Continental Drift, Sea-floor Spreading, & Plate Boundaries

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.

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

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.

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.

Predict what the Earth will look like in 3 million years as sea-floor spreading continues.

• The Rocky Mountains will be taller than they are now.
• The continents will drift back to their original Pangaea positions.
• The oceans that produce more rock than it subducts will decrease in size.
• The oceans that have a mid-ocean ridge but fewer deep ocean trenches will continue to grow.

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.