Video 3: The Endless Voyage
The World in Motion

Basics:

• There is a relationship between the deep sea floor and plate tectonics.  Is sea floor spreading associated with shallow or deep ocean?  Is subduction associated with shallow or deep ocean?
• Which kind of boundary has the most violent earthquakes (where plates separate, or where they come together?
• How deep do old ocean lithosphere go into the mantle? 
• What is the remarkable phenomenon that occurs at 600 km depth?
• What is the zone of earthquakes that marks the trajectory of earthquakes from the trench into the mantle called?

Divergent plate boundary:

• When two ocean plates separate at a divergent boundary what fills the void?
• Is divergence occurring on any continental plate? 
  What about in the U.S.? 
• How does the total volcanism generated at divergent plate boundaries compare to that in convergent and transform plate boundaries?
• How did the spreading rates 100 million years ago compare to those of today?

Convergent plate boundaries

• Why does a lithospheric slab subduct (what is the force that causes it to dive into the Mantle)?
• What do the Cascade Mountains, the Andes and Japan's mountains have in common?

Transform plate boundaries

• What is the relative motion between two plates at a transform boundary?
• What are the two plates that are separated by the San Andreas Fault?
• What occurs along transform boundaries that may be destructive to human activity?

Other features of the sea floor

• What is a sea mount?
• What is a Guyot?
• Where was the source of volcanism for the Hawaii-Emperor seamount chain located?  What is this phenomenon called?

Driving mechanisms for Plate Tectonics

• What can we learn about the earth's interior from mantle zenoliths?  What are mantle zenoliths?
• How hot is the earth at it's core (compared to the heat at the surface of the sun)?
• Why is the earth hot at it's core?
• What is the process by which the earth loses it's heat?

Questions still being asked about Plate Tectonics

• How long has active tectonics been going on in the mid continental rift of the United States? 
• Can we predict earthquakes and volcanic eruptions?
• How well can we predict what the earth will look like 100 million years in the future?
• The contact between the east coast of North America and the North Atlantic is not a plate boundary.  If it becomes one in the future, what is the most likely kind of boundary?  What will happen to the North Atlantic Ocean as a result?