5.2 Plate Tectonics

Question 1

How many layers does earth have?

Answer 1

The crust
The mantle
The outer core
The inner core

Question 2

What types of crust exist?

Answer 2

Continental - a thicker (up to 70km), less dense layer mainly composed of granite
Oceanic - a thinner (5-10km) , denser layer mainly composed of basalt

Question 3

Outline the structure of mantle

Answer 3

The mantle is between the crust and core and is the widest layer (2900km)
The upper mantle has two layers
The rigid layer above the asthenosphere which together with the crust makes up the lithosphere
The asthenosphere is a plastic-type layer which moves very slowly under high pressure and carries the lithosphere on top
The lower mantle is hotter and denser than the upper mantle
The intense pressure, at depth, keeps the lower mantle solid

Question 4

Outline the structure of core layer

Answer 4

The core is the hottest part of the Earth, and this heat is the main driver of tectonic activity
There are two key causes of this extreme heat:
Radioactive decay of elements such as uranium and potassium inside the earth’s core
Heat left over from the collisions of asteroids and other small bodies which resulted in the formation of Earth