The structure of the Earth

Question 1

How thick is the Earths crust on average?

Answer 1

20km thick

Question 2

What is the lithosphere?

Answer 2

The crust and the upper/ rigid section of the mantle

Question 3

What is the asthenosphere?

Answer 3

The upper part of the mantle (the boundary between the earths crust and mantle)

Question 4

What causes the movement of plates?

Answer 4

convection currents

Question 5

What is the outer core made up of?

Answer 5

molten iron and nickel

Question 6

What is the inner core made up of?

Answer 6

solid iron and nickel

Question 7

The cores temperature is over how many degrees celcius?

Answer 7

5000

Question 8

What is primordial heat?

Answer 8

heat left over from the earths formation

Question 9

What is radiogenic heat?

Answer 9

heat produced by radioactive decay of isotopes

Question 10

Approximately how thick is the earths lithosphere?

Answer 10

approximately 80-90km thick

Question 11

What is Mohorovicic Discontinuity?

Answer 11

semi-molten (plastic-like) rock that can move very slowly

Question 12

How thick is oceanic crust?

Answer 12

6-10km thick

Question 13

How thick is the continetial crust?

Answer 13

30-70km thick

Question 14

Which is more dense oceanic or continential crust?

Answer 14

Oceanic

Question 15

What crust can be subducted?

Answer 15

Oceanic

Question 16

Which crust cant be renewed or destroyed?

Answer 16

Continential

Question 17

How old is the oceanic crust?

Answer 17

less than 2 million years

Question 18

How old is the continental crust?

Answer 18

over 1500 million years

Question 19

What is the oceanic crust made out of?

Answer 19

Basalt

Question 20

What is the continential crust made out of?

Answer 20

Granites/ sedimentary rock

Question 21

What crust moves faster?

Answer 21

Oceanic

Question 22

What are the rules for plate movement?

Answer 22

-Plates cant overlap
- No ‘gaps’ can occur on the surface
- As new crust is created, it must be destroyed somewhere else
-Very little change occurs in the middle of plates

Question 23

How quick is plate movement?

Answer 23

Very slow but continuous approximately 5-10 cm per year

Question 24

How do convection currents occur?

Answer 24

• the earth core radiates heat so the semi-molten lower mantle becomes less dense
• as a result it rises
• then it drags the plates along due to friciton
• eventually the magma cools and becomes denser
• then the dense, cool magma sinks back to the core
• this repeats