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Plate Tectonics
Alfred Wegener
Published The Origin
of Continents and
Oceans (1915)
Father of
“Continental Drift”
Evidence for Plate Tectonics
Jigsaw Fit of Continental Shelves
Evidence for Plate Tectonics
Mesosaurus (Late Paleozoic to Early Mesozoic)
Fossil Correlation Across Seas
Evidence for Plate Tectonics
Rock Correlation Across Seas
Evidence for Plate Tectonics
Rock Correlation Across Seas
Evidence for Plate Tectonics
Glacial
Imprints
in Rocks
in Tropics
Differences in Ancient Climates
WW2 – Sonar – mapping seafloor
North
Pole
South
Pole
Magnetite (Fe3O4)
Minerals retain their
magnetic moment when
they are cooled below the
Curie Temperature
Magnetic
Reversals
South
North
Magnetic
Reversals
Through
Geologic
Time
Magnetic Polarity
Time Scale
established back
to about 180
million yrs
Earth’s Magnetic
Flux Lines
N
S
Intensity of
Magnetism
Magnetic
Stripes on
the
Seafloor
Age of seafloor determined – led
to acceptance of Plate Tectonics
15 Tectonic Plates
Tectonic Motions
Location of World’s Major Volcanoes
Lithosphere – The rigid outer layer of
the Earth, including the
crust and part of the
upper mantle
Asthenosphere – The portion of the
upper mantle below
the lithosphere that is
easily deformed
Subduction
The thrusting of oceanic
plate into the mantle at a
plate boundary
Continent-Ocean Plate Orogeny
Juan
de
Fuca
Plate
Mt. St. Helens, Before 1980
Ocean-Ocean Plate Orogeny
Many mountain belts are built by
Ocean-Continent AND ContinentContinent collisions.
Mountain
Building
(Orogenesis)
ContinentContinent
Collisions
Continent-Continent Orogeny
Mt. Makalu, Nepal
Divergent plate boundaries
Birth of an
Ocean at a
Divergent
Margin
Transform (or Strike-Slip) Faults
San
Andreas:
A
Transform
Fault on
Land
Hot
Spots
Tectonic Motions
Convection
Convection
Cell
The transfer
of heat by the
movement of
matter.
Depressurized Melting
Double-Layer Convection