Plate Tectonics Flashcards
(10 cards)
What is the age of the earth?
About 4540 million years
What are the oldest rocks on the continent??
3900ma - million years
What are glaciations?
Matching outcrops found in rocks from South America, India and Africa
What is the idea of passive tectonics?
That the plates were carried along convention currents - the mantle motion was what drove this
What is the idea of active tectonics?
The sinking of plates is what drives the process
Why are convention currents not a reason for plate motion anymore? 2 points
No correlation between speed of plate motion and size of the plate
Currents don’t have enough energy
What is ridge push?
At constructive plate margins, magma rises to the surface and forms new crust and heats area which expands and rises above surface of surrounding crust and new crust cools and is more dense
What is slab pull?
At destructive plate margins, denser crust is subducted under less denser crust and the sinking of the plate edge pulls the rest towards the boundary
What is sea floor spreading?
As tectonic plates diverge, magma rises to fill gap created and then cools to form new crust and floor gets wider overtime
When does sea floor spreading occur?
When 2 plates diverge
