Category: Class 8

Balbharti Maharashtra State Board Class 8 Geography Solutions Chapter 6 Land Use Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 8 Geography Solutions Chapter 6 Land Use

Class 8 Geography Chapter 6 Land Use Textbook Questions and Answers

1. Examine the following statements and correct the incorrect ones:

Question A.
Mining Is not type of land use.
Answer:
Incorrect.
Correct statement: Mining is a type of land use.

Question B.
There are factories in the Central Business District.
Answer:
Incorrect.
Correct statement: There are many shops, banks and offices in the Central Business District.

Question C.
In urban areas, the largest area is used for residential purposes.
Answer:
Correct.

Question D.
The village attendant issues the 7/12 extract.
Answer:
Incorrect.
Correct statement: The village talathi issues the 7/12 extract.

Question E.
In rural areas, residential areas occupy large tracts.
Answer:
Incorrect.
Correct statement: In rural areas, residential areas occupy small tracts.

Question F.
Extract 7 indicates Record of Rights.
Answer:
Correct.

Question G.
Extract 12 indicates change in ownership.
Answer:
Incorrect.
Correct statement: Extract 12 indicates tracts under cultivation.

2. Give geographical reasons.

Question A.
Land use for public facility is extremely important in urban areas.
Answer:

1. Government provides various services to fulfill the needs of citizens. The land used for fulfilling these needs is known as public utility/ facility area.
2. The lands used for post offices, police stations, public grounds, public schools, public hospitals, etc. are included public facility land use.
3. Land use for public facility increases the’ social welfare. Therefore, land use for public facility is extremely important in urban areas.

Question B.
The record of ownership of non- agricultural land is same as that of agricultural land.
Answer:
1. The record of agricultural land is maintained in the form of 7/12 extract. Similarly the record of ownership of non-agricultural land is maintained in the form of property card.

2. Like 7/12 extract, property card provides details of ownership of land, city survey number, plot number, amount of tax, area of property assessed, right to access, etc. Thus, the record of ownership of non-agricultural land is same as that of agricultural land.

Question C.
A region can be classified as developed or developing on the basis of land use.
Answer:

1. The land used in a particular region for agriculture, grazing, etc. indicates that the region is underdeveloped or developing.
2. The land used in a particular region for commercial purposes, transportation, recreation, etc. indicates that the region is developed. In this way, a region can be classified as developed or developing on the basis of land use.

3. Write answers:

Question A.
Why is agriculture important in rural land use?
Answer:

1. In India, agriculture is the main occupation of most of people in rural areas.
2. In India, farming occupation is very important as it satisfies the need of food grain and provides raw material to industries.
3. The maximum land in rural areas is used for carrying out agricultural activities. Therefore, agriculture is important in rural land use.

Question B.
State the factors affecting land use.
Answer:
(a) The factors affecting rural land use :

1. The factors like climatic conditions, fertility of soil, altitude and slope of land, irrigational facilities, natural resources, government policies, etc. affect rural land use.
2. For example, the land with gentle slope is not used for residential purpose, but is used for step farming.

(b) The factors affecting urban land use :

1. The factors like location of land, natural resources, housing development policies of government, transportation routes, industrialisation, trade and commerce, entertainment facilities, government policies, etc. affect urban land use.

2. For example, the land site near the railway station, market, etc. is mostly used for commercial purposes.

Question C.
Clarify the differences between rural and urban land use.
Answer:
The differences between rural and urban land use are as follows :

1. Land in rural areas is used for limited purposes. On the other hand, land in urban areas is used for many purposes.
2. The pattern of rural land use is comparatively simple. On the other hand, the pattern of urban land use is comparatively complex.
3. Use of land for cultivation is the major form of rural land use. On the other hand, use of land for commercial activities and residence are the major forms of urban land use.

Question D.
Differentiate between 7/12 extract and property card.
Answer:
The differences between 7/12 extract and property card are as follows :

1. 7/12 extract is issued by public revenue department of the government. On the other hand, property card is issued by city survey office of government.
2. 7/12 extract is the land record of ownership and history of ownership of the land in rural areas. Property card is the land record of ownership and history of ownership of the land in urban areas.

Activity:

Question A.
Obtain information about a town close to your village based on the following points and make a presentation in class.
(site, condition. development, land use pattern work)
a. Classify your settlement as rural or urban
b. Note the changes in land use from Central Business District outwards to the periphery in your settlement after consulting elders. Prepare a land use pattern.

Question B.
Study the 7/12 extract or the Property Card in your house and write a note.

Class 8 Geography Chapter 6 Land Use Additional Important Questions and Answers

Choose the correct answer:

Question a.
Recreational land use is use of land for …………………
(A) garden
(B) farming
(C) industry
(D) rail route
Answer:
(A) garden

Question b.
Which of the following is a planned city in India?
(A) Seoul
(B) Zurich
(C) Chandigarh
(D) Brasilia
Answer:
(C) Chandigarh

Question c.
Of which city are Bandra, Bhandup, etc. suburbs?
(A) Pune
(B) Nagpur
(C) Nashik
(D) Mumbai
Answer:
(D) Mumbai

Examine the following statements and correct the incorrect ones:

Question A.
Government policies affect the land use.
Answer:
Correct.

Question B.
The areas of mixed land use are found in cities.
Answer:
Correct.

Answer the following questions in one sentence each:

Question A.
What is meant by land use?
Answer:
Land use is the way or purpose for which land in a particular region is used.

Question B.
What is called fallow land?
Answer:
The agricultural land which is temporarily not in use is called fallow land.

Question C.
What is called forest land?
Answer:
The land which is reserved for forest area is called forest land.

Question D.
Which products are obtained from forest areas?
Answer:
The products like firewood, flowers, fruits, gum, grass, honey, etc. are obtained from forest areas.

Question E.
What is called grassland?
Answer:
The land owned by Village Panchayat or the government and which is used for grazing is called grassland.

Question F.
What is meant by commercial land use?
Answer:
Commercial land use is the use of land in urban areas for commercial purpose.

Question G.
What is meant by mixed land use?
Answer:
Mixed land use is the use of land in urban areas for more than one purpose at a time.

Answer the following questions in brief:

Question A.
How does the pattern of land use get developed?
Answer:

1. The pattern of land use gets developed through the continuous interactions between man and geographical factors.
2. The interaction between the factors like availability of land, quality of land, human needs, etc. leads to the development of specific pattern of land use.
3. For example, mineral rich land is used for carrying out mining activity.
4. For example, fertile piece of land is used for carrying out farming activity, etc.

Question B.
Write in brief about residential land use in rural areas.
Answer:

1. The density of population is found to be low in rural areas.
2. As population in rural areas is comparatively limited, the residential land use in rural areas is found to be limited.
3. In rural areas, the land close to the areas of main occupations is used for settlements.
4. For example, farmers’ residences are found near farms, fishermen’s settlements are found near coastal areas, etc.

Question C.
Write in brief about features of trAnswer:itional areas.
Answer:
The following are the features of transitional areas:

1. The intermediate areas between rural settlements and urban settlements are known as transitional areas.
2. The blend of rural and urban land use and culture is found in transitional areas.
3. Over time, trAnswer:itional areas are converted into urban areas and they are called suburbs.
4. For example, Bandra, Bhandup, etc. are the suburbs of Mumbai city.

Question D.
Write in brief about property card.
Answer:
The brief information of property card is as follows:

1. Property card is the land record of ownership and history of ownership of the land in urban areas.
2.  It is a land record of non-agricultural land.
3. Property card is issued by city survey office of government.
4. Property cards provide details of city survey number, plot number, amount of tax, area of property assessed, right to access, etc.

Answer the following questions in detail:

Question A.
Give information about arable land use and fallow land use in rural areas.
Answer:
The information about arable land : use and fallow land use in rural areas is as follows :
(a) Arable land use :

1. The use of land for cultivation is called arable land use.
2. In India, in 2011, nearly 57 per cent of land was under arable land use.
3. Generally, arable land is owned I individually.
4. The arable land can be classified on the basis of ownership of the land and types of agriculture.

(b) Fallow land use:

1. The agricultural land which is temporarily not in use is called fallow land.
2. Fallow land use is a form of rural land use.
3. To increase the fertility of soil, farmers do not use a part of agricultural land for few seasons.

Question B.
Give information about grassland use and forest land use in rural areas.
Answer:
The information about grassland use and forest land use in rural areas is as follows:
(a) Grassland land use:

1. The land owned by village panchayat or the government and which is used for grazing purpose is called grassland.
2. It is also called pastureland.
3. Mostly, grassland is owned by entire village. Very limited individual ownership of grassland is found.

(b) Forest land use:

1. The land kept reserved for forest area is called forest land.
2. Large trees, bushes, creepers and grass are found in forest land.
3. The forest products like firewood, fruits, flowers, gum, grass, honey, etc. are obtained from forest land.

Question C.
Give information about commercial land use and residential land use in urban areas.
Answer:
The information about commercial land use and residential land use in urban areas is as follows:
(a) Commercial land use:

1. The use of urban land for commercial use is called commercial land use.
2. Many shops, banks and offices are found in commercial land areas.
3. The concept of Central Business District (CBD) has emerged from commercial land use.
4. For example, Fort area or BKC (Bandra Kurla Complex) in Mumbai are the areas of commercial land use.

(b) Residential land use:

1. The use of urban land for residential purpose is called residential land use.
2. Houses and residential buildings are found in residential land areas.
3. The density of population is found to be high in urban areas. As its effect, the percentage of residential land use in urban areas is increasing day by day.

Question D.
Give information about trAnswer:port land use and public utility area in urban areas.
Answer:
The information about transport land use and Public utility area in urban areas is as follows:
(a) TrAnswer:port land use:

1. The use of urban land for providing transportation facilities is called transport land use.
2. The land used for roadways, railways, petrol pumps, vehicle repairing centres, etc. is included in transport land use.

(b) Public utility area:

1. Government provides various services to fulfill the needs of citizens. The land used for fulfilling these needs is known as public utility area.
2. Post offices, police stations, public grounds, public schools, public hospitals, etc. are included in public utility area.

Question E.
Give information about recreational land use and mixed land use in urban areas.
Answer:
The information about recreational land use and mixed land use in urban areas is as follows:
(a) Recreational land use:

1. Recreational land use is a use of urban land for fulfilling the needs of entertainment of people.
2. Public parks, swimming pools, theatres, etc. are included in recreational land use.

(b) Mixed land use:

1. Mixed land use is a use of urban land for fulfilling more than one wants at a time.
2. For example, area used for residential and entertainment purposes.

Question F.
Write about the features of planned cities.
Answer:
The features of planned cities are as follows:
(a) Need:

1. After industrial revolution, unplanned urbanisation occurred on a large scale all over the world.
2. Due to unplanned urbanisation, cities began to develop in a very haphazard manner.
3. People started migrating to cities in search of employment opportunities.

(b) Nature: City which is developed as per the pre-determined and planned layout of land use is called planned city.

(c) Singapore, Seoul from South Korea, Zurich from Switzerland, Washington D.C. from U.S.A., Brasilia from Brazil, Chandigarh, Bhubaneshwar from India are the examples of planned cities.

Question G.
Give information about 7/12 extract.
Answer:
The information about 7/12 extract is as follows:

1. 7/12 is an extract published and given by public revenue department of the government.
2. 7/12 extract gives detailed information of a particular registered land.
3. The register of the revenue department keeps a record of details of ownership rights of family, status of debt and loans, transfer of ownership, areas under different crops etc. related to registered land.
4. Village form no. 7 and Village form no. 12 are combined and 7/12 extract is prepared.
5. These village forms are available with the talathi of every village.
6. The accurate reading of 7/12 extract gives exact idea about ownership of land, tax levied on land, status of loan taken, etc.

Study the following map/figure/graph and answer the following questions:

Can you tell?

Study the Figure and answer the following questions:

Question A.
In which country is the land under forests more?
Answer:
The land under forests is more in Japan.

Question B.
In which country is the land under agriculture more?
Answer:
The land under agriculture is more in India.

Question C.
Considering the two questions above, how will you relate the physiography and climate of India and Japan with their respective land uses?
Answer:
Due to plains and monsoon climatic conditions, the population in India is more. Therefore, agricultural land use is prominent in India. Due to mountainous region and more proportion of precipitation, the forest land use is prominent in Japan.

Question D.
Correlate their land use and development.
Answer:
The land use in India shows comparatively low development. On the other hand, land use in Japan shows comparatively high development.

Question E.
Which land use is found in Japan?
Answer:
The land use like agricultural land use, forest land use, grassland land use, other land use, etc. are found in Japan.

Question F.
Considering the land use in both the countries, make a list of factors affecting land use.
Answer:
Considering the land use in both the countries, lists of factors affecting land use are as follows:
(a) Factors affecting land use in India:

1. Fertility of soil
2. Climatic conditions
3. Natural resources
4. Slope of land, etc.

(b) Factors affecting land use in Japan:

1. Technical advancement
2. Availability of resources
3. Government policies, etc.

Can you tell?

Study the Figure and answer the following questions:

Question A.
What kind of land use is shown in Figure 6.2 and 6.3?
Answer:
Land use shown in Figure 6.2 is agricultural land use and land use shown in Figure 6.3 is non-agricultural land use.

Question B.
Can you tell in which area the property is located?
Answer:
The property shown in Figure 6.2 is located in rural areas and the property shown in Figure 6.3 is located in urban areas.

Can you tell?

Study the Figure and answer the following questions:

Question A.
Which are the land uses of 1990-91 that show decline in 2010-11? What could be reasons for this?
Answer:
Total agricultural land use and other non-agricultural land use of 1990-91 show decline in 2010-11. Increased urbanisation could be reason for this.

Question B.
Which type of land use is the maximum? What would be the impact of this on India’s environment?
Answer:
Agricultural land use is the maximum. It indicates that India is an agrarian country and its environment is comparatively more natural.

Question C.
Can a decline in the area under agriculture equated with food shortage?
Answer:
A decline in the area under agriculture cannot be equated with food shortage. With modern technology, the maximum agricultural food production can be undertaken in limited areas.

Can you tell?

Study the figure and answer the following questions:

Question A.
What is the percentage of land suitable for cultivation?
Answer:
The percentage of land suitable for cultivation is 56.8.

Question B.
What is the percentage of barren land?
Answer:
The percentage of barren land is 8.3.

Question C.
What is the percentage of land under forest in Maharashtra?
Answer:
The percentage of land under forest in Maharashtra is 16.9.

Question D.
What is the percentage of non- agricultural land in Maharashtra?
Answer:
The percentage of non-agricultural land in Maharashtra is 10.2.

Give it a try.

Study the Figure. It shows the satellite images of Mondha Village (Taluka – Hingna, District – Nagpur).

Question A.
Find out the changes in land use pattern over time and write a note.
Answer:

1. The satellite image of Mondha Village in Hingna taluka in Nagpur district shows that agricultural land use in the village has declined from 2010 to 2017.
2. The satellite image of Mondha Village in Hingna taluka in Nagpur district shows that residential land use in the village has increased from 2010 to 2017.
3. Urbanisation, increasing population, etc. factors must be responsible for changes in land use pattern over time in Mondha Village.

Thought Provoking Question:

Think about it.

Question A.
If land is left fallow, or is not in use, then can it be termed as a kind of land use?
Answer:
1. The agricultural land which is temporarily not in use is called fallow land.
2. Fallow land use is a form of rural land use.
3. To increase the fertility of soil, farmers do not use a part of agricultural land for few seasons. After one or two seasons fallow land is again utilized for cultivation. Therefore, if land is left fallow, or is not in use, then it can be termed as a kind of land use.

Open-Ended Question:

Question A.
Write the advantages of planned cities in your own words.
Answer:
The advantages of planned cities are as follows:

1. There will not be a problem of traffic jam in planned cities.
2. The level of pollution will be the minimum in the planned cities.
3. The planned cities will be clean and they will maintain environmental balance.
4. The quality of human life will be superior in planned cities.

Balbharti Maharashtra State Board Class 8 Geography Solutions Chapter 2 Interior of the Earth Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 8 Geography Solutions Chapter 2 Interior of the Earth

Class 8 Geography Chapter 2 Interior of the Earth Textbook Questions and Answers

1. Tick [✓] the correct options in the box:

Question A.
There are two layers in the crust.
(a) Inner and outer crust [ ]
(b) Continental and oceanic crust [ ]
(c) Surface and oceanic crust [ ]
(d) Mantle and core [ ]
Answer:
(b) Continental and oceanic crust [✓]

Question B.
Which element is found in both mantle and crust?
(a) Silica [ ]
(b) Magnesium [ ]
(c) Aluminium [ ]
(d) Iron [ ]
Answer:
(b) Magnesium [✓]

Question C.
Which of these minerals are found in the core of the earth?
(a) Iron – magnesium [ ]
(b) Magnesium – nickel [ ]
(c) Aluminium – iron [ ]
(d) Iron – nickel [ ]
Answer:
(d) Iron – nickel [✓]

Question D.
The inner core is in which state?
(a) Gaseous [ ]
(b) Solid [ ]
(c) Liquid [ ]
(d) Semi-solid [ ]
Answer:
(a) Gaseous [✓]

Question E.
The outer core is made up of
(a) Iron [ ]
(b) Gold [ ]
(c) Hydrogen [ ]
(d) Oxygen [ ]
Answer:
(a) Iron [✓]

Question F.
The layer of the earth on which we live…
(a) Mantle [ ]
(b) Core [ ]
(c) Crust [ ]
(d) Continental crust [ ]
Answer:
(d) Continental crust [✓]

2. Tell whether right or wrong. Correct the wrong statement

Question A.
The density of various materials is not the same in the interior of the earth.
Answer:
Correct.

Question B.
The core of the earth’s interior is made up of hard rocks.
Answer:
Incorrect.
Correct statement: The core of the earth’s interior is made up of elements, viz. iron and nickel.

Question C.
Secondary waves cannot pass through outer core.
Answer:
Correct.

Question D.
Continental crust is made up of silica and magnesium.
Answer:
Incorrect.
Correct statement: Continental crust is made up of silica and aluminum.

3. Answer the following

Question A.
What are the two parts of the crust? What is the basis of classification?
Answer:

1. Continental crust and the Oceanic crust are the two parts of the crust.
2. The crust is classified on the basis of whether it lies below the land or the ocean.
3. The part of the crust lying below the continent is known as the continental crust.
4. The part of the crust lying below the ocean is known as the oceanic crust.

Question B.
Why is the upper layer of the mantle known as the asthenosphere?
Answer:

1. The upper layer of the mantle is in liquid state.
2. The rocks in the upper 100 to 200 km of the mantle melt due to the heat and magma is created. Magma chambers are found in this layer of the earth.
3. Due to the heat and pressure, the energy waves are created in mantle. These energy waves move in vertical direction and magma comes out on the surface of the earth by volcanic eruptions.
4. These endogenitic movements continuously occur in the upper layer of the mantle. Therefore, the upper layer of the mantle is known as the asthenosphere.

Question C.
Magnetosphere of the earth is a result of rotation. Explain.
Answer:
1. The average temperature of the outer core of the earth is around 5000° C. The average temperature of the inner core of the earth is around 6000° C. This difference between the temperature results in formation of vertical currents.

2. The rotation of the earth gives eddy (circular) motion to these currents.

3. Electric currents develop in these spiral eddies of liquid iron leading to generation of the magnetic field of the earth. This magnetic field is called magnetosphere. In this way, the magnetosphere is formed due to the rotation of the earth.

4 Draw neat diagrams. label them and explain.

Question A.
The interior of the earth
Answer:

Explanation:

1. Inner Core: It is the center and the hottest layer of the Earth. The inner core is solid and made up of iron and nickel.
2. Outer Core: The outer core of the Earth is similar to a very hot ball of metals. It is composed of metals such as iron and nickel. The outer core surrounds the inner core.
3. Mantle: Mantle is the widest section of the Earth. Mantle is mainly made up of semi-molten rock known as magma. The rock is hard in the upper part of the mantle, but lower down the rock is softer and begins to melt. The mantle consists of very hot and dense rock.
4. Crust: The crust is the outer layer where we live. It’s a solid rock layer divided into two types: Continental crust covers the land and Oceanic crust covers water.

Question B.
Magnetic pole and equator
Answer:

5. Give geographical reasons:

Question A.
There are discontinuities in the interior of the earth.
Answer:
1. There is a difference between the elements, temperatures and the pressure found in the three parts of the interior of the earth, viz, crust, mantle and core.

2. In the interiors of the earth, the transitional areas are found between (a) continental crust and oceanic crust (b) crust and mantle (c) upper mantle and lower mantle (d) mantle and core and (e) outer core and inner core. Therefore, there are discontinuities in the interior of the earth.

Question B.
There is correlation between the density of metals and their location in the interior of the earth.
Answer:
1. The rocks found in the crust have predominance of the compounds of silicon, aluminium, magnesium, etc. These compounds are lighter in weight. Therefore, they are found in the upper layer of the interior of the earth.

2. The elements like iron, nickel are found in the core of the earth. These elements are heavier in weight. Thus, metals with low density are found in upper level in the interior of the earth and the metals with high density are found in the lower level in the interior of the earth. Thus, there is correlation between the density of metals and their location in the interior of the earth.

Question C.
Mantle is the centre of earthquake and volcanic eruptions.
Answer:
1. The rocks in the upper 100 to 200 km of the mantle melt due to the heat and the magma is created.
2. Magma chambers are found in this layer of the earth.

3. Due to the heat and pressure, the energy waves are created in mantle. These energy waves move in vertical direction and magma comes out on the surface of the earth by volcanic eruptions. Thus, mantle is the centre of earthquake and volcanic eruptions.

Question D.
The thickness of the crust below the continents is more as compared to oceans.
Answer:
1. The density of the crust below the continents is 2.65 to 2.90 gm/cm³ The density of the crust below the oceans is 2.90 to 3.3 gm/cm³

2. As the density of the crust below the continents is comparatively low, it keeps floating on the mantle. It does not subduct into mantle. As its effect, the thickness of the crust below the continents is found to be high.

3. As the density of the crust below the ocean is comparatively high, it subducts into mantle leading to its low thickness. Thus, the thickness of the crust below the continents is more as compared to oceans.

Question E.
Earth is protected because of the magnetosphere.
Answer:

1. The ozone layer protects the earth from ultraviolet radiation.
2. The earth’s magnetosphere serves to deflect most of the solar wind, whose charged particles would otherwise strip away the ozone layer. In this way, the earth is protected because of the magnetosphere.

Know this too:

1. The average density of the earth is 5.5 gm/cm³.
2. The rocks in the upper 100 to 200 km of. the mantle melt due to heat.
3. The mixture of molten rocks, volatiles, etc. found beneath the surface of the earth is called magma.
4. The mixture of molten rocks, volatiles, etc. erupted from volcano or fissure on the surface of the earth is called lava.

Activity:

Question 1.
Prepare a model of the earth’s interior.
Answer:

1. The density of the earth goes on increasing from its surface to the centre.
2. The average density of the crust of the earth is approximately 2.98 gm/cm³.
3. The average density of the mantle of the earth is approximately 5.7gm/cm³.
4. The average density of the outer core of the earth is approximately 9.8 gm/cm³.
5. The density of the inner core at the centre of the earth is approximately 13 gm/cm³.

Class 8 Geography Chapter 2 Interior of the Earth Additional Important Questions and Answers

Tick [✓] the correct options in the box:

Question A.
Which seismic waves can travel through liquid medium?
(a) Primary waves [ ]
(b) Secondary waves [ ]
(c) Surface waves [ ]
(d) Oceanic waves [ ]
Answer:
(a) Primary waves [✓]

Question B.
Which of the following layers of the earth has the highest density?
(a) Crust [ ]
(b) Mantle [ ]
(c) Outer core [ ]
(d) Inner core [ ]
Answer:
(d) Inner core [✓]

Question C.
Which of the following waves can travel through all the layers of the interior of the earth?
(a) Primary [ ]
(b) Secondary [ ]
(c) Tertiary [ ]
(d) Surface [ ]
Answer:
(a) Primary [✓]

Question D.
Which of the following layers of the interior of the earth is in solid form and cool?
(a) Crust [ ]
(b) Mantle [ ]
(C) Outer core [ ]
(d) Inner core [ ]
Answer:
(a) Crust [✓]

Examine the statements and incorrect ones :

Question A.
As we move deeper the surface, temperature keeps decreasing.
Answer:
Incorrect.
Correct statement: As we move deeper the surface, temperature keeps increasing.

Question B.
Magma chambers are found in lower mantle.
Answer:
Incorrect.
Correct statement: Magma chambers are found in upper mantle.

Question C.
The discontinuity is found between the crust, mantle and core.
Answer:
Correct.

Answer the following questions in one sentence each:

Question A.
In which of the layers of the interior of the earth is magma formed?
Answer:
Magma is formed in the mantle (upper mantle) of the earth.

Question B.
What are the two parts of the core?
Answer:
Outer core and inner core are the two parts of the core.

Match the columns and complete the chain :

Question A.

‘A’ Column (The layer of the interior of the earth)	‘B’ Column (Density)	‘C’ Column (Elements found)
1. Sial	(i) 13.3 gm/cm3	(a) Silica and Magnesium
2. Sima	(ii) 2.65 to 2.90 gm/cm3	(b) Nickel and Iron
3. Inner core	(iii) 2.90 to 3.3 gm/cm3	(c) Silica and Aluminium

Answer:

‘A’ Column (The layer of the interior of the earth)	‘B’ Column (Density)	‘C’ Column (Elements found)
1. Sial	(ii) 2.65 to 2.90 gm/cm3	(c) Silica and Aluminium
2. Sima	(iii) 2.90 to 3.3 gm/cm3	(a) Silica and Magnesium
3. Inner core	(i) 13.3 gm/cm3	(b) Nickel and Iron

Answer the following questions in brief:

Question A.
Describe the changes that take place in the temperatures from the surface of the earth to its centre.
Answer:

1. The process of cooling of the earth started from the surface. The temperature goes on increasing from the surface towards the core.
2. The surface of the earth is cool and solid.
3. The centre of the earth is extremely hot. The temperature at the centre of the earth is around 5500° to 6000° C.

Question B.
Describe the changes that take place in the density of the earth from its surface to the centre.
Answer:

1. The density of the earth goes on increasing from its surface to the centre.
2. The average density of the crust of the earth is approximately 2.98 gm/cm³.
3. The average density of the mantle of the earth is approximately 5.7gm/cm³.
4. The average density of the outer core of the earth is approximately 9.8 gm/cm³.
5. The density of the inner core at the centre of the earth is approximately 13 gm/cm³.

Question C.
Write in brief about the travelling of various types of earthquake waves through the layers of interior of the earth.
Answer:

1. The primary earthquake waves travel through the mantle as well as the core of the earth.
2. While travelling through the core of the earth, the direction of the primary earthquake waves gets altered.
3. While travelling through the core, the speed of the primary earthquake waves decreases.
4. The secondary earthquake waves can travel only through the mantle of the earth. These waves get absorbed in the core of the earth. Thus, these waves cannot travel through the core of the earth.

Write short notes on the following:

Question A.
The crust.
Answer:
1. The uppermost layer of the interior of the earth is called the crust. Continental crust and the oceanic crust are the two parts of the crust.

2.The thickness of the continental crust is approximately 16 km to 45 km. On the other hand, the thickness of the oceanic crust is approximately 7 km to 10 km

3. The density of the continental crust is approximately 2.65 to 2.90 gm/cm. On the other hand, the density of the oceanic crust is approximately 2.65 to 2.90 gm/cm³.

4. Silica and aluminium are the main elements found in the continental crust. Therefore, it is also called Sial. On the other hand, Silica and Magnesium are the main elements found in the oceanic crust. Therefore, it is also called Sima.

Question B.
The mantle.
Answer:
1. The mantle is located below the crust of the earth. The mantle is divided into the upper mantle and the lower mantle.

2. The thickness of the mantle is approximately 2870 km. The average density of mantle is approximately 4.5 gm/cm³.

3. The rocks in the upper 100 to 200 km of the mantle melt due to the heat and magma is created. Magma chambers are found in this layer of the earth. Due to the heat and pressure, the energy waves are created in mantle. These energy waves move in vertical direction and magma comes out on the surface of the earth by volcanic eruptions.

4. These endogenitic movements continuously occur in the upper layer of the mantle. Therefore, the upper layer of the mantle is known as the asthenosphere.

5. The average thickness of mantle is approximately 2870 km. Its average density is approximately 4.5 gm/cm³. The temperature at the depth of 2400 to 2900 km is around 2200° to 2500° C. The density of the lower mantle is approximately 5.7 gm / cm³.

Question B.
The outer core.
Answer:
1. The outer core is located below the lower mantle.
2. It is located at the depth from 2900 km to 5100 km from the surface of the earth.
3. The average temperature of the outer core of the earth is around 5000° C. The density of the outer core of the earth is approximately 9.8 gm/cm.

4. The secondary earthquake waves cannot travel from the core of the earth. Therefore, it is inferred that the outer core of the earth must be in liquid or semi-liquid form. The primary earthquake waves can travel from the outer core of the earth.
5. The vertical currents originate in the outer core of the earth.

Question C.
The inner core.
Answer:

1. The inner core is located below the upper core.
2. It is located at the depth from 5150 km to 6371 km from the surface of the earth.
3. The average temperature of the inner core of the earth is around 6000° C. The density of the inner core of the earth is approximately 13.3 gm/cm³.
4. The elements, viz. Iron (Ferrous) and Nickel (Ni) are mainly found in the inner core of the earth. Therefore, it is also called Nife.
5. The temperature at the centre of the earth is almost equivalent to the surface temperature of the sun.

Give geographical reasons for the following:

Question A.
The secondary waves of earthquake cannot travel through the core of the earth.
Answer:

1. The secondary waves of earthquake can travel only through the solid state of the interior of the earth.
2. The outer core of the centre of the earth is in liquid state. Therefore, the secondary waves of earthquake cannot travel through the core of the earth.

Question B.
The inner core is called Nife.
Answer:

1. The inner core predominantly comprises iron and nickel.
2. The word Nife is derived from the word Nickel (Ni) and Iron (Ferrous) (Fe). Therefore, the inner core is called (Ni + Fe) Nife.

Question C.
The upper layer of the crust is called Sial.
Answer:

1. The rocks in the upper layer of the crust have predominance of the compounds of silicon and aluminium.
2. The word Sial is derived from the word Silica (Si) and Aluminium (Al). Therefore, the upper layer of the crust is called (Si + Al) Sial.

Question D.
The lower layer of the crust is called Sima.
Answer:

1. The rocks in the lower layer of the crust have predominance of the compounds of silicon and magnesium.
2. The word Sima is derived from the word Silica (Si) and Magnesium. (Ma). Therefore, the lower layer of the crust is called (Si + Ma) Sima.

Study the following map/ figure /graph and answer the following questions : 

Question A.
At what depth does the curve of the secondary waves seem to have ended in figure (A)?
Answer:
The curve of the secondary waves seems to have ended around the depth of 2900 km in figure (A).

Question B.
What is the velocity of the secondary waves around the boundary of the outer core shown in figure (A)?
Answer:
The velocity of the secondary waves is 6 to 8 km/sec around the boundary of the outer core shown in figure (A).

Question C.
What conclusion can be drawn on the basis of the curve of the secondary waves stopping around the depth of 2900 km?
Answer:
On the basis of the curve of the secondary waves stopping around the depth of2900 km, it can be concluded that secondary waves do not enter the core.

Question D.
What is the velocity of the primary waves at the time of entering the outer core shown in figure (A)?
Answer:
The velocity of the primary waves at the time of entering the outer core shown in figure (A) is 8 km/sec.

Question E.
What conclusions can be drawn about the intensity of the gravitational force shown in Figure (B)?
Answer:
The following conclusions can be drawn about the intensity of the gravitational force shown in Figure (B):

1. Gravitational force increases at certain depth from the surface of the earth and then it reduces according to the depth.
2. At the centre of the earth, the gravitational force is zero.

Thought-Provoking Question:

Think about it:

Question 1.
Imagine about the earth’s interior and- write 10-12 sentences on it.
Answer:

1. The interior of the earth will be very hot.
2. Huge sized rocks will be present I in the upper layers of the interior of the earth.
3. Due to extreme heat and pressure, the rocks must be melting in the interior of the earth.
4. Due to the melting of the rocks, magma will be created in the interior of the earth.
5. Due to endogenous movements in the interior of the earth, volcanic eruptions will occur on the surface of the earth.
6. The primary earthquake waves will be travelling through the mantle and the core of the earth.
7. The secondary earthquake waves will be travelling only through the mantle of the earth.
8. The temperature in the interior of the earth will get increased with the depth.
9. The highest temperature will be found at the centre of the earth.
10. The elements like silica, aluminium, magnesium, iron and nickel will be found in the various layers of the interior of the earth.

Open-Ended Question:

Question A.
What precautions can be taken to reduce the damage caused by earthquakes?
Answer:
The following precautions can be taken to reduce the damage caused by earthquakes:

1. Taking cover under a desk or a table or sturdy piece of furniture to protect oneself.
2. Finding clear spot away from buildings, trees and power lines. Dropping to the ground and staying there until the shaking stops.
3. Switching off the power supply, gas in-home/office, etc.
4. Helping the victims at the earliest.

Balbharti Maharashtra State Board Class 8 Geography Solutions Chapter 4 Structure of Ocean Floor Notes, Textbook Exercise Important Questions and Answers.

Maharashtra State Board Class 8 Geography Solutions Chapter 4 Structure of Ocean Floor

Class 8 Geography Chapter 4 Structure of Ocean Floor Textbook Questions and Answers

1. Choose the correct option:

Question a.
Like there are landforms on land, ocean floor also has submerged landforms because ………….
(i) there is land under water
(ii) there are volcanoes under water
(iii) land is continuous and there is water in deeper parts
(iv) though land is continuous, its level is not the same everywhere like that of water
Answer:
(iv) though land is continuous, its level is not the same everywhere like that of water

Question b.
Which part of the ocean floor is most useful to the man?
(i) Continental shelf
(ii) Continental slope
(iii) Abyssal plains
(iv) Marine deeps
Answer:
(i) Continental shelf

Question c.
Which one of the following option is related to marine deposits?
(i) Rivers, glaciers, continental shelf, remains of plants and animals
(ii) Volcanic ash, continental shelf, remains of plants and animals
(iii) Volcanic ash, lava, fine particles of soil
(iv) Volcanic ash, remains of plants and animals, abyssal plants
Answer:
(iii) Volcanic ash, lava, fine particles of soil

2. Question a.
Name the landforms shown in the following figure.
(Note: The answer is given directly.)

Answer:

Question b.
Which of these landforms are useful for deep sea research?
Answer:
Submarine plateau and marine trench are the landforms useful for deep sea research.

Question c.
Which of these are appropriate to be used for the protection of marine borders and naval base building?
Answer:
Continental shelf is appropriate to be used for the protection of marine borders and naval base building.

3. Give geographical reasons:

Question a.
The study of ocean floor is useful to man.
Answer:

1. Various minerals, rocks, fine I soil particles are found on the sea floor.
2. Remains of marine plants and animals are also found on the ocean floor.
3. To study the marine life, mineral wealth as well as the process of volcanic eruption, the study of ocean floor is useful to man. ‘

Question b.
The continental shelf is a paradise for fishing activity.
Answer:

1. Being a shallowest part of the ocean bed, sunlight reaches up to continental shelf easily.
2. As its effect, algae, plankton, etc. grows on a large scale on continental shelf.
3. Algae, plankton, etc. is food for fish. Therefore, fish are found on a large scale on continental shelf. Therefore, the continental shelf is paradise for fishing activity.

Question c.
Some marine islands are actually the peaks of sea mountains.
Answer:

1. The hundreds of kilometres wide and thousands of kilometres long hills found on the ocean bed are called submerged hills.
2. Peaks of some of the submerged hills come above the sea level.
3. These peaks are the visible land areas surrounded from all sides by water. These peaks are called islands. Thus, some marine islands are actually the peaks of sea mountains.

Question d.
The continental slope is considered to be the boundary of continents.
Answer:

1. Continental slope lies beyond the continental shelf.
2. The deep abyssal plain begins beyond the continental slope. Therefore, the continental slope is considered to be the boundary of continents.

Question e.
The disposal of waste materials in the oceans by man is harmful to the 1 environment.
Answer:

1. The disposal of waste materials in the oceans by man increases the pollution of sea water.
2. This disposed waste materials harm the life of marine animal life and marine plant. Thus, the disposal of waste materials in the oceans by man is harmful to the environment.

4. Observe the map on Pg 27 in ‘Give it a try’ and answer the following questions:

Question a.
Madagascar and Sri Lanka are related to which landform of the ocean floor?
Answer:
Madagascar and Sri Lanka are related to island of the ocean floor.

Question b.
Near which continent are these landforms located?
Answer:
Madagascar is located near the continent of Africa and Sri Lanka is located near the continent of Asia.

Question c.
Which islands in our country are examples of peaks of submerged mountains?
Answer:
Andaman and Nicobar islands in our country are examples of peaks of submerged mountains.

Activity:

Question a.
prepare a model of the ocean floor.
Answer:

1. While studying the ocean floor, we must keep in mind the age of the ocean bed. By studying the deposits on the ocean bed, it occurred to the scientists that the deposits at the ocean floor are not older than 200 million years.

2. The maximum age of the rocks on the continents is supposed to be 3200 million years. Then where have the deposits on the sea bed which are older than 200 million years gone? This made the scientists restless. Then they started the study of the rocks along with the deposits.

3. This made them realize that the rocks are also not older than 200 million years. It was inferred that the ocean floor is very young as compared to the earth’s surface. Now this is unanimously accepted. This research was then used in the study of the concept of plate tectonics.

Class 8 Geography Chapter 4 Structure of Ocean Floor Additional Important Questions and Answers

Choose the correct answer and complete the sentences:

Question a.
Continental slope has slope.
(a) flatter
(b) broader
(c) steeper
(d) lower
Answer:
(c) steeper

Question b.
The average depth of the oceans is around metres.
(a) 7300
(b) 3700
(c) 3900
(d) 3300
Answer:
(b) 3700

Examine the following statements and correct the incorrect ones:

Question a.
Abyssal plain lies beyond the continental shelf.
Answer:
Incorrect.
Correct statement: Abyssal plain lies beyond the continental slope.

Question b.
Around 51 per cent of the surface of the earth is covered by water.
Answer:
Incorrect.
Correct statement: Around 71 per cent of the surface of the earth is covered by water.

Question c.
Natural gas and mineral oil can be obtained from the continental shelf.
Answer:
Correct.

Question d.
For survey purpose in India, the height of sea level at Kanyakumari is considered to be zero.
Answer:
Incorrect.
Correct statement: For survey purpose in India, the height of sea level at Chennai is considered to be zero.

Question e.
Active volcanoes are mostly seen in marine trenches.
Answer:
Correct.

Answer the following questions in one sentence each:

Question a.
What is called continental shelf?
Answer:
The land near the coast and submerged under the sea is called continental shelf.

Question b.
What is called continental slope?
Answer:
The steeper slope of the sea bed beyond the extent of continental shelf is called continental slope.

Question c.
What is called abyssal plain?
Answer:
The flat part of the sea bed that lies
beyond the continental slope is called abyssal plain.

Question d.
What is called submerged hills?
Answer:
The hundreds of kilometres wide and thousands of kilometres long hills found on the ocean bed are called submerged hills.

Question e.
What is called marine islands?
Answer:
Peaks of some of the submerged hills that come above the sea level are called marine islands.

Question f.
What is called submarine plateau?
Answer:
The flat and extensive summit of marine island is called submarine plateau.

Question g.
What is called marine deep?
Answer:
The landforms on the ocean bed that are comparatively less extending and shallower ones are called marine deep.

Question h.
What is called marine trench?
Answer:
The landforms on the ocean bed that are comparatively more extending and deeper ones are called marine trench.

Match the columns and complete the chain:

Question a.

‘A’ Column	‘B’ Column	‘C’ Column
1. Andaman – Nicobar	(i) Submarine plateau	(a) Pacific Ocean
2. Chagos	(ii) Located on continental shelf	(b) Bay of Bengal
3. Mariana	(iii) Islands	(c) Arabian Sea
4. Mumbai High	(iv) Marine deep	(d) Indian Ocean

Answer:

‘A’ Column	‘B’ Column	‘C’ Column
1. Andaman – Nicobar	(iii) Islands	(b) Bay of Bengal
2. Chagos	(i) Submarine plateau	(d) Indian Ocean
3. Mariana	(iv) Marine deep	(a) Pacific Ocean
4. Mumbai High	(ii) Located on continental shelf	(c) Arabian Sea

Answer the following questions in brief:

Question a.
What is marine deposits?
Answer:

1. Marine deposit is a type of marine deposition.
2. The rivers and glaciers flowing from the continent bring pebbles, clay, soil, etc. with them when they meet sea or ocean.
3. These materials get deposited on the continental shelf. The deposits are known as marine deposits.
4. Due to pressure of sea water and deposition of layers over layers of sediments, sedimentary rocks are formed.
5. Marine life and the availability of minerals in the sea bed can be studied with the help of marine deposits.

Question b.
What is marine oozes?
Answer:

1. Marine oozes is a type of marine deposit.
2. Lava and ash erupting out of volcano, fine soil particles, remains of plants and animals, etc. get deposited on marine abyssal plains. Deposits of these materials on the abyssal plains are known as marine oozes.
3. Marine oozes are in the form of fine clay. The percentage of remains of plants and animals in marine oozes is up to 30 per cent.
4. Marine oozes are also useful to study marine life and the availability of minerals in the sea bed.

Question c.
Write in brief about the continental shelf.
Answer:
1. The land near the seacoast and submerged under the sea is called continental shelf. The depth of continental shelf is about 200 metres below the sea level.

2. Continental shelf is found to be narrow along the coasts of some continents and broad along the coasts of some other continents.

3. Being a shallowest part of the ocean bed, sunlight reaches up to continental shelf easily. As its effect, the food for fish like algae, plankton, etc. grows on a large scale on continental shelf. Therefore, continental shelf is useful for fishing occupation.

4. Various minerals, natural gas and mineral oil, etc. can also be obtained from mining the continental shelf. For example, Mumbai High located on the continental shelf of the Arabian Sea is a source from where the mineral oil and natural gas is obtained.

Question d.
Write in brief about the continental slope.
Answer:

1. The steep slope of the sea bed beyond the extent of continental shelf is called continental slope.
2. The depth of the continental slope is from 200 metres to 3600 metres below the sea level.
3. The continental slope is found to be comparatively narrower.
4. The lower boundary of the continental slope is considered as the boundary of I continent.

Question f.
Write in brief about the abyssal plains.
Answer:

1. The flat part of the sea bed that lies beyond the continental slope is called abyssal plains.
2. Various submerged landforms like
   submerged hills, submerged mountains, etc. are seen on abyssal plains.
3. Submarine plateaus are also found on the abyssal plains.

Question g.
Write in brief about mean sea level.
Answer:

1. The average of the highest high tide and the lowest low tide is considered to calculate the mean sea level.
2. This average is considered to be zero sea level.
3. The altitude of any place above the sea level is measured and expressed in positive value. (For example, Mount Everest is 8848 metres high.)
4. The depth of any place below the sea level is measured and expressed in negative value. (For example, Mariana Trench is 11034 metres below sea level.)

Study the following map/figure/graph and answer the following questions:

Can you tell?

Question a.
What parameters were used for classifying the landforms on the earth?
Answer:
Altitude and the shape of the land were the parameters used for classifying the landforms on the earth.

Question b.
What parameters were used for naming the landforms below water?
Answer:
Depth from the seafloor and the shape of the land were the parameters used for naming the landforms below water.

Give it a try.

Question a.
Name the submerged landforms shown in the diagram.
(Note: The answer is given directly.)

Answer:

Question b.
Identify the ocean shown in the map of the ocean floor.
Answer:
The ocean shown in the map of the ocean floor is Indian Ocean.

Question c.
Which region would be ideal for fishing and why?
Answer:
The region near Madagascar island would be ideal for fishing. Madagascar island has a shallow continental shelf. The warm stream and cold stream also meet near Madagascar island. Therefore, the region near Madagascar island would be ideal for fishing.

2. Name the landforms shown in the following figure and answer the following questions:
(Note: The answer is given directly.)

Question a.

Answer:

Thought-Provoking Questions

Think about it.

Question a.
If the classification of landforms on land can be done on the basis of altitude and size, then how can the landforms submerged underwater are classified?
Answer:
If the classification of landforms on land can be done on the basis of altitude and size, then the landforms submerged underwater are classified on the basis of the depth from the seafloor and the shape of the land there.

Use your brainpower!

Do this activity when you go to the seashore with your parents or teachers. Observe the materials which have come with the waves. Classify them as per the flowchart given below:

Question a.
Which of these are perishable items?
Answer:
Plants, conches and shells, aquatic animals of these are perishable items.

Question b.
Which are non-perishable?
Answer:
Chemicals, metals and plastic/glass are non-perishable.

Question c.
What will happen because of perishable items?
Answer:
Perishable items will not create pollution of seacoast and seawater on a large scale. The remains of perishable items will get deposited in the form of marine oozes on the ocean bed.

Question d.
What will happen because of non-perishable items?
Answer:
Non-perishable items will create pollution of seacoast and seawater on a large scale.

Question f.
Suggest measures to control deposition of non-perishable items on the coast.
Answer:
The following measures can be taken to control deposition of non-perishable items on the coast:

1. Plastic bags, plastic or glass containers must be prohibited on the seacoasts.
2. Strict action must be taken against offenders carrying the banned products on the seacoasts.
3. Hoardings explaining the importance of clean seacoasts must be displayed on all the seacoast.

Question g.
How will you run a campaign of environmental conservation to keep the coasts clean?
Answer:
We will run a campaign of environmental conservation to keep the coasts clean as follows:

1. We will display hoardings explaining the importance of clean seacoasts on the seacoasts.
2. We will arrange street plays, dramas, etc. highlighting the importance of clean seacoasts.
3. We will arrange special programmes during the festivals like Ganeshotsav, Diwali, Christmas, etc. to keep the seacoasts clean.

Open-Ended Questions:

Question a.
Suggest measures to control deposition of non-perishable items on the coast.
Answer:
The following measures can be taken to control deposition of non-perishable items on the coast:

1. Plastic bags, plastic or glass containers must be prohibited on the seacoasts.
2. Strict action must be taken against offenders carrying the banned products on the seacoasts.
3. Hoardings explaining the importance of clean seacoasts must be displayed on all the seacoasts.

Question b.
How will you run a campaign of environmental conservation to keep the coasts clean?
Answer:
We will run a campaign of environmental conservation to keep the coasts clean as follows:

1. We will display hoardings explaining the importance of clean seacoasts on the seacoasts.
2. We will arrange street plays, dramas, etc. highlighting the importance of clean seacoasts.
3. We will arrange special programmes during the festivals like Ganeshotsav, Diwali, Christmas, etc. to keep the seacoasts clean.