7.Chapter3.Geo.The Surface and Interior of the earth
Chapter 3,Geography
3. The Surface and Interior of the earth.
Keywords
Geologist : a scientist who studies geology ( study of earth).mean
Sea level : the level of the ocean surface between the level of mean high tide and low tide.
Seismic waves : a wave of energy generated by an earthquake or other earth vibrations that travel within the earth or along it's surface.
Something to know
A. Tick the correct option.
1. Living organisms do not survive inside the earth due to -
Ans- (a) high temperature
2. Earthquakes and volcanoes are caused by-
Ans- (a) internal disturbance
3. Respective layers of the earth from top to bottom are-
Ans- (b) crust, mantle, core
4.The full form of SIMA is-
Ans- (b) silica and magnesium
5. The original rock from which Gneiss formed is-
Ans- (c) granite
B. Fill in the blanks.
1. Earth was formed about 4.6 billion years ago.
2. The behaviour of scismic waves tells us about the Earth's interior.
3. The thickness of crust varies from place to place.
4. Rocks are classified into three groups on the basis of their Formation.
5.The core of the Earth is Rich in iron and nickel.
C. Give a single term for each of the following statements.
1. It is the hardest substance. Diamond
2. The molten rock material present inside the earth. Magma
3. Rocks which are formed due to cooling and solidification of magma. Igneous
4. Shaking and trembling of the Earth's surface. Earthquake
5. A naturally occurring solid substance made up of a mixture of minerals. Ores
D. Answer the following questions in brief.
1. What is the special feature of sedimentary rocks ?
Ans:- (I) They are then deposited on the river beds or sea beds.
(II) They are hardened to form sedimentary rocks.
(III) This type of rocks are layered and therefore, are also called stratified rocks. Sandstone, limestone, clay, shale, chalk, are some examples of sedimentary rocks.
2. How are metamorphic rocks formed ?
Ans:- Rocks which originally are igneous or sedimentary in nature, get changed in character and appearance due to the heat and pressure and are called metamorphic rocks. For instance , granite is igneous but changes into metamorphic as Gneiss. The limestone is a sedimentary rocks but changes into metamorphic as marble.
3. What is lava ?
Ans:- The igneous rocks are formed due to intensive heat and pressure where molten material called magma comes out and solidifies over the Earth's surface as lava.
4. Why are igneous rocks called the primary rocks ?
Ans:- Igneous rocks general, slow cooling inside the earth results in large size crystals Igneous rocks are also called primary rocks as they were formed first over the Earth's surface.
5. What are sediments ?
Ans:- The continuous action of these agents on rocks breaks them into small rock pieces that are carried by rivers . They are then deposited on the river beds or sea beds. These deposits are called sediments which form layers, one above the other.
E. Answer the following questions.
1. Differentiate between the P- wave and the S-wave.
Ans:-. There are two main types of seismic wave.
a.P-Wave The Primary Wave or P Wave can travel through both solid and liquid mediums is faster in speed.
b.S-Wave.The S-wave on the other hand can pass through only a solid medium and that to at a slower speed.
2. Write two characteristics of each of the following.
(a) Crust:- (I) The thin solid layer covering the outside of the Earth is called crust.
(II) It is made of a layer called SIAL (silica+ aluminum).
(b) Mantle:- (i) Beneath the crust is a very thick layer of rocks called the mantle.
(ii) The mantle extends up to 2900 km in depth.
(c) The Core:- (i) The innermost part of the Earth is known as core.
(ii) It is further divided into inner core and outer core. The core and outer core. The core of the Earth is Rich in iron and nickel (NIFE)
3. What are fossil fuels? Name any two fossil, fuels and specify their importance.
Ans:- Sometimes, the remains of animals and plants get buried and trapped under the layers, and over a period of time get converted into coal, oil and natural gas. That is why , they are called fossil fuels. The fossil fuels have a great economic importance all over the world as they are a major source of energy.
4. Why is the knowledge of the earth's interior based on indirect observation ?
Ans:- Our knowledge of the Earth's interior is therefore, based on indirect observation,as it is impossible to collect data regarding earth's interior due to intense heat and ample pressure inside the earth.
The behavior of seismic waves or earthquakes,the occurrence of volcanoes are the other factors.
5.What are minerals? On what basis can the minerals be identified? Give examples.
Ans:- A rocks has single or a combination of several mineral. These minerals are present in small or large quantities at any given site of the earth are iron, silver, gold,mica, bauxite and lead. Minerals are identified on the basis of their colour, hardness and lustre.
3. The Surface and Interior of the earth.
Keywords
Geologist : a scientist who studies geology ( study of earth).mean
Sea level : the level of the ocean surface between the level of mean high tide and low tide.
Seismic waves : a wave of energy generated by an earthquake or other earth vibrations that travel within the earth or along it's surface.
Something to know
A. Tick the correct option.
1. Living organisms do not survive inside the earth due to -
Ans- (a) high temperature
2. Earthquakes and volcanoes are caused by-
Ans- (a) internal disturbance
3. Respective layers of the earth from top to bottom are-
Ans- (b) crust, mantle, core
4.The full form of SIMA is-
Ans- (b) silica and magnesium
5. The original rock from which Gneiss formed is-
Ans- (c) granite
B. Fill in the blanks.
1. Earth was formed about 4.6 billion years ago.
2. The behaviour of scismic waves tells us about the Earth's interior.
3. The thickness of crust varies from place to place.
4. Rocks are classified into three groups on the basis of their Formation.
5.The core of the Earth is Rich in iron and nickel.
C. Give a single term for each of the following statements.
1. It is the hardest substance. Diamond
2. The molten rock material present inside the earth. Magma
3. Rocks which are formed due to cooling and solidification of magma. Igneous
4. Shaking and trembling of the Earth's surface. Earthquake
5. A naturally occurring solid substance made up of a mixture of minerals. Ores
D. Answer the following questions in brief.
1. What is the special feature of sedimentary rocks ?
Ans:- (I) They are then deposited on the river beds or sea beds.
(II) They are hardened to form sedimentary rocks.
(III) This type of rocks are layered and therefore, are also called stratified rocks. Sandstone, limestone, clay, shale, chalk, are some examples of sedimentary rocks.
2. How are metamorphic rocks formed ?
Ans:- Rocks which originally are igneous or sedimentary in nature, get changed in character and appearance due to the heat and pressure and are called metamorphic rocks. For instance , granite is igneous but changes into metamorphic as Gneiss. The limestone is a sedimentary rocks but changes into metamorphic as marble.
3. What is lava ?
Ans:- The igneous rocks are formed due to intensive heat and pressure where molten material called magma comes out and solidifies over the Earth's surface as lava.
4. Why are igneous rocks called the primary rocks ?
Ans:- Igneous rocks general, slow cooling inside the earth results in large size crystals Igneous rocks are also called primary rocks as they were formed first over the Earth's surface.
5. What are sediments ?
Ans:- The continuous action of these agents on rocks breaks them into small rock pieces that are carried by rivers . They are then deposited on the river beds or sea beds. These deposits are called sediments which form layers, one above the other.
E. Answer the following questions.
1. Differentiate between the P- wave and the S-wave.
Ans:-. There are two main types of seismic wave.
a.P-Wave The Primary Wave or P Wave can travel through both solid and liquid mediums is faster in speed.
b.S-Wave.The S-wave on the other hand can pass through only a solid medium and that to at a slower speed.
2. Write two characteristics of each of the following.
(a) Crust:- (I) The thin solid layer covering the outside of the Earth is called crust.
(II) It is made of a layer called SIAL (silica+ aluminum).
(b) Mantle:- (i) Beneath the crust is a very thick layer of rocks called the mantle.
(ii) The mantle extends up to 2900 km in depth.
(c) The Core:- (i) The innermost part of the Earth is known as core.
(ii) It is further divided into inner core and outer core. The core and outer core. The core of the Earth is Rich in iron and nickel (NIFE)
3. What are fossil fuels? Name any two fossil, fuels and specify their importance.
Ans:- Sometimes, the remains of animals and plants get buried and trapped under the layers, and over a period of time get converted into coal, oil and natural gas. That is why , they are called fossil fuels. The fossil fuels have a great economic importance all over the world as they are a major source of energy.
4. Why is the knowledge of the earth's interior based on indirect observation ?
Ans:- Our knowledge of the Earth's interior is therefore, based on indirect observation,as it is impossible to collect data regarding earth's interior due to intense heat and ample pressure inside the earth.
The behavior of seismic waves or earthquakes,the occurrence of volcanoes are the other factors.
5.What are minerals? On what basis can the minerals be identified? Give examples.
Ans:- A rocks has single or a combination of several mineral. These minerals are present in small or large quantities at any given site of the earth are iron, silver, gold,mica, bauxite and lead. Minerals are identified on the basis of their colour, hardness and lustre.
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