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INTERNAL STRUCTURE OF THE EARTH

Geograpphy Sec Sch

The internal structure of the earth is made up of three concentric layers which are

(a) The crust (Lithosphere)

(b) The mantle (Mesosphere)

(c) The core (Barysphere)

 

The Crust

This is subdivided into upper and lower crust. The upper crust consists of granite rocks and forms the continent. The main minerals here are silica and aluminium, collectively referred to as SIAL. It has an average density of 2.7

 

EVALUATION QUESTIONS

  1. Mention the 3 concentric layers of the internal layer of the earth.
  2. SIAl is a combination of—– and —–minerals

 

The lower part of the earth crust consists of basalt rocks and forms the ocean floor. It contains minerals like silica, iron and magnesium, collectively referred to as SIMA. It has an average density of  3.0

The Mantle

This zone is found just beneath the crust. It is about 290km thick with a density of 3.3 Its main mineral is olivine. It is plastic and in semi- liquid form.

The Core

This is the innermost  part of the earth. It is about 3500km in radius. It contains two minerals, iron and nickel, collectively referred to as NIFE. The temperature of the core is estimated to be as high as 2000o C. It is in molten state.

 

EVALUATION QUESTIONS

  1. What is the density of sial and sima?
  2. A major mineral found in the mantle is called _____.

 

GENERAL EVALUATION

  1. Iron and Nickel is found in ______.
  2. State two characteristics of  the crust.
  3. Describe the core of the earth.
  4. Which minerals make up Sial?
  5. The core of the earth is made up of ______.

 

WEEKEND ASSIGNMENT

  1. The barysphere can also be referred to as (a) crust (b) core (c) mantle
  2. The percentage composition of Nitrogen in the Atmosphere is ————-

(a)78%  (b) 0.03% (c) 21%

  1. Which of the following minerals is found in the lower lithosphere? (a) Olivine (b) Magnesium (c) Carbon
  2. The temperature of the core is ….. (a) 200oC (b) 25000C  (c) 20000C
  3. The density of the mantle is ————- (a) 3.0 (b) 2.7 (c) 3.3

    

THEORY

  1. Draw the inner structure of the earth.
  2. Write short note on the crust of the earth.

 

See also

STRUCTURE OF THE EARTH

CALCULATION OF DISTANCES AND LOCAL TIME

LATITUDE & LONGITUDE

EARTH AS A PLANET

THE SOLAR SYSTEM

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