Ocean Trenches

Ocean trenches develop in subduction zones at a convergent boundary between two tectonic plates. When a continental plate collides with an oceanic plate the oceanic plate is forced beneath the lighter continental plate. When two oceanic plates meet at a convergent boundary the colder and heavier of the two oceanic plates subducts.

Ocean spreading center and trench formation. USGS

Subduction zone trenches

A trench forms between the two plates in a subduction zone. Trenches are depression in the ocean floor. They are also the deepest part of the seafloor. Trenches form natural boundaries between two tectonic plates. There are 20 major trenches on Earth and 17 of these trenches can be found around the Pacific Ocean Basin. The Mariana Trench contains the Challenger Deep, which is the deepest known place on our planet.

Volcanic arcs

Volcanic mountain ranges form on the continental side of a trench where a continental and an oceanic plate converge. The mountain range is called a volcanic arc. If two oceanic crusts converge an island arc forms on the overriding plate parallel to the trench. Volcanic arcs and island arcs have volcanic mountains that often produce violent volcanic eruptions.


More Ocean Links

What Causes Tsunamis Today we know that tsunamis are naturally generated waves. Find out how and why they form.

Mid Atlantic Ridge The Mid-Atlantic Ridge is a mountain range that runs down the center of the Atlantic Ocean through Iceland. 

Ocean Trenches  Ocean trenches are found all around the Pacific Ring of Fire. Find out how and why they develop.


Sea mount  There are more than 60,000 sea mounts located in the world's oceans.

Oceanic Zones  Find out about the four major zones where plants and animals live in the ocean. 

Ocean Facts  Discover what causes tsunamis, where ocean trenches are located and how the Mid-Atlantic Ridge was discovered.

Home Page  The Science Site contains information on our planet, volcanoes, science projects, earthquakes and much more.


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