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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.
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.
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 ...
The study of the causal relations of the phenomena present in a region; a comprehensive explanatory study of a region. [4] choropleth A map showing the distribution of a phenomenon by graded shading which indicates the density per unit area of that phenomenon; the darker the shading, the greater the density. [12] chott. Also shott and shatt.
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 ...
[11] [12] Marianas Trench is an example of a deep slab, thereby creating the deepest trench in the world established by a steep slab angle. [13] Slab breakoff occurs during a collision between oceanic and continental lithosphere, [14] allowing for a slab tear; an example of slab breakoff occurs within the Himalayan subduction zone. [4]
Murray was the first to study marine trenches and in particular the Mid-Atlantic Ridge, and map the sedimentary deposits in the oceans. He tried to map out the world's ocean currents based on salinity and temperature observations, and was the first to correctly understand the nature of coral reef development.