NCERT Solutions for Class 11 Geography Chapter 3 Interior of the Earth

Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 3 Interior of the Earth Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.

Interior of the Earth NCERT Solutions for Class 11 Geography Chapter 3

Interior of the Earth Questions and Answers Class 11 Geography Chapter 3

Question 1.
Multiple choice questions :
(i) Which one of the following earthquake waves is more destructive?
(a) P-waves
(b) S-waves
(c) surface waves
(d) None of the above
Answer:
(c) surface waves.

NCERT Solutions for Class 11 Geography Chapter 3 Interior of the Earth

(ii) Which one of the following is a direct source of information about the interior of the earth?
(a) Earthquakes waves
(b) Volcanoes
(c) Gravitational force
(d) Earth magnetism
Answer:
(b) Volcanoes.

(iii) Which type of volcanic eruptions have caused Deccan Trap formations?
(a) Shield
(b) Composite
(c) Flood
(d) Caldera
Answer:
(b) Flood.

(iv) Which one of the following describes the lithosphere :
(a) upper and lower mantle
(b) crust and core
(c) crust and upper mantle
(d) mantle and core
Answer:
(c) crust and upper mantle.

NCERT Solutions for Class 11 Geography Chapter 3 Interior of the Earth

Question 2.
Answer the following questions in about 30 words each :

(i) What are body waves?
Answer:
The waves generated due to the release of energy at the focus are called body waves. They radiate and move in all directions from ” the point of hypocenter and travel through the body of the earth.

(ii) Name the direct sources of information about the interior of the earth,
Answer:

  • Mining ar|as
  • Deep Ocean Drilling Project
  • Integrated Ocean Drilling Project
  • Volcanic eruptions

(iii) Why do the earthquake waves develop shadow zone?
Answer:
The earthquake waves get recorded world over, but it is found that earthquakes are not recorded in some specific zones. Such a zone is called ‘shadow zone.’

(iv) Briefly explain the indirect sources of information of the interior of the earth other than the seismic activity.
Answer:
Analysis of properties of matter indirectly provides the information about the interior. Through the mining activities, we know the temperature and pressure increases with the increase in distance from the surface to the depth. Gravitation, magnetic field and seismic activity are the other indirect sources of information,

Question 3.
Answer the following questions in about 150 words each :

(i) What are the effects of propagation of earthquake waves on the rock mass through which they travel?
Answer:
There are three types of waves. The velocity of waves changes K as they travel through materials with different densities.
There are two types of Body waves ‘P’ and ‘S’ waves. ‘P’ waves move faster and are the first to arrive at the surface. They travel through gaseous, liquid and solid materials. ‘S’waves move slowly and arrive at the surface with some time lag. They can travel only through solid materials. It has helped scientists to understand the structure of the t interior of the earth.

Both ‘P’ and ‘S’ waves reflect and refract as they encounter different a materials along their path. Reflection causes waves to rebound and move in different directions. The surface waves are the last to report. These waves are the most destructive. They cause displacement of rocks and, hence, the collapse of structures.

(ii) What do you understand by intrusive form? Briefly describe various intrusive forms.
Answer:
The lava released during volcanic eruptions on cooling develops into igneous rocks. Depending on the location of the cooling of the lava, igneous rocks are classified as volcanic rocks and plutonic rocks. The lava that cools within the crustal portion assumes different forms.

NCERT Solutions for Class 11 Geography Chapter 3 Interior of the Earth

These forms are called intrusive forms.
NCERT Solutions for Class 11 Geography Chapter 3 Interior of the Earth
Different Intrusive forms are :

Batholiths : A large body of magmatic material that cools in the deeper depth of the crust develops in the form of large domes. These are the cooled portion of magma chambers.

Lacoiiths : These are large dome-shaped intrusive bodies with a level base and connected by a pipe-like conduit from below. Karnataka plateau is spotted with domal hills of granite-rocks.

Lapolith, Phacolith and Sills : When the lava moves upwards, a portion of the same may tend to move in a horizontal direction and develop into a saucer shape, concave to the sky body, it is called lapolith. A wavy mass of intrusive rocks, having a definite conduit to source are called phacoliths. The near horizontal bodies of the intrusive igneous rocks are called sills or sheets.

Dykes : When the lava makes its way through cracks and the fissures developed in the land, it gets cooled to develop a wall-like structure, called dykes.

NCERT Solutions for Class 11 Geography Chapter 3 Interior of the Earth

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