Lesson 3

• What is the rate at which tectonic plates move on top of the asthenosphere?

  Between 1 and 10 cm per year
• How do tectonic plates move with respect to one another?

  They can converge, diverge, or move past one another
• What are the regions between tectonic plates called?

  Plate boundaries
• What develops on Earth's crust as tectonic plates move?

  Fractures called faults
• What are the three types of plate boundaries?

  • Divergent Plate Boundary
  • Convergent Plate Boundary
  • Transform Plate Boundary
• What is formed when two tectonic plates move away from each other?

  Divergent plate boundary
• What are the features formed at a divergent plate boundary?

  • New ocean floor
  • Mid-oceanic ridges
  • Rift valleys
• What occurs at a convergent plate boundary?

  Two plates move toward each other
• What are the two main formations at a convergent plate boundary?

  • Subduction zone (one plate moves underneath the other)
  • Orogenic belt (plates collide or compress)
• What are the three kinds of convergence?

  • Oceanic-oceanic collision
  • Oceanic-continental collision
  • Continental-continental collision
• What is formed during an oceanic-oceanic collision?

  Volcanic islands, trenches, and underwater volcanoes
• What happens during an oceanic-continental collision?

  The oceanic plate subducts beneath the continental plate
• What features are formed in an oceanic-continental collision?

  • Volcanic mountains
  • Volcanoes
  • Trenches
• What occurs during a continental-continental collision?

  No subduction happens; the continents unite and create mountains
• What is created as a result of continental-continental collision?

  • Mountains
  • Mountain ranges
• What happens at a transform plate boundary?


  The plates slide against one another in opposite directions
• What is the result of the movement of plates at a transform boundary?


  Earthquakes
• What is an earthquake?


  The shaking of the earth due to the breaking or shifting of rocks
• Why do earthquakes occur?

  Due to pressure underneath Earth's crust pushing blocks of rocks along fault lines
• What is an example of a transform boundary?


  San Andreas Fault
• What is the scientific theory describing the large-scale motion of tectonic plates called?

  Tectonic theory
• What is proposed about today's continents in relation to tectonic forces?

  They were once joined together and gradually drifted apart
• How long ago did tectonic processes begin on Earth?

  Between 3 and 3.5 billion years ago
• Where are the continents cradled?

  By continental tectonic plates found on the lithosphere