The document discusses convection in the mantle and how it relates to plate tectonics. It explains that convection currents, along with ridge push and slab pull, are responsible for the movement of tectonic plates. Ridge push occurs as new ocean crust is formed at mid-ocean ridges, lifting and pushing the plates apart. Slab pull results from the subduction of ocean plates at trenches, where cooling slabs pull the plates into the mantle.

1. 4 6 2
.1 .1
• Article Review due Friday
• Homework: Pg 468 #1-14

2. Ob e t e
j c iv s
• 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

3. Qu s io
et n
What makes the plates move?

4. M n l Co v c io
a te n e t n
• Does anyone remember the
layers of the Earth?
• What about their properties

5. E r hL y r
a t ae s

6. M n l Co v c io
a te n e t n
• 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

7. M n l Co v c io
a te n e t n
• Look at a diagram of the
Earth again
• What role do you think that
convection plays in moving
Earth’s plates?

8. E r hL y r
a t ae s

9. M n l Co v c io
a te n e t n
• 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

10. M n l Co v c io
a te n e t n
• 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

11. M n l Co v c io
a te n e t n
• The edge of the plate
sinking into the trench
pulls on the rest of the
plate
• Called Slab Pull