Objective 10/15/12
Describe the three forces thought to move tectonic plates.
Intro
•Pick up worksheet from front table.
•Weekly Worksheet #8:
•What do you think causes tectonic plates to move?
Causes of Plate Motion
• 3 causes of plate
motion
• Convection Currents
• Ridge Push
• Slab Pull
Causes of Plate Motion
• Ridge Push
• New magma pushes
older rock at mid-ocean
ridges
Causes of Plate Motion
• Slab Pull
• Gravity pulls down the
subducting plate back
into the mantle
Causes of Plate Motion
• Convection
Currents
• Hot magma expands
and rises
• Cool magma sinks
• Changes in density
Causes of Plate Motion
• Mantle Plumes
• An upwelling of hot
magma from the core
• Creates volcanic “hot
spots”
• Example:
– Hawaii
– Yellowstone N.P.,
Wyoming
Objective 10/15/12
Describe the three forces thought to move tectonic plates.
Outro
List two ways convection currents affect your life.