The lithosphere is broken into separate sections
called plates. They “float” on the asthenosphere
Sea-floor spreading and continental drift into a
single theory – The Theory of Plate Tectonics
Plate Tectonics – is the geological theory that states
that pieces of 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
1. Transform Boundaries –
Crust is neither created nor destroyed
Place where two plates slip past each
other, moving in opposite directions
2. Divergent Boundaries
Place where two plates move apart
When develops on land, two of Earth’s plates
pull apart. A deep valley called a rift valley
forms along the divergent boundary
3. Convergent Boundaries
Place where two plates come together
Converging oceanic plate and oceanic plate collide one
plate is subducted through a trench and volcano islands
Converging oceanic plate and continental plates – when
continental plates and oceanic plate collide, the oceanic
plate is subducted and volcanoes on land are formed
Converging continental plates – where two continental
plates collide, the crust buckles and mountain ranges
The plates are moving at a very slow rate of about one
to ten centimeters per year.
In areas plates are moving together and others are
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