Plate tectonic theory

Question 1

Who was Alfred Wegener?

Answer 1

a german

Question 2

What was Wegener’s theory about?

Answer 2

the theory was that there was a supercontinent about 300 million years ago, it slit into two continent and that today’s continents were formed from the two continents splitting up.

Question 3

what is the name of the supercontinent?

Answer 3

Pangea

Question 4

what was the name of the southern continent?

Answer 4

Gondwanaland

Question 5

what was the name of the northern continent?

Answer 5

Laurasia

Question 6

what did the geological evidence include?

Answer 6

• the fit of South America and West Africa
• deposits found in South America, Antarctica and India-evidence of late-carboniferous glaciation.
• striations in Brazil and West Africa which indicate a similar situation.
• rock sequences in Northern Scotland and Eastern Canada indicate they were laid down in the same conditions in the same place.

Question 7

what does the biological evidence include?

Answer 7

• fossil brachiopods found in Indian limestone are comparable with similar fossils in Australia.
• fossilised remains of a plant which existed when coal was being formed have been located only in India and Antarctica.

Question 8

what is the mid-Atlantic ridge?

Answer 8

a boundary where two lithospheric were rifting or being pulled apart

Question 9

who created the theory of seafloor spreading?

Answer 9

Harris Hess

Question 10

What did he do?

Answer 10

he was a US navy in WW2?

Question 11

What did he use to create this theory?

Answer 11

Sonar (echo sounding underwater) to map the ocean floor across the North pacific.

Question 12

When was the theory of seafloor spreading published?

Answer 12

1962

Question 13

what did he discover?

Answer 13

oceans were shallower in the middle and identified the presence of Mid Ocean Ridges.

Question 14

what did he theorise?

Answer 14

Oceans grew from their centres and that the crust was destroyed at the ocean trenches.

Question 15

what did Vine and Matthews publish a paper about in 1963?

Answer 15

magnetic anomalies over ocean ridges. (paleomagnetism)

Question 16

what did Vine and Matthews work look at?

Answer 16

magnetic strips on the ocean floor

Question 17

what does the theory say about the Earth’s magnetic field?

Answer 17

the Earth’s magnetic field switches direction over time from its current (normal) direction to the opposite (reversed) direction

Question 18

how often does the Earth’s magnetic field change?

Answer 18

400,000

Question 19

what does material from the mantle do when it rises up through mid-ocean ridges and cools?

Answer 19

preserves a record of the polarity of the Earth’s magnetic field. Due to magnetites in the basalts being strongly magnetic.

Question 20

what was noticed about the pattern of mid-ocean ridges?

Answer 20

there was a symmetrical pattern of magnetic strips

Question 21

what was found once basalts (rocks) were dated?

Answer 21

they were found to be the same age at similar distances away from ridge on each side.

Question 22

What did the symmetrical pattern suggest?

Answer 22

the ocean floor was created by the mid-ocean ridge

Question 23

which scientists works supported Harry hess’s words?

Answer 23

Morley

Question 24

why is palaeomagnetism possible?

Answer 24

minerals that make up the rock become permanently magnetised despite being parallel to the earth’s magnetic field at the time of their formation

Question 25

who was the first person to explain plate movement?

Answer 25

Dan Mckenzie

Question 26

what did Mckenzie put forward in 1966?

Answer 26

Mckenzie submitted his PhD on convection in the Earth’s mantle.