Plate Tectonics. Mrs. Anton. Continental Drift Caused By Plate Tectonics. Continental Drift. C ontinents once one large landmass - Pangea Broke and moved apart into 7 continents Alfred Wegener Proof – there are three 1 . Fossil E vidence – Mesosaurus found on Africa and S. America.
3. Mountain Ranges Evidence –
Think of an egg on the surface of boiling water.
Egg moves as convection currents move the water.
When it shows above the water, it’s an island
When a mid ocean ridge (ocean mountain) shows above the water, it’s an island
What is the term used for the chain of mountains on the sea floor?
Where does magma pour out of on the sea floor?
Where is the older sea floor, and where is the younger sea floor?
The older sea floor is closer to the continents and the younger sea floor is close to the rift valley (middle of ocean).
-long v-shaped valley
the deepest part of the
-Many at coast lines of
Subduction Zone – Place where old crust is pushed down into a trench
Evidence #1 – Disappearing Crust
Earth is 4.5 billion years old BUT the oldest rocks on sea floor is only 175 million years old
It is believed – old sea floor has subducted into the trenches, down into the mantle.
What would happen to the Earth if the sea floor didn’t subduct into the trenches?