Plate Tectonic Movements
Name: _____________________________________________________________________ Period: ____ Date: ______
EQ: How is Earth’s crust changed by plate movements?
Plate Tectonics: Welcome to the greatest show on Earth. Propelled by intense heat simmering beneath the crust or the
mantle, Earth’s surface is dramatically reshaping itself in an endless, slow-motion movement called plate tectonics.
Tectonic plates or huge slabs of solid rocks separate, collide, and slide past each other causing earthquakes, feeding
volcanic eruptions, and raising mountains. Scientists now have a fairly good understanding of how the plates move and
how such movements relate to earthquake activity. Most movement occurs along narrow zones between plates, plate
boundaries, where the results of plate-tectonic forces are most evident.
Types of plate boundaries:
1. Divergent boundaries -- where new crust is generated as the plates
pull away or separates from each other.
Examples: mid ocean ridge, rift valleys
2. Convergent boundaries -- where crust come together. One crust is
destroyed as it dives under another, known as subduction.
Examples: subduction, Marianas trench, mountains, volcanoes
3. Transform boundaries -- where crust is neither produced nor
destroyed as the plates slide horizontally past each other. Example:
San Andreas fault
Plates Move Apart: Divergent Boundary
Atlantic ocean, along a global system of mountain ridges, Earth’s
plates are growing and spreading apart. Each year these oceanic
spreading ridges erupt more than three times as much molten rock as
do all the volcanoes on land. Magma rises from Earth’s mantle at
spreading ridges and cools on and beneath the ocean floor, adding to
the plates on either side. The growing plates inch away from the
ridges—widening ocean basins and rafting apart entire continents.
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Plates Come Together: Convergent Boundary
Where plates come together, or converge, we see some dramatic manifestations of
plate tectonics. At convergent margins, continents grow as plates are consumed.
Three types of Convergent Boundaries
1. Convergent boundary between continental and oceanic crust results to
subduction, volcanoes, and trenches.
2. Convergent boundary between two oceanic crust results to subduction, and the
trenches formed are deeper like the Marianas Trench, which can sink Mt. Everest.
3. Convergent boundary between two continental crust results to building up the
rocks forming mountains like the Appalachian and Himalayas mountain ranges.
