma
Ms. Arti
Ms. Himani Ashija
Economics:
Ms. Anubha Malhotra
Ms. Vintee Sharma
Ms. Chaitali Sengupta
Core-Research
Ms. Renu Anand
Ms. Gayatri Khanna
Dr. N. K. Sehgal
Ms. Anita Sharma
Ms. Rashmi Kathuria
Ms. Neha Sharma
Ms. Neeta Rastogi
Ms. Manjushtha Bose
Ms. Varsha Manku
Dr. K. L. Chopra
ICT:
Mr. Yogesh Kumar
Ms. Nancy Sehgal
Ms. Purvi Srivastava
Ms. Babita Mahajan
Ms. Ritu Arora
Ms. Swati Panhani
Ms. Chanchal Chandna
Geography:
Ms. Meena Bharihoke
Ms. Parul Tyagi
Ms. Sudha Tyagi
Ms. Sonia Jarul
Ms. Neena Phogat
Mr. Nisheeth Kumar
History:
Ms. Sajal Chawala
Ms. Jyoti Sharma
Ms. Kamma Khurana
Ms. Shalini Chatarvedi
Mr. Dalia Haldar
Ms. Preeti Gupta
Political Science:
Dr. Sangeetha Mathur
Ms. Ananya Roy
Ms. Sunita Rathee
Ms. Amarjit Kaur
Ms. Nishu Sharma
Ms. Manisha Anthwal
Ms. Mamta Talwar
Chief Co-ordinator : Ms. Kshipra Verma, EO
Coordinators:
Ms. S. Radha Mahalakshmi, E O
Sh. R. P. Sharma
Consultant (Science)
Ms. Monika Munjal Gandhi
(Coordinator)
Mr. Navin Maini, RO (Tech)
Ms. Neelima Sharma,
Consultant (English)
Mr. Sanjay Sachdeva, DO
Shri Al Hilal Ahmed, AEO
Ms. Deepa Shukla
Consultant (Biology)
Shri R. P. Singh, AEO
Ms. Reema Arora
Consultant (Chemistry)
Contents
1.
Meaning of Landform
1
2.
Science of landforms study- Geomorphology
5
3.
Agents of denudation
5
4.
Cycle of erosion
6
5.
Weathering Action
7
6.
Landforms made by
l
Fluvial landforms
13
l
Karst landforms
21
l
Glacial landforms
25
l
Sea wave landforms
l
Eolian landforms
31
7.
Meaning of Soil
8.
Soil formation
33
9.
Soil texture
34
10. Factors affecting soil formation
35
11. Soil Profile
37
12. Causes of Soil Erosion
39
13. Soils Susceptible to Erosion
14. Soil erosion causes two main problems
40
15. Control of Soil Erosion
40
16. Ways to Conserve Soil
41
17. Worksheets
49
LANDFORMS
Watch the video
Earth – one video you need to see
INTRODUCTION
In the previous chapters we studied that the lithosphere is broken into a number of
plates known as the Lithospheric plates. These plates move around very slowly – just a
few millimeters each year. This is because of the movement of the molten magma inside
the Earth. The molten magma inside the Earth moves in a circular manner.
The movement of these plates
causes changes on the surface of
the Earth. The Earth movements
are divided on the basis of the
forces which cause them.
The forces which act in the
interior of the Earth are
called as Endogenic forces
and
the forces that work on the
Fig. 2.1
surface of the Earth are
called as Exogenic forces
Endogenetic forces – This force is generated in the interior of the Earth and cause
Mountains, Plateaus, etc. to subside. We have no direct knowledge of the generation of
these forces because the field of their activities is in the interior parts of the Earth. Some
scientists think that these forces are caused by contraction of Earth on cooling, change in
the rotation of the Earth or due to the action of the radioactive elements.
1
On the basis of intensity, these forces can be divided into two sub-groups:
a)
Sudden Endogenetic forces – The main forces in this sub-group are volcanic eruption
or Earthquake. Landscape undergoes disintegration suddenly. For example,
production of deep fissures in plain areas, the sudden changes in the routes of river,
the formation of small hills, etc; are some of the effects of these forces.
b)
Diastrophic forces – These forces act very slowly. Their effect becomes
discernable after thousands of years. For example, the coast of the Baltic Sea rises
by 1.3 metres in a century. There are a large number of places where the coast is
either rising or sinking.
The landforms created by the endogenetic forces can be grouped into two divisions:
a)
Crustal bending – Diastrophic forces raise an area at a place. Broad domes are
created in this process. The diameters of these domes range from 160 to 325 km.
The rocks are at no place inclined by more than 10 or 20 from the horizontal. The
process of dome-formation is known as warping.
When the endogenetic forces, instead of raising the area force it down, the rocks become
concave and a broad basin is formed. These basins are thus formed by a process which
is opposite to dome formation. These basins are filled in by sediment. If contraction
process takes place over a broad area, sedimentary rocks hundreds of meters deep are
warped up. The sedimentary area thus warped up is known as Geanticlines. If warping
makes a broad sedimentary area to subside down, the subsided area of the sedimentary
rocks is known as Geosync-line.
The sedimentary rocks when warped up or down by endogenetic or other forces form
an acute angle with the horizontal. This angle is known as the Angle of Dip. Direction
of dip is the direction of the greatest inclination of the bed. The line intersecting the
surface of the bed and horizontal surface is known as the strike of the inclined bed. The
dip is always measured at right angle to the strike. The dip angle and the strike both
represent the attitude of the inclined plane.
2
Fold – When compression takes place on the crust due to endogenetic forces, a part of
the crust is raised up in the form of folds. The area is contracted in this process. Due to
the forces acting upon it, the crust takes a wave like form. The up-fold part is known as
Anticline. The down-fold part between two Anticlines is called Syncline. Various parts
of the fold – The two sides of a fold are called limbs. The fold axis passes between the
limbs through the highest or the lowest part. The fold axis passing through the
Anticline is called Axis of Anticline and that passing through the Syncline is called Axis
of Syncline. The imaginary plane which stands in the middle of the fold and passes
through the fold axis is called Axis Plane.
Faults – If the blocks along the surface of fracture have significant movement, the
feature is called Fault. The surface of fracture where movement takes place is called
Fault plane. When the Fault plane becomes smooth on account of movement of blocks,
it is called Slickenside. If the movement of blocks produces scratches on the fault plane,
the scratches are known as Fault strike. A study of these scratches gives an idea of the
direction of movement. Rock waste is produced by the movement of blocks. If the rockwaste has rough fragments, it is known as Fault Breccia but if it has fine particles it is
called Gouge.
Both of them are responsible for creating a variety of landscape which are immediately
subjected to exogenetic forces.
Exogenetic forces – These forces are produced and act on the surface of the Earth.
Wind, water and snow are such forces which erode the surface of the Earth or make
depositions on it. These external (exogenetic) forces are also called processes.
The systematic study of topographic relief forms is known as Geomorphology (geoEarth; morph form; ology-science).
Before learning about the evolution and geomorphic processes, it will be better to have
a review and clarify some simple topographic relief forms or grouping of forms.
3
Watch the video
Landforms of the world-flv
Broadly there are three major landforms namely Plains, Plateaus and Mountains.
A Plain is a flat surface or gently rolling with elevation not more than 200 m from the
sea level. In some case it may be higher than 200 m, they are referred as high plains e.g.;
Mississippi plain (USA) and Ganga plain (India) etc.
A Plateau is an elevated flat or rolling land standing above from the surrounding area
with at least one side by steep slope. e.g.; Arabian plateau and Tibetan plateau etc.
A Mountain is a land surface higher than the surrounding area with broad base and
narrow summit. The height of the mountain is a subject matter of human judgement.
The Pilani hill of south India is only 1500 m when compared with mighty Himalayas
which are standing as high as 6000 m and above, while the white mountains of New
England (USA) is even lower than Pilani hills of India.
Evolution of landforms
Prof. William Morris Davis (1850-1934 AD) (Harvard University) around 1890 AD
proposed the systematic study of landforms, according to their origin and stage of
development. He propounded that as the surface uplift agents of denudation start
working on it to bring it down up to the base level. The base level is the point up to
which erosion is possible. In general the base level is sea level because all erosions
activities can be done till the sea level. Below sea level only depositional activities can
take place.
His idea that different landforms are largely explainable in terms of differences in
geological structure, geomorphic processes and stages of development of landforms.
4
Some Fundamental Concepts of geomorphic cycle:
1.
The same Physical processes and law that operate today must have been
operated throughout Geological time, although not necessarily always with the
same intensity as now.
2.
Geological structure is a dominant controlling factor in the evolution of
landforms and is reflected in them.
3.
To a large degree the Earth’s surface possesses relief because the Geomorphic
processes operate at differential rate.
4.
Geomorphic processes leave their distinctive imprint upon landforms and each
Geomorphic process develops its own characteristic assemblage of landforms.
5.
As the different erosional agents act upon the Earth’s surface, they produced an
orderly sequence of landforms.
6.
Complexity of geomorphic evolution is more common than simplicity.
7.
Little of the topography is older than tertiary and most of it no older than
Pleistocene.
8.
Proper interpretation of present day landscapes is impossible without a full
appreciation of the manifold influences of the geologic and climatic changes
during the Pleistocene.
9.
An appreciation of world climates is necessary for a proper understanding of the
varying importance of the different geomorphic processes.
10. Geomorphology, although concerned primarily with present day landscapes,
attains its maximum usefulness by historical extension.
The surface of the Earth is made up of rocks and soil particles and all landforms is
combined product of one or more land sculpturing forces such as running water (run
off) and ground water, sea waves, moving glaciers and blowing winds on the rocks and
soil.
5
All the agents of Denudation have the same object; to bring the elevated surface up to
the base level of erosion i.e.;; the sea level.
Denudation creates different types of landforms involving Weathering, mass wasting,
and Erosion etc;
Denudation is the process of levelling of the Earth surface by cutting form higher
regions and depositing the sediments in depressions.
Weathering is the process of decomposing and disintegrating of Earth surface (rocks)
due to exposure at or near the Earth surface. It changes hard rock into fine fragments
and soft residual masses.
Mass wasting is Earth and rock movement due to sliding, rolling, flowing or creeping
down from slopes under the influence of gravity.
Erosion is the wearing away of the top layer of the Earth’s surface by different agents of
denudation e.g.; running water, blowing wind, moving glacier; etc.
Note: Mass wasting and erosion have almost
similar connotation. Different geologist and
geographer consider it differently.
6
Deposition is the process of settling down of sediments.
Source: http://pubs.usgs.gov
Weathering can take place without subsequent erosion and
erosion is possible without previous weathering. It is to be
noted here that weathering is a preparatory process that
makes erosion easier but it is not prerequisite to nor
necessarily followed by erosion.
Conditioning factors of weathering
There are four factors influence the type and rate of rock
weathering. These are rock structure, climate, topography
Source:
http://pubs.usgs.gov
and vegetation.
Rock structure is used in the broad sense to include the many
physical and chemical characteristics of rocks. It includes Mineralogical compositions as
well as such Physical features as joints, bedding planes, faults and minute intergrain
fractures and voids. The Minerals forming the rock in part determine whether it is more
susceptible to chemical or physical weathering. Physical features such as joints, lesser
7
fractures, bedding lanes and faults to a large degree determine the ease with which
moisture enters the rock.
The major Climatic Factors of temperature and humidity determine not only the rate at
which weathering proceeds but also whether chemical or physical processes
predominate.
Topography affects the amount of rock exposure and also has important effects upon
such factors as the amount and kind of
precipitation, temperature and indirectly the
kind and amount of vegetation.
The abundance and type of vegetation influences the rate and type of weathering by
determining the extent of rock outcrops and the amount of decaying organic matter
from which carbon dioxide and humic acids may be derived.
Weathering process can be divided into two large groups as Physical Weathering or
Mechanical weathering and Chemical weathering.
Physical weathering
Physical weathering is the process of disintegration of rocks into fine particles from
massive rock by the exertion of stresses sufficient to fracture the rock, but do not change
its chemical composition. It is most common in sub-tropical and mid-latitude regions
where diurnal range of temperature is quite high. They are of different types:
8
Granular disintegration – It is process in which rocks are disintegrated into small
particles due to alternate expansion and contraction during day and night.
Exfoliation: In this process rocks get disintegrated in the form of layer from top
to bottom.
Block disintegration: When rocks are disintegrated in the form of blocks, it is
called as block disintegration.
Shattering: it is a type of disintegration in which rocks are broken into small
pieces with angle and sharp corners edges.
Organic: plants and trees sometimes put pressure on the surface of the rock and
that break it into small pieces.
Chemical weathering
Chemical weathering is the decomposition of soil and rock (change in composition) by
chemical processes. The chief Chemical weathering processes are hydration, hydrolysis,
oxidation, carbonation and solution. In general, it is probably true that Chemical
Weathering is more important than Physical Weathering. This may be true even in arid
9
regions, although the more advanced chemical weathering processes are not significant
there. It is most common in warm and humid regions of the world. When water fall on
the surface they react with chemical present in the soil and produce different types of
landforms.
The principle of mineral stability must be understood to appreciate fully the persistence
of certain minerals in nature. In general, the least stable minerals are at the top of the
surface while the most stable are at the bottom.
Watch the video
Weathering and erosion
Fluvial action
Among all agents of Denudation river is the most active. Water running on the slopes
flows into gullies or irregularities in the surface of the ground. The gullies join up and
form small streams. Erosion begins with the birth of every stream.
Rivers erode
sediments from higher regions and deposit it in lower areas while it flows from origin
to its mouth. There are mainly three activities involved in Landform creation namely
Erosion, Transportation and Deposition.
Erosion by a stream is the progressive removal of mineral material from the sides
and floor of the river channel.
Transportation consists of movement of the eroded particles by dragging along
the bed by suspension in the water.
Deposition is accumulation of transported particles on the floor of stagnant
water body into which the rivers drain their water.
10
Corrasion – A stream always follows the shortest and easiest path downhill. On the
steep slopes running water moves quickly and can rapidly deepen the channel and
remove rock fragments. The force of the current tears and rubs of pieces of soil and
particles of rock as it rushes over them. It also uses tools to help it. It drags and rolls
along stones which knock against one another and against the sides and bottom of the
valley. The power of the flushing water is sufficient to pull apart the loose materials
room the bed of the streams. This kind of mechanical erosion is known as Corrasion.
Pot holing is a special case of corrasive action. This usually happens at the foot of a
waterfall. Hollows occur in the channel and create whirlpools which suck in sand and
pebbles, whirling them round in the potholes. When several pot holes from close to one
another the rock walls separating them are finally worn away and the bed of the river is
further lowered.
Hydraulic action: the pressure of running water also causes considerable amount of
erosion. Loosely joined blocks of rocks may be removed by mere pressure of the
currents flowing against them.
Solution: Small amount of carbon dioxide and oxygen found in all water in nature,
increase the solubility of rocks and minerals. Limestone, for instance, is eroded easily by
water that is charged with carbon dioxide.
Stream transportation
Streams carry its loads in three principle form i.e.;
Dissolved matter is transported invisibly in the form of chemical ions.
Suspended load are those particles that remain hanging and flow in turbulent
eddies in the stream.
Bed load are those heavy particles that settle down on the river bed and they roll
or slide on the river bed.
11
The maximum quantity or load of sediments that river can carry is called carrying
capacity of a stream.
Load carrying capacity of stream is directly proportional to the stream’s velocity. When
the Velocity will be high then its load carrying capacity will be increased and vice versa.
So when stream is in mountain stage their velocity is high while near the mouth of river
it becomes slow. In plain area it is in the state of equilibrium.
12
The work of rivers
If a typical stream from its source to its mouth is followed then three visible sections can
be seen:
(1)
The Upper Mountain Course, where the main work is that of erosion.
(2)
The Middle Plain Course, where the main work consists of the transportation
of the material eroded. There is also some amount of deposition.
(3)
The Lower Delta Course, where deposition of the transported material is the
main work.
Source: http://cronodon.com/files/River_Processes
13
Source: http://cronodon.com/files/River_Processes
Fluvial Landforms
14
The upper course
The source of rivers is generally in
hilly or mountainous areas. Here
the volume of water is small but its
flow is very fast. The young
streams, therefore, rapidly erode a
channel through the rocks. If the
down cutting is very rapid or if the
rock is very hard to wear out, a
steep sided Gorge may be formed.
A canyon is similar to a gorge but it
is much greater in size. The most
famous canyon in the world is the grand canyon of Colorado River in the United States.
Gorges and canyons present some of the world’s spectacular scenic wonders.
Sometimes big pieces of rock fall into it which cause temporary damming of the stream.
Rivers which sweep down from steep mountain valleys on to comparatively level lands
drop their load of coarse sands and gravel as there is sudden decrease in velocity. The
load generally assumes a fan shape; hence it is called an Alluvial Fan.
In some respects the alluvial fans are like deltas. The main difference is that whereas
deltas are laid down in the sea or lakes, alluvial fans are formed at the foot of the hills.
The alluvial fan sometimes grows till many kilometres across and several fans together
when united they form a continuous plain known as a Piedmont Alluvial Plain.
Alluvial fans and plains are generally of great agricultural value as their soils are fertile
and easy to irrigate as plenty of water is available in nearby area.
When a stream rushes over a steep slope in its bed it forms Rapid. They are often due to
layers of hard rocks jutting out above the regular surface. Bigger rapids are called
Cataract.
15
When a stream plunges down a very deep slope or over a cliff, it forms a Waterfall.
Source: http://cronodon.com/files/River_Processes
16
Source: www.oup.com/pdf/oxed/geog
The middle course
The second stage begins when the river leaves the mountains to enter a low lying
region. At this stage the volume of water has increased as the catchment area (the areas
drained by a single river system) has also been increased. Some more tributaries also
join the main river.
In order to cope up with the increased volume of water the river has to widen its valley.
The lateral corrosion tends to replace vertical Corrasion.
In this processes any
interlocking spurs that project from both sides of the valleys are then worn away, as the
water exerts its greater force and pressure on them.
The material eroded from the valley sides is then deposited on the valley floor to from a
flood plain, i.e.; that part of the river valley which is covered by water during flood.
Flood is temporary inundation of dry land caused due to spilling of water from river’s
bank.
17
As more and more material is deposited
on the bed of the river the normal level of
water rises and deposition occurs on the
banks which are also raised until they
form broad ridges, called natural levees,
on the both sides of the river. The level of
the river bed is then raised above the
level of the surrounding plain.
Artificial embankments are often built in
order to lessen the risk of flooding. When
there
are
excessive
floods
the
embankments gives way, the river water
invades the adjacent plains, resulting in
great loss of life and property.
When the course of a river
lies in a flat country, it
swings from side to side in
wide
loops
and
Meanders. The
derived
from
forms
name
the
is
river
Meander of Asia Minor
which in its lower course
runs through a twisting
course. The current flows
faster at the outside of a
bend where the bank is
worn away while on the
inside of the bend solid material is deposited. Ultimately the meanders may form a
18
complete circle. An interesting type of lake known as Cut-off or Oxbow lake is formed
when a meandering river cuts across the narrow neck of land between the two
stretches, and leaves back water. When silt is deposited at the entrance to this
backwater it becomes a lake. Oxbow lakes gradually fill up with clay and silt.
Sometimes due to dead flatness of the surface streams, deposit their load within the
stream and Riverine Island are formed. This typical feature is called as Braided channel.
The lower course
In the lower course the main work is the deposition of material transported to form a
Delta. Before draining the water into the sea or ocean, streams deposit their load in
their path and block their mouth. When the mouth is blocked up, the level of the river
rises and the water is unable to find its way directly towards the sea. This water then
runs from the main stream and flows into several channels. Each of these channels is
called a distributary. The distributaries wander over the delta plain forming a network
of channels resembling the fingers of a hand spread out toward the sea. The whole area
gets almost triangular in shape which is made up of fine soil sediment is termed as
Delta. Delta is taken from Greek letter from which Herodotus in the 5th century BC
coined the term for the river Nile. Deltaic plain deposits consist of alternating clay and
salty clays which locally are sandy. Deltas are different in size, shape, growth and
19
importance. Every river does not make Delta. There may be no delta if the last course of
river is very swift as it carries little or no alluvium up to the sea or the sea near the coast
is very deep. Tidal current at the mouth of the river can also wash away the silt. If there
are larger lakes in the course of a river much of the sediment is removed before the river
reaches the sea.
Many of the rivers emptying into seas have no deltas, but instead they have the shape of
a gradually widening bay cutting deep inland. Such a bay is called an Estuary. The
formation of estuaries is often due to the scouring action of tides and ocean currents.
Non silted Estuaries are an excellent site for the river port.
Drainage pattern
Almost all steams follow some branching pattern as they do on receiving tributaries
which are joined by still smaller tributaries, these patterns depends upon:
(1)
Differences in the slope of the land upon which the drainage system developed.
(2)
Differences in the resistance of the underlying rocks to erosion.
20
The three stages in the life of a river
An observation of a river valley shows that in the course of development it has passed
through a life cycle of Youth, Maturity and Old age. Each of these stages can be traced
separately, for each has its characteristics. But the word ‘Young’, ‘Mature’, ‘Old’ are not
used in terms of years. They refer to the stages in the course of the development of the
landmass through which a river passes. Any projecting spurs are cut back so that the
21
level ground bordering the river is constantly widened. In course of time (Several
centuries) the whole hilly area in its basin may be converted into a gently rolling plain
which is slightly above the sea level. The word peneplain [meaning ‘almost a plain’] is
used to describe the very low relief thus produced in the old age stage in the cycle of
erosion.
Youth stage: Streams that have just entered upon their work of erosion and still have
rather steep gradients are called young streams. A Young stream is a powerful agent of
erosion with abrupt changes in gradient. The valley show V shaped cross sections. Its
Tributaries are short, and many rivers have a torrential course with narrow ravines,
steep walled canyons, rapids and waterfalls. Young rivers with their rapids and
waterfalls are not suitable for navigation, but they are useful for hydroelectricity.
Maturity: A mature valley is wider. It has a broad flood plain and a slight gradient. It
swings from side to side and the work of widening becomes more rapid than that of
deepening. The valley floor becomes flat and does not have the narrow V shaped cross
section characteristic of a young stream. A mature river may have several well
developed Tributaries. When there are exceptionally high floods the river may abandon
its natural channel and spread out over the valley floor. When the flood recedes it may
leave behind a layer of silt and sand. These layers left behind after successive floods
form fertile soil
Old age: In this stage the water flows sluggishly and there are numerous meandering
streams. There are no waterfalls, no rapids. The valley becomes broad and shallow; and
the work of erosion comes almost to a standstill. Tributaries are few and large and the
deposits are fine in texture. The heaviest deposition occurs at the mouth of the river
where, if the conditions are favourable, a delta is formed.
22
Watch the video
The journey of a river from source to mouth
Karst Landforms
Of the entire world’s water only about six tenths of one percent is found underground.
Well developed Karst topography is found in Greek, Yugoslavia and neighbouring
countries. This water is stored in aquifer below the Earth surface. Water saturated zone
of rocks are called Groundwater. The upper limit of groundwater is called the Water
table. Groundwater is an important erosional agent. The powerful dissolvent agent
makes several interesting features.
The action of groundwater is most active in limestone or calcareous cement areas. Rain
water when get mixed with atmospheric sulphur dioxide and carbon dioxide and fall
on the limestone area, which actively erodes the surface.
23
The underground water does not flow like river water. The following are the causes of
motion of underground water:
(a)
Porosity of rocks: The amount of water that is locked up in rock depends upon
the porosity of the rocks. The ratio of the total volume of the open spaces in rocks
to the total volume of the rocks is called porosity of the rocks. This porosity
depends upon the size, arrangement, closeness and compactness of the rock. The
seeping water dissolves the salts of the rocks and increases their porosity.
(b)
Permeability of rocks: It is the ability of the water to flow through rocks. Some
rocks allow more flow of water than others. This capacity of rocks to transmit
water through them is known as permeability of rocks. The absence of pores
rocks do not allow water to transmit. When sediments get deposited in the pores
then the rock becomes impermeable.
24
Erosional features
Clints, grikes and limestone pavement
In areas of limestone with steep
slope rainwater runs down the
slope in the form of rills. Due to
continuous erosion the rills get
enlarged making the surface into
a series of ridges and trenches.
The ridges are called Clints or
Lapies while the trenches are
called Grikes. The region is called
limestone pavement. It is difficult
to walk barefoot on limestone pavement as clints are sharp pointed.
Sinkholes swallow holes and blind valley
Stagnant water in limestone region dissolves the surface and form a funnel shaped
depression. These funnel shaped depressions are called Sinkholes. Large sinkholes are
25
called Swallow Holes. When a large cavity is from under swallow holes the roof
collapses and resembles a valley. Such a valley is called Blind Valley as no river flow
through it.
Underground features
Underground streams: When river enters in limestone region it dissolves the surface
and flows underground for several kilometres, it is known as underground stream.
After some distance the river reappears on the surface as non-permeable rocks do not
allow water to seep downwards and force it to flow upwards.
Caverns
In limestone rich area groundwater dissolves weak joints. With the passage of time the
dissolving process slowly enlarges into a cavity which further converts into caverns.
26
The dissolved material is carried away and discharged into streams. Caverns are
enlarged form of caves. These are sometimes as big as football ground. Caverns are
often connected through underground passages.
Stalactites and stalagmites
These are the most magnificent feature of karst topography. When limestone solvent
drips from the cave ceiling, trace amount of limestone is deposited at the point of
precipitation. The dripped solvent water still has trace amount of calcium carbonate
which it deposits just below the ceiling hanging. Ceiling hanging column is called
stalactite and column on the floor is called stalagmite. Stalactites develop ground wards
while stalagmites grow upwards. When stalactites and stalagmites meet with each
other, the resultant feature is called cave pillar. Cave pillar can also be formed by either
growing of stalactites and stalagmites towards ground and roof respectively.
Watch the video
How are caves formed?
Glacial Action
Glaciers are slow moving river of crystalline ice masses found in high latitude and
altitude areas.
In cold regions snowfall ice gets accumulated and compacted due to weight of layers of
snow. The snow at the bottom get compressed and crystallized into dense ice called as
Firn or Nave.
Types of glaciers
Glaciers are grouped into two types namely
Continental Glaciers
Valley/Mountain/Alpine glaciers
27
As the name suggests itself, very vast expansion of thick layer of ice on a flat surface are
called Continental Glacier. Greenland and Antarctica have continental type of glaciers.
These glaciers move in all directions with one or many centres.
When small peaks peep out of the continental glaciers surface they are called as
Nunatkas. While reaching at the shore big pieces of snow block get detached with the
glacier and float in sea or ocean. The floating ice blocks are called ice bergs. These ice
bergs are quite dangerous for the movement of ships as only one ninth of the ice berg
remains above the water level while remaining nine tenth remains submerged in water.
Some of the ice bergs are kilometers in length and breadth with several meters in
height. A very massive size of floating ice bergs are called as ice shelves.
Mountain glaciers are tongue shaped. When these glaciers descend on the mountain
slope and reach below the snow line they start melting. Rivers are formed due to
melting of glacier snow. When several glaciers meet together at the foothills they are
termed as Piedmont glacier. When these glacier move, they carve out several interesting
features with their actions.
Glacial Landforms
Erosional features
Bowl shaped depression with steep wall on three sides and down valley side opening
feature is called Cirque. It resembles like an arm chair. Advancing glacier on the vertical
wall develops deep crevasse (crack) these are termed as Bergschrund. During summer
snow melts and leaves behind a small lake at the bottom of cirque. These lakes are
called Tarn.
Col: When two cirques are formed back to back (common head wall) the feature made
is termed as a col.
Arêtes and Matter horns: Sharp edged ridges are called arêtes. They resemble a knife.
The summits are free from ice as they are very narrow and due to frost action ice rolls
28
down immediately. A pyramid shaped arêtes edged peak and cirques surrounding it
from all directions is called Horn or Matter Horn.
Hanging valleys: Hanging valleys are formed at the confluence points of the main
glacier and its tributary glacier. As the base level of main glacier and tributaries glaciers
are different, so the tributary glacier valley seems to be hanging above the main valley.
After glaciations a waterfall takes the place at the confluence point of the main and
tributary glacier.
Roche Moutannee: These are small streamlined hills on the rocky surface. They are
formed by the glacial abrasion on the smooth front side of the hill while steeps are
formed on the opposite side due to plucking action of advancing ice.
Here the teacher can ask how a layman can identify the direction of advancement
of glacier by seeing the Roche Moutannee.
29
Depositional Features
Glaciers make several interesting landforms by their depositional activities. Most of the
features are made by Tills. Tills are the rock debris fallen into glaciers.
The rock debris that falls into the glacier along the margin forms a lateral pattern of
unsorted rock debris. This lateral pattern is called Lateral Moraine. When two glaciers
coalesce to form a single glacier, the till that was carried along the edges of each glacier
joins to form a single dark strip of debris within the newly enlarged glacier, the joint till
strip is called as Medial Moraine. At the snowline the glaciers melts and deposit tills in
convex arc form. This convex shaped till deposit is termed as Terminal Moraine.
Sometimes when glacier ablation exceeds the nourishment, they recede. The receding
enables the glacier to make a new terminal moraine. When this process continues for
several times then a rolling layer of till is laid down, this is termed as Ground Moraine.
Fluvio-glacial deposits
Fine clay formed by rolling tills in glaciers is called Boulder clay. When boulder clay
get deposited on whale back shaped elongated hills of low height they are called
30
Drumlins. Drumlins have steep slope facing the snow while elongated tail is in the
direction of advancement of glacier.
When boulder clay gets deposited in a vast area they form Outwash Plain. Sometimes
boulder clay is deposited in the form of small mound known as kame. Small
depressions in outwash plains are called Kettles. Eskers are another interesting feature
made by melted glacier water. They are long, narrow and sinuous ridge composed of
gravels and sand.
Watch the video
Glaciers and glacial landforms
31
Sea waves landforms
Sea waves are the most active agent of landform creation in coastal areas. Continuous
splash of sea water shapes the coastline. This splash of sea water cause several types of
action in coastal region.
Know more
Sea waves action
Most of the landform in coastal areas is formed due to several types of actions.
Some of them are
Hydraulic action: it includes the picking up of loose materials by waves
and shattering of rocks as wave crashes against the cliffs.
Corrasion: sea waves are armed with rocks debris and gravels. When the
splash of water falls on coastal rocks they hurl them. The material is then
eroded by sea waves back into the sea.
Corrosion: it is the solvent action of the sea water. Disintegration of rocks
takes place due to chemical action. This is limited to regions of limestone
and rocks with calcareous cement deposits.
Attrition: due to constantly to and fro moving water rock fragments
worn themselves and the cliffs. It produces fine sand particles.
Coastal erosion features
Capes and bays: When alternate hard and soft rocks are found near coast, the soft rock
is worn away by waves while the hard rock remains resistant of erosion. Due to
wearing away of soft rocks sea inlets are formed. These sea inlets are called bays while
the protruding hard resistant rocks are called capes.
32
Sea cliff: Sea cliffs are bench like features with almost vertical wall and wide flat
platform in front. In areas of high land, sea waves erode the coastal rock between the
region of high tide and low tide. As the cliff recedes a flat platform is made in front of
cliff known as Wave Cut Platform.
Sea Caves, sea arches, sea stacks and stumps
When waves wear away the softer and highly fractured rocks located at the shore it
forms sea cave. When two sea caves on opposite sides of a common shore-land rock
gets united they form Sea Arch. Sometimes the roof of arch collapses and an isolated
remnant pillar like structure is left behind. This rock pillar is called as Sea Stack. The
worn down sea stack which is visible during low tides only are called stumps.
Blow holes: When water splashes against sea cave, they trap the air inside the cave by
blocking the mouth. The compressed air exerts pressure on the rock and weakens the
roof of the cave. Continuous action leads to formation of hole in the roof of the cave.
The formed feature is called Blow Hole which whistles at the time of splashing water at
the cave mouth.
33
Coastal depositional features
Sea Beaches
Features of Coastal erosion
Beaches
They are formed by deposition of sand, gravels, pebbles and marine organism shells
laid down along the coast. Beaches made up of gravels and pebbles are called Shingle
Beaches while beaches made up of sand are called Sandy Beaches.
Spits: Spits are long slender sandbars deposited by sea waves. They are connected with
the mainland from one side while another side ends into open water of sea. When
another spit develops from the main one towards the mainland, they are called Hook or
Hooked Spit.
Tombolo: Tombolo is sandbar connecting an island with the main land.
Lagoon: Lagoon is an enclosed water body. When sandbar develops along the coast and
encloses the sea water leaving a small inlet through which water can move in or out is
called lagoon.
Eolian Landforms
Eolian landforms are made by the action of wind in arid [dry] regions of the world.
Strong winds are quite common in arid and semi arid regions of the world. Strong wind
34
picks up sand particles from one place to another and while transporting and
deposition they make several interesting landforms.
Know more
Action of wind
There are three main types of action which are responsible for landforms creation.
Abrasion or Corrasion: Strong winds lift sand particles and blast sand particles
on stones or rocks lying in their path. Blasting of sand particles cause scooping
out of rock.
Deflation: the process of lifting and removal of loose material from the Earth’s
surface.
Attrition: the mutual wearing of sand particles is called attrition.
Erosional features
Ventrifacts: Multifaceted, sharp edged pebbles are called Ventrifacts. These are made
by mechanical weathering by wind. Stone with three facets is called Dreikanter.
Blowout: In scanty vegetation and loose soil area, strong winds deflate the loose
particles. The removal of sand particles happens until it reaches the saturated
groundwater soil. Deflation gets restricted due to cohesive sand particles.
Mushroom rock: In arid regions strong winds carry heavy load near surface called as
Bed Load. These bed loads moves by skipping or bouncing on the surface –termed as
Saltation. Light weight particles remains in suspension in air and they are called
Suspended Load. As the bed loads are bigger in size they abrade and scoop out rocks
more near the surface. The suspended load which are lighter they do not scoop that
much. Result of two, rocks in arid area get shaped as mushroom and termed as
Mushroom Rock or Rock Pedestals or Gour.
35
Yardangs: These are found in areas where hard and soft rocks are found in alternative
vertical bands parallel to the direction of wind. Strong winds wear away soft rocks
leaving behind hard rocks. It results into formation of ridged landscape or furrow called
as yardangs.
Inselberg:
Inselberg
is
controversial
landform of arid region as few such similar
structures are seen in glacial areas.
These are conical or dome shaped isolated
rocky hills. They are mostly made up of
hard rocks like granite and gneiss etc.
Depositional features
The most interesting landform created by sand deposition is sand dune. Sand dune is a
heap of sand made by wind. These can be formed into many shapes. A clump of grass
or a thorny shrub obstructs wind carrying sand and forces them to settle down. Slowly
gradually continuous deposition of sand makes sand dune.
Sand Dunes
36
Sometimes wind elongates the margins
of sand dunes in the direction of wind
which gives it a crescent shape. These
crescent
shaped
dunes
are
called
Barchans. Due to continuous blowing
of wind in one direction for long period
of time either of the horn gets extended.
The
elongated
dunes
are
called
Longitudinal Dunes or Seif Dunes.
The slope facing the wind is gentle in
slope while the leeward side is steep. By saltation, strong winds roll the grain particles
which are deposited on leeward side. Due to continuous saltation sand dunes moves
from one place to other but these movements are quite slow.
Loess: Loess are made by deposition of very fine sand and dust particles blown from
one place and settled at distant place. The most extensive loess deposit is seen in North
West china named as Loess Plain. The Hwang-ho River flows through loess plain and
cut deep gorge.
Watch the video
The beauty of planet Earth (HD Quality)
Soil and its formation
The brown loose grainy particle that covers most of the Earth’s land surface is called
Soil. It determines the food habit, clothing and housing of the population and many
more. Soil formation is a dynamic phenomenon. The layer of soil itself is dynamic in
which many complex chemical physical and biological activities go on simultaneously.
37
Soil is made up of substance existing in three states Solid, Liquid and Gaseous. There
should be proper balance of all three for proper growth of plants.
The solid portion of soil consists of both Inorganic and Organic material. Weathering of
rocks produces the inorganic material while the organic material consists of living and
decayed plant and animal matters. The chief organic product is a Complex brown jelly
like substances known as Humus. Humus makes the soil fertile by increasing the
moisture retention capacity.
The liquid portion of soil is a complex solution of chemical compounds necessary for
many activities that happens in the soil. Without water there will be no chemical
reaction nor can it support any type of life.
Gass in the pore spaces between soil grains are the third fundamental component. They
are the principal gases of the atmosphere. Gases help in aeration of the soil, which
increases the fertility of the soil.
Watch the video
Soil and Soil Profile
38
Soil texture: Soil texture means the particle size that makes the soil. Particles are
classified as various grades of
Gravel particles 1mm to 2 mm in diameter,
Sand particles 1 mm to 0.05 mm in diameter,
Silt particles 0.05mm to 0.005 mm in diameter and
Clay particles less than 0.005mm in diameter.
The Bureau of Soils of the US Department of Agriculture describes various soil textures
as follows:
Sand – 80% or more sand and 20% of less silt or clay.
Sandy loam – more than 20% but less than 50% silt and clay while remaining
sand.
Loam – 20% clay, 30-50 % silt and 30-50 % of sand. (Silt loam if silt predominates
or clay loam if clay predominates).
Clay- contains 80% or more clay and silt, 10-20 % of sand.
Soil texture is important to determine the water retaining capacity of the soil. Too
grainy soil will drain the water while the clay soil particles are so small that they do not
allow water to percolate easily.
39
Video to be shown to students. Click on the link to play the video
Watch the video
Soil Texture by feel
Factors affecting soil formation
There are many processes and influences that are involved in the formation of soil
which are together known as soil formers.
Some of these are passive conditions while other is active agents. There are five
principal soil formers:
Parent material or rock
Topography or relief
Passive agents
Time
Climate
Active agents
Biological activities
Parent rock or material determines which type of rocks will be formed in which region.
Residual or transported disintegrated rock material makes the bulk of the soil. In the
case of transported soil different type of parent rocks can contribute for the formation of
soil. New soil or In Situ is made up of residual parent material soil. Black soil is an
example of residual parent rock material soil while alluvial soil is an example of
transported soil.
Topography of the place also affects the soil formation. On the steep slope surface
erosion by runoff is more rapid and water penetration is less than gentle slope. On steep
slopes soil is thinner and weathering process will produce less soil material. Contrary to
40
this, the gentle slope with good
drainage and slow erosion helps in
good soil formation. On these slopes
there is balance between removal of
soil and formation of soil.
Another influence of topography can
be seen in mid latitude areas of
Northern Hemisphere. Only south
Facing Mountain slopes of Northern
Hemisphere experience warming and
drying effect of sunlight. This is
reflected by the type of vegetation and
soil found on Northern and Southern slopes.
Time is one of the most important factors in the soil formation. A soil is said to be
mature when it has been acted upon by all soil forming processes for a long time and
has developed a profile that remains the same for long period of time. No age in terms
of years can be given to all mature soils because the rate is extremely slow from human
point of view. A centimetre thick layer of soil takes several thousand years to from.
Climate is an active agent of soil formation. Climatic elements involved in soil
formation are:
Moisture conditions (Precipitation, evaporation, humidity)
Temperature
Wind
Precipitation provides water for chemical and biological activities and leads to
disintegration of rock particles into simpler grain and so on.
41
Temperature affects the soil formation in
two ways. Firstly, chemical activity is
increased in warm and humid regions
while slow in cold conditions and it is
ceased in frozen conditions. Secondly,
bacterial activity is increased in warmer
soil regions.
Among all wind is of minor importance
as climatic factor. Wind increases the rate
of evaporation and makes top soil loose and dry. Strong wind removes loose soil and
deposits it at far off places such as loess plains of China.
Both plants and animals influence soil formation. Sometimes we see plant coming out
from the crack of a rock. Slowly the plant
grows bigger and bigger which enable
stem to exert pressure on the rocks
which leads to disintegration. Similarly,
there are some bacteria and fungi which
eat rocks and decompose it.
Soil Profile
As the name suggests profiling of soil is
called Soil Profile. As the formation of
soil take place from top to bottom there
is layer wise vertical difference in
composition,
texture,
structure
and
colour etc.
42
Vertical section of the soil showing different layers is called soil horizon. These are
named after English alphabets as A, B and C.
The top layer of the soil is called A Horizon (top soil). This is the most important
layer for agriculture point of view as all agricultural activities take place in this
layer only. The thickness of this layer varies from one region to another.
Approximately it is 25-30 cm. in thickness in general condition.
Immediately below the A Horizon is Horizon B. Horizon B layer soil have
coarser grain and less nutrient minerals. This is termed as sub soil. The thickness
of this layer ranges from the bottom of top soil to a few meters downwards.
Micro nutrient washed away from the top layer gets deposited in sub soil thus it
is also called as Zone of accumulation. Too much of fine clay particles
accumulated in subsoil makes it extremely dense and impermeable. Such dense
layer is called as Hardpan.
Below the sub-soil is the C horizon. C horizon mostly consists of partially altered
parent rock and very little or no organic matter. About 2-3 meters from the
surface starts the zone of subsoil. Below this layer is the platform of bed rock.
In warm and humid areas there a very thin layer of dark brown colour substance
above top soil called as the Humus Layer or O Layer. The Humus layer is very
fertile.
The humus layer, top soil and subsoil together called as Solum or true soil. All
processes of soil formation and living roots, animal life are confined in this layer only.
A thin layer of soil takes several hundred of years to form get washed away by several
activities. Let us see the causes of removal of soil.
43
Causes of soil erosion
Land use: Humans play a major role in soil erosion through their use and abuse of
natural resources, for example; deforestation, grazing, arable land use, faulty farming
systems, high crop intensity, housing construction, mining etc.
Climate: The two most important climatic factors having a direct effect on erosion are
Precipitation and Wind Velocity. Other climatic factors have an indirect effect on soil
erosion. For erosion control it is necessary to investigate physical characteristics of
rainfall, including the amount, distribution, intensity, energy load, seasonality and
variability of rainfall and the formation and course of surface run off.
Soil: The susceptibility of a soil to erosion is influenced by its physical, hydrological,
Chemical and Mineralogical properties as well as its Soil profile characteristics.
Important Soil physical and hydrological properties that affect the resistance of a soil to
erosion include texture, structure, transmission properties and water retention.
44
Hydrology: Infiltration, surface detention, overland flow velocity, and subsurface water
flow are important soil erosion components of the hydrological cycle. The different
types of flow and their velocities may be turbulent or laminar, steady or unsteady,
uniform or non-uniform and influence the extent of erosion
Landforms: Slope gradient, slope length and shape of slope are the important variables
of landform that affect erosion processes for all types of soil erosion, e.g.;, splash, sheet,
rill, and gully erosion.
Soil erosion causes two main problems:
Loss of soil productivity: When topsoil erodes, the less fertile and harder B
horizon becomes exposed. This leads to lower forage production, lower water
infiltration and greater run off.
Sediment pollution: When eroded sediment is rich in fertilizers or pesticides, it
can upset the ecosystem at its point of deposition. In addition, sediments may
damage machinery, agitate respiratory problems and reduce visibility.
Control of Soil Erosion
Soil Erosion prevention measures are implemented on a large-scale today. To
name a few, they are shifting vegetation, afforestation, conservation tillage,
gardening and contour farming.
Erosion control products help in retaining the organic value of the soil as well as
the pH. The requirements of the soil are restored by mulching.
Soil erosion control is also carried out by planting erosion control plants. Native
plants, willow trees, yarrow flowers help to retain the moisture of the soil.
One of the most effective techniques to prevent soil erosion is by controlling the
rate of grazing in a land vulnerable to erosion.
45
Regular watering of soil also keeps loose particle attached with the ground.
Thus, preventing it from getting eroded.
Soil, which is one of the most important natural resources, is often less heeded. The
importance of soil conservation is relatively less talked about as compared to the
conservation of water and other natural resources. The almost omni-present soil is
mostly taken for granted. Its omnipresence is ironically the reason behind us, human
beings, taking it for a ride. We rarely even think of it as a natural resource that needs to
be conserved, a part of the natural wealth that needs to be preserved.
The concept of the conservation of soil takes into account, the strategies for preventing
the soil from getting eroded and preventing it from losing its fertility due to an adverse
alteration in its chemical composition. Here are some ways to conserve soil.
Ways to conserve soil
Plant trees: We all know that the roots of trees firmly hold on to the soil. As trees
grow tall, they also keep rooting deeper into the soil. As the roots of the trees
spread deep into the layers of soil, they contribute to the prevention of soil
erosion. Soil that is under a vegetative cover has hardly any chance of getting
eroded as the vegetative cover acts as a wind barrier as well.
Terraces: Terracing is one of the very good methods of soil conservation. A
terrace is a levelled section of a hilly cultivated area. Owing to its unique
structure, it prevents the rapid surface run off of water. Terracing gives the
landmass a stepped appearance thus slowing the easy washing down of the soil.
Dry stonewalling is a method used to create terraces in which stone structures
are created without using mortar for binding.
No-till farming: When soil is prepared for farming by ploughing it, the process
is known as tilling. No-till farming is a way of growing crops without disturbing
it through tillage. The process of tilling is beneficial in mixing fertilizers in the
46
soil, shaping it into rows and preparing a surface for sowing. But the tilling
activity can lead to compaction of soil, loss of organic matter in soil and the death
of the organisms in soil. No-till farming is a way to prevent the soil from being
affected by these adversities.
Contour ploughing: This practice of farming across the slopes takes into account
the slope gradient and the elevation of soil across the slope. It is the method of
ploughing across the contour lines of a slope. This method helps in slowing the
water run off and prevents the soil from being washed away along the slope.
Contour ploughing also helps in the percolation of water into the soil.
Crop rotation: Some pathogens tend to build up in soil if the same crops are
cultivated consecutively. Continuous cultivation of the same crop also leads to an
imbalance in the fertility demands of the soil. To prevent these adverse effects
from taking place, crop rotation is practiced. It is a method of growing a series of
dissimilar crops in an area sequentially. Crop rotation also helps in the
improvement of soil structure and fertility.
Soil pH: The contamination of soil by addition of acidic or basic pollutants and
acid rains has an adverse effect on the pH of soil. Soil pH is one of the
determinants of the availability of nutrients in soil. The uptake of nutrients in
plants is also governed to a certain extent, by the soil pH. The maintenance of the
most suitable value of pH, is thus, essential for the conservation of soil.
Water the soil: We water plants, we water the crops, but do we water the soil? If
the answer is negative, it is high time we adopt the method of watering soil as a
measure of conserving soil. Watering the soil along with the plants is a way to
prevent soil erosion caused by wind.
Salinity management: The salinity of soil that is caused by the excessive
accumulation of salts, has a negative effect on the metabolism of the crops in soil.
Salinity of soil is detrimental to the vegetative life in the soil. The death of
47
vegetation is bound to cause soil erosion. Hence, salinity management is one of
the indirect ways to conserve soil.
Soil organisms: Organisms like Earthworms and others benefiting the soil
should be promoted. Earthworms, through aeration of soil, enhance the
availability of macronutrients in soil. They also enhance the porosity of soil. The
helpful organisms of soil promote its fertility and form an element in the
conservation of soil.
Indigenous Crops: Planting of native crops is known to be beneficial for soil
conservation. If non-native plants are grown, the fields should be bordered by
indigenous crops to prevent soil erosion and achieve soil conservation.
Watch the video
Watch the video
Soil who need it
Soil and water
conservation
48
WORKSHEETS
WORKSHEET–1
Answer the following questions:
1.
What are the main landforms of the Earth?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
What is the name of the study of Earth’s landforms?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
Who propounded the cycle of erosion for the first time?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
4.
What is meant by denudation?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...........................................................................................................................................
49
5.
Answer the following questions briefly:
a)
How wreathing can be stated with your understanding about the term?
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
b)
How erosion can be stated with your understanding about the term?
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
c)
How mass wasting can be stated with your understanding about the term?
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
d)
How Deposition can be stated with your understanding about the term?
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
50
WORKSHEET–2
Collect pictures of all types of landforms (mountain, plateau, plains, valleys and any
other) for all continents of the world. You can use different sources like internet, old
newspaper, old magazines and journals etc; for collection of pictures.
Asia
Africa
North America
South America
Europe
Australia
51
WORKSHEET–3
Collect and write information on the following:
1.
2.
3.
Highest mountain peak of ____________ with its height.
a)
Asia
b)
Africa
c)
North America
d)
South America
e)
Europe
f)
Australia
g)
Antarctica
Important plateaus of
a)
Asia
b)
Africa
c)
North America
d)
South America
e)
Europe
f)
Australia
Name important plains of
a)
Asia
b)
Africa
c)
North America
d)
South America
52
e)
Europe
f)
Australia.
MCQ
1.
Choose the correct answer form the given options:
a)
b)
c)
d)
The upper part of the Earth is called?
i.
Lithosphere
ii.
Athensphere
iii.
Core
iv.
Mantle
The forces that cause changes on the suface of the Earth can be divided into
i.
2
ii.
3
iii.
4
iv.
5
Which of the following is an example of sudden Endogenic force?
i.
Earthquake
ii.
Mountain building
iii.
Rivers action
iv.
Wind action
Which of the following is an example of Exogenic force
i.
Volcano
ii.
Landslide
53
e)
2.
iii.
Earthquake
iv.
Glaciers
Which among the following is Endogenic force but is a slow process?
i.
Earthquake
ii.
Volcano
iii.
Landslide
iv.
Mountain building
Answer the following questions:
a)
Where is the Earth Crust floating and why?
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
b)
What are the different types of Earth processes?
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
c)
What is the study of geomorphology?
..........................................................................................................................................
..........................................................................................................................................
54
..........................................................................................................................................
..........................................................................................................................................
d)
Give a brief description on the weathering and erosion as stated by ancient
thinkers.
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
..........................................................................................................................................
3.
Fill the blanks given in the diagram?
55
Answer the question with reasoning:
Q.
Form where do the Earth plates get energy to move and how this happens?
Explain with diagram.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
56
WORKSHEET–4
MCQ
1.
Choose the correct answer form the given options:
a)
Which among the following is important for chemical as well as physical
weathering?
b)
c)
d)
i.
Rock structure
ii.
Topography
iii.
Climate
iv.
Human
Which of the following is an example of physical weathering?
i.
Exfoliation
ii.
Hydration
iii.
Hydrolysis
iv.
Oxidation
CaSo4 + 2H2O → CaSo4 · 2H2O is an example of
i.
Hydrolysis
ii.
Hydration
iii.
Oxidation
iv.
Carbonation
Which of the following will take place in karst region?
i.
2Fe2O3 + 3H2O → 2Fe2O3 ·3H2O
ii.
KAISi3O8 + HOH → HAISi3O8 + KOH
57
iii.
2KOH + H2CO3 → K2CO3 + 2HOH
iv.
CaCO3 + H2O + CO2 → Ca (HOH3)2
Answer the following questions
1.
What are the main processes of weathering?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
..............................................................................................................................................
2.
What is mechanical weathering?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
..............................................................................................................................................
3.
What is meant by chemical weathering?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
..............................................................................................................................................
4.
What types of mechanical weathering are there?
...................................................................................................................................................
58
...................................................................................................................................................
...................................................................................................................................................
..............................................................................................................................................
5.
What types of chemical weathering are there?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
..............................................................................................................................................
6.
Which regions are important for different types of weathering?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
..............................................................................................................................................
59
WORKSHEET–5
Explain the following diagrams.
(a)
(b)
(c)
(d)
60
1.
Study the figure and answer the questions below.
a
Where is the rainwater going?
b
What happens when temperatures fall below 0°C?
c
Why has the crack widened?
d
What effect will this have on the rock?
e
Which process does this flow chart illustrate?
2.
Study the figure and answer the questions below.
a
What kind of weathering is this?
b
How does this kind of weathering affect the rock?
c
Which climates speed up this kind of weathering?
3.
61
Study the figure and answer the questions below.
a
What happens to the crack as the roots get bigger?
b
What kind of weathering is this?
c
When the plant dies the roots decay and chemicals are produced.
d
What kind of weathering does this process cause?
4.
Study the figure and answer the questions below.
a
Are the changes in temperature gradual or rapid?
b
In which regions do these fluctuating temperatures often occur?
c
Where are the points of weakness in the rock?
d
What is this weathering process called?
e
Which types of rock are affected by this process?
62
WORKSHEET–6
MCQ
1.
Choose the correct answer form the given options:
a)
b)
c)
The load carried by the river water is called?
i.
Carrying capacity
ii.
Load capacity
iii.
Freight capacity
iv.
Weight capacity
Which of the following is the most active in higher altitude?
i.
Deposition
ii.
Transportation
iii.
Erosion
iv.
Erosion and deposition
Which of the following is an example of upper course landform made by
river?
d)
i.
Natural Levees
ii.
Interlocking spurs
iii.
Ox bow lake
iv.
Delta
Ox bow lakes are formed due to
i.
Erosion activity only
ii.
Erosion transportation depositional activity
63
iii.
Depositional erosion activity
iv.
Depositional activity.
Answer the following questions:
1.
What are the main actions of a river?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
How do rivers carry their load?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
Where do rivers have higher and lower rate of weathering?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
4.
In which areas of a river, there is equilibrium in supply of material and erosion?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
64
5.
How many stages are there in the journey of a river?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
6.
Erosion is most active in which stage of a river?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
7.
Deposition is prominent in which stage of a river?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
8.
Name the landforms made by rivers in youth stage of a river.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
65
WORKSHEET–7
1.
What landforms are made by rivers in equilibrium stages?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
What is flood?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
What is meant by Braided channel of river?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
4.
What is delta?
...................................................................................................................................................
...................................................................................................................................................
..................................................................................................................................................
5.
Where do rivers make delta?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
66
WORKSHEET–8
MCQ
1.
Choose the correct answer form the given options:
a)
b)
c)
d)
Karst topography is found in
i.
Sandy region
ii.
Coastal region
iii.
High altitude
iv.
Limestone region
Which of the following is smallest in size?
i.
Swallow holes
ii.
Sink hole
iii.
Valley sinks
iv.
Uvalas
Well developed karst topography can be seen in which region of the world?
i.
North America
ii.
South America
iii.
Europe
iv.
Asia
The hanging feature in karst caves are called
i.
Cave pillar
ii.
Stalagmite
iii.
Stalactite
iv.
Blind valley
67
Answer the following questions:
1.
In which areas Karst landforms can be seen?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
What Erosional landforms are made by groundwater?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
Why is it difficult to walk on limestone pavement?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
4.
A landform is called blind valley even river do not flow through it. Why?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
68
5.
What is the most magnificent landform made in Karst region?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
6.
What are cave pillars or columns?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
7.
How do chemical reactions occur in Karst region?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
69
WORKSHEET–9
Answer the following questions:
1.
What are glaciers and where are they found?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
What is Firn or Nave?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
How many types of Glaciers are there?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
4.
What are Nunatkas?
...................................................................................................................................................
...................................................................................................................................................
70
...................................................................................................................................................
...................................................................................................................................................
5.
What are Ice Shelves?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
6.
What are Ice Bergs and why are they dangerous for navigation?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
7.
What is Plucking and Abrasive action of Glacier?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
8.
What are Crevasses in Glaciers?
...................................................................................................................................................
...................................................................................................................................................
71
...................................................................................................................................................
...................................................................................................................................................
9.
What is tarn and where is it formed in Glacier Topography?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
72
WORKSHEET–10
Answer the following questions:
1.
Name the Erosional landforms made by glaciers.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
By observing Roche Moutannee how can we know the direction of glacier
advancement?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
What are Tills?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
4.
What do you mean by Moraine? Name different types of Moraines.
...................................................................................................................................................
73
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
5.
Why do Fluvio-glacial actions create only depositional landforms?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
6.
Name Fluvio-glacial deposits landform made by glacier.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
7.
Why do only small grains and sand particles make the Fluvio-Glacial Landforms?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
74
Word worksheet
Find out word from the box related to glacial topotraphy. Words can be in row,
column, and diagonals.
A
N
D
R
U
M
L
I
N
Q
A
S
T
E
A
M
O
R
A
I
N
E
S
X
L
R
A
U
V
W
C
R
U
U
N
A
D
M
I
W
G
S
I
K
S
D
A
M
S
T
V
D
R
C
S
E
T
O
L
O
H
N
L
T
E
E
B
A
E
R
E
F
G
S
M
Z
G
I
R
D
O
R
L
B
A
T
L
H
P
S
P
O
N
A
S
K
T
R
E
R
I
A
K
E
Y
A
R
S
L
T
T
E
I
R
E
A
R
E
T
E
S
A
L
I
E
E
C
G
G
S
E
S
O
L
E
C
O
M
K
E
L
V
I
K
E
L
K
I
I
R
O
U
T
W
A
S
H
P
L
A
I
N
P
O
E
L
C
E
I
M
M
E
S
S
T
A
A
J
C
N
A
A
D
W
E
L
E
S
K
E
R
S
V
E
U
O
N
S
I
S
L
A
N
D
N
E
W
Z
A
T
P
A
B
O
U
L
D
E
R
C
L
A
Y
N
A
F
D
U
G
L
A
C
I
E
O
L
A
P
E
N
75
1
4
5
6
5
1
2
3
34
2
Crossword worksheet
In the above crossword features associated with sea wave action is given. With the help
of hints given fill the crossword with appropriate words.
76
Down
1.
Place near the coast. (7)
2.
Bar connecting mainland and island. (7)
3.
Protruding hard resistant rock towards sea. (4)
4.
Small enclosed water body. (6)
5.
The hurling action of sea water with debris and gravels (9)
Across
1.
Bars formed near sea shore by sea wave deposit. (4)
2.
The whistling coastal landform. (8)
3.
Small inlet of water by cutting soft rocks. (3)
4.
Vertical wall like structure near coast.
5.
Pillar like structure. (8)
6.
The solvent action of sea water. (9)
77
WORKSHEET–11
Answer the following questions:
1.
What are the main actions of sea waves?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
What is the Whistling landform near Sea Coast?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
What is the basic difference between Shingle beaches and Sandy beaches?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
..................................................................................................................................................
4.
What are tombolos?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
5.
What is a lagoon and how is it formed?
...................................................................................................................................................
...................................................................................................................................................
78
WORKSHEET–12
MCQ
1.
Choose the correct answer from the given options:
a)
b)
c)
The topography made by wind in dry areas is called
i.
Karst topography
ii.
Sea wave topography
iii.
Eolian topography
iv.
Glacial topography
Dreiknaters are
i.
Two facet sharp edge pebbles
ii.
Three facet sharp edge pebbles
iii.
Four facet sharp edge pebbles
iv.
Multi facet sharp edge pebbles
Removal of sand particles till it reaches the groundwater saturated soil
topography is.
d)
i.
Vertrifacts.
ii.
Mushroom rock
iii.
Yardangs
iv.
Blow out
The fertile deposition of very fine sand and dust particles are called.
i.
Yardangs
ii.
Zeugens
79
iii.
Mesa and butts
iv.
Loess
Answer the following questions:
1.
Why winds are the most active agent of denudation in dry areas only?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
What are the main actions of the wind responsible for Landform creation?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
What are Dreikanters?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
4.
How winds in dry regions carve Mushroom Rocks?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
80
...................................................................................................................................................
5.
What are Sand Dunes and name different types of Sand Dunes?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
6.
Do Sand Dunes move and if yes then how?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
7.
What is loess and how do they form?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
8.
What are oases and what is its importance?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
81
WORKSHEET–13
MCQ
1.
Choose the correct from the given option:
a)
b)
c)
The complex brown jelly like substances is called?
i.
Air
ii.
Water
iii.
Humus
iv.
Mineral matter
Which of the following is having the largest share in soil composition?
i.
Air
ii.
Water
iii.
Organic matter
iv.
Mineral matter
Which of the following is having the smallest share in soil composition?
i.
Air
ii.
Water
iii.
Organic matter
iv.
Mineral matter
Answer the following questions:
1.
What is soil?
...................................................................................................................................................
82
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
What is importance of soil?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
The components that make the soil are found in which state?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
4.
What is humus and what is its importance in soil?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
5.
What is importance of water in soil?
...................................................................................................................................................
83
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
6.
Where do gases found in soil and what is its importance?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
84
WORKSHEET–14
MCQ
1.
Choose the correct from the given option:
a)
b)
c)
d)
Which of the following is smallest in size?
i.
Gravel
ii.
Clay
iii.
Sand
iv.
Silt
Which among the following is the biggest in size?
i.
Gravel
ii.
Clay
iii.
Sand
iv.
Silt
Which of the following soil will not allow water to percolate easily?
i.
Sand
ii.
Silt
iii.
Clay
iv.
Loam
Which among the following will be having maximum porosity?
i.
Loam
ii.
Clay loam
iii.
Clay silt
iv.
Silt loam.
85
2.
Observe the following data and answer the following questions:
Comp.
Clay
clay
silt
loam
Loam
Silt
Sandy
loam
loam
Sand
10%
33%
40%
5%
75%
Clay
45%
25%
18%
13%
11%
Silt
45%
42%
42%
82%
14%
After US Dept. of Agriculture, Yearbook 1938.
a.
Which soil is having the maximum proportion of clay in it?
b.
Which soil will be having maximum silt in it?
c.
In clay loam and loam soil both have same proportion of silt in it, among
these two which soil the proportion of sand is high?
d.
3.
What is percentage of sand in sandy loam soil?
Complete the following triangular diagram
86
WORKSHEET–15
MCQ
1.
Choose the correct from the given option:
a)
b)
c)
d)
How many factors affect soil formation?
i.
2
ii.
3
iii.
4
iv.
5
How many passive agents from soil?
i.
2
ii.
3
iii.
4
iv.
5
Which of the following soil is an example of residual soil?
i.
Red soil
ii.
Yellow soil
iii.
Alluvial soil
iv.
Black soil.
Which slope will not have more active soil formation?
i.
Northern slopes of mountains north of tropic of cancer
ii.
Southern slopes of mountains north of tropic of cancer
iii.
Northern slopes of mountains south of tropic of cancer
87
iv.
Southern slopes of mountains south of tropic of cancer
Answer the following questions:
1.
Which factors affect the formation of soil?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
What do you mean by active and passive agents of soil formation?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
How does topography play important role in soil formation?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
4.
Which climatic factors affect soil formation?
...................................................................................................................................................
...................................................................................................................................................
88
...................................................................................................................................................
...................................................................................................................................................
5.
Which biological factors contribute in soil formation?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
89
WORKSHEET–16
MCQ
1.
Choose the correct from the given option:
a)
b)
c)
How many horizons in the soil profile?
i.
2
ii.
3
iii.
4
iv.
5
The top most layer of soil profile is
i.
A horizon
ii.
B horizon
iii.
C horizon
iv.
Bed rocks
Zone of accumulation lies in
i.
A horizon
ii.
B horizon
iii.
C horizon
iv.
Bed rocks
Answer the following questions:
1.
What is meant by soil profile?
...................................................................................................................................................
90
...................................................................................................................................................
...................................................................................................................................................
2.
On what basis soil is stratified?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
Into how many vertical sections soil is divided, in general?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
4.
What is the importance of top soil?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
5.
What is meant by hard pan?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
6.
What is found above the top soil in warm and humid regions?
...................................................................................................................................................
91
...................................................................................................................................................
...................................................................................................................................................
7.
What is solum?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
92
WORKSHEET–17
MCQ
1.
Choose the correct answer from the given below:
a)
b)
2.
Which of the following is a human factor in cause of soil erosion?
i.
Climate
ii.
Topography
iii.
Land use
iv.
Hydrology
Which of the following is not a factor of soil that is susceptible to erosion?
i.
Soils with high water infiltration capability
ii.
Soils with low organic matter content
iii.
Soils on steep hills (especially in regions of high rainfall)
iv.
Soils with poor (unstable) structure
Observe the given diagram and explain how erosion is taking place and which
region this type of soil erosion is most common.
93
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Answer the following questions:
1.
What factors control the soil erosion?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2.
How is soil an important resource to us?
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3.
Suggest some ways to conserve soil form erosion.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
94
4.
Make a list of five processes that is responsible for soil degradation.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
5.
Make a list of five practices to conserve soil.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
95
REFERENCES
http://armyengineer.tpub.com
www.google.com/images
www.natgeo.com
www.discoverychannel.com
www.wikipedia.com
www.youtube.com
Tarbuck and Lutgen, the Earth: an introduction to physical geology, 3rd ed.
Merrill pub. New York.
Thornberry, Principles of Geomorphology, 2nd ed. Wiley pub. New York.
Strahler, A. N., Physical Geography, 2nd ed, Wiley pub. New York
Environment, NCERT Textbook in Geography, Class 7th
96
CENTRAL BOARD OF SECONDARY EDUCATION
Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110 092 India