Download Earth Structure and Plate Tectonics

Chapter 3
Earth Structure and Plate Tectonics
◦ The inner core is primarily
iron and nickel plus other
heavy elements.
It is theorized to be solid
due to enormous
pressure.
◦ The outer core is made up
of the same elements.
This layer is liquid and its
movement is thought to
produce earth’s
magnetic field.
◦ The mantle is thought
to contain mostly
silicon and oxygen, with
some iron and
magnesium.
Solid/liquid mixture
that moves in
convection circles.
◦ The crust is composed
mainly of oxygen,
silicon, magnesium, and
iron. Two types of
crust: continental and
oceanic. Solid.
 Oceanic Crust
 Denser, thinner and younger than
continental crust
 Oceanic crust lies lower on the
mantle because of increased density.
 Continental Crust
 Lighter, thicker and older than
oceanic crust
 Continental crust rises higher above
mantle because of lesser density.
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Color
Include all labels
Use the text to describe each of the layers:
lithosphere, asthenosphere, lower mantle,
core
Use the text to explain how oceanic and
continental crust are different.
Lithosphere - _____________
Asthenosphere - __________
Lower mantle -____________
Core – ____________________
Oceanic vs Continental crust
___________________________
___________________________
___________________________
Sir Francis Bacon (1600s)and Leonardo
DaVinci(1500s)
Noticed that the continents seemed to fit
together like a puzzle
 Alfred Wegener backed up idea with evidence:
Coal deposits and other geological
formations across oceans matched
Fossils of a land reptile across oceans also
matched
Fossilized tropical plants in Antarctica
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 States that continents were once joined
to form Pangaea over 200 million years
ago.
 Broke up into pieces and continents float
on top of a liquid mantle and are
constantly drifting.
 Volcanic activity was powered by
continental movement.
 He incorrectly thought the continents
moved because of the rotation of the
Earth.
 Most detractors did not believe that the
continents could float on top of a liquid
mantle.
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Crust is broken up into lithospheric plates
that move on top of the mantle.
The plates move because of convection
currents in the mantle.
Plate Tectonics Map by USGS
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Zone along the edge of the Pacific Ocean that
has many volcanoes and earthquakes.
This horseshoe-shaped belt stretches about
25,000 miles.
Place where crust moves over
a mantle plume (column of superheated
mantle).
 Magma seeps out, cools, and
hardens: forms an underwater volcano
 Magma continues to build
up until it breaks the surface of the water forming an
island
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Significant because hot spots do not move with tectonic
plates because they originate in the mantle.
Volcanic island chains, are the result of the plate
moving over a hot spot.
◦ 1. Orderly pattern of oceanic ridges and volcanoes
suggesting the Earth’s crust is divided into sections.
◦ 2. Sediment samples – the layers were thin or absent at
the oceanic ridges, and thicker away from the oceanic
ridges. This suggests newer crust at the ridges.
◦ 3. Radiometric dating was used to determine the age of
rocks. Scientists have found seafloor rock to be
significantly younger than rock in the center of the
continents.
◦ 4. Magnetometer data -This instrument measures the
polar orientation of magnetism of minerals. A
symmetrical pattern exists in the magnetic alignment in
seafloor rock. This pattern radiates outward from the
point of seafloor spreading.
Age of Oceanic Rocks:
Red = Newest
Blue = Oldest
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At a spreading or divergent boundary, two
plates are moving apart. As this happens, the
crust pulls apart and forms valleys. Magma
flows up through the rift valleys creating new
crust and widening the seafloor.
At a colliding or convergent boundary, two
plates push together.
◦ They are also called destructive boundaries because
movements along these destroy crust.
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At a transform boundary or fault, two plates
slide past each other.
Divergent Boundary
Mid-ocean ridges
and rift valleys
mark divergent
boundaries.
Cause seafloor
spreading
Volcanoes
along oceanic
ridges
Only one
island above
water: Iceland
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Because it is on a
spreading zone,
magma is very near to
the surface
This produces hot
springs
◦ Pools of warm water
at the surface
◦ Temperatures can be
150°F and more
(very warm bath
water)
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Oceanic-Oceanic
Causes underwater
volcanoes and island
formation.
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ContinentalContinental
collide and “push
together”
forming
mountain chains
◦ Example:
Himalayas
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ContinentalOceanic
The oceanic plate is
subducted
underneath the
continental plate
As plate moves
down into mantle it
melts
Increased magma is
forced up through
surface forming
land volcanoes
◦ Example: Mount
St. Helens
Also called transform faults or
shear boundaries
 Plates move side-by-side, but in
opposite directions
 No sea floor is created or
destroyed
 Earthquake activity
due to friction
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◦ Example: San Andreas
Fault in California
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Use the descriptions in table 3.1 pg 75 to draw all the
types of plate boundaries.
Divergent Boundaries
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Convergent Boundaries
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◦ Ocean-Ocean
◦ Continent-Continent
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Ocean-Ocean
Continent-Continent
Ocean-Continent
Transform Boundaries
Illustrations must be colorful, fill the entire poster,
show direction of plate movement, label type of
boundary, and describe events observed there.