The development of plate tectonic theory Scientists agree that the plates move, but there is still debate over the mechanisms that cause the movement

Question 1

What is Wegners theory 1912

Answer 1

of continental drift

(He hypothesized that all of the modern-day continents had previously been clumped together in a supercontinent he called Pangaea

Question 2

How did Harry Hess reveal shape of ocean floor 1940

Answer 2

sonar and radar

( he had discovered that hundreds of flat-topped mountains, perhaps sunken islands, shape the Pacific floor.)

Hess explained how the once-joined continents had separated into the seven that exist today. The continents don’t change dramatically or move independently, but are transported by the shifting tectonic plates on which they rest.)

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Question 3

What happened in 1960

Answer 3

Crust samples gathered and radiometric dating carried out

Question 4

What did Wilson propose 1963

Answer 4

Sea floor spreading

(describes the repetitive opening of ocean basins by seafloor spreading, and closure by subduction, resulting in continental collision and orogeny, followed eventually by continental drifting, leading to seafloor spreading.

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Question 5

What do Wilson and Hess propose in 1965

Answer 5

They propose the theory of plate tectonics combining sea floor spreading with continental drift

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