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A gas main being laid in a trench. A trench is a type of excavation or depression in the ground that is generally deeper than it is wide (as opposed to a swale or a bar ditch), and narrow compared with its length (as opposed to a simple hole or pit). [1] In geology, trenches result from erosion by rivers or by geological movement of tectonic ...
A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to and about 200 km (120 mi) from a volcanic arc. Much of the fluid trapped in sediments of the subducting slab returns to the surface at the oceanic trench, producing mud volcanoes and cold seeps.
Depth of oceanic trenches seems to be controlled by age of the oceanic lithosphere being subducted. [5] Sediment fill in oceanic trenches varies and generally depends on abundance of sediment input from surrounding areas. An oceanic trench, the Mariana Trench, is the deepest point of the ocean at a depth of approximately 11,000 m (36,089 ft).
Oceanic trenches are the deepest parts of the ocean floor. Beyond the trench is the forearc portion of the overriding plate. Depending on sedimentation rates, the forearc may include an accretionary wedge of sediments scraped off the subducting slab and accreted to the overriding plate. However, not all arc-trench complexes have an accretionary ...
This glossary of geography terms is a list of definitions of terms and concepts used in geography and related fields, including Earth science, oceanography, cartography, and human geography, as well as those describing spatial dimension, topographical features, natural resources, and the collection, analysis, and visualization of geographic ...
Hydrology is the study of the hydrosphere and the movement of water on Earth. It emphasizes the study of how humans use and interact with freshwater supplies. Study of water's movement is closely related to geomorphology and other branches of Earth science. Applied hydrology involves engineering to maintain aquatic environments and distribute ...
The Clipperton fracture zone is the southernmost of the north east Pacific Ocean lineations. It begins east-northeast of the Line Islands and ends in the Middle America Trench off the coast of Central America, [4] [11] [6] forming a rough line on the same latitude as Kiribati and Clipperton Island, from which it gets its name.
Earthquakes trace the path of the downward-moving plate as it descends into asthenosphere, a trench forms, and as the subducted plate is heated it releases volatiles, mostly water from hydrous minerals, into the surrounding mantle. The addition of water lowers the melting point of the mantle material above the subducting slab, causing it to melt.