Continental Drift
Who proposed the theory of Continental Drift?
Alfred Wegener
What tool do scientists use to map the ocean floor?
Sonar
The process where dense ocean crust sinks back into the mantle is called ____________.
subduction
This is the supercontinent that slowly drifted apart over time.
Pangaea
What is a huge underwater mountain range on the seafloor?
Mid-Atlantic (Mid-Ocean) ridge
A deep V shaped valley that forms on the ocean floor where subduction happens is known as a deep-ocean _________.
trench
Why did most scientists reject Alfred Wegener's Theory?
He could not explain how the continents moved.
What is the name of the man who proposed Seafloor Spreading?
Fossils of the tropical plant Glossopteris were discovered in Antarctica. This evidence shows _______________.
Antarctica was once closer to the equator.
The Mesosaurus fossil, a freshwater reptile, was found on both South America and Africa.
What does this show about the continents?
South America and Africa were once touching!
Where is the youngest ocean rock found?
at the mid-Atlantic ridge
Earth's total size doesn't get larger even though seafloor spreading creates new ocean crust because _______________.
Old crust is recycled at deep trenches.
Glacial scratches were found in India.
What does this show you about India's location at one time?
What happens to the older ocean rock?
This heavy, old crust sinks back into the mantle and is recycled.
When old crust moves farther away from the mid-ocean ridge, it becomes ________________.
cooler and denser