Structure of the Earth

Question 1

Core

Answer 1

The centre of the Earth, an iron-nickel mass that gives the Earth its magnetic field. The inner core is 1,250km thick. The outer core is liquid and is 2,200km thick

Question 2

Mantle

Answer 2

Accounts for more than 80% of the volume of the Earth. It consists of semi-solid rock containing silicon and oxygen, 2,900km deep. The upper part of the mantle consists of two layers: a layer extending from 100km to 300km - the asthenosphere. The layer above this is the lithosphere, a rigid layer between the crust and the asthenosphere

Question 3

Crust

Answer 3

The outer shell consisting of oceanic crust (solid) composed of dense basaltic rock, average 5km deep, and the continental crust (solid), mainly granite which is less dense than basalt, averaging 30km deep. Continental crust can be up to 100km deep under major mountain ranges

Question 4

The oceanic and continental plates are made up by…

Answer 4

… the lithosphere and crust

Question 5

Why do convection currents occur in the asthenosphere?

Answer 5

The intense heat generated in the mantle means that this semi-molten layer “flows”, carrying with it the solid lithosphere and crust