L1- Earth's structure (Tectonics)

Question 1

Crust

Answer 1

Forms the outer layer of the Earth. It’s also known as the lithosphere
Relatively low density, rests on top of semi- fluid mantle. Gets hot quickly with depth – 200-400oc
Very thin compared to the other layers

Two types: Continental – old, less dense and Oceanic – younger, denser (iron rich)
Crust is continuously stressed, breaking it up; due to convection currents operating in the mantle
When two plates pulled away from each other = deep cracks, magma rises up through
Pressure release means boiling point drops, rock melts

Question 2

Mantle

Answer 2

Upper part is solid – like the crust; together called the lithosphere
Then you get the asthenosphere below
Here is sticky, viscous, dense rock – slowly starts to moved
This is due to convection currents that begin at the earth’s core.
Rock is heated, rises, spreads, cools, sinks back to the bottom, reheats and rise again. This relies on temperature difference with depth
These move the plates that make up the crust above.

Question 3

Core

Answer 3

Made up of iron and nickel
Radioactivity is caused by radioactive decay of uranium and thorium
Core temperature is 5,000oc