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Plate Tectonics
Continental drift
• – Wegner’s idea that states continents have
moved horizontally along Earth’s surface to
their present positions
The drawbacks to continental drift 
Pangaea – one supercontinent
Plates are
constantly
moving
Plate Boundary Features
Evidence that supports Continental
Drift
1. Continents fit together like puzzle
pieces.
Going Back in Time!!! 230 mya
Evidence that supports
Continental Drift
2. Matching rock layers that were found on
Africa and South America.
Evidence that supports
Continental Drift
3. Matching fossils of
land-based
dinosaurs such as
Mesosaurus in the
southern region of
both Africa and
South America.
Evidence that supports Continental
Drift
4. Ancient Climates – Evidence of ice sheets on
continents.
•
Tropical plant fossils found in the rocks of Antarctica.
Evidence that supports Continental
Drift (seafloor spreading) Harry Hess
20km
Paleomagnitism
http://www.classzone.com/books/earth_science/terc/content/visualizations/es0803/es0803pa
ge01.cfm?chapter_no=visualization
20km
Seafloor Spreading and Magnetization
Glomar Challenger
Evidence that supports Continental
Drift (seafloor spreading)
Age of ocean rock
The Glomar
Challenger was a
drilling ship that
found that the
youngest ocean
rock is near the rift
zones and gets
older the further
away you get from
them.
Red – Young
Yellow – Average
Blue - Old
Convergent Boundaries – Coming
together
Subduction – trenches form
Convergent
Divergent
Subduction
Asthenosphere underneath
Divergent Plate Boundary
Old Ocean Floor
Mid-Ocean Ridge
Rift Valley
Young Ocean
Floor
Old Ocean Floor
Divergent Boundary
Mid-Oceanic Ridges
• Place on the Earth’s
crust where the plates
are moving away from
each other.
New Ocean Floor Creation
Rift Valley
*Tension Forces
Two plates moving against one
another
Strike-Slip (Transform)
Transform Fault / Strike Slip
(Shearing force)
San Andreas fault
(California) Transform Fault/
Strike-Slip Boundary
Two Continental Plates 
Continental Plates Collide
Continental Plates
Form Mountains (Himalayas, Ural)
Convergent Margins: India-Asia Collision I
Convergent Boundary
• Occur in areas where two tectonic plates are colliding
into one another.
Subduction
Continental
Plate
Oceanic Plate
Continental
Plate
http://www.classzone.
com/books/earth_scie
nce/terc/content/visual
izations/es0808/es080
8page01.cfm?chapter
_no=visualization
Continental-Continental Convergence
• Two low density granitic plates
colliding creates mountains like the
Himalayas (Mt. Everest)
Oceanic-Continental Convergent
Boundaries (Subduction)
Oceanic plate in water
Oceanic Crust
WET
Continent
Subduction!!!!!
Magma Chamber
Oceanic-Continental Convergence
• Pressure eventually melts the oceanic plate
creating less dense magma that comes to the
surface through continental volcanic arcs
(Andes).
Less dense continental plate
More dense oceanic plate
Subduction
Zone!!!!
Yummy!
ANDES
Oceanic-Oceanic Convergent
• Volcanoes form on the ocean floor
creating volcanic islands arcs.
(Philippines, Japan)
Hotspots (like Hawaii)
Seamounts
• The Hawaiian Islands
were formed as the
Pacific Plate moved in a
Northwesterly direction
over a hot spot. The hot
spot never moves.
Magma spurts out of the
hot spot creating a
volcanic island chain.
Quiz – Part 1
Indicate divergent, convergent, transform
Quiz!!!!!
1. What is the name of the ancient super
continent.
2. Who proposed the theory of Continental Drift?
3. Name three pieces of evidence that support
continental drift.
4. Draw a convergent Oceanic-Continental
boundary. Label all features.
5. Name a famous transform fault.