9.3 theory of plate tectonics. i. earth’s moving plates a.earth’s crust is broken into large...
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B.Cause of Movement: convection currents in the mantle C.Effect: plates move 5 cm per year 1.Results: earthquakes, volcanoes, mountainsTRANSCRIPT
9.3 Theory of Plate Tectonics
I. Earth’s Moving PlatesA.Earth’s crust is broken into LARGE
pieces called “plates”1. Plates contain continents and oceans 2. Faults = cracks between each plate
a. separate each plate
B.Cause of Movement: convection currents in the mantle
C. Effect: plates move 5 cm per year 1. Results: earthquakes, volcanoes,
mountains
9.4: MECHANISMS OF PLATE MOTION
I. CAUSE OF PLATE MOTIONA.Convection Currents 1.Movement of material due to
differences in densitya. Warm material less dense &
risesb. Cool material is more dense &
sinks2.Occurs in the mantle3.Heat source: the core (middle
of Earth)4.Plates are the “top” of the
currentshttps://www.youtube.com/watch?v=kwfNGatxUJI
II. MANTLE CONVECTION
A.Downward movement: 1. Slab-pull: gravity pulls old crust
into the mantle2.Ridge-push: crust slides below into
the mantleB.Upward movement:
1.Mantle plumes: rising column of mantle rock to the crusta. Creates "hot spots“ & volcanoes
https://www.youtube.com/watch?v=ryrXAGY1dmE