Write four points about crust, mantle, outer core and inner core.

Crust 

• The upper layer of the Earth is termed as crust
• It is a thin layer
• It consists of continental land mass and oceanic beds
• Sial and Sima are found in these components respectively

Mantle

• Beneath the crust, mantle, the next layer is found
• It consists of rocks and it lies between crust and outer core
• It extends upto a depth of 2900 kms below the crust
• It is a thick layer due to the composition of rocks

Outer core 

• It is a liquid layer
• It is composed of iron and nickel
• It lies above the inner core and below the mantle layer
• The temperature is very high in this layer

Inner core

• It is the inner most layer of the earth
• It has a radius of about 3500 km
• The temperature prevalent in this layer is similar to that of temperature of Sun
• The main components found in this layer are iron and nickel