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PLATE TECTONICS:
A UNIFYING THEORYGeology
The Walker School
Earth’s crust is about 5% of it’s mass.
Oceanic Crust
5 to 8 km thick.
Composed mainly of basalt
and gabbro.
Not older than 180 million
years.
Covered with dead organism
and sediment, about 1 km
thick.
Little variability in
composition.
Continental Crust
Composed of many
rock types.
Can be as old as 4
billion years.
Varies in thickness
from 20 to 80 km.
Makes up about 41%
of Earth’s surface.
Cratons are the oldest parts of the
continents.
Crust is made of 10 Major Plates
Fig. 1-11, p. 17
Activity Along Plates
Volcanism
Earthquakes
Mountain Building
Basin Formation
Plate Activity
Fig. 1-12, p. 18
Composite Satellite Image of
Himalayan Peaks
Interactions Between Plates and Climate
Movement between Plates
Location of Continents and Ocean
Basins
Colliding Plates Create
Mountains
Mountain Shape and Size Affect Atmospheric Circulation
Ultimately Affects Global Climate
WHAT IS CONTINENTAL
DRIFT?
Alferd Wagner Proposed the Theory
of Continental Drift
Fig. 2-2, p. 35
Evidence for Continental Drift
Shorelines of Continents
Similar Rock Sequences
Similar Mountain Ranges
Matching Glacial Deposits
Similarity in Extinct Plants and Animals
Shorelines of Continents
Fig. 2-3, p. 36
Similar Rock Sequences
Fig. 2-4, p. 37
Trends of Mountain Ranges
Glacial Evidence from Striations
Fig. 2-5, p. 38
Fossil Evidence
Fig. 2-6, p. 39
TYPES OF PLATE
BOUNDARIES
Types of Plate Boundaries
Table 2-1, p. 47
DIVERGENT PLATE
BOUNDARIES
Mid-Atlantic Ridge
Fig. 2-10, p. 43
Earth’s Magnetic Field Recorded in
Oceanic Crust
Fig. 2-11, p. 44
Fig. 2-12, p. 45
Red:
48
MYAYello
w: 68
MYA
Green:
155
MYA
Age of the World’s Oceans
Sediments Increase Away from
Ridges Toward Continents
Fig. 2-13, p. 45
Divergent
Plates Form
Oceans
Fig. 2-15, p. 48
East African
Rift Valley
Formed from
Divergent
Plates
Fig. 2-16a, p. 49
Red Sea: Example of Adv. Rifting
Fig. 2-16b, p. 49
Indicators of Rifting
Faults
Dikes (Vertical Intrusions of Magma)
Sills (Horizontal Intrusions of Magma)
Lava Flows
Thick Sedimentary Sequences
Pillow Lava
Pillow Lavashttp://www.youtube.com/watch?v=xsJn8izcKtg
Example of Paleo-Rifting in the United States
Hudson River Valley: Palisades, NJ
Fig. 2-17, p. 52
CONVERGENT PLATE
BOUNDARIES
Oceanic Plate Boundaries
Fig. 2-18a, p. 53
Oceanic-Continent
Plate Boundaries
Fig. 2-18b, p. 53
Continental-Continental
Fig. 2-18c, p. 53
Indicators of Convergence
Melange
Ophiolites
TRANSFORM FAULTS
Most transform faults connect two oceanic
ridges.
Fig. 2-20a, p. 56
A transform fault can connect a ridge and
a trench.
Fig. 2-20b, p. 56
A transform fault can link two ridges.
Fig. 2-20c, p. 56
San Andres Fault
Fig. 2-21, p. 57
HOT SPOTS: AN
INTRAPLATE FEATURE
Mantle Plumb remains stationary while
plates move.
Fig. 2-22, p. 58
PLATE MOVEMENT
Plates, Zones, and Movements
Fig. 2-14, p. 46
Methods for determining movement.
Measuring age of sediment.
Dating magnetic anomalies on the seafloor.
Satellite-Laser ranging techniques.
Hotspots
Supercontinent Cycle
DRIVING MECHANISM OF
PLATE TECTONICS
Fig. 1-10, p. 16
Model I: Thermal convection cells are
restricted to the asthenosphere.
Fig. 2-24a, p. 60
Model II: Thermal convection cells involve
the entire mantle.
Fig. 2-24b, p. 60
DISTRIBUTION OF NATURAL
RESOURCES
Mineral Deposits Associated with
Plate Boundaries
Fig. 2-26, p. 62
Fig. 2-25, p. 61
Mineral Formation Processes
Sedimentation (coal)
Precipitation (salts, metals)
Crystallization from Magma Plutons (ores)
Changes in Temperature and Pressure (ores)
Fluid Inclusions (ores)
Greatest Copper Deposits
The greatest known deposit of copper is in
porphyries formed by volcanic activity in the Chile's
Andean Mountains.
Chile's copper mines provide over 30% of the
world's mine production of recoverable copper.
Escondida Copper Mine is today the world's
largest producing mine with 750,000 metric tons of
production which was 5.6% of the world's
production in 2000.
Escondida Copper Mine, Chili
The Escondida copper-
gold-silver mine is
located in the arid,
northern Atacama
Desert of Chile about
160km southeast the
port of Antofagasta, at
an elevation of 3,050m
above sea level.
Copper is the Oldest Minded Mineral
Copper is mankind's oldest metal, dating back more
than 10,000 years.
A copper pendant discovered in what is now
northern Iraq goes back to about 8700 BC.
Archeologists have recovered a portion of a water
plumbing system from the Pyramid of Cheops in
Egypt. The copper tubing used was found in
serviceable condition after more than 5,000 years.
Copper was mined in Ancient Rome
Copper was named for
the island of Cyprus,
where the Romans
obtained their supply.
Copper in Early America
When Columbus sailed to the Americas, his ships,
Nina, Pinta and Santa Maria, had copper skins
below the water line. The copper sheathing
extended hull life and protected against barnacles
and other kinds of biofouling.
Paul Revere, produced the bronze cannon, spikes
and pumps for the famous ship, Old Ironsides.
Revere was one of the earliest American
coppersmiths.