Transcript Structure of the Earth Crust

Forces
of
Change
Spheres of Earth
A.Lithosphere: includes all
landmasses on Earth - about
30% of the Earth’s surface
B. Hydrosphere: includes all
water bodies on Earth - about
70% of the Earth’s surface
C. Atmosphere: the layer of
gasses extending 1,000 miles
above the Earth’s surface - 78%
Nitrogen, 21% Oxygen
D. Biosphere: supports all life
on Earth - animals, humans,
and plants
Internal
Forces
of the Earth
Structure of the Earth
Structure of the Earth
A Layered
Planet:
-Inner Core
- Outer Core
- Mantle
-Crust
Structure of the Earth
Inner Core—
super hot,
dense and
solid iron and
nickel
Outer Core Molten or
liquid iron
and nickel
Structure of the Earth
Mantle—
Thick layer of
rock (1800
miles thick);
mostly solid,
but has
pockets of
magma
(melted rock)
Structure of the Earth
Crust— very
thin layer;
rocky
surface
•
Below the oceans,
the crust is about 5
miles thick. Below
the continents it
averages 22 miles
in thickness.
The Plate Tectonic Theory
1. The lithosphere— the earth’s crust and
upper layer of the mantle —are broken
into a number of large, moving plates.
2. The plates slide very slowly over a
hot, pliable layer of mantle.
Mantle
3. The earth’s oceans and continents
ride atop of the plates and constantly
pull apart, collide, and grind against
one another at plate boundaries
4. This constantly changes the
Earth’s surface
- pushes up mountains
- creates new land
5. Most earthquakes &
volcanoes occur along the
plate boundaries.
The Ring of Fire is a circle of
volcanic mountains surrounding
the Pacific Ocean
Ring of Fire
What Happens When
Plates Meet?
Nice to
meet you!
Tectonic Plates Move in 3 Ways
Convergent = Collide
Two of a Kind Oceanic
• If 2 oceanic plates
collide, one slides
under the other.
• Islands often form
this way.
Convergent
Two of a Kind - Continental
• If 2 continental plates collide, the land
folds or cracks into huge blocks.
• Example:
Mountains
Continental Convergent
Convergent
Two Different
A.When a continental and sea plate meet, the
heavier oceanic plate slides under the lighter
continental plate.
• The sea plate becomes magma
and burst to through
the crust to form
volcanic mountains.
This is called Subduction
Convergent
Two Different
B. Or when sea plates
slide under continental
plates, they leave
behind debris. This can
cause continents to
grow outward. It is
called accretion.
Divergent = Pull Away
Plates pull apart from each other and the
deep rift, or crack, allows magma to well
up between plates.
These areas are
likely to have
earthquakes,
volcanoes, and
rift valleys.
Spreading Zone
Two sea plates moving away
Transform =Move Horizontally
•When they meet, friction can lock them
into place for a long periods, allowing
pressure to build below the crust.
•When the pressure gets too great the
plates come unstuck and move. This is an
earthquake.
Fault
At a FAULT, the
plates will grind or
slide past each
other rather than
colliding.
Example: San
Andres Fault.
Other Information
Hot Spots
Hot regions deep within the mantle that
produce magma, which rises to the surface.
Volcanic island chains form as oceanic plates
drift over the hot spot.
Example:
Hawaiian Islands.