Sea Floor Spreading and Plate Tectonics

Fossils of a dinosaur have been found in both southern Africa and South America but nowhere else.  What does this mean?

• The fossils evolved into different organisms. 
• The climate changed and became much colder. 
• In the past, Africa and South America were part of the same continent. 
• In the future, Africa and South America will be part of the same continent.

  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

Climate change over time is evidence to support the theory of continental drift.  Which example below supports this evidence?

• Pangaea broke apart causing an ice age.
• Antarctica drifted farther from the equator causing its climate to cool.
• North America drifted farther from the equator causing its climate to heat up.
• Over time the equator gradually became warmer and the poles became colder.

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.

How do Mid-Ocean Ridges support both the idea of continental drift and the theory of plate tectonics?

•   Oceanic lithosphere is destroyed at mid-ocean ridges.
• New crust forms at mid-ocean ridges.
• Tectonic plates collide at mid-ocean ridges.
• The crust at mid-ocean ridges is old oceanic lithosphere.

  Compare the process that occurs at a mid-ocean ridge to the process that occurs at a deep ocean trench?

• Older rock is formed at the mid-ocean ridge and newer rock is subducted at a deep ocean trench.
• New rock is being created at a mid-ocean ridge and old rock is being subducted at a deep ocean trench.
• Old rock returns to the mantle at the mid-ocean ridge and volcanoes are created at a deep ocean trench.
• Rocks move towards each other at a mid-ocean ridge and move away from each other at a deep ocean trench

Which piece of evidence did Wegener NOT use to support his theory of continental drift?

• Climate
• Sea-floor spreading
• Continents’ shape   
• Plant and animal fossils

What is the name for the process where new ocean floor is constantly being created AND recycled?

• Plate Tectonics 
• Subduction 
• Convection currents       
• Sea floor spreading