Oceanic Trench
The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. They are also the deepest parts of the ocean floor. Oceanic trenches are a distinctive morphological feature of convergent plate boundaries.
Along convergent plate boundaries, plates move together at rates that vary from a few mm to over ten cm per year. A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to a volcanic island arc, and about 200 km (120 mi) from a volcanic arc. Oceanic trenches typically extend 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor. The greatest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench, at a depth of 10,911 m (35,797 ft) below sea level. Oceanic lithosphere moves into trenches at a global rate of about .
Read more about Oceanic Trench: Geographic Distribution, History of The Term "trench", Trench Rollback, Morphologic Expression, Filled Trenches, Accretionary Prisms and Sediment Transport, Water and Biosphere, Empty Trenches and Subduction Erosion, Factors Affecting Trench Depth, Major Oceanic Trenches, Notable Oceanic Trenches, Ancient Oceanic Trenches
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