Download The Earth How the crust moves…

Learning Objective
• Identify and describe earth’s major geological processes.
• Describe earth’s major geological hazards.
Agenda
• Notes
Homework
The Earth
• Core: innermost zone, solid
inner part surrounded by
molten rock
• Mantle: layer on which the
crust floats
• Ch. 8 Aquatic Biomes Quiz Zero Hour
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–
•
Asthenosphere: pliable inner
layer
Lithosphere: rigid outer layer +
crust
Crust: outer/thinnest zone
made mostly of oxygen
–
Continental and oceanic
How the crust moves…
• Convection cells move rock and heat in loops
in the mantle like giant conveyor belts causing
rigid plates (tectonic plates) to move
extremely slow over the surface.
– “Float” on the asthenosphere
• Much geological activity takes place at the
plate boundaries
Pg. 346
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The Earth’s 15 Major Tectonic Plates
3 Major Kinds of Plate Boundaries
• The extremely slow movements of these plates cause
them to move apart , grind into one another, and/or
slide past one another.
Divergent Plate Boundaries
• Oceanic plates moving
apart from one another
in the ocean, causing
magma to flow up.
– Creates oceanic ridges
Transform Faults
• Plates slide and grind
past one another along
a fracture in the
lithosphere.
• Most are located on
ocean floor, a few on
land
– Friction spawns
earthquakes along slipstrike faults
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Convergent Plate Boundaries
• Plates collide into one
another
• Oceanic-continental:
continental less dense
so rises above
oceanic; oceanic
pushed down
(subduction)
Convergent Plate Boundaries
• Oceanic-oceanic: a
trench usually forms
– Also causes island arcs
– Forms volcanoes
Convergent Plate Boundaries
• Continentalcontinental: push up
mountain ranges
Plate Tectonics video
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Hot Spots
• Fixed places in the
mantle or oceanic
lithosphere where rocks
melt to generate
magma.
Plate Boundaries WS
– In the ocean, it can create
shield volcanoes that may
build high enough to
become volcanic islands
(Hawaii)
– The Yellowstone hotspot
creates calderas
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