Plate Tectonics

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Plate Tectonics
The Earths crust consists of a number of plates
which are in motion (quite slow)
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The Layers of the Earth
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The movement of crustal plates results from
convection currents in the Mantle. Heat from the
formation of the Earth and radioactive decay
escapes at the Earths surface.
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Some plates contain mainly oceanic crust and some
contain both continental and oceanic crust.
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Shortcut to Bullard Fit of Continents
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The Glomar Challenger was the first research
vessel specifically designed in the late 1960s
for the purpose of drilling into and taking core
samples from the deep ocean floor.
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Remote Sensing- uses energy signals from Earth to
determine many different kinds of information
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Earthquake Zones
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Earthquake and Volcano Activity closely matches
the plate boundaries!
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Mid-Ocean Ridges
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Computer-generated detailed topographic map of a
segment of the Mid-Oceanic Ridge
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Shortcut to Sea Floor Spreading Shortcut to
Formation of Ocean Crust
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There is evidence of Sea floor spreading on
either side of the Mid-Atlantic Ridge
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Divergent boundaries occur along spreading
centers where plates are moving apart and new
crust is created by magma pushing up from the
mantle.
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Iceland is right on an oceanic-oceanic Divergent
Plate Boundary
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Plate Boundaries
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Convergent boundaries are where plates are moving
toward each other, and sometimes one plate sinks
(is subducted) under another. The location where
sinking of a plate occurs is called a subduction
zone.
subduction
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Heat from friction melts rock and the magma forms
volcanoes
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Mount Baker (Washington)
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Mount Rainier (Tacoma in foreground)
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Deep trenches are formed in the ocean floor where
subduction begins
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Oceanic-oceanic convergent boundaries produce
volcanic Island Arcs
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An oceanic-oceanic convergent boundary.
They also produce a trench
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Where might we find trenches?
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The Mariana Trench is the deepest known trench.
The bottom of the trench (Challenger Deep) is
further below sea level than Mount Everest is
above it. The trench has a maximum depth of
10,911 m (35,798 feet) below sea level.
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Continental-continental Convergent plate
boundaries can produce mountain ranges.
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Transform Boundaries
The zone between two plates sliding horizontally
past one another is called a transform-fault
boundary, or simply a transform boundary.
transform faulting
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Some Transform Boundaries
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The San Andreas Fault
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Measuring displacement in a small transform fault
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Remote sensing from satellites can detect small
movements on either side of a fault.
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In Transform Boundaries, no new crust is formed
and no crust is destroyed. Earthquakes often
occur along transform boundaries.
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Hot Spot Volcanoes
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Hot Spot Volcanoes are not at plate boundaries
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Oceanic Crust moves over fixed hot spot.
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hot spot volcanoes
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The oldest volcanic island is farthest from the
hot spot in the direction of the plate movement.
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Eroded volcanic islands which are below the
surface are called Seamounts
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The trail of underwater mountains created as the
the tectonic plate moved across the Hawaii
hotspot over millions of years, known as the
Hawaiian-Emperor seamount chain, or the Emperor
Seamounts (Which direction do you think the
Pacific Plate is moving?)
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Mauna Loa, comprising over half of the Big
Island, is the largest shield volcano on the
planet. The measurement from the base locally
depressing the sea floor in the Hawaiian Trough
to its peak is about 17 km (56,000 feet)
Sea Level to peak of Everest is 8,848 meters
(29,028 feet)