Major Geological Events Caused by Plate Tectonics

Types of Boundaries

• Divergent

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― Plates move apart • Convergent

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― Plates come together • Transform ― Plates slide horizontally past each other

Divergent Structures

• New crust is formed as plates pull apart • Land features include: ― Mid-Ocean Ridges Ex. - Mid-Atlantic Ridge ― Rift Valleys Ex. - African Rift Valley ― Earthquakes

Mid–Ocean Ridge (Location of Sea Floor Spreading)

Older Sea Floor Spreading (Mid-Ocean Ridge) Younger Older Divergent Structure

Rift Valley

Divergent Structure

Convergent Boundaries

• Crust is destroyed and recycled back into the mantle • Three types of convergent collisions • Features include: ― Trenches – Mariana Trench ― Volcanic Arc (Volcanic Mountains) – Andes mountains ― Mountain Ranges – Himalayan Mountains ― Earthquakes

Subduction • Result of convergent boundary • A more dense plate slides under a less dense plate and sinks into the mantle.

• Features include: ― Oceanic-Oceanic = Trenches ― Oceanic-Continental = Mountain Ranges

Subduction Examples

Convergent Boundary • Oceanic-Oceanic • Land Features – Trench and Island Arc

Oceanic-Oceanic convergence

Convergent Boundary • Oceanic-Continental • Land Features – Trench and Volcanic Arc (Volcanic Mountains)

Oceanic-Continental convergence

Convergent Boundary • Continental-Continental • Land Features – Folded Mountains

Continental-Continental convergence

Mountain Ranges

Transform Fault Structures • Crust is neither destroyed nor created • Can occur between two oceanic plates or oceanic-continental plates • Features include: ― Earthquakes ― Fault line – San Andreas Fault

Transform Boundary • Oceanic-Oceanic • Land Feature – Fault Line

Transform Boundary San Andreas Fault Line

Transform Boundary • Continental-Continental • Land Features – Fault Line

Earthquakes – All Boundaries

Volcanoes

Mountain Ranges

Putting It All Together

Plate Boundaries

Plate Movement