Download thetheoryofplatetectonics

Warm-up
What are the phases of the moon
starting with the New Moon?
Draw them.
Vocabulary Words
• Asthenosphere-plasticlike layer of Earth on which the lithospheric plates float and
move around
• Continental drift- Wegener’s hypothesis that all continents were once connected
in a single large landmass that broke apart about 200 million years ago and
drifted slowly to their current positions
• Convection current- current in Earth’s Mantle that transfers heat in Earth’s interior
and is the driving force for plate tectonics
• Lithosphere- rigid layer of Earth about 100 km, made of the crust and part of the
upper mantle
• Pangaea- large ancient landmass that was composed of all the continents joined
together
• Plate- a large section of Earth’s oceanic or continental crust and rigid upper
mantle that moves around the asthenosphere
• Plate tectonics- theory that Earth’s crust and upper mantle are broken into plates
that float and move around the plasticlike layer of the mantle
• Seafloor spreading- Jess’s theory that new seafloor is formed when magma is
forced upward toward the surface at mid-ocean ridge
• Convergent boundary- when plates collide with each other
• Transform boundary- when plates slide pass each other
• Divergent boundary- plates are moving apart
Cornell Notes
Title: Plate Tectonics
• Standards: S6E5. Students will investigate the scientific
view of how the earth’s surface is formed.
e. Recognize that lithospheric plates constantly move and
cause major geological events on the earth’s surface.
f. Explain the effects of physical processes (plate tectonics,
erosion, deposition, volcanic eruption, gravity) on
geological features including oceans (composition,
currents, and tides).
EQ: What is plate tectonics?
The Theory of Plate Tectonics
Plate Tectonics
• The Earth’s lithosphere is divided into
plates that move on top of the
asthenosphere.
Lithosphere
Asthenosphere
When the water moves beneath
the raft, the raft moves with it.
When the asthenosphere moves,
the lithosphere moves with it…
Earth’s Major Plates
Types of Plate Boundaries
•
•
When two plates meet, they form a
boundary.
There are three types of boundaries
1. Convergent
2. Divergent
3. Transform
Convergent Boundaries
•
Two plates push together
**Oceanic crust sinks,
**Continental crust rises!!
•
•
Term to know: SUBDUCTION means the
crust is SINKING!
Three types of convergent boundaries:
1. Oceanic/Oceanic = subduction = TRENCH
2. Oceanic/Continental = TRENCH
3. Continental/Continental = MOUNTAINS
Convergent Collision #1
(Oceanic/Oceanic)
Both oceanic plates SINK (subduction!) and
form a TRENCH. Magma rises and forms
and island arc of volcanoes.
Convergent Collision #2
(Oceanic/Continental)
• The oceanic plate sinks (subduction!)
below the continent and the continental
plate slides over the top of the oceanic
plate. Forms a TRENCH.
Subduction Zone
Convergent Collision #3
(Continental/Continental)
• Both continental plates collide and rise up
forming MOUNTAINS. (Ex. Himilayas)
Divergent Boundaries
• Two plates pull apart causing a rift valley
in the middle.
Rift Valley
• Sea-floor spreading is created by a
divergent boundary.
Mid Ocean Ridge
Sea Floor Spreading
• Mid Ocean Ridges – underwater mountain
chains that run through the Earth’s Basins
• Magma rises to the surface and solidifies
and new crust forms
• Older Crust is pushed
farther away from the ridge
Transform Boundaries
• Plates slide past each other (Ex.
San Andreas Fault)
• Causes earthquakes!
This fence used
to line up!!
San Andreas Fault
WHY do the plates move?
…CONVECTION CURRENTS in the
mantle…Hot rock (less dense) rises to the
surface, cools (more dense), and sinks
back to the mantle.
COOL
ROCK
SINKS
HOT
ROCK
RISES
Convection Currents
Brain Pop!