The Earth

Question 1

What is the depth of the earth?

Answer 1

The earth is 6371 kms in depth.

Question 2

The seasonal changes in the earth is due to:

1. The rotation of the earth
2. The nature of orbit of around the Sun, i.e. aphelion and perihelion.
3. Earth’s tilt in its axis.
4. Gravitation forces of the Sun and/or Moon.

Answer 2

3. The tilt

Question 3

Where does the latitude converge?

Answer 3

Latitude don’t converge anywhere. They are parallel lines.

Question 4

What are the depth of Crust, Mantle and Core of the earth?

Answer 4

Crust: 0-30 kms
Upper Mantle: 30-700 kms
Lower mantle: 700-2900 kms
Outer core: 2900-5150
Inner core: 5150-6371 kms

Question 5

What is Weichart - Gutenberg discontunity?

Answer 5

Between the lower mantle and outer core, the earths density increases significantly from 5.5 to 10 g/cm3. This is known as Weichart - Gutenberg discontinuity.

Question 6

What is SIAL, SIMA and NIFE?

Answer 6

The earth’s crust is solid and is made of SIAL (Silica & Aluminum)
Mantle is plastic and is made of SIMA (Silica & Magnesia)
Core is liquid and is made of NIFE (Nickel and Ferrous)

Question 7

What do the term Lithosphere, Pyrosphere and Barysphere imply?

Answer 7

These are modern nomenclature of the earth’s layers.
Lithosphere: 0 - 100 kms
Pyrosphere: 100 - 2900 kms
Barysphere: 2900 - 6371 kms

Question 8

What is Pangea?

Answer 8

Before the carboniferous period (more than 280 million years ago), earth’s continent were not divided. There was one super continent surrounded by a super ocean.
Pangea is the name of the super continent that was surrounded by a super ocean called Panthalassa.

Question 9

What is Laurasia and Gondwana land?

Answer 9

Around 280 million years ago i.e. at the end of Carboniferous period, Pangea split into two parts. The northern part was named Laurasia or Angaraland and the southern part was known as Gondwanaland.
Between these landforms, a shallow sea emerged which was named Tethys.

Question 10

Explain the drifting of continents that took place at the end of cretaceous period.

Answer 10

Around 65 million years ago i.e end of cretaceous period, the continents further broke apart. North America drifted westward after separating from Laurasia, while Gondwanaland broke into several continents such as South America, Africa, Australia and Antarctica. The peninsular part of India broke apart and drifted northeastward and collided with the asian plate.

Question 11

What are different rock types?

Answer 11

1. Igneous: directly from molten magma. Eg: basalt, granite
2. Sedimentary: disintegrated igneous rock gets eroded by water and is sedimented in water bed. Eg: sandstone, limestone
3. Metamorphic: these rocks are the result of high temperature and pressure. Igneous and sedimentary rocks under extreme pressure and temperature gets transformed to metamorphic rock.