Transcript Power Point - Fort Bend ISD

Bell Ringer
Take out a sheet of paper, put your name on it.
Write your answer to the questions.
1. What type of tectonic activity made Hawaii?
2. What activity within the mantle causes plate
movement?
3. What type of erosion created the Great
Lakes?
4. What type of plate boundary is the San
Andreas fault in California.
5. What type of external force of change
carries away pieces of rock and creates
sediment?
Earth is composed
of 3 layers:
1. Core
2. Mantle
3. Crust
1. Core (inner &
outer) – made of
iron & nickel
a. inner – super
hot solid
-about 4,000 mi.
below surface of
earth
b. outer – super
hot liquid
-about 1,800 mi. below the
surface of earth
-temperatures can reach
8,000*F
2. Mantle
-hot, dense
mostly liquid
rock
-pockets of
magma (rise &
fall)
-made of
silicon,
aluminum,
iron,
magnesium,
and oxygen
3. Crust
-rocky shell
which forms
earth’s surface
-broken into
more than a
dozen slabs of
rock called plates
that rest on layer
of the upper
mantle
-these plates
carry earth’s
oceans &
continents
-Continental Drift :
theory that
continents were
once joined and
then slowly drifted
apart
*super-continent
was called Pangaea
PANGEA
-Plate Tectonics – term scientists use to
describe the activities of continental drift and
magma flow which create many of Earth’s
physical features
*plates crash into each other, pull apart, or grind
and slide past each other (about 4 inches or
less per year)
-Why do plates move?
-convection currents
*hotter material is less
dense & rises (toward
crust of Earth)
*cooler material is more
dense & sinks (toward
core of Earth)
*creates continuous
circular
motion/movement
Why might a scientist want to study plate
tectonics?
Divergent Boundary
-Plates move apart (rift) from each other (tension)
1. Continental-Continental = creates gap (rift
valley) in which water can flow in
*ex: Red Sea; Great Rift Valley
2. Oceanic-Oceanic = magma rises up & creates
new crust on edges of the 2 plates
-enlarges the ocean floor & forms underwater
mountain ranges called ocean ridges
*example: Mid-Atlantic Ridge
– North American plate & Eurasian
& African plates pulling apart
Convergent Boundary
In general:
- Plates move
toward each
other & collide
(compression)
- One plate is
forced below
the other
(subduction)
1. Oceanic-Continental
-subduction occurs = heavier sea plate
dives beneath lighter continental plate
*sea plate begins to melt into magma 
pressure builds  magma bursts thru crust to
form volcanic mtns
*ex: Andes
Mountains
in S.
America –
collision of
Nazca and
SA plates
2. OceanicOceanic
-subduction
occurs
*sea plate
begins to melt &
magma rises to
ocean surface in
form of volcanic
islands
*example:
Philippine islandscollision of
Philippine &
Pacific
plates
3. ContinentalContinental
-pressure builds
until one plate is
subducted
*sometimes sinking
plate melts & rises as
volcanic mountains are
formed
*example: Himalaya
mountains (South
Asia) – collision of
Indian & Eurasian
plate
Transform Boundary
-Plates slide past each other along faults
(cracks in the earth’s crust)
- Crust is pulled and stretched (tension) until
tension is released (Earthquake)
-example: San Andreas Fault in California
HOT SPOTS
-Magma rises thru
the tectonic plate
-The magma erupts
on the surface as
lava & hardens to
form volcanic islands
-Magma continues to
rise from the hot
spot, building up an
undersea volcano
that will one day
become an island
-a chain is formed
Animations
Hot Spot Animation
Guess the
Tectonic Activity!
Oceanic-Oceanic Convergent
Oceanic-Oceanic Divergent
Transform
Continental-Continental Convergent
Continental-Continental Divergent
Oceanic-Continental Convergent