Lecture 4 - Plate Tectonics Flashcards
What evidence is there for continental drift?
The coastlines of the continents fit together.
Continuities in mountain ranges on opposite sides of the Atlantic ocean.
Similarities of fossil land animals on continents now separated by oceans.
Glacial striations in Australia, India and S. America.
Who suggested the idea of Pangaea?
Alfred Wegener in 1912
Why do glacial striations in Australia, India and S. America provide evidence for Pangaea?
They only make sense when reconstructed into Pangaea. The glaciers flowed outwards from a large ice sheet centred on Antarctica/SE Africa.
What happened to Pangaea in the Jurassic Period?
(180 Ma) Pangaea breaks in two supercontinents: Laurasia and Gondwanaland. India then rifts from Gondwanaland.
What happened to Pangaea in the early Cretaceous?
(135 Ma) North Atlantic starts opening, splitting Laurasia. India continues to move northwards.
What happened to Pangaea at the end of the Cretaceous?
(65 Ma) South Atlantic opens. Italy collides with Europe, raising the Alps. India approaches Eurasia.
What happened to Pangaea in the present day?
Australia has separated from Antarctica. Arabia has rifted from Africa, and India and Arabia have collided with Eurasia.
When did we get the geophysical data that revealed plate tectonics?
World War II and its aftermath
What are plate tectonics?
the mechanism behind continental drift
