Transcript Mechanisms of Plate Motion

EARTH SCIENCE JOURNAL
DATE:
• Examine the diagram above. Describe the
movement of the plates and the processes
that are occurring.
• What type of plate boundary is this?
Mechanisms of Plate Motion
• MANTLE
CONVECTION
CURRENTS
• Mantle rock is so
warm that it
churns slowly
around like very
very thick syrup
boiling on the
stove!
Mechanisms of Plate Motion
• MANTLE PLUMES
AND HOT SPOTS
• Hot spots are created
by mantle plumes.
• Mantle plumes are hot
currents that rise all
the way from the core
through the mantle.
• Mantle plumes can
come up under the
crust and burn their
way through to create
hot spot volcanoes.
Mechanisms of Plate Motion
• HOT SPOTS stay
in the same place
while tectonic
plates move over
them.
• Each time the plate
moves the hot spot
creates a new
volcano. (Hawaiian
Islands)
Hot Spots track plate movement!
Click here to see this in motion
Shifting Poles
Paleomagnetism
• The magnetic poles
typically wander
around slowly.
• But every so often
flip completely,
reversing the
magnetic polarity
of the planet.
More Evidence of Plate Tectonics
• The experts are reasonably sure the earth's
magnetic field is a result of movement in the
planet's liquid iron and nickel core.
• As the iron-rich magma pushing up from beneath
the plate boundary cools and spreads out, the
mineral crystals align themselves with the
magnetic field as it then exists.
• The alternating stripes indicate field flip-flops
over geological time.
The alternating stripes indicate field flipflops over geological time.
Magnetic Reversals Record SeaFloor spreading