200 meters are certain areas of transition (up to 2000 m), coming after a sharp and deep stage, which is the limit of the pelagic region, with close examinations included between 2000 and 6000 meters.
This is the greatest development in the oceans. In this area the deposits are already scarce, very thin and uniform, consisting of silts and clays, which according to their color, origin and chemical composition, are classified into different types. Also abound in such deep deposits of organic origin, such as silt of Globigerina, pteropods, radiolarians, etc..
The relief of the abyssal plain, is poorly developed and can be considered as a reversal of the massive high-rise on the continents. In general, related to high altitude areas, a phenomenon of great importance for the explanation of the great depressions and cracks or geoclasas. For its small size and extraordinary depth are called pits. The main ones are:
The gap Emden, in the Philippines, 10,793 meters
That of Rampao in the oceanic Bonin Islands, of 10,660 meters
That of Nero, in the Marianas, in 9,636 meters
The grave in Japan, 9,435 meters
The abyss of Aldrich, the islands Kermadek of 9427 meters
The Tonga Trench, in 9,184 meters
The gap Planet, in the Solomon Islands, in 9,148 meters
All of them are in the Pacific. In the North Atlantic is the Puerto Rico Trench, which reaches 8,821 meters. In the South Sandwich Islands, in southern waters, there is a mass of 8,091 meters. In these deep areas there is only the big funds clay, mineral and red, whose formation appears due to the decomposition of silicates eruptive origin.
Are marine regions where greater depths are reached. Are closely related to the subduction zones of the plates and only appear on the active continental margins or Pacific-type. Mid-ocean ridges are undersea alignments deployed as a submerged mountain ranges of several thousand kilometers in length and with heights of 1500-2500 meters above the ocean abyssal plains.
The first dorsal was discovered and studied the mid-Atlantic ridge, which stretches from Iceland to the southern Atlantic Ocean, dividing it into two halves rather symmetric. This ridge is continued through southern Africa with the dorsal indica, which in turn is closely connected to the system of grabens (rifts Valleys) of East Africa. The ridge continues along the Indian Ocean south of Australia with the Pacific Ocean ridge. The ridges now known to have a length of 60,000 kilometers.
[...] There are also deep chasms in the Grand Canyon would be a simple gully. The pits, all located along the archipelago, have, together, an area of 1% of the ocean floor. This may not seem like much, but actually amounts to half the area of the United States, and the graves contain 15 times more water than all the rivers and lakes in the world. The deepest of them is located in the Pacific.
These graves were found along the islands of the Philippines, Marianas, Kuril and Aleutian Solomon. There are other great depths in the Atlantic near the West Indies and the South Sandwich Islands, and one in the Indian Ocean, next to the East Indies (Isaac Asimov)
Structure of mid-ocean ridges: The progressive knowledge is providing important data on the dynamics of Earth’s crust. A cross section shows a typical spine is formed by two mountain alinenaciones several hundred miles wide, separated by a moat that occupies the axis of the ridge and has a width of 20-50 km.
Longitudinally, the ridges are formed by line segments displaced relative to each other and separated by faults, called transform faults, perpendicular to the direction of the ridge. The operation of such failures, causing the displacement of the sectors or groups that delineates the main cause of many earthquakes whose foci are located in the ridges.
Exploring the deep ocean:
The man began to probe the deep ocean when the century was well advanced. The ocean floor became a matter of commercial interest when it decided to lay a telegraph cable across the Atlantic. To that end, in 1850, Maury mapped the bottom of the Atlantic. After 15 years, marked by numerous interruptions and failures, before the Atlantic cable was laid, at last, thanks mainly to drive, incredibly persistent, the American financier Cyrus West Field, who lost a fortune on it.
The systematic exploration of the seabed began with the famous expedition around the world the British ship Challenger in 1870. To measure the depth of the oceans, the Challenger used the traditional method of lower 6 km of cable, with a weight at its end, to the background. In this way, there were more than 360 surveys.
This procedure is not only extremely laborious, but also rather accurate. The exploration of the ocean floor experienced a revolution in 1922, while introducing the method of transmission of sound waves and reception of their echoes.
There are plateaus the size of a continent, and mountain ranges longer and higher than those of the landmass. Hawaii Island is the summit of an underwater mountain of 9,900 m in height, taller than any of the Himalayas, so Hawaii can be called with any property, the highest mountain on Earth. There are also numerous truncated cones, called seamounts or guyots. They named it in honor guyot Swiss-American geologist Arnold Henry Guyot.
After the Second World War, Ewing and Heezen explored with renewed zeal accidents on the ocean floor. To his surprise, diverse and detailed surveys, conducted in 1953, they showed that along the ridge, and just at its center, ran a deep ravine. In due time it was discovered this feature into all portions of the dorsal transoceanic. This led to some call “the Great Rift of the Globe.” There are places where it is very close to the Earth up through the Red Sea between Africa and Arabia, bordering the Pacific coast, crosses the Gulf of California and outlines the coast of California.
At first it seemed as if that were continuous Cleavage (65,000-km crack in Earth’s crust). However, a more detailed examination showed that it was composed of short straight sections separated as if they had a seismic shock off each section as follows. And indeed, along the Rift is where they usually arise earthquakes and volcanoes. In its day, this cleft was a failure for emerging slowly from the inside, molten rock, or magma. There cooled and agglomerated to form a dorsal, and even extending beyond it.
This diffusion can reach speeds of 16 cm / year, and consequently, the entire Pacific ocean floor would be covered by a new layer to 100 million years. Certainly the seafloor sediments are removed rarely older cul it may seem astonishing in a planetary life would be forty-five times older if mediera the concept of “sprawl on the sea floor.”
The Hedidura and its branches appear to divide the earth’s crust in six massive plinths, and some smaller ones. These base-driven move reigning activity along the Rift, but they do as independent units, ie, produces no significant movement in the accidents of a particular socket. The removal of such sockets explains the failure of the Pangea and continental drift occurred since then. (Asimov) [...]
Bacteria and deep sea creatures: principañes Among the expeditions which provided data about life in deep waters is that of the Challenger (1872-1976), directed by English Wyville Thomson, who showed that there was life to 5000 meters deep. Others have been the Meteor (1950-52), Danal I and II, Discovery I and II (1925), Galathea (1950-52), Nautile, Trieste, Kaiko and Shinkai latest 6500, which reached the 10,900 meters, from which, at 6400 meters, the scientist James Hunt, spotted a strange creature about which we do not know almost nothing.
Research (2004) by Henry A. Ruhl and Kenneth L. Smith of the Scripps Institution of Oceanography in California showed the influence of climatic conditions of the surface species living at 4000 meters deep in the Pacific. His work showed a marked tendency in the community structure of dominant epibenthic megafauna synchronous with the evolution of El Niño / La Niña, during the period 1989-2002. The Elpidia minutissima increased heavily during the period 1989-1996, to decrease markedly in the period 1999-2000 to virtually disappear between 2001 and 2002.
The vitreous Peniagone showed similar behavior. Other agencies such as Abyssocucumis abyssorum, Scotoplanes globosa, Psychropotes longicauda, etc., For most of the period studied, appeared at low concentrations while its population grew abundantly during the period 2001-2002. Nether biomass is only 22 to 56 g/m3 between 200 and 500 m, and 9 to 26 g/m3 of 2000 to 9000 m. The hadal zone benthos or ultraabisal able to adapt to the pressure, darkness and lack of oxygen and nourishment. The temperature ranges between 5 and 1 C.
Bacteria constitute the most abundant biomass. Some are chemosynthetic autotrophs, that meet their carbon requirements at the expense of bicarbonate ion, oxidizing ammonia, hydrogen, nitrite, methane or inorganic substances. The heterotrophic, feed on dissolved organic mass that accounts for the circulating water and debris. Among animal species are various forms of rhizopods and a variety of sponges, among which are especially characteristic of hexaltinélidas. Among the coelenterates are hydrozoans, such as solitary large polyps, pennatularios and anemones. We found 375 species of echinoderms below 2000 meters.
Abyssal bryozoans are rare, there are some polychaete annelids and brachiopods are in a very notable. Most are deep bathypelagic cephalopods. Among the life forms there is a tactile organ elongation. Through bioluminescence seeks to attract prey. In addition to the agencies with transparent bodies, the pigment is between pink and violet. The red is not attractive because the red light waves do not penetrate the upper layers of the ocean. It is assumed that the growth of deep-sea creatures is slow and very long life.
The deepest ocean trenches found on Earth in the Pacific Ocean. Six of the pits deeper than the 10,000 feet deep, with the deepest Siema Challenger to 11.033 meters.
The water temperature in the trenches is usually very low. Normally body is usually about 0 ° and 2 ° C. Believe it or not, in the trenches there is life, such as molluscs. For years were surprised that the deepest ocean areas were not found at its center, but along the coasts of islands (volcanic) and continents.
The phenomenon is perfectly understandable in light of the theory of plate tectonics and continental drift. The trenches are formed at subduction zones, places of the earth’s crust where two plates converge, collide, and one of them (higher density) is introduced (subducting) beneath the other. This produces a large depression in the ground submarino.Dichas subduction zones are associated with intense seismic activity caused by tension, compression and friction between the two plates. To measure the depths of the trenches, use echolocation sonar is the animal, the animal emits a sound that bounces off an obstacle to finding and analyzing the received echo.