Download InternalExtrnal Notes

Internal/External
Forces
of the
Earth
Inner Structure of the
Earth
1. Inner Core—dense and solid
2. Outer Core—Molten or liquid
• Both are mostly hot and made
of hot metal (iron)
3. Mantle—thick layer of rock
(1800 miles thick); mostly solid,
but has pockets of magma
(melted rock)
4. Crust—very thin layer; rocky
surface
Natural forces interact with
the crust, creating landforms
on the surface of the earth.
·
Below the oceans, the crust is
about 5 miles thick. Below the
continents it averages 22 miles
in thickness.
Inner Structure of
the Earth
Internal Forces that
Shape Landforms
1. Volcanoes—form when magma
inside the earth breaks through
the crust. Lava flows and may
produce a large, cone-shaped
mountain
2. Fault—a break in the earth’s
crust. Movement along a fault
can send out shock waves,
causing an earthquake.
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.
3. The earth’s oceans and
continents ride atop of the
plates.
1.The Ring of Fire is a circle of
volcanic mountains surrounding
the Pacific Ocean
2.Hot Spots are 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.
What Happens
When
Plates Meet?
Converging (Collision) Zone
They collide and push slowly against
each other and form a collision or
converging zone.
•If 2 oceanic plates collide, 1 slides
under the other. Islands often form
this way.
•If 2 continental plates collide,
mountains are formed. Example:
Himalayas
Continental Crush (Collide)
SPREADING ZONE
Plates pull away from each
other and form a spreading
zone. These areas are
likely to have earthquakes,
volcanoes, and rift valleys
(a large split along the
crest of a mountain).
Spreading Zone
They meet, or CONVERGE
and form a subduction zone.
*If an oceanic plate collides
with a continental plate, the
heavier oceanic plate will
slide under the lighter,
continental plate. This
results in volcanic mountain
building and earthquakes.
Subduction
Fault
At a FAULT, the plates will
grind or slide past each other
rather than colliding.
Example: San Andres Fault.