4/16
DESCRIPTION
Notes for Monday's classTRANSCRIPT
4.16.12
Article Review due Friday
Homework: Pg 468 #1-14
Objectives
Explain the process of convection.
Summarize how convection in the mantle is related to the movement of tectonic plates.
Compare and contrast the process of ridge push and slab pull
Question
What makes the plates move?
Mantle Convection
Does anyone remember the layers of the Earth?
What about their properties
Earth Layers
Mantle Convection
remind me how a convection current works
A substance warms and becomes less dense
It rises
As it cools it becomes more dense
It sinks
Mantle Convection
Look at a diagram of the Earth again
What role do you think that convection plays in moving Earth’s plates?
Earth Layers
Mantle Convection
As magma rises at a ridge it forces the plates apart
Magma that cools at the ridge forms new ocean floor
The sideways movement of the magma pulls the plate
Cooling, sinking magma pulls plates into the subduction zone
Mantle Convection
Convection currents alone aren’t enough to push the plates
When magma rises the ridge is lifted up
Gravity causes the ridge to push the plate towards the subduction zone
Called Ridge Push
Mantle Convection
The edge of the plate sinking into the trench pulls on the rest of the plate
Called Slab Pull