1.a) Wegener and continental drift

Question 1

What did Wegener hypothesise in the continental drift theory?

Answer 1

Hypothesised that all continents were one single land mass that drifted over time have drifted apart

Question 2

Whats the name of the one big continent ?

Answer 2

Pangea

Question 3

What are the names of the two continents it split up into ?

Answer 3

1. Laurasia
2. Gondwana

Question 4

Why did Alfred Wegener’s theory of continental drift receive a lot of criticism when it was first published in 1912?

Answer 4

• Inaccurate predictions / being over exaggerated not fitting reality → critical due to his absence of evidence originally
• However this theory was rejected by many academics preferring their own fixed earth paradigm attacking him rather than his ideas

Question 5

What did Ewing find in 1947?

Answer 5

Mid atlantic ridge

Question 6

What did Hess do

Answer 6

• Investigated mid atlantic ridge more finding new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge→ almost causing for the seafloor to spread (so found sea floor spreading)
• It was found fresh asthenosphere rock reached the ocean bed older rock was pushed away → so sea floor spreading moves material across the floor as a ‘conveyor belt’

Question 7

Explain sea floor spreading

Answer 7

• earths magnetic field switches polariy
• As plates diverge a new land is formed
• as lava cools iron within the crust aligns to the polarity of the day
• paried bands move away
• The further away the band the older the rock

Question 8

What is the name of the data that allowed Hess to find mid atlantic ridge ?

Answer 8

paleomagnetic data

Question 9

How does the sea floor spreading links to continental drift theory ?

Answer 9

• Due to increased knowledge about shape and size of crustal plates
• It became clear that the plates were moved by sea floor spreading from the mid ocean ridges to subduction at ocean trenches

Continents were carried by the plates supporting the idea of the breakup of Pangea

Question 10

Define Paleomagnetism

Answer 10

Technology designed to track submarines measured very small variations in Earth’s magnetic field (also known as earths polarity)

• So when used by geologists the magnetic field showed up as a striped pattern across the ocean floor