Class VII GEOGRAPHY
• Internal structure of the earth
• Rocks and minerals
• Types of rocks
• Formation of rocks
• Rock cycle
• Uses of rocks
• Comprehension exercise
TOPIC TO DICUSS
CHAPTER
CRUST
5 5-35 km
THICKNESS OF CRUST
CLASSIFICATION OF CRUST
The Earth’s crust is thinnest in valleys and thickest under mountain ranges.
Valley
Mountain
The continental crust is composed of sial .
The oceanic crust is composed of sima.
Percentage wise share of
crust
1 %
Mantle
Heat and pressure generally increases with depth .
The viscosity also
varies greatly.
Precentage –wise share of Mantle
84%
84 %
Core
Nickel + Iron = nife
Temperature and pressure inside core
Percentage wise share of Core
C c
15 %
15 %
Igneous rocks
How extrusive and intrusive igneous are formed
Example
Sedimentary rocks
Metamorphic rock
Igneous and sedimentary rocks can change into metamorphic rocks under
Great heat and pressure . For example , clay changes into slate and lime stone into Marble.
Example
Feel the difference between different types of rocks
ROCK CYCLE
Mineral
OF
Chapter -2
Inside our earth
OF
NCERT BOOK
Answer -- The three layers of the earth are
crust, mantle and core.
Q.1 (ii) What is a rock ?
(iii) Name three types of rocks ?
Answer (ii)
Answer (iii)
Q1 (iv) How are extrusive and intrusive rocks formed ?
Answer
Q1. (v) What do you mean by a rock cycle?
(vi) What are the uses of rocks?
Answer (v) --- The process of transformation of the rocks from one to another is known as the rock cycle.
Answer (vi) -- Rocks are used for making roads, buildings, utensils, ornaments and many more things.
Q.1 (vii) What are metamorphic rocks ?
ANSWE R
due to high pressure and temperature
Under great heat and pressure
as sediments are compressed and hardened to form layers of rocks.
DO comprehension EXECERCISE and draw diagram neatly in copy (fair copy, blank pages of last year’s copy , rough
copy or on what ever available to you at home .
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