Continental movement

Question 1

What is Alfred Wegner’s Theory

Answer 1

1. Continents were all once together as a supercontinent: Pangea
2. the continents have separated since because of continental drift

Question 2

how many years ago were continents joined together (Pangea) in the Paleozoic era

Answer 2

245 million years ago

Question 3

What were some observations that Wegner made which supported his theory?

Answer 3

1. the continents appear to fit togther like a jigsaw
2. Fossils of the same prehistoric species were found on different continents that were far apart from one another.

Question 4

What layers are tectonic plates composed of

Answer 4

• crust & upper mantle

Question 5

What does the lithosphere consist of?
hint* (what layers of Earth)

Answer 5

• crust & upper mantle

Question 6

The lithosphere floats on a semi-fluid middle mantle that lays below the lithosphere called the??

Answer 6

ASTHENOSPHERE

Question 7

What are these mainly made up of:
- Crust
- Asthenosphere
- Mantle
- Outer core
- Inner core

Answer 7

• solid rock and minerals
• partially melted
• mainly solid
• liquid
• solid

Question 8

Forces that can move tectonic plates include:

Answer 8

• convection currents
• slab pull
• ridge push

Question 9

What are the types of crust

Answer 9

Oceanic crust and Continental crust

Question 10

Ocean crust:

Answer 10

• the solid layer of rock on the ocean floor
• Thin (approx. 5km)
  dense due to presence of iron and magnesium

Question 11

Continental crust:

Answer 11

• Above sea level (continents)
• Thickness (approx. 30km)
• less dense due to the presence of aluminium and silicon

Question 12

What is rifting

Answer 12

• convection currents move tectonic plates away from each other (diverge)
• the movement creates a rift(gap) in the earths crust
• Rifting results in the crust thinning/ cracking/ fracturing

Question 13

what place has experienced rifting?

Answer 13

Lake Thingvallavatn- Iceland

Question 14

Hess’s theory fo sea floor spreading

Answer 14

• when rifting occurs underwater the seafloor spreads

Rifts are filled with new molten rock which cools, creating oceanic ridges (mountains)

Question 15

when rifting occurs and the basin is filled with water what may happen?

Answer 15

Water may leak into other water bodies or slowly fill with rain.

Question 16

what are the three pieces of evidence that support Hess’s theory of seafloor spreading?

Answer 16

1. magnetic striping
2. age of sefloor
3. sediment thickness

Question 17

What is magnetic striping?

Answer 17

The patterns of magnetism trapped in rocks on either side of ocean rifts

Question 18

many rocks contain magnetic iron oixide mineral called?

Answer 18

Magnetite

Question 19

Does magnetite have a seeking pole?

Answer 19

yes
South seeking and north seeking (like a compass)

Question 20

When molten rock solidifies, all the
magnetite lines up with…

Answer 20

Earth’s
magnetic field.

Question 21

The pattern of magnetism is symmetrical:

Answer 21

• the rocks at equal distances on each side of the ridge were formed at the same time
• magnetic fields pointing in the
  same direction

Question 22

Geomagnetic reversals:

Answer 22

• the magnetic poles have been swapping over long periods of time (thousands to millions of years)