Download Notes : Motion of the Lithosphere

2/10/17
MOTION OF THE
LITHOSPHERE
Objective: I will diagram the driving
mechanism for lithospheric motion,
convection within the mantle.
Page 59
Mantle Convection
• Convection- movement of heated material due to
differences in density
• caused by differences in temperatures
• Scientists believe the movement of the
lithosphere is due to convection in the mantle
(asthenosphere)
Mantle Convection
Mantle Convection
• Heat from the core transfers to the mantle
• Within the asthenosphere:
• As hot (less dense) material rises, cooler (more
dense) material flows away and sinks into the
mantle to replace the rising material
• As the material moves, it drags the overlying
lithosphere along with it
Mantle Convection
Ridge Push
Ridge Push
• Seafloor spreading is driven by convection
in the asthenosphere
• This exerts a force on the lithosphere
called ridge push
Ridge Push
Slab Pull
Slab Pull
• As oceanic crust moves away from the ridge, it
becomes more dense
• When it comes in contact with less dense
continental crust, the oceanic crust is pulled under
• this process is called subduction
• A force is exerted, called slab pull, that drags the
rest of the lithosphere
• Ridge push and slab pull work together to move
the lithosphere
Slab Pull
Animation
Output Activity (page 58)
• Using Figure 6 from textbook Page 252
• Diagram convection within the mantle
• Label all parts of the process
• Identify where ridge push and slab pull
occur
• Make the diagram big and detailed