Plate Tectonics- content

Question 1

An example for jigsaw fit

Answer 1

Africa and South America seem to fit together

Question 2

An example for geological evidence

Answer 2

• rocks of the same age and type and displaying the same formations are found in SE Brazil and South Africa
• mountains in Canada and Scotland are similar
• glacial deposits are found in Antarctica, South America and India

Question 3

An example of climatological evidence

Answer 3

Antarctica, North America, Svalbard and the UK all contain coal deposits of similar age that were formed in wet, tropical conditions

Question 4

An example of biological evidence

Answer 4

Mesosaurus

Glossopteris

Question 5

What was the problem with Wegener’s theories?

Answer 5

They were unable to explain how continental movement had occurred

Question 6

What happened in the 1950s?

Answer 6

In the 1950s, nuclear submarines were used to map the ocean floors with better accuracy. They found the Mid Atlantic Ridge, an underwater mountain chain and deep ocean trenches which were seismically active.

Question 7

What happened in 1962?

Answer 7

Harry Hess studied the age of the rocks on the Atlantic sea floor and found that the youngest were in the middle next to the ridge and the oldest further out near the USA and Caribbean, and so the floor must be spreading out from the centre.

Question 8

What is the result of palaeomagnetism?

Answer 8

The result is a series of magnetic stripes. The striped pattern is mirrored across the Atlantic ridge so suggests that the ocean crust is spreading away from the boundary.

Question 9

What was the new issue that the discovery of sea floor spreading brought up?

Answer 9

It implied that the Earth must be getting bigger, but it wasn’t

Question 10

How was the issue solved?

Answer 10

It was solved with the discovery of ocean trenches, where crust is being destroyed, such as that in the Pacific Ocean.

Question 11

What are the physical formation evidence that supported sea floor spreading?

Answer 11

• mid oceanic ridges
• magnetic stripes
• oceanic trenches
• convection currents in the asthenosphere

Question 12

How many major plates is the Earth split up into?

Answer 12

Seven major plates

Question 13

What are the seven major plates?

Answer 13

1. Pacific Plate
2. North American Plate
3. South American Plate
4. Antarctic Plate
5. Eurasian plate
6. Indo-Australian plate
7. Nazca Plate

Question 14

What are the four main evidence for Wegener’s theory of continental drift?

Answer 14

1. Jigsaw fit
2. Geological evidence
3. Climatological evidence
4. Biological evidence