Transcript File - Earth Science With Mrs. Locke

Pangaea and Continental Drift
The Theory of Continental Drift
• A hypothesis that the
continents were once
joined in a single, giant
landmass called
Pangaea- but they
have since drifted apart
and continue to drift
(move).
• First purposed by
Alfred Wegner
http://www.rocksinmyheadtoo.com/Pangea.jpg
3 PIECES OF EVIDENCE
FOSSILS
PUZZLE PIECES
The SHAPE
of the
continents
look like
puzzle pieces
that fit
together
The same or
similar fossils are
found on the
edges of cont.
that look like they
fit together
CLIMATE CHANGE
• Warm climate
plant fossils
found in the
Antarctic
• large glacial
scratches left in
rocks
Why do the
continents move?
The Theory of
Plate Tectonics
They move because the Earth’s
lithosphere is broken into pieces
called tectonic plates.
• The plates move very slowly and
don’t last forever
How they moveHeat is transferred in the asthenosphere
making Convection currents.
magma closer to core is heated- becomes less
dense- rises to crust- cools & gets more dense
again- sinks back to lower mantle- creating giant
looping patterns
• Plates are dragged with the moving
Asthenosphere.
3
Plate Boundaries
Trans form
CONVERGENT
Divergent
•
•
•
•
Mountains
Volcanoes
Subductions
Trenches in the
ocean
• Earthquakes
• Mid Ocean
Ridge
• Sea-Floor
Spreading
CRUST IS DESTROYED
CRUST can be CREATED
Crust NEITHER
CREATED or
DESTROYED
Results of Plate Tectonics
1. Earthquakes
2. Volcanoes
3. Mountain and land formation
4. Sea-floor spreading
• Oceans grow and sink
5.
Continental
Drift