Download Theory of Plate Tectonics

Theory of Plate Tectonics
Key Vocabulary
Lithosphere = Rigid Rock, Crust and
upper Mantle
Asthenosphere = hot weak zone found
within the upper Mantle, allows the
Lithosphere to move
Rift Valley: found at divergent plate
boundaries with continental crust
(Red Sea)
Seafloor Spreading: occurs at
divergent plate boundaries (for
example, the Atlantic Ocean is getting
larger) Mid Atlantic Ridge
Volcanic Island Arcs: at Convergent
Plate Boundary, Aleutian Chain, Tonga
Islands and Japan
Continental Volcanic Arc: at
Convergent Plate Boundary, Andes,
Cascade Mnts.
Driving Mechanisms for Plate
Tectonics: Core: upwelling and slab
pull
Convergent Plate Boundaries
: occur when edges of continental or oceanic plates move toward each other and collide. Lithosphere is destroyed.
Subduction Zone
: when an oceanic plate collides with a continental plate, the oceanic plate bends underneath the continental plate. Convergent Plate Boundaries Continued
Deep Sea Trench
: forms when the sub­
ducting plate bends as it sinks. (up to 11 km deep)
Divergent Plate Boundaries: occur when plates separate. (mid­Atlantic ridge) Lithosphere is created.
Mid Ocean Ridge
: an underwater chain of volcanoes which forms from the less dense rising hot rock moving above the cold and dense oceanic rock.
How ocean ridges form
Convection Currents Driving Plate Tectonics
Two main components
1 ­ Slab Pull: this occurs at Convergent Plate Boundaries. The plate that is more dense gets pulled by gravity downward. This pulls on the rest of the plate behind it.
2 ­ Upwelling: this occurs at Divergent Plate Boundaries. The rising magma hits the surface, forms new rock and pushes the plate around it.
Transform Plate Boundaries: occur when plates slide past each other. Lithosphere is neither created nor destroyed.
San Andreas Fault
Seattle Fault Line on the south end of Bainbridge Island, WA
How Do These Plates Move?
Convergent Plate
Boundary
Oceanic
Lithosphere
(Crust)
Divergent Plate Boundary
Or Hot Spot
Oceanic
Trench
Oceanic
Lithosphere
(Crust)
Convergent Plate
Boundary
Oceanic
Trench
Slab Pull
Slab Pull
Mantle Plumes
Subduction
Zone
HEAT SOURCE (CORE OF THE EARTH)
Subduction
Zone
Types of Rocks:
Igneous - Formed from magma or lava (basalt, granite,
obsidian) - crystals
Intrusive- Igneous rocks created within the earth
Extrusive- Igneous rocks created on the earth's surface
Sedimentary - rocks formed by sediments that become
compacted (sandstone, limestone)
Metamorphic - heat, pressure, time, rocks that are formed
below the earth's surface (marble)
Seismologist
A scientist that studies earthquakes.
Earthquake:
Vibrations in the earth caused by the sudden release of energy, usually as a result of the movement of rocks along a fault.
Seismograph
How do scientists locate the epicenter of an earthquake?
OPEN NOTE
QUICK QUIZ ON PLATE TECTONICS
Place a #1 on a clean sheet in your journal and be ready!
1 - Look at the satelite image below and draw a cross section picture of what is occuring.
Make sure you label the following: type of plate boundary, the oceanic trench, subduction
zone and volcanoes.
2 - What is the name for a chain of volcanoes that are on continental
crust?
3 - What is the name for a chain of volcanoes that come out of oceanic
crust that have the same plate boundary as question #2.
4 - What common type of plate boundary is found near the above
volcanic chains?
5 - What are the two categories of igneous rocks?
6 - The islands of Hawaii were formed by magma rising to the earth's surface. This point on the
surface is a called a ______________.
A
B
C
D
E
7 - Which island above has the oldest rock? A,B,C,D, or E?
Label the following with the type of plate boundary that the red arrow is pointing to.
8 - ___________
9 - ______________________
Green Arrows show the direction
the plates are moving.
10 - _________________
Extra Credit
What type of volcanoes are these...
1 ____________
2 ____________
3 ________________