Transcript 9-5 The Theory of Plate Tectonics

9-5 The Theory of Plate Tectonics
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Discuss the theory of plate tectonics?
Describe the three types of plate
boundaries?
Plate Tectonics
Geological theory that states that pieces of the
Earth’s Lithosphere are in constant, slow motion,
driven by convection currents in the mantle.
The Theory of Plate tectonics explains the
formation, movement, and subduction of Earth’s
plates.
J. Tuzo Wilson
1965 proposed that the
lithosphere was broken into
pieces creating sections called
plates
Stated that the plates closely fit
together along cracks in the
lithosphere
Plate Tectonics video
Characteristics of Plate Tectonic
As plates move they collide, pull apart, and grind
past each other
Convection currents in the asthenosphere
provide the energy for movement.
Plated move away from each other at rifts or
ridges and toward each other at convergent
zones.
Plate boundaries three types
Convergent – plates coming together
Divergent – plates moving apart
Transform- plates sliding past each other
Transform Boundaries
Two plates sliding past
each other
Frequent Earthquakes
San Andreas Fault
California
Divergent Boundaries
Plates moving away from each other
Mid Ocean Ridge (MOR)
Great Rift Valley in Africa
Convergent Boundary
Two plates coming
together
One usually
pushes out on top
Produces
Mountain ranges
and trenches
depending on the
plate type.
Rates of Movement
North America away from Europe at about 2.5
cm per year
225 million years ago Pangaea began to break
up
Movement is slow, about the same rate as your
fingernails grow.
Summary
What is the theory of plate tectonics?
The theory of plate tectonics explains the formation,
movement, and subduction of Earth’s plates.
What are the different types of plate boundaries
Transform boundaries, divergent boundaries, and
convergent boundaries
What major event in the earth’s history began 225
million years ago
The Supercontinent Pangaea began to break apart