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Inside the Earth
Layers of the Earth
• CRUST
• MANTLE
• OUTER CORE
• INNER CORE
Layers of the Earth(p90)
• CRUST (Lithosphere)
– outermost layer
– thinnest layer (5-70km thick)
– consists of loose rocks & soil
– 1% of Earth’s mass
2 Types of Crust
• Continental=
dry land
• Oceanic=
ocean floor
Layers of the Earth
• MANTLE (Asthenosphere)
-layer on which pieces of lithosphere move
(solid rock that moves)
-thickest layer (2900km thick)
-66% of earth’s mass
Layers of the Earth
• CORE
– 2 parts of the core
• 1) Outer Core=liquid iron and nickel spinning
• 2) Inner Core=solid layer of iron and nickel
-33% of Earth’s mass
How do we know?
• Seismic waves
produced by
earthquakes
travel at different
speeds through
solid rock and
liquids
Continental Drift (p95)
• Theory that
continents can drift
apart from one
another and have
done so in the past
• Pangaea= single
landmass
ALFRED WEGENER
THEORY OF CONTINENTAL
DRIFT
•Found evidence for
PANGAEA and
proposed the theory of
continental drift.
• Continents
“fit together”
like puzzle
pieces
WEGENER’S EVIDENCE
•Fossil Evidence
•fossils are remains
of living things that
lived long ago.
•similar fossils have
been discovered in
matching coastlines
on different
continents.
WEGENER’S EVIDENCE
• Mountains
– Some mountain ranges on different continents
seem to match.
• Ex: ranges in Canada match Norway and Sweden
• Ex: Appalachian Mtn. match UK mtn
WEGENER’S EVIDENCE
• Climatic evidence such as glacial deposits
in areas that are now close to the Equator
Theory of Plate Tectonics
• Theory that pieces of lithosphere move
around on top of the asthenosphere
How do the plates move?
• CONVECTION CURRENTS
• Hot material from deep within the Earth
rises while cooler material near the
surface sinks
Convection currents
How do we know?
• Sea-floor spreading
=new ocean floor is
created as two
lithospheric plates
pull away from
one another.
Seafloor spreading
So the plates move.
Now What?
•As the plates move,
they produce changes
in Earth’s surface,
including volcanoes,
earthquakes, mountain
ranges, and deepocean trenches.
Plate Boundaries
• The edges of
different pieces of
The lithosphere
meet at lines
called plate
boundaries
3 Types of Plate Boundaries
Divergent
Convergent
Transform
3 Types of Boundaries
Divergent boundary= two plates move apart
• Magma rises and creates new crust or
seafloor
Ex:
sea-floor
spreading or a
rift
Boundary animation
Divergent Boundaries
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Diverging Africa
edge of the Eurasian continent/plate where it drops into a rift valley
which lies between the former and the North American tectonic plate.
3 Types of Boundaries
• Convergent= when two tectonic
plates push into one another.
Convergent Boundaries
• Continental vs. Continental
• Continental vs. Oceanic
• Oceanic vs. Oceanic
Continental vs. Continental
•When two continental
crustal plates collide,
the continents buckle
upward and form
mountains.
Himalayas- Asia
Himalayas- Asia
Continental vs. Oceanic
•The oceanic plate
slides under the
continental plate.
•The continental crust
crumbles and forms
new mountains or volcanoes.
Subduction Zone
Oceanic vs. Continental
• Ex: Andes mtn in S.
America
Cascade Mtns. in N.
America- Mt. St.
Helens
Oceanic vs. Oceanic
•Two oceanic plates
collide, one of the
oceanic plates slides
under the other.
•also called a
subduction zone
Oceanic vs.
Oceanic Hawaiian
Islands
Transform boundary
• When two tectonic plates slide past each
other horizontally
Produces?
Earthquakes
San
Andreas
Fault
New Madrid Fault
The Plates Move…
So what now?
Which way?
• 50 million years