Download Crust

The Structure of the Earth
and Plate Tectonics
By: Ms. Nikki
Journey to the
Center of the
Earth
What would I
find if I
journeyed to
the center of
the Earth?
How did the layers form?
How did the layers form?
• The Earth’s layers were
formed because of
density.
How did the layers form?
• The Earth’s layers were
formed because of
density.
–The heavier, more dense,
materials were pulled in
more by gravity.
How did the layers form?
• The Earth’s layers were
formed because of density.
–The heavier, more dense,
materials were pulled in
more by gravity.
–Lighter, less dense, materials
were not pulled in as much
by gravity.
What are the layers made
of?
What are the layers made
of?
• Inner Core: solid iron (Fe)
and Nickel (Ni).
What are the layers made
of?
• Inner Core: solid iron (Fe)
and Nickel (Ni).
–Pressure is 48 to 52 million
psi.
What are the layers made
of?
• Inner Core: solid iron (Fe)
and Nickel (Ni).
–Pressure is 48 to 52 million
psi.
–Temperatures range from
about 9,000 to 12,000
degrees Fahrenheit.
What are the layers made
of?
• Outer core: liquid iron (Fe)
and Nickel (Ni).
What are the layers made
of?
• Outer core: liquid iron (Fe)
and Nickel (Ni).
–Temperatures range from
about 4,400 to 6,100 degrees
Fahrenheit.
What are the layers made
of?
• Outer core: liquid iron (Fe)
and Nickel (Ni).
–Temperatures range from
about 4,400 to 6,100 degrees
Fahrenheit.
–It is believed that the Earth’s
magnetism is produced here.
What are the layers made
of?
• Mantle:
What are the layers made
of?
• Mantle:
–Made of various minerals
(Iron (Fe), Magnesium (Mg),
Aluminum (Al), Silicon (Si),
and Oxygen silicates ) that
are in constant motion.
What are the layers made
of?
• Mantle:
–Made of various minerals
(Iron (Fe), Magnesium (Mg),
Aluminum (Al), Silicon (Si),
and Oxygen silicates ) that
are in constant motion.
–Temperatures of up to 6,700
degrees Fahrenheit.
What are the layers made
of?
• Crust:
What are the layers made
of?
• Crust: The top layer of the
Earth
What are the layers made
of?
• Crust: The top layer of the
Earth
–The two types are continental
and oceanic.
What are the layers made
of?
• Crust: The top layer of the
Earth
–The two types are continental
and oceanic.
–Made of mostly Silicon (Si),
Aluminum (Al), Calcium (Ca),
Sodium (Na), and Potassium
(K)
What are the layers made
of?
• Crust: The top layer of the
Earth
–The two types are continental
and oceanic.
–Made of mostly Silicon (Si),
Aluminum (Al), Calcium (Ca),
Sodium (Na), and Potassium
(K)
–Fractures during
earthquakes.
Where is the lithosphere?
Where is the lithosphere?
• The lithosphere
contains:
Where is the lithosphere?
• The lithosphere
contains:
–The crust.
Where is the lithosphere?
• The lithosphere
contains:
–The crust.
–A small layer of the upper
mantle.
Where is the lithosphere?
• The lithosphere contains:
–The crust.
–A small layer of the upper
mantle.
• Large chunks or plates that
move gradually because they
ride on hotter parts of the
mantle.
Where is the lithosphere?
• The lithosphere contains:
–The crust.
–A small layer of the upper
mantle.
• Large chunks or plates that
move gradually because they
ride on hotter parts of the
mantle.
–These “chunks” or plates
make up the surface of the
Structure of the Earth
• The Earth is
made up of 3
main layers:
– Core
– Mantle
– Crust
Crust
Mantle
Outer core
Inner core
What IS the Lithosphere?
• The lithosphere is made up of
the crust and small layer of the
upper mantle that together form
large chunks or plates that move
gradually because they ride on
hotter mantle. These plates make
up the surface of the Earth.
Warm Up
• 1. Take out a piece of paper and
put your name on it.
• 2. BE QUIET!
The Crust
• This is where we live!
• The Earth’s crust is
made of:
Continental Crust
Oceanic Crust
- thick (10-70km)
- buoyant (less dense
than oceanic crust)
- mostly old
- thin (~7 km)
- dense (sinks under
continental crust)
- young
How do we know what the
Earth is made of?
• Geophysical surveys: seismic, gravity,
magnetic, electrical, geodesy
– Acquisition: land, air, sea and satellite
– Geological surveys: fieldwork, boreholes, mines
• http://video.google.com/videoplay
?docid=4835712194315869074#
What are Plate Tectonics?
• If you look at a map of the world, you may notice that
some of the continents could fit together like pieces of a
puzzle.
Plate Tectonics
• The Earth’s crust is divided into 12
major plates which are moved in various
directions.
• This plate motion causes them to collide,
pull apart, or scrape against each other.
• Each type of interaction causes a
characteristic set of Earth structures or
“tectonic” features.
• The word, tectonic, refers to the
deformation of the crust as a
consequence of plate interaction.
World Plates
What are tectonic plates made
of?
• Plates are
made of rigid
lithosphere.
The lithosphere is
made up of the
crust and the upper
part of the mantle.
What lies beneath the tectonic
plates?
• Below the
lithosphere
(which makes
up the
tectonic
plates) is the
asthenospher
e.
Continents of the Past
• “Pangaea” : exists ~ 225 million years
ago
– Supercontinent: the only continent on
Earth
• Division of Pangaea ~ 135 million years
ago
– Into “Laurasia” (N. Hem)
• Included modern North America & Eurasia
– And “Gondwana” (S. Hem)
• Included modern South America, Africa,
Antarctica, Australia, Madagascar, India and New
Zealand
250 Million Years Ago
200 Million Years Ago
135 Million Years Ago
Jurassic Period
65 Million Years Ago
Present Day
In 50 Million Years
In 150 Million Years
In 250 Million Years
What is a convection
current?
• A convection current is a circular
flow due to molecules heating,
moving faster, and becoming less
dense-so they weigh less and rise.
• When they cool, they move slower
and closer together-so they weigh
more per space and sink.
Plate Movement
• “Plates” of lithosphere are moved
around by the underlying hot mantle
convection cells
e
Warm Up
• 1. What is the lithosphere?
• 2. List the EM spectrum in order
from lowest frequency to highest.
• 3. How do we hear?
• 4. What is refraction?
• 5. How do plates move?
What happens at tectonic
plate boundaries?
Three types of plate boundary
• Divergent
• Convergent
• Transform
Divergent Boundaries
• Spreading ridges
– As plates move apart new material is
erupted to fill the gap
What happens when plates
move toward each other?
• This is called a Convergent
boundary
– The continental plates push up and
make mountains OR….
DRAW
Plate Boundaries
• It’s called Subduction
– When one plate dives under the
other.
Subduction
Plate Boundaries
• Transform boundary
– Happens when 2 plates beside each
other move in opposite directions
• http://science.discovery.com/tvshows/greatestdiscoveries/videos/100-greatestdiscoveries-plate-tectonics.htm
• http://www.youtube.com/watch?v
=KCSJNBMOjJs&safe=active (15
mins)
Age of Oceanic Crust
Courtesy of www.ngdc.noaa.gov
Iceland: An
example of continental rifting
• Iceland has a divergent
plate boundary running
through its middle
Convergent Boundaries
• There are three styles of
convergent plate boundaries
– Continent-continent collision
– Continent-oceanic crust collision
– Ocean-ocean collision
Continent-Continent Collision
• Forms mountains, e.g. European Alps,
Himalayas
Himalayas
Continent-Oceanic Crust Collision
• Called SUBDUCTION
Subduction
• Oceanic lithosphere
subducts underneath the
continental lithosphere
• Oceanic lithosphere
heats and dehydrates as
it subsides
• The melt rises forming
volcanism
• E.g. The Andes
Ocean-Ocean Plate Collision
• When two oceanic plates collide, one
runs over the other which causes it to
sink into the mantle forming a
subduction zone.
• The subducting plate is bent downward
to form a very deep depression in the
ocean floor called a trench.
• The worlds deepest parts of the ocean
are found along trenches.
– E.g. The Mariana Trench is 11 km(6.8
miles) deep!
Transform Boundaries
• Where plates slide past each other
Above: View of the San Andreas
transform fault
Plate Tectonics Summary
• The Earth is made up of 3 main layers
(core, mantle, crust)
• On the surface of the Earth are tectonic
plates that slowly move around the
globe
• Plates are made of crust and upper
mantle (lithosphere)
• There are 2 types of plate
• There are 3 types of plate boundaries
• Volcanoes and Earthquakes are closely
linked to the margins of the tectonic
plates