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Earth’s Interior and Plate
Tectonics
Physical Science
Section 17.1
This is how the continents
formed….
• http://www.youtube.com/watch?v=TzzGPf
Vx32M&list=PLABDC7B24FAFE33FD
The Earth is like a parfait, it has layers
• If you cut the earth in half, it would look
very much like a parfait, with different
layers and compositions based on density
• The earth has three main layers, the crust,
the mantle, and the core
The Crust
• We live on this layer
• Its is cool, and made of
solid rock
• Oceanic crust is thinner
and denser than
continental crust.
• The crust is the least
dense portion of the earth
and only about 12-25
miles thick
The Mantle
• Layer of rock that is
denser than the crust
• About 1800 miles thick
• Outer mantle is solid rock
• Inner mantle the rocks
are extremely hot and
bendable like gum
(plastic)
The Core
• The center of the earth
• Made mostly of iron and nickel
• The inner core is solid metal while the
outer core is liquid metal
The Earth heats up with depth
• At only 2 miles down the temperature
increase to 120 F
• The core is much hotter than the mantle
• In the core, temperatures reach over
10,000 F
The earth heats up with depth
• The earth gets warmer towards the core
because it contains so many radioactive
isotopes
• These unstable isotopes are constantly
breaking down, releasing huge amounts of
energy, which in turn heat the earth
How do plates move?
http://www.youtube.com/watch?v=ryrXAGY1dmE
Evidence #1:
The Pangea Puzzle • In the 20th century, Alfred
Wegener noticed that eastern S.America fits into western Africa
• He also noticed that several of the other continents fit together like puzzle pieces
• He also found that fossil evidence showed that several of the same organisms are found on continents now separated by oceans
• He theorized that 250 million years ago all the continents combined to form the giant land mass he named pangea
How did this happen?
• The earth’s outer shell, called the
lithosphere is made of the crust and upper
portion of the mantle.
• This lithosphere is very rigid and consists
of 7 large pieces and a few small ones that
fit together like a puzzle
• These large pieces are called tectonic
plates
Plate Tectonics • These plates fit together like puzzle pieces and
move in relation to each other
• these plates move away, towards, or alongside
each other
• Tectonic plates move about 6 inches per year
Divergent Plate Boundaries
• In some areas, the plates move away from
each other
• When this occurs, hot liquid rock called
magma rises and cools, forming new
lithospheric rock
Convergent Plate Boundaries
• Less dense continental plate floats over more dense oceanic plate
• This process is called subduction
• As this more dense rock goes down into the mantle, it heats up and melts
• The magma rises and pushes up the crust, forming volcanic mountains also earthquakes
• Subduction - two plates meet, the more
dense plate (oceanic crust), dives beneath
the less dense plate (continental crust)
Continental vs. Continetal
• Same density
so no
subduction
• Builds non-
volcanic mts.
• Earthquakes
Oceanic vs. Oceanic
• Similar
density, but
subduction
anyway
• Earthquakes,
trenches,
• volcanic
island arcs
Transform Fault Boundaries
• These are areas where plates move along side one another
• As plates move, they can cause cracks in the lithosphere called faults
• As plates move along side each other at these faults, the plates cause a great deal of force and create earthquakes
RECAP
• Divergent Plate Boundaries – Divergent means plates MOVE AWAY from
each other
• Convergent Plate Boundaries – Convergent means plates MOVE TOWARD
each other
• Transform Fault Boundaries – areas where plates move along side one another
• like this or this
•
• Earth is made of 3 main layers
– Crust- cool, thin, made of rock, 10-25 miles
thick
– Mantle, denser than crust, 2500 miles thick,
80% of earth’s volume: inner mantle solid
rock, outer mantle bendable gummy rock
– Core- center of earth, made of iron and nickel,
made of 2 layers: inner solid metal, outer
liquid metal
• Pangea- 250 million years ago all the
continents combined to form the giant land
mass called Pangea
• Lithosphere (earth’s outer shell) is made of
the crust and upper portion of the mantle.
• lithosphere -very rigid and consists of 7
large pieces (called tectonic plates) and a
few small ones that fit together like a
puzzle
• Plate Tectonics
• These plates fit together like puzzle pieces
and move in relation to each other
• these plates move away, towards, or
alongside each other
• Tectonic plates move 6 inches per year
Evidence 2:
Biogeographical
Final views
• http://www.youtube.com/watch?v=QrQDX
nnXOo4&feature=player_embedded#!