8th Standard, Social, Geography CHAPTER – 12
LITHOSPHERE
Exercises
I Fill in the blanks with suitable words:
1. The continental crust is also called SIAL (Silica and Aluminium).
2. Vast basin shaped volcanic mouth is ‘Caldera’.
3. The most destructive earthquake waves are Surface Waves (LW).
4. Stalactities and Stalagmites are most common in Underground water.
5. The Beaches are formed by sea wave work.
II Answer the following questions briefly:
6. Mention the three major layers of the interior of the Earth.
Answer: The three major layers of the interior of the Earth are,
1. The Crust
2. The Mantle
3. The Core.
7. Name the types of volcanoes on the basis of frequency of eruption.
Answer: The types of volcanoes on the basis of frequency of eruption are as follows.
1. Active Volcanoes
2. Dormant Volcanoes
3. Extinct Volcanoes
8. Mention the important earthquake zones of the world.
Answer: The important earthquake zones of the world are,
1. Primary Waves (PW)
2. Secondary Waves (SW)
3. Surface Waves (LW)
9. What is weathering? Name the three main types of weathering.
Answer: Weathering is the wearing away or breaking down or gradual disintegration of rocks by agents (Temperature, rainfall, wind etc.) present in the atmosphere. The three main types of weathering are,
1. Mechanical weathering:
2. Chemical weathering:
3. Biological weathering:
10. Name the landforms associated with the work of river.
Answer: The landforms associated with the work of river are,
1. The Upper Course:
2. The Middle Course:
3. The Lower Course:
III. Match the following:
A B
i. SIMA a) Earthquake
ii. Sandstone b) Yellow soil
iii. Epicentre c) Oceanic crust
iv. Geyser d) Sedimentary rock
v. Loess e) Underground water
Answer:
A B
i. SIMA c) Oceanic crust
ii. Sandstone d) Sedimentary rock
iii. Epicentre a) Earthquake
iv. Geyser e) Underground water
v. Loess b) Yellow soil
IV. Define the following:
11. Aqueous rocks
Answer: The sedimentary rocks are formed after the disintegration of igneous rocks. Therefore they are called secondary rocks. These rocks are also called aqueous rocks because they are formed in the water bodies (Lake, Sea and Ocean beds).
12. ‘Pacific ring of fire’
Answer: Coastal margins of the Pacific Ocean consisting of Philippines, Japan, USA, Central America, South America etc. Where world’s largest volcanoes are found.
13. Mechanical weathering
Answer: When the rock is broken and disintegrated without any chemical alteration, the process is called Physical weathering or Mechanical weathering. The important processes of mechanical weathering are Granular disintegration, Block disintegration and Exfoliation.
14. Moraine
Answer: ‘Moraines’ are the most important landforms of the glaciated region. The important depositional landforms produced by glaciers are Moraines, Drumlins, Esker, Kames, Outwash plains, Till plains etc.
15. Carbonaceous rocks
Answer: When the rainwater falls on limestone rocks, the calcium carbonate present in the rocks absorbs carbon dioxide from rainwater and becomes calcium bicarbonate.
16. Tsunami
Answer: Tsunami is a large sea wave occasionally experienced along the coasts of Japan and in other regions caused by an underwater earthquake. In Japanese language ‘Tsunami’ means ‘harbour waves’.
17. Continental glacier
Answer: Continental glaciers are extensive ice sheets found in polar regions eg., Greenland and Antarctica.
18. Hot spring
Answer: Whenever warm or hot water comes out naturally it is called hot spring or thermal spring. They are usually found near the volcanic regions.
V. Terms to remember:
1. NIFE: The most important materials of the core are Nickel (NI) and Ferrous (FE) (Iron). So it is known as NIFE.
2. Arenaceous and Argillaceous rocks: Mechanically formed sedimentary rocks built up by fragments of pre-existing rocks which have been produced by the processes of weathering and erosion eg., Sandstone (Arenaceous rocks) and Shale (Argillaceous rocks).
3. Tectonic forces: Tectonic forces are internal Earth forces caused by the movement of lithospheric plates, which result in changes to the Earth’s surface, such as the formation of mountains, volcanoes, and earthquakes.
4. Mountain glacier: The glaciers found in the Polar regions are called Mountain glaciers.
5. Aeolian cycle: The “Aeolian cycle” refers to the continuous processes of wind eroding, transporting, and depositing sediment, shaping landforms like sand dunes
6. Beaches: Sea waves are the regular undulation of water on the sea or ocean. The work of sea waves is significant along the sea shore or coasts. Beaches are the important landforms associated with sea waves.
Additional Questions:
- What are the three types of Rocks?
Answer: The three types of Rocks are,
- Igneous rocks: Types of igneous rocks are Intrusive igneous rocks and Extrusive igneous rocks.
- Sedimentary rocks: Types of Sedimentary rocks are Mechanically formed sedimentary rocks, Chemically formed sedimentary rocks and Organically formed sedimentary rocks
- Metamorphic rocks.
2. Mention the Distribution of earthquakes.
Answer: The Distribution of earthquakes is as follows.
1. The coastline around the pacific ocean: This includes Newzealand, Phillippines, USA, Japan, Peru, etc.,
2. Coastal area around the Mediterranean sea.
3. The Himalayan Mountain region of India (Shivalik region).
3. What is Tsunami?
Answer: Tsunami is a large sea wave occasionally experienced along the coasts of Japan and in other regions caused by an underwater earthquake. In Japanese language ‘Tsunami’ means ‘harbour waves’.
4 . Mention the different types of Chemical weathering.
Answer: The different types of Chemical weathering are,
- Oxidation
- Carbonation
- Hydration
- Solution
5. What are the Types of Glacier?
Answer: The Types of Glacier are as follows.
- Glacier are Continental glaciers,
- Mountain or Alpine or Valley glaciers
6. What are types of springs?
Answer: The types of springs are as follows.
- Perennial spring
- Intermittent springs:
- Hot springs
- Geyser
- Artesian wells
VI. Activities:
1. Collect the different rocks from your environment.
2. During a school excursion, observe how a waterfall is formed.
