plate tectonics theory

Question 1

What is the structure of the lithosphere?

Answer 1

lithosphere: continental crust, oceanic crust & upper mantle
- continental is thicker (70km thick) but less dense
- oceanic is thinner (10km thick) but denser.
- lithosphere is roughly 90km when all sections are added together.

Question 2

What are the 7 major plates?

Answer 2

African Eurasian
Pacific S American
Indo-Australian Antarctic
N American

Question 3

Name some of the other similar plates.

Answer 3

Indian Scotia
Fillipino Arabian
Juan de Fuca Caribbean
Nazca Cocos

Question 4

What is the continental drift theory?

Answer 4

= the theory that these plates move across the mantle relative to each other and in differing directions.

• proposed in 1880 by Alfred Wegener, a German meteorologist and geophysicist.
• was swiftly rejected due to lack of evidence

Question 5

Who are Mantovani and Taylor?

Answer 5

• *Mantovani published a theory about an expanding Earth in 1889
• *Taylor suggested that the crusts were being moved by tidal forces in 1908

Question 6

What is the signifiance of 1912 for Wegener?

Answer 6

this was the time when Wegener found more evidence to support his theory. This entailed:

• rejection of tidal theories
• convection currents caused by the radioactive elements in the Earth’s core heats the semi-molten mantle, causing the molten substance to rise then subsequently fall when it reaches the upper mantle that is significantly colder. This causes a current that pulls repels plates from one another.

Question 7

Why was Wegener’s theory finally accepted in 1950?

Answer 7

Further exploration of the ocean floors created extensive evidence to support his theory.

Question 8

State the idea of continental fit.

Answer 8

some of the continents fit together like a jig-saw e.g. S America and Africa. This supports the idea that there was once a Pangaea and that tectonic drift caused the continents to drift apart.

Question 9

state the climatological evidence for continental drift.

Answer 9

coal deposits have been found in Antarctica. coal can only be formed from tropical woodland.This suggests that the continents were once joined with the same temperatures and humidity but have since parted.

Question 10

state the biological evidence for continental drift.

Answer 10

-marsupials e.g. Kangaroos & Wombats are only found in Australia. this is because the continent moved away from the mainland of Pangaea before predators could invade and kill off these mammals.