Tectonics - How does the Earth's structure influence plate tectonics?

Question 1

Name the layers of the Earth?

Answer 1

inner/outer core
mantle
crust

Question 2

Describe the crust

Answer 2

Thinnest layer

two types - oceanic and continental

Question 3

What is the difference between oceanic and Continental crust? ( made of and how thin is it)

Answer 3

OCEANIC is made of basaltic rock and is 5 to 8 km thin
CONTINENTAL is thick 30 to 40 km (this can vary and can be 70km under some mountains) and is made of granitic rock. It is lighter than oceanic crust because it is less dense.

Question 4

Describe the mantle?

Answer 4

thickest layer (2900km)
divided into two layers -upper/lower

Question 5

Describe the upper mantle?

Answer 5

Upper layer = mostly solid but some melting at plate boundaries and hotspots - flows very slowly. Mantle become hotter and denser with depth

Question 6

Describe the lower mantle?

Answer 6

Lower Mantle solid despite higher temperature.

Question 7

Describe the core?

Answer 7

Centre of the earth
Very hot and dense
Made of two parts outer/inner

Question 8

Describe the outer and inner core of the earth?

Answer 8

Outer core - made liquid iron and nickel, temperature between 4500 and 5500
Inner core temperature up to 6000 (hot as surface of the sun) It is a solid ball of iron and nickel

Question 9

The upper mantle is divided into two further layers

Answer 9

lithosphere
asthenosphere
They are both involved in tectonic activity

Question 10

What is the lithosphere broken into?

Answer 10

tectonic plates which float or move on the asthenosphere

Question 11

What is the asthenosphere?

Answer 11

denser mobile layer in the upper part of the mantle. The tectonic plates float on top of it

Question 12

What are convection currents?

Answer 12

Rising hot currents within the mantle. They are circular in motion.
They exert a weak pull on the plates above them which causes the tectonic plates to move apart or closer or slide.
This causes earthquakes or forms volcanoes. SEE PICTURE PAGE 38 OF BOOK

Question 13

What do convection currents need before they can form?

Answer 13

A source of heat
This comes from radioactive decay (formed naturally by chemical elements) and residual heat (heat left over from when the earth formed)

Question 14

What is residual heat?

Answer 14

heat left over from when the earth formed