PLATE BOUNDARIES 2

FOR YOUR NOTEBOOK:

Lesson 5:  Plate Tectonics in the Ocean

​Landforms Made by Plate Boundaries in the Ocean

Convergent - One ocean plate goes under another.

• Ocean trench - a deep area right where one plate slides under another.  If there is a big slip in plates, it can generate an earthquake, causing a tsunami!

• Volcanic Islands and Island Arcs - when one ocean plate goes under the other, sometimes it brings water.  The water actually lowers the temperature needed to melt the subducting crust.  That new magma seeps up through the less dense plate and forms new mountains/islands chains.

Divergent - Two ocean plates move away from one-another.

• Mid Ocean Ridge - a continuous mountain chain formed by new crust formation. Magma seeps up at the crack and cools to form this new crust.

  • Rift Valley - a ​small gap or depression formed right at the plate boundary as the seafloor spreads.

• Seamounts - Sometimes magma plumes (large volumes of magma) rise up and form little mountains in the ocean.

• Hydrothermal Vents - little openings in the sea floor where warm, mineral-rich water flows.

Transform - two ocean plates slide past each other.  

• Fracture lines - Long faults formed by changes in the overall movement of the plates.  These generate large earthquakes and tsunamis.  

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