Just to the east, the ocean floor dips into the South Sandwich Trench, the second-deepest trench in the Atlantic Ocean. At its lowest point, this trench is 8, meters 27, feet below sea level. Subduction of the South Atlantic plate by the Scotia plate formed this trench, as well as the archipelago of islands, also known as the Scotia Arc, that extends to the tip of Antarctica. The deepest part of the Atlantic Ocean lies just north of the island of Puerto Rico, where the North American and Caribbean plates slide past each other.
Subduction of the larger North American plate by the Caribbean plate has created a trench that is 8, meters 28, feet deep. The interaction produces earthquakes in the region -- as such plate interactions do worldwide -- but a recent study has shown that there is a greater hazard. As the plates collide, the lighter Caribbean plate cracks and ruptures, while giant landslides occur on the down-going North American plate. Both phenomena, which are also common in the deeper Pacific trenches, are capable of producing devastating tsunamis.
A mountain range separates the ocean floor into the Eurasian and Amerasian Basins under the Arctic Sea, and the former descends to a depth of 4, meters 14, feet in the Barents Abyssal Plain.
This depth is part of the Fram Basin, which lies directly under the geographic North Pole. Unlike ocean trenches, the Fram Basin isn't V-shaped, but vast and flat, much like the floor of a desert on dry land. Scientists haven't completely mapped the Arctic Ocean floor, but they know that, beneath the Fram Strait between Greenland and Svalbard, it descends to a depth of 5, meters 18, feet in the Molloy Deep.
Long ago, Australia used to be part of Antarctica, but as they drifted apart, fracture zones were created in the Earth's crust. His shark research has spanned the globe from the frigid waters of the Arctic Circle to coral reefs in the tropical Central Pacific. Much of his current research centers on the use of acoustic telemetry and satellite-based tagging technology to study the ecology and behavior of sharks.
He has written dozens of scientific research papers and has appeared in a number of film and television documentaries, including programs for National Geographic, Discovery Channel, BBC, and numerous television networks. His most recent book, The Shark Handbook, is a must buy for all shark enthusiasts.
Robert D. He served in the U. Navy for more than 30 years and continues to work with the Office of Naval Research. A pioneer in the development of deep-sea submersibles and remotely operated vehicle systems, he has taken part in more than deep-sea expeditions. In , he discovered the RMS Titanic , and has succeeded in tracking down numerous other significant shipwrecks, including the German battleship Bismarck , the lost fleet of Guadalcanal, the U.
He is known for his research on the ecology and evolution of fauna in deep-ocean hydrothermal, seamount, canyon and deep trench systems. He has conducted more than 60 scientific expeditions in the Arctic, Atlantic, Pacific, and Indian Oceans. Sunita L. Her research explores how the larvae of seafloor invertebrates such as anemones and sea stars disperse to isolated, island-like habitats, how larvae settle and colonize new sites, and how their communities change over time.
Kirstin also has ongoing projects in the Arctic and on coral reefs in Palau. Her work frequently takes her underwater using remotely operated vehicles and SCUBA and carries her to the far corners of the world. What are ocean trenches? How are trenches formed? What is it like in a trench? How does life survive there? What do we know about trenches? Why are ocean trenches important?
What can ocean trenches tell us about earthquakes? With a maximum depth of 9 km, the Japan trench stretches from the Kuril Islands to the Bonin Islands and is also the extension of the Kuril-Kamchatka Trench and the Izu-Ogasawara Trench to the north and south respectively.
The trench was formed due to the subduction of the oceanic Pacific plate beneath the continental Okhotsk Plate. Lies at a depth of 8. Efforts for a complete mapping of this trench have been undergoing on for a quite long time now. This South Sandwich Trench is also associated with an active volcanic arc. The Atacama Trench has a maximum depth of 8.
The deepest point of the trench is known as Richards Deep. The trench measures around 5, km in length and 64 km in mean width while it covers an area of about , square kilometres. The Atacama Trench was formed as a result of a convergent boundary, between the subducting Nazca and the South American Plates.
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The article or images cannot be reproduced, copied, shared or used in any form without the permission of the author and Marine Insight. Tags: deepest parts of the ocean. The Puerto Rico Trench is a tectonically complex depression in part formed by the Lesser Antilles subduction zone. Here, the oceanic crust of the enormous North American plate carrying the western Atlantic Ocean is being subducted beneath the oceanic crust of the smaller Caribbean plate.
Accretionary wedge s form at the bottom of ocean trenches created at some convergent plate boundaries. Accretionary wedges form as sediment s from the dense, subducting tectonic plate are scraped off onto the less-dense plate. Sediments often found in accretionary wedges include basalt s from the deep oceanic lithosphere, sedimentary rocks from the seafloor, and even traces of continental crust drawn into the wedge.
The most common type of continental crust found in accretionary wedges is volcanic material from islands on the overriding plate. Accretionary wedges are roughly shaped like a triangle with one angle pointing downward toward the trench. Because sediments are mostly scraped off from the subducting plate as it falls into the mantle , the youngest sediments are at the bottom of this triangle and the oldest are at the more flattened area above.
This is the opposite of most rock formations, where geologist s must dig deep to find older rocks. Active accretionary wedges, such as those located near the mouth s of river s or glacier s, can actually fill the ocean trench on which they form. Rivers and glaciers transport and deposit tons of sediment into the ocean. The Caribbean island of Barbados, for example, sits atop the ocean trench created as the South American plate subducts beneath the Caribbean plate.
Ocean trenches are some of the most hostile habitats on Earth. Pressure is more than 1, times that on the surface, and the water temperature is just above freezing.
Perhaps most importantly, no sunlight penetrate s the deepest ocean trenches, making photosynthesis impossible. Organisms that live in ocean trenches have evolve d with unusual adaptation s to thrive in these cold, dark canyon s. In general, life in dark ocean trenches is isolated and slow-moving.
Pressure at the bottom of the Challenger Deep, the deepest spot on Earth, is about 12, tons per square meter 8 tons per square inch. Large ocean animals, such as sharks and whales, cannot live at this crushing depth.
Many organisms that thrive in these high-pressure environments lack gas -filled organ s, such as lung s. These organisms, many related to sea stars or jellies, are made mostly of water and gelatinous material that cannot be crushed as easily as lungs or bones.
Many of these creatures navigate the depths well enough to even make a vertical migration of more than 1, meters 3, feet from the bottom of the trench—every day. Even the fish in deep trenches are gelatinous.
Several species of bulb-headed snailfish, for example, dwell at the bottom of the Mariana Trench. The bodies of these fishes have been compared to tissue paper. Shallower ocean trenches have less pressure, but may still fall outside the photic or sunlight zone , where light penetrates the water. Many fish species have adapted to life in these dark ocean trenches.
Anglerfish, for instance, use a bioluminescent growth on the top of their heads called an esca to lure prey. The anglerfish then snaps up the little fish with its huge, toothy jaws. Without photosynthesis, marine communities rely primarily on two unusual sources for nutrient s. Marine snow is mostly detritus , including excrement and the remains of dead organisms such as seaweed or fish.
This nutrient-rich marine snow feeds such animals as sea cucumbers and vampire squid. Another source of nutrients for ocean-trench food webs comes not from photosynthesis, but from chemosynthesis. Chemosynthesis is the process in which producer s in the ocean trench, such as bacteria , convert chemical compound s into organic nutrients. The chemical compounds used in chemosynthesis are methane or carbon dioxide eject ed from hydrothermal vent s and cold seep s, which spew these toxic , hot gases and fluids into the frigid ocean water.
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