Samacheer Kalvi 8th Social Science Guide Geography Chapter 1 Rocks and Soil

Tamilnadu State Board New Syllabus Samacheer Kalvi 8th Social Science Guide Pdf Geography Chapter 1 Rocks and Soil Text Book Back Questions and Answers, Important Questions, Notes.

Tamilnadu Samacheer Kalvi 8th Social Science Solutions Geography Chapter 1 Rocks and Soil

Samacheer Kalvi 8th Social Science Rocks and Soil Text Book Back Questions and Answers

I. Choose the correct answer:

1. Which of the following is known as sphere of rocks
a) Atmosphere
b) Biosphere
c) Lithosphere
d) Hydrosphere
Answer:
(c) Lithosphere

2. World soil day is observed on
a) 15th August
b) 12th January
c) 15th October
d) 5th December
Answer:
(d) 5th Decembe

3. Fossils are found in
a) Sedimentary rocks
b) Igneous rocks
c) Metamorphic rocks
d) Plutonic rocks
Answer:
(a) Sedimentary rocks

Samacheer Kalvi 9th Social Science Guide Geography Chapter 2 Lithosphere – II Exogenetic Processes

4. The top layer of soil is called as
a) organic layer or humas
b) topsoil
c) subsoil
d) bedrock
Answer:
(b) topsoil

5. Ideal soil for growing cotton is
a) Red soil
b) Black soil
c) Alluvial soil
d) Mountain soil
Answer:
(b) Black soil

6. The major components of soil is
a) Rocks
b) Minerals
c) Water
d) All the above
Answer:
(b) Minerals

7. Which one of the following is the most widespread most and productive category of soil
a) Alluvial soil
b) Black soil
c) Red soil
d) Mountain soil
Answer:
(a) Alluvial Soil

II. Fill in the blanks.

1. Scientific study of rocks is called …………….
Answer:
Petrology

2. ……………. soil is highly suitable for millets cultivation.
Answer:
Black

3. The “Skin of earth” is
Answer:
Soil

4. ……………. is the kind of metamorphic rock using which Taj Mahal was built.
Answer:
White marble

5. ……………. is known as the primary rocks.
Answer:
Igneous rock

True or False:

1. Igneous rocks are called primary rocks.
Answer:
True

2. Slate is formed from shale.
Answer:
True

3. Red soil is formed by the process of leaching.
Answer:
False

4. M-sand is used as alternative for natural sand in construction.
Answer:
True

5. Volcanic mountains are covered with sedimentary rocks.
Answer:
True

IV. Match the following:
1.
Samacheer Kalvi 9th Social Science Guide Geography Chapter 1 Advent of the Europeans 1
Answer:
A) 2 14 3
Samacheer Kalvi 9th Social Science Guide Geography Chapter 2 Lithosphere – II Exogenetic Processes

2.
Samacheer Kalvi 9th Social Science Guide Geography Chapter 1 Advent of the Europeans 2
Ans: D) 3, 1, 4, 2

V. Choose the incorrect statement from the following:

1. a) Igneous rocks are called the primary rocks.
b) Soil is the product of weathering of rocks.
c) Sedimentary rocks are the hardest ones.
d) Deccan plateau is the region of Igneous rocks.
Answer:
d) Deccan plateau is the region of Igneous rocks.

2. a) Soil erosion decreases its fertility.
b) Dynamic metamorphism is caused by high temperature.
c) Soil is a renewable source.
d) Humus is a part of the top layer of soil.
Answer:
c) Soil is a renewable source.

VI. Consider the. following statements and choose the right option from the given ones:
Statement (1): Sedimentary rocks consist of many layers.
Statement (2) : Sedimentary rocks are formed by the sediments deposited at different points of time.
(a) 1 and 2 are correct and 2 explains 1
(b) 1 and 2 are correct but, 2 does not explain 1
(c) 1 is correct but, 2 is incorrect
(d) 2 is correct but, 1 is incorrect.
Answer:
(a) 1 and 2 are correct and 2 explains 1

VII. Give reasons for the following:

1. Chemical sedimentary rocks are found in the beds of reservoirs.

  • Because these are formed by precipitation of minerals from water.
  • It is formed usually through evaporation of chemical rich solutions.

2. Igneous rocks are found in the regions of volcanoes
The formation of igneous rocks takes place when there is an outflow of molten magma.

VIII. Distinguish the following:
1. Metamorphic rock and sedimentary rock.

Metamorphic rocks Sedimentary rocks
i) A rock formed by the alteration of igneous and sedimentary rocks subject to the high temperature and pressure is called metamorphic rocks. Due to high temperature and pressure, the undisturbed sediments of long period is cemented to form sedimentary rocks.
ii) Metamorphism is of two types:
a) Thermal Metamorphism and
b) Dynamic Metamorphism.
Sedimentary rocks are of three types:
a) Organic Sedimentary rocks,
b) Mechanical Sedimentary rocks and
c) Chemical Sedimentary rocks.

2. Soil conservation and Soil erosion.

Soil conservation Soil erosion
i) The process of protecting the soil from erosion to maintain its fertility. The removal or destructive of the top layer of soil by natural forces and human activities.
ii) Practised for the conservation of afforestation, controlled grazing, construction of dams, crop rotation, wind break, etc. Reduces the fertility of soil which leads to the reduction in the agricultural productivity.

IX. Give short answers
1. How are igneous rocks formed?
Igneous rocks are the primary rocks formed by the solidification of the molten magma.

2. Describe about the composition of soil.

  • The basic components of soil are mineral, organic matter, water and air.
  • It consists of about 45% mineral, 5% organic matter, 25% of water and 25% air.
  • The composition of soil varies from place to place and from time to time.

Samacheer Kalvi 9th Social Science Guide Geography Chapter 2 Lithosphere – II Exogenetic Processes

3. Define ‘rock’.

  • The rocks are the solid mineral materials forming a part of the surface of the earth and other similar planets.
  • The earth’s is crust is composed of rocks.

4. State the types of soils.

  • Alluvial soil
  • Black soil
  • Red soil
  • Laterites soil
  • Mountain soil
  • Desert soil

5. What is soil conservation?
Soil Conservation is the process of protecting the soil from erosion to maintain its fertility.

X. Give detailed answer for the following:
1. Explain the process of soil formation.
Soil and its Formation:
Samacheer Kalvi 9th Social Science Guide Geography Chapter 1 Advent of the Europeans 3

  • Soil is a mixture of organic matter, minerals, gases, liquids and organisms that together support life.
  • Soils are produced from rocks through the processes of weathering and natural erosion.
  • Water, wind, temperature changes, gravity, chemical interaction, living organisms and pressure break down parent material.
  • It leads to the formation of loose material.
  • In the course of time, they further break down into fine particles and releases the locked minerals in the rock.

2. Classify and explain the rocks.

  • The rocks are the solid minerals material forming a part of the surface of the earth and other similar planets.
  • The earth’s crust is composed of rocks.

Classification of Rocks:
Rocks are classified into three types namely,

  • Igneous Rocks
  • Sedimentary Rocks
  • Metamorphic Rocks

Igneous Rocks:
These rocks are formed by the solidification of molten magma. These rocks are also called as Primary or Parent Rocks. There are two types of igneous rocks:

  • Extrusive Igneous Rocks
  • Intrusive Igneous Rocks

Sedimentary Rocks:
The Sedimentary rocks are formed by the sediments derived and deposited by various agents. It is also known as stratified rocks. There are three types of sedimentary rocks namely,

  • Organic Sedimentary Rocks
  • Mechanical Sedimentary Rocks
  • Chemical Sedimentary Rocks

Metamorphic Rocks:
When Igneous and Sedimentary rocks subject to high temperature and pressure, the original rocks get altered to form a new kind of rock called metamorphic rocks.
There are two types of Metamorphism rocks namely,

  • Thermal Metamorphism
  • Dynamic Metamorphism

Samacheer Kalvi 9th Social Science Guide Geography Chapter 2 Lithosphere – II Exogenetic Processes

3. Give an account on different layers of soil.
Layers of soil:
O – Horizon or humus:
This layer is dominated by organic material eg: leaves
A – Horizon or Top soil:
It is a part of top soil composed of organic matter mixed with mineral matter.
E – Horizon or Elevated layer:
E – stands for elevated layer. This layer is significantly leached of clay, iron and aluminium oxides, which leaves a concentration of ore.
B – Horizontal or sub soil:
This layer reflects the chemical or physical alternation or parent material. Thus iron, clay, aluminium and organic compounds are found accumulated in the Horizon.
C – Horizon or Parent Rock:
Partially weathered parent material accumulates in this layer.
R – Horizon or Parent Rock:
This layer consists of unweathered part of bed rock.

4. Classify and explain the soil?
Soil are classified on the basis of their formation, colour, physical and chemical properties Based on these, soil is classified into six major types. They are:
i) Alluvial Soil
ii) Black soil
iii) Red Soil
iv) Laterites Soil
v) Mountain Soil
vi) Desert soil

Allivial Soil:

  • It found in the regions of river valleys, flood plains and coastal regions.
  • It is formed by the disposition of silt by the running water. It is suitable for cultivation of sugarcane, jute, rice, wheat and other food crops.

Black Soil:
* These soils are formed by whethering of igneous rocks.
* It is ideal for growing cotton.

Red Soil:

  • It is formed by weathering of metamorphic and crystalline rocks.
  • The presence of iron oxide makes this soil red in colour. It is suitable for millet cultivation.

Laterite soil:

  • It is formed by the process of leaching.
  • It is found in tropical region.
  • It is suitable for the cultivation of tea and coffee.

Mountain soil:

  • These soils are found over the slopes of mountain.
  • Soils in these regions are thin and acidic.
  • It differs from region to region based on the altitude.

Desert soil:

  • There are the sandy soil found in the hot desert regions.
    These soils are porous and saline. It is infertile for agriculture.

XI. Activity Corner.

1. Complete the following table with the help of internet source.
Samacheer Kalvi 9th Social Science Guide Geography Chapter 1 Advent of the Europeans 5

Samacheer Kalvi 8th Social Science Rocks and Soil Additional Important Questions and Answers

I. Choose the Correct answer.
1. Petrology is derived from the ………….. word.
a) English
b) Latin
c) Greek
d) French
Answer:
(c) Greek

2. The soils found in the desert regions are ….
a) Mountain Soils
b) Desert Soils
c) Black Soil
d) Red Soil
Answer:
(b) Desert Soils

3. Which Soils are formed by weathering of metamorphic rocks?
a) Red Soils
b) Rock Soils
c) Laterite Soils
d) Mountain Soils
Answer:
(a) Red Soils

4. …………….. is a part of composed of organic matter mixed with mineral matter.
a) Humus
b) Top Soil
c) Elevated layer
d) Sub-soil
Answer:
(b) Top Soil

5. The time to form one cm of soil is
a) 100 years
b) 200 years
c) 500 years
d) 1000 years
Answer:
(b) 200 years

6. …………….is known as zone of accumlation.
a) Humus
b) Top Soil
c) Elevated layer
d) Sub-soil
Answer:
(d) Sub-soil

7. In the soil composition ………….. are minerals.
a) 5%
b) 10%
c) 25%
d) 45%
Answer: (d) 45%

8. In the soil composition is air.
a) 5%
b) 10%
c) 25%
d) 40%.
Answer:
(c) 25%

9. ……………. soils are formed by the deposition of silt by the running water.
a) Black
b) Red
c) Alluvial
d) Desert
Answer:
(c) Alluvial

10. In the Soil composition are organic matter.
a) 5%
b) 10%
c) 25%
d) 45%
Answer:
(a) 5%

II. Fill in the blanks:
1. A rock is an aggregate of ………….. or more minerals.
Answer:
one

2. There are ………….. different types of minerals found on the earth Surface.
Answer:
2000

Samacheer Kalvi 9th Social Science Guide Geography Chapter 2 Lithosphere – II Exogenetic Processes

3. Rocks are classified in to ………….. types.
Answer:
three

4. The two types of Intrusive Igneous rocks are ………….., …………..
Answer:
Plutonic rocks, Hypabysal rocks

5. Igneous Rocks are ………….. rocks
Answer:
Primary

6. ……………. into slate caused by thermal metamorphism.
Answer:
Basalt

7. Soil is a basic requirement for the growth of ………….. and …………..
Answer:
Plants, animals

8. To become a well matured soil, it takes about ………….. years.
Answer:
3000

9. Parent Rock is converted to loose Rock by ………….. .
Answer:
soil

10. Laterite soil is suitable for plantion crops like ………….., …………..
Answer:
tea, coffee

III. State whether the following statements are true or false:

1. To become a well matured soil, it taken about 2000 years. .
Answer:
False

2. Lava comes out from a volcano.
Answer:
True

3. The word Ignis means rock.
Answer:
False

4. Oldest Sedimentary rocks of the world has been identified in Green land.
Answer:
True

5. Soil supports ecosystem and play an important role in land management.
Answer:
True

IV. Match the following:
1.
Samacheer Kalvi 9th Social Science Guide Geography Chapter 1 Advent of the Europeans 4
Answer:
D) 3 1 4 2

V. Choose the incorrect statement from the following:
1. a) Basalt into slate caused by thermal metamorphism.
b) Chemical Sedimentary rocks are also called evaporates.
c) Taj mahal in India was built with white marbles of a Sedimentary rocks.
d) Rocks have been used by mankind throughout the history.
Answer:
c) Taj mahal in India was built with white marbles of a Sedimentary rocks.

VI. Consider the following statements and choose the right option from the given ones:
1. Statement (1): Petrology is a branch of geology.
Statement (2) : It deals with the Study of water researches.
a) 1 and 2 are correct and 2 explains 1
b) 1 and 2 are correct but, 2 does not explain 1
c) 1 is correct but, 2 is incorrect
d) 2 is correct but, 1 is incorrect.
Answer:
c) 1 is correct but, 2 is incorrect

VII. Give reasons for the following:
1. Why soil is known as ‘Skin of the earth’?

  • Soil minerals form the basis of soil.
  • It forms on the surface of the earth.
  • so It is known as the ‘Skin of the earth’:

VIII. Distinguish the following:
1. Black Soil and Red Soil.

Black Soil Red Soil
1. These Soils are formed by weathering of igneous rocks. These soils are formed by weathering of metamorphic rocks and crystalline rocks.
2. It is retensive of moisture. Iron Oxide is present.
3. It is ideal for growing cotton. It is Suitable for millet cultivation.

IX. Give short answers:
1. Explain about Petrology.

  • Petrology is a branch of geology which deals with the study of rocks.
  • ‘Petrology’ is derived from the Greek word “Petrus” refers to rock and “Logos” refers to study

2. Name the layer in the Earth.
The layer found in the Earth are namely

  • Lithosphere
  • Hydrosphere
  • Atmosphere
  • Biosphere.

Samacheer Kalvi 9th Social Science Guide Geography Chapter 2 Lithosphere – II Exogenetic Processes

3. Explain type of Igneous Rocks.

  • Extrusive Igneous Rocks
  • Intrusive Igneous Rocks.

X. Give detailed answer for the following:
1. What are the uses of soil?
Soil is one of the important natural resource. It is a basic requirement for plant growth and supports various life forms on the earth.

  • The minerals present in the soil enhance and nourishes the crops and plants.
  • It is used in making of ceramics or pottery.
  • It is a source of material for construction and handicraft works.
  • It acts as natural filter of water and purifies it.
  • Soil supports ecosystem and play an important role in land management.

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