Sea-Floor Spreading and Plate Tectonics

___________ help explain why Earth is not getting any larger even though the tectonic plates are always moving.

• earthquakes
• subduction zones
• fossils
• volcanoes

If there are MORE mid-ocean ridges than subduction zones, what happens to the ocean?

• It gets larger
• It gets smaller
• It sinks
• Its size does not change

What type of boundary moves side by side in opposite directions?

• Convergent
• Divergent
• Transform
• Insurgant

The average density of one of the continental crusts is 2.8 g/cm³ and the average density of one of the oceanic crusts is 3.2 g/cm³. If these two plates came together, what could be expected to happen? 

•   The two plates would push apart and form a rift zone. 
• The oceanic plate would rise up over the continental plate. 
• The oceanic plate would be pushed under the continental plate. 
• The two plates would meet head on and rise up to form mountains.

  Sea-floor spreading states that new ocean crust is being formed constantly.  Which of the following is also true?

• The oceans are constantly getting bigger.
• The amount of land on earth is constantly increasing.
• The amount of land on earth remains the same due to subduction.
• When the size of the crust reaches a certain amount, sea-floor spreading will stop.

Which of the following objects best represents the movement that occurs during sea-floor spreading?

• Elevator
• Conveyor belt
• Rollercoaster
• Hot air balloon

What process is occurring at Z?

• Convection currents       
•  Subduction 
• Two plates moving apart
• New ocean floor forming

Why does the ocean floor sink beneath the continent at Z?

• The ocean floor is less dense than the continent.
• The ocean floor is more dense than the continent.
• The ocean floor is moving faster than the continent.
• The ocean floor is moving slower than the continent.

What do convergent (oceanic and oceanic) plates form?

• Mountains
• Rift valley
• Subduction, Volcanoes, & Trenches

What do convergent (continental and continental) plates form?

• Volcanoes, subduction, trenches
• Rift valley
• Mid-Ocean Ridges
• Mountains