Conclusion
This experiment proves that carbon dioxide is essential for photosynthesis.
SUMMARy
• Various activities carried out by living organisms, which are necessary to maintain
and continue life are called life processes.
• The biological process in which living organisms produce their own kinds by asexual
or sexual method is called reproduction.
• The method of reproduction which takes place from a single parent without the
fusion of a male gamete and a female gamete is called asexual reproduction.
• The method of asexual reproduction in which a parent organism divides into two or
more daughter organisms is called fission.
• The method of asexual reproduction which takes place by the formation of a bud is
called budding.
• The method of asexual reproduction which takes place by means of spores is called
sporulation.
• Fragmentation is the method of asexual reproduction in which a multicellular
organism breaks into two or more fragments and each fragment develops into a new
complete organism.
• Vegetative propagation is the method of asexual reproduction in which new plants
are produced by vegetative parts of plants like root, stem or leaf.
• Pollination is the transfer of pollen grains from the anther to the stigma of a flower.
• The heart is a hollow, conical organ made up of cardiac muscle.
• The wall of right ventricle is more muscular than that of auricles because it has to
pump blood to a much farther distance to the lungs.
• Blood vessels are the pipes through which blood flows. They are of three types, viz.
arteries, veins and capillaries.
• The circulation of blood from the left ventricle to the right auricle of heart via body
tissues (except lungs) is called systemic circulation.
• The circulation of blood from the right ventricle of heart to the left auricle via lungs
is called pulmonary circulation.
• The continuous rhythmic beat throughout the life which is produced due to the
contraction and relaxation of heart muscles is called heart beat.
• Green plants prepare their own food in chlorophyll by using carbon dioxide and
water as raw materials and sunlight as the source of energy. This process is called
photosynthesis.
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Exercise
1. Choose the best answer from the given alternatives.
a. The method of asexual reproduction which is common in amoeba
is.......................... .
i. budding ii. fission iii. sporulation iv. fragmentation
b. Which of the following is a hermaphrodite animal?
i. tapeworm ii. frog iii. roundworm iv. butterfly
c. Which of the following valves is present between left auricle and left ventricle?
i. aortic valve ii. pulmonary valve
iii. bicuspid valve iv. tricuspid valve
d. The blood cells that transport oxygen are .......................... .
i. RBCs ii. WBCs iii. platelets iv. none of them
e. The gas which is essential for photosynthesis is.......................... .
i. oxygen ii. carbon dioxide iii. hydrogen iv. nitrogen
2. Tick (√) the correct statement and cross (×) the incorrect one.
a. Paramecium reproduces by budding.
b. Gametes are formed in sexual reproduction.
c. RBCs appear red due to the presence of haemoglobin.
d. Aorta transports blood to the lungs.
e. Veins carry deoxygenated blood .
f. Photosynthesis occurs in leaves.
3. Fill in the blanks using appropriate words.
a. Hydra and yeast reproduce asexually by ………......… .
b. Zygote is formed in ………......… reproduction.
c. Blood is made of ………......… and blood corpuscles.
d. The membrane that surrounds the heart is called ………......… .
e. All veins carry ………......… blood except ………......… vein.
f. ………......… is released during photosynthesis.
4. Answer the following questions.
a. What are life processes? Give any three examples.
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b. What is reproduction? Why do living beings reproduce?
c. What is asexual reproduction? Name various methods of asexual
reproduction.
d. What is fission? Name any two animals and two plants that reproduce by this
method.
e. Define budding and regeneration with examples.
f. What is fragmentation? Name an organism that reproduces by this method.
g. What is sexual reproduction? Write any two advantages of asexual and sexual
reproduction.
h. What is blood circulatory system? Write down its major components.
i. Where is heart located? Name the valves found in human heart.
j. What is blood? Draw a neat and labelled figure showing composition of blood.
k. What are blood vessels? Name three types of blood vessels with one function
of each.
l. What is photosynthesis? Write down the raw materials for photosynthesis.
5. Differentiate between:
a. Asexual and Sexual reproduction
b. External and Internal fertilization
c. Unisexual and Bisexual organism
d. RBC and WBC
e. Auricles and Ventricles
f. Arteries and Veins
6. Describe the structure of human heart with a neat and labelled figure.
7. How is blood circulated in human body? Describe in brief.
8. What is iodine starch test? How is this test carried out? Explain.
9. Describe an experiment to prove that sunlight is essential for photosynthesis.
10. Describe an experiment to prove that carbon dioxide is essential for
photosynthesis.
11. Describe an experiment to demonstrate that oxygen is released during
photosynthesis.
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19uNIt Estimated teaching periods : Th Pr
6 1
Earth
StruCturE oF thE
EArth
objectives
After completing the study of this unit, students will be able to:
• define minerals and explain physical properties and advantages of
minerals.
• give general introduction to major minerals (iron, copper, lead, zinc,
limestone and graphite) found in Nepal.
• explain the process of soil formation and make soil profile.
• describe soil erosion and deposition and explain the method of soil
conservation.
Course of Study
• Introduction to minerals
• Characteristics and uses of minerals
• Some important minerals found in Nepal (iron, copper, lead, zinc, limestone
and graphite)
• Process of soil formation
• Composition of soil
• Soil profile, erosion and deposition
• Conservation of soil
Points to be Focused/Questions to be Discussed
• What are minerals?
• What are the characteristics and uses of minerals?
• What are the major minerals found in Nepal?
• How is soil formed in nature?
• What is soil profile? What is erosion and deposition?
• How is soil conserved?
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19.1 Introduction
Earth is the only planet having all the conditions necessary for survival of plants and
animals. The earth's crust is made of rocks, sand, soil, etc. The rocks present on the earth's
surface are of different shape, size, colour, density, etc. The rocks contain different types
of minerals like rock salt, lead, mica, granite, slate, limestone, sandstone, etc. Soil forms
the uppermost layer of the earth's crust. It consists of minerals, humus and small particles
of sand. Soil is formed by weathering of rocks. We should conserve soil as it supports life.
Lead Mica
Rock salt
Granite Limestone Sandstone
Fig. 19.1 Some minerals
19.2 Minerals
Minerals are the compounds which are found in rocks. Some minerals contain only
one element whereas others contain more than one elements. Minerals like haematite,
magnetite, cuprite, chalcopyrite, bauxite, etc. are found in the form of compounds and
minerals like sulphur, diamond, gold, etc. are found in the form of elements. Minerals
are important natural resources. The natural materials which contain metals, non-metals
and their compounds are called minerals. They are non-renewable natural resources.
Minerals were formed as a result of slow changes which took place in the earth's crust
over millions of years.
Minerals are broadly classified into two types. They are : (i) Metallic minerals and (ii)
Non-metallic minerals.
(i) Metallic minerals
The minerals that contain metals in a large amount are called metallic minerals.
These minerals are the compound of metals. Those minerals from which metals can
be extracted conveniently and profitably are called ores. An ore contains a good
percentage of metal and there are very less impurities in it. Heamatite and magnetite
are the ores of iron. Similarly, cuprite and chalcopyrite are the ores of copper and
argentite and horn silver are the ores of silver.
humus /ˈhjuːməs / - a substance made from dead leaves and plants
weathering /ˈweðəriή/ - the action of sun, rain or wind on rocks, making them change shape or colour
geology and astronomy Oasis School Science and Environment - 8 299
Haematite ore Magnetite ore Cuprite ore Chalcopyrite ore Argentite ore
Fig. 19.2 Metallic minerals
(ii) Non - metallic minerals
The minerals that do not contain a significant amount of metals are called non-
metallic minerals. These minerals contain metals in very less amount. So, metals
cannot be extracted from these minerals. Non-metallic minerals are used for making
cement, chemical fertilizers, houses, bridges, roads, chemical substances, idols,
sculptures, fuels, etc. Limestone, sulphur, galena, coal, mica, granite, slate, petrol,
etc. are some examples of non-metallic minerals.
Sulphur Coal Slate Granite
Fig. 19.3 Non-metallic minerals
Differences between Metallic minerals and Non-metallic minerals
Metallic minerals Non-metallic minerals
1. Metallic minerals are the minerals that 1. Non-metallic minerals are the min-
contain metal in a large amount. erals that do not contain significant
amount of metal.
2. Metallic minerals are used to extract 2. Non-metallic minerals are used for
metals. making cement, houses, bridges,
roads, chemical fertilizers, etc.
19.3 Characteristics of Minerals
Different types of minerals have their own characteristics. Minerals can be identified from
their characteristics. The major characteristics of minerals are as follows:
1. Minerals have their own colour. The colour of haematite is reddish-brown and that
of chalcopyrite is bright-green.
2. Minerals have their own lustre. Generally, metallic minerals are lustrous.
3. Minerals are crystalline substances.
4. Generally, minerals are hard.
lustre / ˈ l ʌ s t ə ( r ) / - the shining quality of a surface
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19.4 uses of Minerals
The major uses of minerals are as follows:
1. Minerals are used for extracting metals.
2. They are used for making fuels.
3. They are used for making decorative items.
4. They are used in construction of roads, bridges, buildings, etc.
5. They are used for making valuable gems.
19.5 Some Important Minerals Found in Nepal
Minerals are very important natural resources. They are essential for industrial
development. There is a great role of minerals in the development of a country. The
establishment and development of various industries depends on the availability
and proper use of minerals. We should conserve the mineral resources by using them
judiciously and avoiding their wastage so that they may last long. The major minerals
found in Nepal are described below:
1. Iron
Iron is a grey coloured metal. It is one of the most useful metals. It is used by
people to make household utensils and weapons. In the past, people of Ramechhap,
Rolpa and Baitadi used to extract iron by traditional methods. In Nepal, haematite
and magnetite ores are found in various regions. These ores of iron are found in
Phulchoki of Lalitpur district, Thoshe of Ramechhap district, Labdi of Tanahun
district and Jeekhabang of Chitawan district. Iron is used for making household
utensils, weapons, vehicles, rods, cables, buildings, bridges, etc.
2. Copper
Copper is a reddish-brown metal. It is the main metal extracted by local people
to earn money. The principal ore of copper is chalcopyrite. In the past, Nepalese
people used to work in copper mines and extract it by traditional methods. In Nepal,
copper mines ore located in Dadeldhura, Bhojpur, Baglung, Tanahun, Udaypur,
Solukhumbu, Dhading and Kalitar of Makawanpur. Copper is used for making
electric wires, household utensils, sculptures, roofs of temples, coins, etc.
3. Lead
Lead is a soft, malleable and heavy bluish white metal. The principal ore of lead
is galena which contains 86.6% lead by weight. Lead has been used by people of
Himalayan region from pre-historic time. In Nepal, lead mines are found in Ganesh
Himal, Phulchoki of Lalitpur, Khairabang of Makawanpur and Solukhumbu
district. Lead is used in construction work. It is also used in lead-acid batteries and
for making bullets.
4. Zinc
Zinc is a bluish-white lustrous metal. The principal ore of zinc is zinc sulphide. In
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Nepal, it is found in Ganesh Himal, Phulchoki, Makawanpur and Sankhuwasabha.
Zinc is used for coating iron to prevent rusting. It is also used for making alloys like
brass and bags of dry cells.
5. Limestone
Limestone is an important mineral which is being used from pre-historic time. The
industries established in Nepal based on limestone are cement and lime factories
(industries). The mines of limestone are found in different parts of Nepal. The
major mines of limestone are found in Udaypur, Godawari, Makawanpur, Chobhar,
Surkhet, Arghakhanchi, Dhading, Kabhre, Dang and Sindhuli. Limestone is used for
making cement, lime, etc. It is used in temples, houses, buildings, etc.
6. Graphite
Graphite is a soft grayish-black greasy mineral. It is generally found in metamorphic
rocks. The mines of graphite are found in different parts of Nepal. The mines of
graphite are located in Ilam, Dhankuta, Sindhupalchowk and Sankhuwasabha.
Graphite is mainly used for making pencils, colours, lubricants, electrodes, etc.
reasonable fact-1
haematite is called a metallic mineral.
Haematite is that mineral in which iron is found in the form of metal. So, hameatite is
called a metallic mineral.
reasonable fact-2
Chalcopyrite is called an ore.
Chalcopyrite is that mineral from which copper can be extracted conveniently and
profitably. So, chalcopyrite is called an ore.
reasonable fact-3
Diamond is called a non-metallic mineral.
Diamond is that mineral which does not contain any metal. So, diamond is called a
non-metallic mineral.
reasonable fact-4
the role of minerals is very important for the development of a country.
Various components which are essential for the industrial development of a country
are obtained from minerals. Minerals are used in the construction of roads, bridges,
buildings, etc. which are the backbone of the development of a country. In the similar
manner, different materials required for daily use are also obtained from minerals. So,
the role of mineral is very important for the development of a country.
abrasive / əˈbreɪsɪv / - related to damage to a surface caused by rubbing sth very hard against it
crevice / ˈ k r e v ɪ s / - a narrow crack in a rock or wall
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19.6 Soil
Soil is the topmost layer of the earth's crust formed Fig. 19.4 Soil
by mineral particles, organic matter, water, sand, clay
and humus. Most part of the land is covered with soil.
Soil provides habitat to plants and animals. Green
plants absorb water and minerals from the soil for
photosynthesis. Various organisms like bacteria, fungi,
earthworms, insects, etc. complete their life cycle in the
soil. Without soil there would be no plants and in the
absence of plants, other forms of life would not exist.
Therefore, soil is a life supporting medium that provides
sustenance to plants and animals.
Formation of Soil
Soil has been formed from parent rock material over millions of years. The process by
which formation of soil takes place is called weathering. A very slow and gradual process
in which large rocks break down into fine particles is called weathering. The various
methods of soil formation are given below:
1. Change in temperature: Rocks expand when heated during day and contract when
cooled during night. The hot sun causes the surface layers of rocks to expand more
than the layers deeper down. These changes cause the rock surface to break into
small pieces. These pieces further break into fine particles. As a result, soil is formed.
2. Water: The big rocks of hilly region are carried away by water of rivers, streams,
springs, etc. These rocks break into small pieces due to collision. As this process
continues, the large rocks change into very fine particles. As a result, soil is formed.
3. Wind: Wind blowing across a rock surface has an abrasive effect on the rocks.
Minute rock particles are carried away by the blowing wind and get deposited
elsewhere. As a result, soil is formed.
4. Frost: Rain water may trap in small crevices of the rocks. In winter, the trapped
water freezes to ice. The ice expands and exerts a lateral pressure causing the
crevices to further open up and finally breaks the rocks into pieces. These pieces of
rocks break into fine particles which help in soil formation.
5. Living organisms: Some species of plants like lichens grow on the surface of rocks.
These plants produce acids which corrode the rocky surface and produce fine
particles. Similarly, some plants grow on cracks of rocks and roots of those plants
weather the rocks and help to form soil.
Composition of Soil
Soil is the mixture of various components. The major components of soil are soil particles
or rock particles, humus, soil water, soil air and soil organisms.
Soil consists of a mixture of different sized particles like clay, silt, sand and gravels or
stones. Humus or organic matter is found at or near the soil surface. It is formed from
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the remains of the dead plants and animals by the action of microorganisms present in
the soil. Some water is present in the soil between its particles which is called soil water.
Similarly, some air is present between the soil particles which is called soil air. Various
types of organisms like earthworm, bacteria, fungi, roundworms, etc. and the dead
remains of plants and animals are found in the soil.
The components of soil differ according to the type of the soil. There are various layers
of the soil. The uppermost layer of soil contains humus. The second lower layer contains
humus, roots of plants, insects and some other substances. The third lower layer contains
minerals like iron, aluminium, magnesium, etc. Similarly, the lowermost layer consists
of pebbles and bed rock. Therefore, soil is made of humus, parts of animals and plants,
minerals, pebbles, bedrock, etc.
Activity 1
• Collect a sample of soil from your surroundings. Water
• Take a glass cylinder and put the soil sample in the cylinder.
• Shake the contents thoroughly. Allow the mixture to settle. Clay
What do you observe? Draw a neat and labelled figure and Silt
Sand
write down the conclusion of this activity. Bed rock
Fig. 19.5
Soil profile Vegetation
If we dig a trench vertically down at a place, we Top soil (Horizon A)
can see various layers of soil called horizons. The Sub-soil (Horizon B)
arrangement of these horizons is called the soil Horizon C
profile. This profile differs for soils found in different
places. So, soil profile is the arrangement of various
layers or horizons of a soil vertically down from the
surface of the soil.
Bed rock
Soil profile has three main layers or horizons which
are as follows: Fig. 19.6 Soil profile
(i) The uppermost layer is called the A-horizon or
top soil. The top soil is the darkest layer of soil which is rich in humus. This layer
is soft, porous and holds enough water. Living organisms like earthworms, insects,
bacteria, fungi, etc. are present in this layer. This layer also consists of roots of
plants. However, the roots of tall trees may go further down to the second horizon.
erosion / ɪˈrəʊʒn / - the process of carrying away of weathered particles by wind, water, etc.
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(ii) The layer of soil below the A-horizon or top soil is called the B-horizon or sub-soil.
This layer is lighter in colour than the upper layer. It is harder, more compact and
rich in soluble minerals as compared to upper layer. Remains of plants and animals
are not found in this layer but roots of tall plants generally reach this level.
(iii) The lowermost layer of soil profile is called C-horizon. It consists of large pieces of
rocks. Beneath the C-horizon, bed rock is located which cannot be easily dug up.
19.7 Erosion and Deposition
The process of carrying away of land surface or weathered particles by the agents like
wind, air, storm, hurricane, etc. is called erosion. It is caused by wind, water, river, glaciers
and even human activities like construction works. The materials taken away during
erosion are deposited at any other places. This process is called deposition. Therefore, the
process of depositing materials taken away during erosion is called deposition. Erosion
and deposition occur side by side. It means erosion is followed by deposition.
19.8 Soil Erosion
Soil erosion is a serious problem which is common in mountainous and hilly regions of
Nepal. It removes the fertile topsoil and reduces the productivity of the soil in that area.
The main agents of soil erosion are wind and water. The removal of top fertile and useful
soil by running water and wind is known as soil erosion.
Generally, the rate of removal of soil particles from one place is the same as the rate of
deposition of soil at another place. But sometimes there may be a disturbance in this
balance. The major causes of soil erosion are described below:
a. Deforestation: The cutting down of trees on a large scale is called deforestation.
The roots of plants hold the soil particles together with great force. When trees are
removed, soil particles are left loose and can be easily carried away by running water
and wind.
(a) (b)
Fig. 19.7 Deforestation
b. Floods and heavy rain fall: Floods and heavy rainfall cause a lot of damage to the
soil, especially when there are no trees and the land is lying bare.
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Fig. 19.8 Floods
c. overgrazing: Repeated grazing by animals on the same place of land leads to the
removal of grass in a large scale. This makes it easy for the wind and running water
to erode the soil.
Fig. 19.9 overgrazing
d. Improper farming: Traditional methods of farming on hills or slopes make it easy
for the wind and water to erode soil.
Fig. 19.10 Improper farming
19.9 Prevention of Soil Erosion
Reduction or prevention of soil erosion is called soil conservation. Soil erosion can be
prevented by the following methods:
a. Afforestation: The process of planting trees in large numbers on bare land is called
afforestation. The roots of trees hold the soil particles together, thus they make it
erode / ɪˈrəʊd / - to gradually destroy the surface through the action of wind, rain, etc.
306 Oasis School Science and Environment - 8 geology and astronomy
difficult for water and wind to erode the soil. Grasses and herbs can be used to cover
large patches of loose soil.
Fig. 19.11 Grassland and afforestation
b. Flood control: Floods can be controlled to a large extent by building dams.
Fig. 19.12 Flood control by dams
c. restricted animal grazing: Over grazing of a single patch by animals should be
avoided. Animals should be moved to different areas from time to time.
d Construction of bunds: Embankment of mud walls should be constructed around
hill slopes or fields to stop the flow of water.
e. terrace farming: It is a method of farming adopted in hilly areas. In this method,
suitable crops are grown on sloping ground which is cut into large steps called
terraces. Terrace farming reduces the speed of water flow down the hill thereby
reducing the amount of soil being carried away.
Fig. 19.13 terrace farming
plateau /ˈplatəʊ / - an area of flat land that is higher than the land around it
contour / ˈkɒntʊə(r)/ - the outer edges of something
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19.10. Effects of Soil Erosion and Deposition
The major effects of soil erosion and deposition are as follows:
1. Soil erosion causes landslides.
2. It destroys the fertility of soil and hence decreases the productivity of crops.
3. Soil erosion and deposition form plains, hills, plateaus, etc.
4. Deposition may increase or decrease the fertility of soil.
5. Soil erosion may destroy smaller plants and vegetation.
19.11. Soil Conservation
Soil is a very important natural resource. It plays an important role in our life. It is used
for growing different crops, fruits and vegetables. The fertility of soil is destroyed by
several factors. So, we should protect and conserve soil. Some major ways of conserving
soil are listed below:
a. terrace cultivation: Cultivation and farming on hills or slopes should be done by
making steps like ridges called terrace.
b. Contour ploughing: During ploughing, the soil should be ploughed sideways rather
than down on hill areas.
c. Afforestation: Trees and plants should be planted in bare and naked hill areas, river
side, landslide-prone zones, etc.
d. Crop rotation: During cultivation, different types of crops should be cultivated in
order to protect the fertility of the land.
e. Shelter belts: In dry places and deserts, shelter belts should be made so that sandy
soil and dry soil may not be carried away by wind.
Project work
• Visit a nearby river side along with your science teacher. Observe the minerals
present in sand and rocks on the bank of the river.
• Collect some samples of rock and study their characteristics.
• Study the soil texture in your surroundings and prepare a short report on it.
• How is soil being eroded in your locality? Observe the places facing soil erosion
in your surroundings. Prepare a short report and submit to your science teacher.
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reasonable fact-5
Soil erosion and deposition occur side by side.
Soil erosion is the process of carrying away of land surface or weathered particles
by the agents like wind, air, storm, hurricane, etc. It is caused by wind, water, river,
glaciers and even human activities like construction works. Deposition is the process
that the materials taken away during erosion are deposited at any other places. This
means erosion is followed by deposition. So, erosion and deposition occur side by side.
If soil erosion occurs in one place, the eroded materials get deposited on another
place. Deposition is not possible without erosion. So, we can say that soil erosion and
deposition occur side by side.
reasonable fact-6
Afforestation helps to conserve soil.
Afforestation is the process of planting trees in a large number on bare land. The
roots of trees hold the soil particles together, thus make it difficult for water to erode
the soil. So, afforestation helps to conserve soil.
reasonable fact-7
Plants having strong roots like bamboo should be planted on the bank of rivers.
The strong roots of plants like bamboo hold the soil particles together, thus, they
make it difficult for running water to erode the soil particles easily. So, plants having
strong roots like bamboo should be planted on the bank of river.
SuMMAry
• The rocks contain different types of minerals like rock salt, lead, mica, granite,
slate, limestone, sandstone, etc.
• The natural materials which contain metals, non-metals and their compounds
are called minerals.
• The minerals that contain metals in a large amount are called metallic
minerals.
• The minerals that do not contain a significant amount of metals are called
non-metallic minerals.
• Iron is a grey coloured metal. It is one of the most useful metals.
• Iron is used for making household utensils, weapons, vehicles, rods, cables,
buildings, bridges, etc.
• Copper is used for making electric wires, household utensils, sculptures,
roofs of temples, coins, etc.
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• Lead is a soft, malleable and heavy bluish white metal.
• Zinc is used for coating iron to prevent rusting. It is also used for making
alloys like brass and bags of dry cells.
• Soil is the topmost layer of the earth's crust formed by mineral particles,
organic matter, water, sand, clay and humus.
• The process by which formation of soil takes place is called weathering.
• The major components of soil are soil particles or rock particles, humus, soil
water, soil air and soil organisms.
• Various types of organisms like earthworm, bacteria, fungi, roundworms,
etc. and their dead remains are found in the soil.
• Soil is made of humus, parts of animals and plants, minerals, pebbles,
bedrock, etc.
• Soil profile is the arrangement of various layers or horizons of a soil vertically
down from the surface of the soil.
• The uppermost layer of soil is called the A-horizon or top soil. It is the darkest
layer of soil rich in humus.
Exercise
1. Choose the best answer from the given alternatives.
a. Which of the following is a metallic mineral?
i. haematite ii. graphite
iii. limestone iv. lead
b. Which of the following is the ore of iron?
i. chalcopyrite ii. magnetite
iii. bauxite iv. argentite
c. Which of the following is used for making electric wire?
i. lead ii. copper iii. iron iv. zinc
d. Graphite is used for making ........................ .
i. lubricants ii. brass iii. cement iv. utensils
e. Weathering of rocks is responsible for ........................... .
i. sand formation ii. soil formation
iii. humus formation iv. clay formation
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2. Fill in the blanks with appropriate words.
a. The minerals from which metals can be extracted are called ........................ .
b. ........................... is the ore of iron.
c. ........................... is used for making brass.
d. Soil is made of ........................... and rock particles.
e. Erosion and ........................... go side by side.
3. tick () the correct statement and cross (×) the incorrect one.
a. Minerals are found in the form of elements and compounds.
b. Metallic minerals are used for making chemical fertilizers.
c. Minerals are generally soft.
d. Galena is the principal ore of lead.
e. Terrace farming helps reduce soil erosion.
4. Answer the following questions.
a. What are minerals? Name two types of minerals with any two examples of
each.
b. Write any three characteristics and three uses of minerals.
c. Name any five minerals found in Nepal.
d. Name any two ores of iron. Where is iron found in Nepal?
e. What is the principal ore of copper? What is copper used for?
f. Where is zinc found in Nepal? Write any two uses each of lead, graphite and
limestone.
g. What is soil? Write down the composition of soil.
h. What is meant by soil profile?
i. What is meant by soil erosion and deposition?
5. Differentiate between:
a. Metallic minerals and Non-metallic minerals
b. Minerals and Ores
c. Zinc and Limestone
d. Erosion and Deposition
6. Explain the various methods of soil formation in brief.
7. Draw a neat and labelled figure showing soil profile.
8. Explain the causes and effects of soil erosion.
9. What is soil conservation? Write any four methods of soil conservation.
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20uNIt Estimated teaching periods : Th Pr
5 1
WEAthEr AND CLIMAtE
objectives
After completing the study of this unit, students will be able to:
• introduce climate and explain the factors affecting climate.
• give general introduction to climate of Nepal.
• introduce monsoon, its formation and monsoon of Nepal.
• describe the effects of monsson.
Course of Study
• Introduction to weather and climate
• Factors affecting climate
– Distance from the equator (latitude)
– Altitude and slope
– Distance from the sea
• Climate of Nepal
• Monsoon and its formation
• Effects of monsoon
Points to be Focused/Questions to be Discussed
• What is meant by weather and climate?
• List the factors affecting climate.
• What type of climate is found in Nepal?
• What is monsoon? How is it formed?
• What are the effects of monsoon?
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20.1 Introduction
Weather and climate both refer to the atmospheric condition of a place. Temperature,
precipitation, humidity etc. are the main components of weather and climate. However,
there are some differences between weather and climate.
Most days are sunny, some are cloudy and others are rainy. Some days are hot and some
days are cold. It may be sunny in the morning but the day may suddenly become dark
and rainy. It is due to change in weather. The condition of the atmosphere at a particular
place and time is called weather. At any given place, weather does not remain constant.
The weather changes from hour to hour, day to day and so on. The weather differs from
place to place also. Climate is the average atmospheric condition over a long period
of time ranging from months to thousands of years. Climate is the totality of existing
temperature, atmospheric pressure, humidity, rainfall, etc.
20.2 Weather
Weather is the atmospheric condition of a particular place during a particular period.
The atmospheric condition of a place in the morning, at noon and in the evening may
be different. It may be sunny at one time and other time it may be cloudy or rainy. The
specific atmospheric condition of a particular place at a particular time is called weather.
Weather varies from time to time over the same place. For example, it may be sunny in the
morning, cloudy at noon and rainy in the evening.
Sunny weather Cloudy weather Windy weather Rainy weather
Fig. 20.1
20.3 Climate
Climate is the average atmospheric condition of a place over a long period of time. In
other words, it is the average weather pattern of a place of the whole year. The climate is
different in different places. The climate is hot and wet in some places and hot and dry in
some other places. Similarly, it is very cold with snowfall in some places.
World is divided into three main climatic regions: tropical, temperate and cold or frigid.
Each climatic region is further divided into many sub-regions called climatic belts. Climate
is one of the major factors to determine the type of natural vegetation, animals and modes
of human life and their activities.
frigid / ˈ f r ɪ d ʒ ɪ d / - very cold
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Differences between Weather and Climate
Weather Climate
1. The specific atmospheric condition of 1. Climate is the average atmospheric
a particular place at a particular time condition of a place over a long
is called weather. period of time.
2. The weather of a place in the morning, 2. The climate of a place remains the
at noon and in the evening may be same throughout the year.
different.
C20l.i4maFtaectors Affecting the North pole
Numerous factors affect the climate in the Sunlight Earth Latitude
world. Climate is not uniform all over the world.
It is different in different places. Distance from South pole
the equator, height from the sea level, slopes of
mountain, winds, oceanic currents, vegetations, Fig. 20.2
types of soil, etc. are the factors which affect the
climate. Some of the major factors that affect
climate are described below:
i. Latitude (Distance from the equator)
Latitude is the angular distance to the north and south of the equator. Equator is
an imaginary line which passes from east to west through the centre of the earth. It
lies at 00 latitude where the sun rays are direct and straight and have more effect of
heating. So, it is hot in the equatorial region. But as the distance from the equator
increases, sun rays become tilted and in the poles which lie at 900 latitudes get the
most tilted sun rays. So, it is very cold in the polar region.
ii. Altitude and slope
Altitude is the height of the place from the sea level. When the altitude increases,
temperature decreases and vice versa. In every 160 – 165 m altitude, temperature
decreases by 10 C. This is the reason why terai region has hot climate and mountain
region has cold climate.
Windward slope Leeward slope
Fig. 20.3
leeward / ˈliːwəd / - the side that is sheltered from the wind
windward / ˈwɪndwəd / - on the side of something from which the wind is blowing
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Similarly, the slope of mountain towards the monsoon winds are windward slopes
which get more rainfall while the slopes in the opposite side are leeward slopes
which often remain dry. Pokhara lies in the windward slope of Annapurna range.
So, it receives more rainfall but Manang and Mustang lie in the leeward slopes and
are dry.
iii. Distance from sea Fig. 20.4
The climate of a place is also affected by the
distance from the sea.The places near the
sea get more influence of sea breeze during
the day time and land breeze during night
which makes the climate near the sea more
moderate. But the influence of sea breeze
is less in the places far away from the sea.
So, the climate of the places that remain far
away from the sea is more extreme, i.e. very
hot in day and very cold at night.
20.5 Climate of Nepal
Nepal lies approximately between 260 and 300 latitudes in northern hemisphere in South
Asia which is the belt in "Tropical Monsoon Region". So, on the basis of latitude, Nepal
lies in tropical monsoon climatic region but the climate is of varied types on the basis of
difference in altitude. The altitude of Nepal ranges between 60 m to 8,848m from the sea
level and the places lying in different altitudes have different types of climate.
The belt between 60 m and 1200 m in the south is Terai and the climate in this region is annual
rainfall. Maximum summer temperature reaches upto 40 0C and minimum temperature
in winter falls around 60 C. It is mostly hot in summer, although it is very cold in winter
due to cold air and cold wave or Seetlahar. Natural vegetation of this region is of tropical
evergreen type.
Legend
HIgh Himal
High
Mountain
Middle
Mountain
Siwaliks
Terai
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geology and astronomy
From 1200 m to 2100 m from the sea level, the climate is moderate. It is warmer in the river
basin and valley. Maximum summer temperature reaches upto 300 C and the minimum
temperature in winter plunges below the freezing point. Deciduous vegetation is found
in this region. Plants of this region shed leaves during winter.
Between 2100 m and 3300 m altitude in the mid-hill region, climate is cool temperate.
Maximum temperature in summer is upto 200C and the lowest temperature is below 00C.
Coniferous forests of pines are found in this region.
In higher altitude, between 3300 m and 5000 m, the climate is cold with maximum
temperature upto 150C in summer and below freezing point during winter. Above 5000m,
the climate is very cold with the average temperature below the freezing point. In this
region, snowfall occurs throughout the year. Since the climate of this region is very cold
with high snowfall, no vegetation is found. This region is commonly called Tundra region.
Climate of Nepal also varies on the basis of the influence of winds. In summer, rainfall
occurs due to the influence of moist summer monsoon winds which come from the Bay
of Bengal whereas winter is dry due to the influence of dry winter monsoon winds which
blow from central Asia. However, sometimes little rainfall occurs in winter due to the
influence of Westerlies which come from Mediterranean sea. Winter rain in Nepal is more
in the west and less in the east.
The Thar desert of India and Arabian desert of Middle-East Asia are in the west from
Nepal and the hot wave of air coming from these deserts makes the climate in Western
Nepal hotter. Climate in the eastern part is comparatively more moderate due to nearness
to the Bay of Bengal.
Many big and permanent rivers which spring up from the Himalayan range also help to
make the climate of Nepal mild and moderate. The Himalayan range in the north prevents
Nepal from cold wave of air which comes from Central Asia.
Differences between Tropical climate and Temperate climate
tropical climate temperate climate
1. It occurs from the altitude of 60m to 1. It occurs from altitude of 2100m to
1200m from the sea level. 3300m from the sea level.
2. The evergreen forests are found in this 2. Coniferous forests are found in this
climatic region. climate region.
Differences between Temperate climate and Tundra climate
temperate climate tundra climate
1. It occurs from the altitude of 2100m to 1. It occurs from the altitude of 5000m
3300m from the sea level. and more from the sea level.
2. Coniferous forests are found in this 2. No vegetation exists in this climatic
climatic region. region.
deciduous / dɪˈsɪdjʊəs / - that loses its leaves every year
westerly / ˈwestəli / - a wind that flows from the west
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20.6 Monsoon
The term 'Monsoon' refers to season or the period of seasons. Monsoon climate is
characterized by season change. In Nepal, monsoon begins with rainfall. Chaitra,
Baishakh and Jestha in Nepal are the months of pre-monsoon season. The cliamte is hot
and mostly dry. However, rainfall begins from this season. Asar, Shrawan and Bhadra
are the months of mid-monsoon. Most of the rainfall (around 90%) occurs during
mid-monsoon. Ashwin and Kartik are the months of late monsoon.
It is cold and dry in winter. Land remains cold but water bodies are warm. High air
pressure prevails in the land of Nepal but air pressure is low in Indian ocean. So, cold and
dry air blows from Nepal to Bay of Bengal which is called winter monsoon wind which is
dry and does not cause rain.
(a) Fig. 20.6 (b)
But in summer, moisture bearing summer monsoon winds blow from Bay of Bengal to
Nepal which bring plenty of rainfall. This is the reason why it is rainy in summer and
dry in winter in Nepal. Summer monsoon winds which blow from sea to land in summer
and winter monsoon winds which blow from land to sea in winter are called seasonal or
periodic winds.
The summer monsoon winds which bring rainfall in Nepal during summer come from the
Bay of Bengal which lies to the south-east from Nepal. So more rainfall occurs in the east
and gradually decreases to the west. Similarly, summer rain occurs more in the southern
slopes of mountains which are called windward slopes. Pokhara lies in windward slope
of mountain and receives the highest amount of rainfall in Nepal. But little or no rainfall
occurs in the northern slopes which are leeward slopes. Such places are called rain shadow
area. Manang and Mustang of Nepal lie in rain-shadow area.
Differences between Winter monsoon and Summer monsoon
Winter monsoon Summer monsoon
1. In Nepal, the Indian winter monsoon 1. In Nepal, the Indian summer monsoon
is not dominant. is dominant.
2. During winter monsoon, there is dry 2. During summer monsoon, there is
and no rainfall. heavy rainfall.
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geology and astronomy
20.7 Effects of Monsoon
Nepal is an agricultural country. Monsoon is the main source of water for irrigation. It is
very useful as it provides sufficient rain water for irrigating the land for the production of
crops. It also increases the level of underground water which helps to supply more drinking
water. Rivers contain large volume of water which helps in generating hydroelectricity.
Monsoon also makes the climate cool in summer.
On the contrary, monsoon causes deluge (excessive rain), river get swollen and cause
floods, landslides, mudslides. Afforestation, river embankment, conservation of forest
resource, scientific farming are the main ways to reduce the adverse effects of monsoon.
Project work
• What is the effect of climate of a place on the vegetation of that area? Study the
climatic condition of your locality and its effect on the vegetation. Prepare a short
report on it and submit to your science teacher.
reasonable fact-1
the coldness increases as we move away from the equator.
As the distance from the equator increases, sun rays become titled and in the poles
which lie at 900 latitudes get the most tilted rays. So, the coldness increases as we move
away from the equator.
reasonable fact-2
In winter, more rainfall occurs in western Nepal than in eastern Nepal.
In winter, cold air blows from western Nepal to Bay of Bengal. So, in winter more
rainfall occurs in western Nepal than in eastern Nepal.
reasonable fact-3
More rainfall occurs in Pokhara and less rainfall occurs in Manang.
Pokhara lies in windward slope of mountain and receives the highest amount of rainfall
but Manang lies in leeward slope of mountain and receives rainfall.
reasonable fact-4
More landslide occurs in the eastern hilly region of Nepal.
Heavy rainfall occurs during monsoon in the eastern hilly regions of Nepal. So, more
landslide occurs in the eastern hilly region of Nepal.
reasonable fact-5
Monsoon is very important for Nepal.
Nepal is an agricultural country. Being a hilly country, we lack adequate irrigation
facilities and depend on the monsoon rain for irrigation. The monsoon recharges snow
and ground water. This is used for the whole year in the form of ground water, streams,
springs, etc. So, monsoon is very important for Nepal.
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SuMMAry
• The specific atmospheric condition of a particular place at a particular time is
called weather.
• Climate is the average atmospheric condition of a place over a long period of
time.
• Climate is one of the major factors to determine the type of natural vegetation,
animals and modes of human life and their activities.
• Distance from the equator, height from the sea level, slopes of mountain,
winds, oceanic currents, vegetations, types of soil, etc. are the factors which
affect the climate.
• Altitude is the height of the place from the sea level. When the altitude
increases, temperature decreases and vice versa.
• The altitude of Nepal ranges between 60 m to 8,848m from the sea level and
the places lying in different altitudes have different types of climate.
• Climate of Nepal varies on the basis of the influence of winds.
• Summer monsoon winds which blow from the sea to land in summer and
winter monsoon winds which blow from the land to sea in winter are called
seasonal or periodic winds.
• Pokhara lies in windward slope of mountain and receives the highest amount
of rainfall in Nepal. But little or no rainfall occurs in the northern slopes
which are leeward slopes.
• Afforestation, river embankment, conservation of forest and scientific farming
are the main ways to reduce the adverse effects of monsoon.
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Exercise
1. Choose the best answer from the given alternatives.
a. Which of the following statements is true?
i. Weather and climate are the same.
ii. Weather determines climate.
iii. Climate determines weather.
iv. There is no relation between weather and climate.
b. The equator ....................................... .
i. divides the earth into eastern and western hemisphere
ii. determines time
iii. divides the earth into northern and southern hemisphere
iv. causes rainfall
c. What type of wind is monsoon?
i. local wind ii. mountain wind
iii. permanent wind iv. periodic wind
d. What is the condition of rainfall in the leeward slope of mountain?
i. high rainfall ii. low rainfall
iii. rainfall throughout the year iv. more rainfall in winter
e. The highest rainfall in Nepal occurs in ......................... .
i. Ilam ii. Manang iii. Pokhara iv. Jhapa
2 Fill in the blanks using appropriate words.
a. The annual average atmospheric condition is called .................... .
b. Sun rays are .................... throughout the year in equatorial region.
c. Temperature decreases by 10C in every .................... to .................... altitude.
d. In Nepal, .................... slopes are warm and wet.
e. .................... winds bring rainfall in Nepal in summer.
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3. Answer the following questions.
a. Define weather and climate.
b. List the factors affecting the climate.
c. How does distance from the sea affect the climate?
d. How does distance from the equator affect the climate?
e. How do altitude and slope affect the climate?
f. Why is it cold in the polar region?
g. What are the major factors affecting the climate of Nepal?
h. What is the climate like in hilly region of Nepal?
i. What is monsoon? Write down its effects.
4. Give reason.
a. Winter crops grow better in Western Nepal.
b. Paddy production is higher in Jhapa.
c. Rainfall is low in Manang.
d. Floods and landslides occur more in eastern hilly region of Nepal.
5. Describe with examples various factors affecting the climate.
6. how does monsoon occur? Describe in brief.
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21uNIt Estimated teaching periods : Th Pr
5 2
Earth
EArth AND SPACE
objectives
After completing the study of this unit, students will be able to:
• explain the hypotheses about the origin of the earth.
• describe the change in the position of the earth in different seasons.
• explain the phases of the moon.
Course of Study
• Some hypotheses about the origin of the earth
• Change in the position of the earth and the sun
• Change in seasons
• Phases of the moon
Points to be Focused/Questions to be Discussed
• What are the hypotheses about the origin of the earth?
• Why is life possible on the earth?
• What are the effects of change in position of the earth and the sun?
• What are seasons? What is the cause of change of seasons?
• What is meant by phases of the moon?
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21.1 Introduction
The earth is one of the members of the solar system. It originated along with other
planets but only on the earth’s surface climatic condition is suitable for survival of living
organisms. The branch of science in which we study about earth is called geology. There
is an unsolved question about the origin of the earth. Many scientists have put forward
their own opinions regarding the origin of the earth. But no universal theory of the origin
of the earth has been proposed yet. Some of the hypotheses regarding the origin of the
earth and solar system are discussed below:
1. Planetesimal hypothesis or George Wofan's hypothesis
A French scientist, George Wofan, put forward a hypothesis in 1749 AD. According
to this hypothesis, the earth along with other planets and satellites were formed
when a comet revolving around the universe struck the sun millions of years ago.
2. Nebular hypothesis or Kant-Laplace nebular hypothesis
A German philosopher Kant in 1755 AD put Fig. 21.1
forward another hypothesis which is called
nebular hypothesis. It was modified by a French
mathematician Laplace in 1796 AD. According
to this hypothesis, the whole of our solar system
including other heavenly bodies was in the form
of a nebula, i.e. an extremely large mass of gas and
dust. The nebula began to contract due to its own
gravity. During this process, an outer ring was
detached from the central core, which started to
revolve around the central core. The masses began
to collide with one another and broke into small
masses due to the effect of gravitation. These
small masses began to revolve around the central
mass. This central mass became the sun and other
revolving bodies became planets and satellites
including the earth.
3. Tidal hypothesis or Jeans and Jeffery’s hypothesis
According to the hypothesis given by Jean and Jeffery in 1917 AD, a big star orbiting
round the sun finally approached it. A large mass of gas was ejected from the sun
due to the tidal effect. In the course of cooling, the tidal matter fragmented into small
pieces forming planets, satellites, etc. As a result, the solar system was formed.
4 Formation of solar system from the Milky way galaxy
According to this hypothesis, the sun was formed by the accumulation of small dust
particles present in the Milky way galaxy due to the gravitational force. Remaining
members of the solar system like planets, satellites, comets, asteroids, etc. were
formed by the same process as the formation of the sun.
nebula / ˈnebjʊlə / - an extremely large mass of gas and dust
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Fig. 21.2 Milky way galaxy
21.2 Causes of Evolution of Life on the Earth
The history of the earth is about 4.5 billion years old. In the beginning, there was no
suitable condition for evolution and survival of living organisms on the earth. Later on,
many changes took place on the surface of the earth which resulted in the formation of
suitable conditions for the evolution of life. The major reasons for evolution of life on the
earth are given below:
i. Earth has suitable temperature for the survival of living organisms.
ii. Earth has sufficient amount of water essential for survival of living organisms.
iii. Earth has sufficient amount of life supporting gases like oxygen, carbon dioxide,
nitrogen, etc. in its atmosphere.
iv. Earth has a protective layer of ozone in its atmosphere that protects living
organisms by blocking harmful radiations coming from the sun.
reasonable fact-1
Evolution of life took place after very long time of the formation of the earth.
During the formation of the earth, the earth is very very hot and there was no suitable
condition for evolution and survival of living organisms on the earth in the beginning.
Later on, many changes took place on the surface of the earth which resulted in the
formation of suitable conditions for the evolution of life. So, evolution of life took place
after very long time of the formation of the earth.
21.3 Change in Position of the Earth and the Sun
The earth is not a perfect sphere. It is bulging at the equator and somewhat flat at the
poles. The earth has two types of motions, viz. revolution and rotation.
comet / ˈkɒmɪt / - a mass of ice and dust that moves around the sun and looks like a bright star
with a tail
asteroid /ˈæstərɔɪd/ - any one of the many small planets which go around the sun
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The motion of the earth around the sun is called revolution. The earth revolves around
the sun at a distance of 15 crore kilometres (approx.) in an elliptical orbit. The earth takes
365.25 days (1 year) to complete one revolution around the sun which is called annual
motion or orbital motion.
Fig. 21.3 Earth revolves around the sun
The earth spins about its own imaginary axis like a top, from west to east. The imaginary
line passing through the north and south pole of the earth is called axis. The earth
completes one rotation about its own axis in 24 hours (1 day). This motion of the earth is
called diurnal motion.
21.4 occurrence of Day and Fig. 21.4 Formation
of day and night
Night on the Earth
The sun gives heat and light all the time. However, only half of the
earth faces the sun due to spherical shape of the earth, whereas
the other half is opposite to the sun. The half of the earth which
receives the sunlight has day and the half opposite to the sun has
night. As the earth steadily moves about its own axis, gradually the
part of the earth having day moves away from the sun, i.e. towards
night side and vice-versa. In this way, days and nights occur on the
earth.
reasonable fact-2
Days and nights are not equal on all the places of the earth.
The axis of rotation of the earth is titled at an angle of 66.50 with its orbital plane. So,
days and nights are not equal on all the places of the earth.
reasonable fact-3
Day and night are equal in all parts of the earth on September 23 and March 21.
On march 21 and on September 23, the rays of sun fall perpendicularly on the equator.
So, day and nights are equal in all parts of the earth.
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The axis of rotation of the earth is tilted at an angle of 66.50 with its orbital plane. It has
following effects on the earth.
i. Days and nights are not equal except in the equatorial region. Some days are longer
than nights and some nights are longer than days.
ii. Change of seasons takes place.
iii. The rays of the sun do not fall perpendicularly in a place all the time. It affects the
climate of that place.
iv. The sunrise and sunset do not always take place from the same place.
v. The height of the sun from the earth in the afternoon changes every day.
21.5 Change of Seasons
The earth revolves around the sun in an elliptical orbit. The earth completes one revolution
in 365 days. The axis of rotation of the earth is tilted at an angle of 66.50 and the earth is not
always at the same distance from the sun due to its elliptical orbit. Due to these reasons,
change of seasons takes place on the earth. The duration of one year is divided into four
seasons. They are as follows:
i. Summer season ii. Autumn season
iii. Winter season iv. Spring season
The tilted axis of rotation of the earth always lies in the same direction. Due to this tilt in
the axis of rotation, the position of the northern and southern hemispheres of the earth
toward the sun keeps changing throughout the year.
D Northern spring
Earth's orbit around the sun
Southern fall
Northern summer 21 March equinox Northern winter
A Southern summer C
Southern winter 22 December solstice
21 June solstice
Northern fall
B Southern spring
23 September equinox
Fig. 21.5 Formation of seasons
When the northern hemisphere is tilted towards the sun, we experience summer, whereas
the people in the southern hemisphere experience winter. Similarly, autumn and spring
occur when the earth lies in between these two extreme position in its orbit.
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On June 21 (Asar 8), the earth is the farthest from the sun in the southern hemisphere, but
nearest in the northern hemisphere. Thus, on June 21, the northern hemisphere has the
longest day, whereas the southern hemisphere has the shortest day. In this time, summer
season occurs in the northern hemisphere and winter season occurs in the southern
hemisphere.
On December 22 (Poush 7), the reverse happens, i.e. the northern hemisphere has the
shortest day and the southern hemisphere has the longest day. In this time, winter season
occurs in the northern hemisphere and summer season occurs in the southern hemisphere.
On Septemeber 23 (Asoj 7), the rays of the sun fall perpendicularly on the equator. So,
days and night are equal in both hemispheres. At this time, autumn season occurs in the
northern hemisphere and summer season occurs in the southern hemisphere.
On March 21 (Chaitra 8), the sun lies once again above equator and days and nights are
equal in all parts of the earth. Both the hemispheres have moderate temperature. At this
time, spring season occurs in the northern hemisphere and autumn season occurs in the
southern hemisphere.
Due to change in the length of days, the amount of heat and light received by the earth
changes every day. This in turn gives rise to four seasons, viz. summer, autumn, winter
and spring.
reasonable fact-4
Change of seasons takes place on the earth.
The axis of rotation of the earth is titled at an angle of 66.50 and the earth is not always
at the same distance from the sun due to its elliptical orbit. Due to these reasons, change
of seasons takes place on the earth.
21.6 Phases of the Moon
The moon is the natural satellite of the
earth. It is the brightest object in the clear
night sky. The moon is a non-luminous
body. It has no light of its own. It only
reflects the light of the sun. The moon
always presents its same face towards
the earth. When the reflected light of
the moon reaches the earth, we see the
moon. Only that part of the moon which
reflects the sunlight towards the earth is
visible. Fig. 21.6 Phases of the moon
When the moon lies in between the sun
and the earth, the reflected light from the moon does not reach the earth and hence the
moon is not visible. This day is called new moon day. On new moon day, the dark side of
the moon faces the earth.
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On the night just after the new moon day, crescent moon is seen. The rest of the moon is
only faintly visible. The crescent goes on increasing every day till the 15th day from the
new moon day when the full bright face of the moon is visible. This day is called full
moon day. When the earth lies between the moon and the sun, the full bright face of the
moon is seen from the earth. This day is called full moon day. The gradual increase in
the bright disc of the moon is called waxing of the moon. The bright disc of the moon
increases for 15 days after the new moon day. This duration is called bright half.
After the full moon, the bright face of the moon goes on decreasing every night for 15
days. This duration is called dark half. The gradual decrease in the bright disc of the
moon is called waning of the moon.
The waxing and waning of the disc of the moon, as the moon revolves around the earth,
is called phases of the moon.
On full moon day, the moon rises in the eastern sky when the sun sets in the western sky
and the moon rises after 50 minutes in the following day. The moon revolves around the
earth in its own orbit. The moon completes one revolution around the earth in 27 1 days.
3
This duration is called sidereal month. Similarly, the duration between two consecutive
full moons or new moons is 29 1 days. This duration is called synodic month. However,
2
as the moon revolves around the earth, the earth moves ahead in its own orbit around the
sun. Thus, from the earth, the moon appears to complete one revolution between one new
moon to next new moon in 29.5 days.
Project work
• Observe the shape of the moon for one month. Draw a chart showing the phases
of the moon and submit to your science teacher.
Differences between New moon and Full moon
New moon Full moon
1. When the moon lies between the sun 1. When the earth lies between the moon
and the earth, the reflected light from and the sun, the full bright face of
the moon does not reach the earth the moon is seen from the earth. This
and hence the moon is not visible. phase of moon is called full moon.
This phase of moon is called new
moon.
2. Night of new moon is dark. 2. Night of full moon is bright.
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Difference between Bright half and Dark half
Bright half Dark half
1. The bright disc of the moon increases 1. After the full moon, the bright face
for 15 days after the new moon day. of the moon goes on decreasing every
This duration is called bright half. night for 15 days. This duration is
called dark half.
2. Nights are bright 1. Nights are dark.
Differences between Synodic month and Sideral month
Synodic month Sideral month
1. It is the duration between two 1. It is the duration that moon completes
consecutive full moons or new one revolution around the earth.
moons.
2. Its duration is 29.5 days. 2. Its duration is 27 days, 7 hours, 43
minutes and 11 seconds.
SuMMAry
• Many scientists have put forward their own opinions regarding the origin of
the earth and solar system. But no universal theory of the origin of the solar
system has been proposed yet.
• In the beginning, there was no suitable condition for evolution and survival
of living organisms on the earth.
• Earth has a protective layer of ozone in its atmosphere that protects living
organisms by blocking harmful radiations coming from the sun.
• The earth takes 365.25 days (1 year) to complete one revolution around the
sun which is called annual motion or orbital motion.
• The earth completes one rotation about its own axis in 24 hours (1 day). This
motion of the earth is called diurnal motion.
• As the earth steadily moves about its own axis, gradually the part of the earth
having day moves away from the sun, i.e. towards night side and vice-versa.
In this way, days and nights occur on the earth.
• The axis of rotation of the earth is tilted at an angle of 66.50 and the earth is
not always at the same distance from the sun due to its elliptical orbit. Due to
these reasons, change of seasons takes place on the earth.
geology and astronomy Oasis School Science and Environment - 8 329
• Due to change in the length of days, the amount of heat and light received
by the earth changes every day. This, in turn, gives rise to four seasons, viz.
summer, autumn, winter and spring.
• The moon is the natural satellite of the earth. It is the brightest object in the
clear night sky.
• When the reflected light of the moon reaches the earth, we see the moon.
• When the earth lies between the moon and the sun, the full bright face of the
moon is seen from the earth. This day is called full moon day.
• The waxing and waning of the disc of the moon, as the moon revolves around
the earth, is called phases of the moon.
• The moon completes one revolution around the earth in 27 1 days. This duration is
3
called sidereal month. Similarly, the duration between two consecutive full moons
or new moons is 29 1 days. This duration is called synodic month.
2
Exercise
1. Choose the best answer from the given alternatives.
a. Nebular hypothesis was proposed by ........................... .
i. George Wofan ii. Kant–Laplace
iii. Jeans and Jefferey iv. Galileo Gallilei
b. The earth completes one revolution around the sun in ........................ .
i. 365 days ii. 356 days
iii. 30 days iv. 24 hours
c. The axis of the rotation of the earth is tilted at an angle of ................. .
i. 65.60 ii. 66.50 iii. 56.50 iv. 55.60
d. The moon revolves around the earth in ............................ .
i. 29.5 days ii. 27 days iii. 25.9 days iv. 30 days
2. Fill in the blanks with appropriate words.
a. The earth has two types of motions, viz. ............................ and revolution.
b. Days and nights are equal in ............................ region.
c. On ............................ , the rays of the sun fall perpendicularly on the equator.
330 Oasis School Science and Environment - 8 geology and astronomy
d. On ............................ , days and nights are equal in all parts of the earth.
e. The decrease in bright disc of the moon is called ............................ of the moon.
3. Answer the following questions.
a. State the hypothesis propounded by George Wofan regarding the origin of the
earth.
b. What do you know about nebular hypothesis regarding the origin of the earth?
c. What is the estimated age of the earth?
d. What are the conditions necessary for existence of life on the earth?
e. Write any three effects of the tilted axis of the earth.
f. Write any two causes of change in seasons on the earth.
g. What is meant by the phases of the moon?
h. What is meant by bright half and dark half?
i. What is a new moon?
j. What is a full moon?
k. Define sidereal and synodic month.
4. Differentiate between:
a. Rotation and Revolution
b. Spring season and Winter season
c. New moon and Full moon
d. Bright half and Dark half
e. Synodic month and Sidereal month
5. Write short notes on:
a. Changes of season
b. Phases of the moon
6. Draw a neat and labelled figure showing the phases of the moon.
geology and astronomy Oasis School Science and Environment - 8 331
22UNIT Estimated teaching periods : Th Pr
12 3
Environment
ENVIRONMENT AND
ITS BAlANCE
Objectives
After completing the study of this unit, students will be able to:
• explain the dependency of human beings on food, habitat, medicinal plants and
other natural resources.
• list and introduce national parks, wildlife reserves and conservation areas of
Nepal.
• describe the need and importance of forest resource of Nepal with its present
status.
• list timbers and important medicinal herbs and introduce them.
• describe the need and importance of fauna and list the endangered species of
Nepal.
• introduce some conserved fauna of Nepal.
Course of Study
• Natural resources and human dependency
• Brief introduction to national parks, wildlife reserves, conservation areas and
hunting reserve of Nepal
• Status of forest resource in Nepal
• Need and importance of forests in Nepal
• Status of fauna in Nepal
• Some endangered species of Nepal
Points to be Focused/Questions to be Discussed
• What are natural resources? Explain human dependency on various natural
resources.
• What are national parks, wildlife reserves, hunting reserves and conservation
areas?
• What is the status, need and importance of forests in Nepal?
• What are endangered species?
332 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE
22.1 Introduction
Various resources like air, water, soil, forest, minerals, vegetation, wildlife, etc. exist in
nature. The resources such as water, minerals, forest, fertile land, sunlight, wind, etc. that
occur in nature are called natural resources. These resources are used by human beings
for economic gain.
Natural resources may include living as well as non-living things. Wildlife, animals,
vegetation, etc. are living natural resources whereas air, water, soil, minerals, sunlight,
etc. are non-living natural resources. Natural resources are derived from the environment.
Some of them are essential for our survival while most of them are used for satisfying our
needs/wants. Natural resources are the materials and components that can be found in
the environment. Every man-made product is composed of natural resources.
22.2 Natural Resources and Human Dependency
The earth is the common habitat for human beings and other organisms. It consists of
various natural resources like forest, soil, air, water, minerals, etc. Natural resources and
human beings are interrelated to each other. Human beings depend on natural resources
to fulfill their needs. People need food, habitat, medicinal plants, air, water, land, etc.
for survival and growth. Human life is not possible in the absence of these resources.
The relation between human beings and natural resources can be discussed under the
following headings.
a. Food
Living beings need energy to survive. They get energy from food. Green plants can
prepare their own food by photosynthesis. Herbivores feed on the green plants.
Human beings get their food from plants and animals. Human beings cultivate land
to get crops (rice, wheat, maize, barley, millet, etc.), different types of vegetables and
fruits. They also raise different types of animals like cows, buffaloes, goats, sheep,
chicken, etc. to get food. We know that plants and animals are natural resources.
Therefore, human beings depend on natural resources to get food.
b. Habitat
The land on the earth's surface is the habitat of human beings. People use different
natural resources to construct their houses. They use furniture, wood, bricks, stones,
marble, sand, gravel, minerals, etc. to build houses. The construction materials are
obtained from nature. Therefore, human beings depend on natural resources for
habitat.
c. Medicinal plants
Medicinal plants are very essential natural resources for human beings. They are
used to treat different kinds of diseases. Spikenard is useful to cure diseases like
cholera and epilepsy. Serpentina is used for treatment of blood pressure and to
ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 333
releive pain. Similarly, panch aunle, yarshagumba, harro, barro, bojho, amla, golden
michalia, jatamashi, etc. are used as medicinal plants. Such plants are mainly used in
ayurvedic medicines. About 800 species of medicinal plants are found in Nepal and
about 70 species of them are exported. But many species of medicinal plants are on
the verge of extinction due to overuse and deforestation.
d. Air
Air is essential for existence of life. Human beings need air to breathe. Human beings
breathe in oxygen and breathe out carbon dioxide. So human beings cannot survive
in the absence of air. Human beings use different types of chemical substances in
industries, agriculture, transportation, research laboratories, etc. These chemicals
causes air pollution. Similarly, the smoke released from industries, vehicles, etc.
also causes air pollution. We suffer from various diseases like asthma, pneumonia,
bronchitis, etc. due to polluted air.
e. Water
Water is an important natural resource. Existence of living beings is impossible in the
absence of water. About 60% of the human body is made of water. Human beings,
plants and animals are adversely affected due to scarcity of water. It is used for
transport and irrigation. Big cities have been established near the sources of water.
We need pure water for drinking. Various human activities are responsible for water
pollution. If we use polluted water, we suffer from various diseases like diarrhoea,
dysentery, typhoid, cholera, hepatitis, etc. Therefore, we should not pollute water
resources.
f. land
Land is the lifeline of human life. Most of the plants and animals depend on
land. Land is necessary for cultivation, construction of houses and other physical
infrastructures. People get different kinds of minerals from the land. Human beings
need land to cultivate cererals, fruits and vegetables. Therefore, land is an essential
natural resource for human beings.
22.3 Introduction to National Parks, Wildlife Reserves and
Conservation Areas of Nepal
Nepal has established a network of protected areas of different categories for conservation
of natural resources. Protected areas are the reserved areas like national parks, wildlife
reserves, conservation areas, etc. established for protection and promotion of wildlife,
vegetation and natural environment.
The government of Nepal has established 12 National Parks, one Wildlife Reserve, one
Hunting Reserve and six Conservation Areas.
verge / v ɜ ː d ʒ / - to be very close to an extreme condition
extinction / ɪ k ˈ s t ɪ ŋ k ʃ n / - a situation in which a plant, an animal, etc. stops existing
334 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE
Api Nampa CA Shey-phoksundo NP
Khaptad NP Rara NP Annapurna CA
Suklaphanta NP Manaslu CA
Bardia NP
Blackbuck CA Banke NP Dhorpatan HR Langtang NP
Sagarmatha NP
Shivapuri Makalu-Barun NP
Nagarjun NP
National Park (NP) Chitwan NP
Buffer Zone
Conservation Area (CA) Gaurishankar CA Kanchanjunga CA
Wildlife Reserve (WR) Parsa NP
Koshi Tappu WR
Hunting Reserve (HR)
Fig. 22.1 Protected areas of Nepal
A brief description of protected areas of Nepal is given below:
A. National Park
A national park is an area set aside for the conservation and management of
natural environment including wild animals, plants and landscapes together with
their utilization. By taking permission from the concerned authorities, we can visit,
entertain ourselves and conduct scientific research inside the National Parks. Nepal
government has established 12 national parks in different parts of the country. These
are:
1. Chitwan National Park
2. Langtang National Park
3. Rara National Park
4. Sagarmatha National Park
5. Shey-Phoksundo National Park
6. Khaptad National Park
7. Bardiya National Park
8. Makalu-Barun National Park
9. Shivapuri Nagarjun National Park
10. Banke National Park
11. Shukla Phanta National Park
12. Parsa National Park
heritage / ˈherɪtɪdʒ / - the history, traditions and qualities that a country or society has had for many
years and are considered as important part of its character
ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 335
1. Chitwan National Park
Chitwan National Park is the first national park of Nepal. It was established in
1973 AD and granted the status of a World Heritage Site in 1984 AD. It covers
an area of 932 km² and is located in the sub-tropical inner Terai of Chitwan,
Makawanpur and Parsa districts.
Chitwan National Park is an excellent habitat for One–horned rhinoceros,
Gharial crocodile and Tiger. Animals like One-horned rhino, Tiger, Sloth bear,
Leopard, Elephant, Sambar deer, Rhesus monkey, Gaur, Wild boar, Wild dog,
Wild cat, Long snouted gharial, Marsh mugger crocodile, Python, etc. and
plants like Sal, Sissoo, Khair, Simal are found in this National Park.
2. Sagarmatha National Park
Sagarmatha National Park is a protected area in the Himalayas of eastern
Nepal. It was established in 1976 AD. It encompasses an area of 1148 km².
In 1979, it became the country’s first National Park that was inscribed as a
Natural World Heritage Site. It is located in Solukhumbu district. High peaks
like Lhotse, Nuptse, Pumori, Amadablam, Thamserku and Mt. Everest also lie
in this National Park. Plants like Gobre salla, Thingre salla, Bhojpatra, Dhupi,
Rhododendron, etc., animals like Himalayan Tahr, Ghoral, Musk deer, Pika
(mouse hare), Jackal, Black bear, Wolf, Lynx, Snow leopard and birds like
Danphe (Impeyan pheasant), Blood pheasant, Redbilled chough, Snow cock,
Snow pigeon, etc. are found in this national park.
3. langtang National Park
Langtang National Park is the Himalayan national park which covers an
area of 1710 km². It was established in 1976 AD. It occupies the parts of
Rasuwa, Nuwakot and Sindhupalchowk districts. The famous religious site
Gosainkunda is also located in this national park. Plants like Khote salla,
Gobre salla, Khasru, Rhododendron, Langtang salla, etc.; animals like Wild
dog, Red panda, Pika, Muntjac, Musk deer, Ghoral, Himalayan tahr, Rhesus
monkey, Snow leopard and different species of birds like Impeyan pheasant
are found in this national park.
4. Rara National Park
Rara National Park is a protected area in the Himalayan region. It was
established in 1976 AD. It covers an area of 106 km² in the Mugu and Jumla
districts. It is the smallest national park of Nepal. The biggest lake of Nepal,
i.e. Rara lake lies in this nationl park. Plants like Rhododendron, Fir, Spruce,
Birch, etc.; animals like Red panda, Musk deer, Himalayan black bear, Leopard,
Jackal, Himalayan tahr, Martin, Wild dog, Langur, Wild boar, Otter, etc. and
birds like Coots, Great crested grebe, Black necked grebe, Gulls, Migrant
water fowls, Mallard, etc. are found in this national park. Coniferous forests
and blue pine dominate the park and lake area respectively. Rara National
336 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE
Park is an excellent habitat for migrating birds from Saiberia and Mansarobar.
5. Bardiya National Park
Bardiya National Park is a protected area in the Terai region. It was established
in 1988 AD. It occupies an area of 968 km² in Bardiya district of Bheri zone.
Sal forests and grasslands cover most area of this national park. Animals like
Royal Bengal tiger, One-horned rhinoceros, Elephant, Swamp deer, Black
buck, etc. and reptiles like Gharial crocodile, Marsh mugger crocodile, etc.
are found in this national park. Similarly, birds like Bengal florican, Lesser
florican, Sarus crane, etc. are found in this national park. Similarly, fresh-water
dolphin is commonly seen in the Karnali river.
6. Shey-Phoksundo National Park
Shey-Phoksundo National Park is the largest and only trans-Himalayan park
in Nepal. It covers an area of 3555 km² in Dolpa and Mugu districts. It was
established in 1984 AD. The park contains the famous Phoksundo lake, the
deepest lake in Nepal. The park contains many gompas and religious sites
including Shey-gompa, the most famous, which was established in the 11th
century. Wild animals like Ghoral, Musk deer, Leopard, Wild dog, Marmot,
Mouse hare, Rhesus monkey, Langur monkey, Himalayan tahr, Black bear,
Jackal, etc. and birds like Tibetan partridge, Wood snipe, White-throated tit,
Finch, Impeyan pheasant, Cheer pheasant, Snow cock, etc. are found in this
national park.
7. Khaptad National Park
Khaptad National Park is a protected area in the Far-Western region of Nepal.
It was established in 1984 AD on the advice of the region’s holy man Khaptad
Baba. This national park covers an area of 225 km² in Bajhang, Bajura, Achham
and Doti districts. Plants like Salla, Khasru, Nigalo, etc. and grasslands add
beauty to this national park. Wild animals like Barking deer, Wild boar,
Ghoral, Himalayan black bear, Marten, Rhesus monkey, Langur monkey, etc.
and birds like Impeyan pheasant, Partridge, Bulbul, Cuckoos and Eagles are
found in this national park.
8. Makalu Barun National Park
Makalu Barun National Park is a protected area in the Himalayas established
in 1992 AD. It covers an area of 2330 km² in Sankhuwasabha and Solukhumbu
districts. Different types of medicinal herbs, orchids, wild rose, Gobre sallo,
Thingre sallo, Bhojpatra, Rhododendron, Champ, Phirphire, etc. are found
in this national park. Similarly, wild animals like Red panda, Snow leopard,
Himalayan black bear, Clouded leopard, Barking deer, Himalayan marmot,
Langur monkey, etc. and different species of birds including Wren babbler,
Ground warbler are found in this national park.
ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 337
9. Shivapuri-Nagarjun National Park
Shivapuri-Nagarjun National Park is the ninth national park of Nepal. It was
established in 2002 AD. It is located in the nothern fringe of Kathmandu valley.
It covers an area of 159 km² in Kathmandu, Nuwakot and Sindhupalchowk
districts. Various species of mushrooms and butterflies are found in this
national park. Wild animals like Leopard, Jungle cat, Golden jackal, Himalayan
black bear, Mongoose, Marten, Barking deer, Wild bear, Monkey, Langur, Pika,
Squirrel, Shrew, etc. and different birds like Eagle owl, Slender-billed babbler,
Flycatcher, Cuckoo, Golden throated barbet, etc. are found in this national
park. This national park is an important watershed supplying drinking water
to Kathmandu.
10. Banke National Park
Banke National Park is the tenth national park of Nepal. It was established
in 2010 AD. It covers an area of 550 km² with most parts falling on the churia
range. This national park is located in Banke district of Mid-western region of
Nepal.
Banke National Park is rich in its forest of sal, sissoo and khayar and grasslands.
Different species of birds and wild animals like Tiger, Elephant, Leopard, Wild
bear, Deer, Langur, etc. and Gharial crocodile are found in this national park.
11. Shukla Phanta National Park
Shukla Phanta National Park is a protected area in the Terai region of the Far-
western region of Nepal. It was established in 1973 AD. This covers an area of
305 km². It includes open grasslands, forest of Sal, Sissso and Khayar, river beds
and tropical wetlands. Wild animals like Bengal tiger, Leopard, Sloth bear,
Swamp deer, Elephant, Hispid hare, One-horned rhinoceros, etc. and birds
like Bengal florican, Babbler, Eagle, Owl, Hornbill, Wood-pecker, Vulture,
Sarus crane, Flycatcher, Painted stork, etc. are found in this national park. The
congregation of swamp deer (in about 2000 in a group) in the grassland of this
national park is the largest in the world.
12. Parsa National Park
Parsa National Park is a protected area in the inner Terai lowlands of south-
central Nepal. It was established in 1984 AD. This national park covers an area
of 499 km² in Parsa, Makawanpur, Bara and Chitwan districts. This national
park contains sal forest, constituting about 90% of the vegetation and grasslands.
Wild animals like Wild elephant, Tiger, Gaur, Wild boar, Leopard, Deer, etc. and
various species of birds are found in this national park.
B. Wildlife Reserve
A separate reserved area for protection and proper management of endangered
wildlife is called a Wildlife Reserve. In Wildlife Reserves, endangered animals are
338 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE
protected by conserving their habitats. Hunting, grazing, cutting down of trees, etc.
are not allowed in Wildlife Reserves. There is one Wildlife Reserve in the eastern
part of Nepal. A brief description of Koshi Tappu Wildlife Reserve is given below:
Koshi Tappu Wildlife Reserve
Koshi Tappu Wildlife Reserve is a protected area in the eastern Terai of Nepal. It was
established in 1976 AD and designated as Ramsar site in 1987. It covers an area of
175 km² of wetlands in Sunsari, Saptari and Udayapur districts. This wildlife reserve
is surrounded by Saptakoshi river from the east and west. The main aim of this
reserve is to conserve and promote the wild water buffaloes. This wildife reserve
mainly contains forests of Sissoo and Khayar, grasslands and marshy vegetation.
Wild animals like Asian elephant, Spotted deer, Hog deer, Wild pig, Blue bull, Water
buffalo, etc. and various species of birds like Watercock, Indian night jar, Dusky ea-
gle owl, Black headed cuckoo, Grassbird, Fish eagle, Swamp francolin, etc. are found
in this wildlife reserve.
C. Hunting Reserve
The reserved area established for licensed hunting is called hunting reserve.
Dhorpatan Hunting Reserve is only one hunting reserve in Nepal where licensed
hunting is allowed. This hunting reserve was established in 1987 AD. It covers an
area of 1325 km² in the Dhaulagiri Himal of western Nepal in Rukum, Myagdi and
Baglung districts.
Wild animals like Snow leopard, Musk deer, Blue sheep, Jharal, Nayan, Himalayan
bear, Himalayan tahr, etc. and birds like Koklas pheasant, Cheer pheasant, Impeyan
pheasant, etc. are found in this hunting reserve. Animals like Blue sheep, Himalayan
tahr, Muntjack, Wild boar and some birds can be hunted in this hunting reserve.
D. Conservation Area
The protected area which is managed according to the plans for conservation of
natural resources, wildlife and their habitat, sustainable development and use of
natural resources is called conservation area. The main goal of a conservation area
is to achieve sustained balance between nature conservation and socio-economic
improvement and to conserve cultural, religious and economic resources of the local
people. In Nepal, six conservation areas have been established in different parts of
the country. They are as follows:
1. Annapurna Conservation Area
2. Manaslu Conservation Area
3. Kanchenjunga Conservation Area
4. Api-Nampa Conservation Area
5. Gauri Shankar Conservation Area
6. Krishnasar Conservation Area
ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 339
1. Annapurna Conservation Area
Annapurna Conservation Area is Nepal’s largest conservation area. It was
established in 1992 AD. It covers an area of 7629 km² in the Annapurna range of
the Himalayas across Manang and Lamjung districts. It is managed by the National
Trust for Nature Conservation. This conservation area is rich in biodiversity. The
natural and cultural features of this conservation area have made it the most popular
trekking destination in Nepal. National Trust for Nature Conservation is conducting
various activities like conservation of resources, community development, tourism
management, education and extension for conservation of this area.
2. Kanchenjunga Conservation Area
Kanchenjunga Conservation Area is a protected area in the Himalayas of eastern
Nepal. It was established in 1997 AD. It covers an area of 2035 km² in Taplejung
district and comprises two peaks of Kanchenjunga. In the north, it adjoins Tibet and
in the east it adjoins Sikkim. This conservation area is being developed by WWF
Nepal in partnership with ICIMOD (International Centre for Integrated Mountain
Development).
Kanchenjunga Conservation Area is a habitat of endangered species. It comprises
cultivated lands, forests, pastures, rivers, lakes and glaciers. Plants like Himali larch
Gobre sallo, Thingre sallo, Dhupi sallo and 24 species of Rhododendron are found in
this conservation area. Wild animals like Snow leopard, Musk deer, Himalayan black
bear, Wolf, Nayan, Ghoral, Red panda, etc. and birds like Golden-breasted fulvetta,
Snow cock, Blood pheasant, Red-billed chough, etc. are found in this conservation area.
3. Manaslu Conservation Area
Manaslu Conservation Area is a protected area located in the Mansiri Himal range
in Gorkha district. It was established in 1998 AD. It covers an area of 1993 km². It is
a classic setting to experience pristine mountain nature and culture. In the north, it
adjoins Tibet and in the west, it adjoins Annapurna Conservation Area. Mt. Manaslu
lies in this conservation area. Wild animals like Himalayan tahr, Nayan, Musk deer,
Snow leopard, etc., different types of birds, reptiles and flowering plants are found
in this conservation area.
4. Api-Nampa Conservation Area
Api Nampa Conservation Area is a protected area in the Far-Western region of Nepal.
It was established in 2010 AD. It covers an area of 1903 km² encompassing 21 VDCs
in Darchula district. The western boundery of this conservation area is formed by
Mahakali river, the northern by the border with Tibet. Baitadi and Bajhang districts
are in the east. Two peaks Api and Nampa lie in this conservation area. Various
types of forests and grassland plateau are found in this area. High peak medicinal
herbs, different types of mammals like Snow leopard, Himalayan black bear, Musk
deer, Ghoral, Serow, Himalayan tahr, Wolf, Clouded leopard, etc. and birds like
Himalayan monal, Snow cock, Blood pheasant, etc. are found in this conservation
area.
340 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE
5. Gaurishankar Conservation Area
Gaurishankar Conservation Area is a protected area in the Himalayas of Nepal. It
was established in 2010 AD. It covers an area of 2179 km² in Ramechhap, Dolakha
and Sindhupalchowk districts. It connects Langtang and Sagarmatha National
Parks. It is the origin of the rivers Khimti, Bhotekoshi, Sunkoshi and Tamakoshi.
This conservation area is rich in biodiversity. Different species of snakes, birds and
mammals like Red panda, Snow leopard, Grey wolf, Musk deer, etc. are found in
this conservation area.
6. Krishnasar Conservation Area
Krishnasar Conservation Area is a protected area in the terai region of Nepal. It was
established in 2009 AD. It covers an area of 16.95 km² in Bardiya district. The main
goal of this conservation area is to protect Krishnasar, i.e. Black buck.
Activity 1
• Visit a National Park, Wildlife Reserve or a Conservation Area nearby your
locality.
• Prepare a short report on the basis of your observation.
Differences between National park and Wildlife reserve
National park Wildlife reserve
1. It is an area set aside for conservation 1. It is a separate reserved area for protection
and management of natural environment and proper management of endangered
including wild animals, plants wildlife.
and landscapes together with their
utilization.
2. By taking permission from the concerned 2. By taking permission from the concerned
authorities, we can visit, entertain authorities, we can visit and conduct
ourselves and conduct scientific research scientific research inside the wildlife
inside the National Parks. research but no permission for
entertainment.
Differences between Wildlife reserve and Hunting reserve
Wildlife reserve Hunting reserve
1. It is a separate reserved area for protec- 1. It is a reserved area established for licensed
tion and proper management of endan- hunting.
gered wildlife.
2. In the wildlife reserves, endangered an- 2. In the hunting reserve, licensed hunting
imals are protected by conserving their is allowed.
habitats.
ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 341
22.4 Status of Forest
Nepal is rich in forest resource. There are
different types of forests in Nepal because of
climatic and topographic variation. In Terai
region, sub-tropical forest is found. Sal, Simal,
Sissoo, Khayar, Jamun, etc. are the species
of trees found in this region. In Mahabharat
range, deciduous forest is found. Oak, Simal,
hill Sal, Peepal are the species of trees found
in this region. In the lower part of Himalayas,
coniferous forest is found. Pine, Spruce, Fir, Fig. 22.2 Forest of Nepal
Larches, Deodar, etc. are found in this region.
Now a days, forest covers only 29% of land of Nepal whereas shrub covers 11.6% only. In
the past, the coverage of the forest was more than 50% in Nepal. The main cause behind
the decrease in forest area is human activities. People depend on forest resource to fulfill
their needs. In villages, people use trees to construct houses. They cut trees to get firewood.
They encroach forestland to expand their agricultural land. Some people also involve
in illegal logging. Despite that the concept of community forest programmes has greatly
contributed to maintain and improve the status of forest in Nepal. This programme has
become a good example in the sector of conservation of forests and natural environment.
22.5 Need and Importance of Forest
Forest is an important natural resource. It fulfills the needs of human beings as well as
other animals. People get firewood, medicinal plants, fodder, fruits, grasses, etc. from
forest. Forest is the habitat for wild animals and birds. Wild fauna like Tiger, Elephant,
Fox, Giant pied hornbill, Salak, etc. are found in the forest. Forest plays an important
role to conserve soil. In the place with large number of trees, there is less chance of soil
erosion, landslides and flood. When rainfall occurs in such places, most of the water
infiltrates below the earth surface. It controls surface run-off. Forest contributes to increase
productivity of soil. People can have more economic benefit from agricultural land. It also
has a vital role in natural processes like oxygen cycle, carbon cycle, water cycle, etc. Forest
is the sink of (CO2) and source of oxygen (O2). Forest provides area for study and research.
People want to visit forest to conduct research and for recreation. These activities help to
boost economic condition of a nation by attracting tourists. Therefore, forest resource is
very important for human beings.
Forest products
People get firewood, wood, medicinal plants, grasses, fruits, etc. from the forest. Many
trees produce gums and resins which is used for making various things. Forest plants
produce their own food by photosynthesis. Plants provide food, oxygen and energy to
the world. Plants also provide fibre, building materials and natural products like oils
coniferous / kəˈnɪfərəs / - plants having cones and naked seeds
encroach / ɪnˈkrəʊtʃ / - to slowly begin to cover more and more of an area
342 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE
and latex. Plants maintain the balance in the amount of oxygen and carbon dioxide in the
environment. Plants help to control soil erosion and landslide. Similarly, plants provide
habitat to wild animals.
Timber trees
It is said that green forest is the wealth of Nepal. Forest is the important natural resource of
Nepal. Forest is the source of timber. Different types of timber trees are found in different
parts of Nepal. Sal, Teak, Asna, Sissoo, Simal, Satisal, Kalo siris, Seto siris, etc. are the timber
trees found in the Terai region. Similarly, Pipal, Bhojpatra, Katus, Deodar, Dhupi Salla,
Khote Salla, Banjh, Phalant, Tooni, etc. are the timber trees found in mid-hills. Likewise,
Gobre salla, Talis Patra, Deodar, Rani salla, Okhar, Thinke, Kharsu, etc. are found in the
mountain region. Timber plants are used for making houses, getting furniture, firewood,
fodder, etc. We should not cut timber haphazardly. We should conserve forest and plant
trees on the bare land.
Activity 2
Observe various kinds of plants found in your locality. Identify the useful parts of
these plants with their uses.
S.N. Name of plants Useful parts Uses
1.
2.
3.
4.
5.
Medicinal plants
A variety of plants are found in the forests of Nepal. Among them, some plants are
used for making medicines. The plants which are used for making medicines are called
medicinal plants. These plants are used for the treatment of different kinds of diseases.
About 800 species of medicinal plants are found in different geographical regions of
Nepal. Medicinal plants like Harro, Barro, Amla, Rajbrikshya, Sarpagandha, Asuro, etc.
are found in the Terai region. Medicinal plants like Chutro, Dhaturo, Chiraito, Bojho,
Sugandhawal, Timur, etc. are found in the Mahabharat range and cold places of the hilly
region. Similarly, medicinal plants like Panchaule, Padamchal, Jatamashi, Yarsagumba,
etc. are found in the Himalayan region. Panchaunle, Kutki, etc. are the medicinal plants
which are banned for collection and export. Jatamasi, Surpagandha, Sugandhakokila,
Sugandhawal, Jhyau, Tulsipatra, Lauth salla, Yarsagumba, etc. are the medicinal plants
which are banned for export without processing. Champ, Khayar, Satisal, Bijaysal, Okhar,
ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 343
etc. are banned for selling, transportation and export. About 70 species of medicinal
plants are exported from Nepal. But due to human activities, medicinal plants are being
adversely affected.
Activity 3
Observe medicinal plants found in your locality and fill in the following table:
S.N. Name of Plant Useful Part Use
1.
2.
3.
4.
5.
22.6 Protected Plants in Nepal
Human activities are responsible for decreasing the number of valuable plants in Nepal.
The plants which are found less in number and are on the verge of extinction are called rare
plants. Such plants should be protected. In Nepal, Sal, Simal, Satisal, Bijaysal, Okhar, etc.
are banned to export. Similarly, Jatamasi, Sarpagandha, Sugandhawal, Sugandhakokila,
Panchaule, Kutki, Yarsagumba, Champ, Khayar, etc. are banned to export without
processing. The main aim of such provision is to conserve the plants.
22.7 Animals and Birds of Nepal
a. Present Status
In Nepal, there are more than 170 species of wild animals and more than 860 species
of birds. Tiger, Rhinoceros, Snow leopard, Deer, Kasturi, Badel, Jackal, etc. are the
major wild animals found in Nepal. Similarly, Kalij, Titra, Danphe, Munal, Koel,
Eagle, etc. are some main birds found in Nepal. 26 species of mammals, 9 species of
birds and 3 species of reptiles are protected in Nepal. Most of the animals and birds
live in the forest. In Nepal, there is rapid deforestation due to population growth.
Nepalese people encroach forest land to expand settlement and to get agricultural
land. They cut down trees for firewood, timber, fodder, etc. Some people also involve
in illegal hunting of wild animals and birds. As a result, many species of animals and
birds are on the verge of extinction.
The number of Elephant, Rhinoceros, Tiger, Wild buffalo, Snow leopard, Musk deer,
etc. is decreasing day by day. Similarly, animals like Black buck, Hispid hare, etc. are
armour / ˈɑːmə(r)/ - cover that protects sth
344 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE
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