Where are deep-sea depressions located? Deep oceanic troughs

For many years, the depths of the sea beckon people. Water, as is known, occupies more than 2/3 of the Earth's surface. Therefore, it can be explored for a very long time. Deep oceanic troughs today attract many scientists. It is no wonder, after all, mankind has long sought to know the unknown. In addition, deep-sea gutters on the map appeared relatively recently.

However, technical possibilities do not always allow us to satisfy our curiosity. Oceans still safely store many mysteries hidden under the water column. People only at the end of the 19th century began to study deep-sea depressions and plains. And this means that we will have enough facilities for research for a long time.

Where are deep-sea depressions located

It is known that the bottom of the World Ocean is a plain that lies at a depth of about two meters to 6 thousand meters. The bottom in some areas is frayed, like wrinkles, depressions. They have different depths. These depressions are located mainly in the zones of geological activity. More than 8 thousand meters is their depth.

How deep-sea depressions appeared

Their emergence is connected with the processes that took place in the old days, when our Earth was only being formed. Today it is difficult to imagine those years when on the planet there was no ocean. However, there have been such times.

A person still does not have access to many knowledge about the processes taking place in the universe. Nevertheless, we know something about the origin of the planets. Let's leave the divine theory aside and tell you what science thinks about this. Gravity, which had tremendous power, twisted balls of planets from a cold cloud consisting of gas and dust. This process can be better understood by imagining how the hostess rolls the dough from the dough. Of course, these coats turned out to be not an ideal form. However, they still went to travel throughout the universe.

Education of volcanoes

The depths of our planet during the first billion years of such space travel have greatly warmed up. This was influenced by the force of gravity compression, as well as the radioactive decay of isotopes with a long lifetime. At that time, there were a lot of such isotopes. Apparently, the bowels of our planet were then something like a nuclear furnace - the upper part of the Earth's mantle melted . And it was at that time that volcanoes began to operate. A huge mass of gases, ash and water vapor began to throw them up. And on the slopes of the volcanoes flowed fire-breathing lava.

The appearance of lakes and the primary ocean

As a result of these processes, our planet was enveloped in fog. It disappeared behind the clouds, which carried with them, in addition to volcanic gases, large masses of water vapor. It should be said that in those days on Earth it was not hot. Scientists have conducted research, which revealed that the temperature on the planet about the first billion years of her life did not exceed 15 ° C.

Cooling water vapor fell on the surface of the Earth with drops of condensate . As a result, it was first covered only by individual ponds and puddles. Initially, the surface of the Earth, as you now know, was not smooth and smooth. However, these irregularities increased as a result of volcanic activity. The water filled the hollows of different depths. All the larger became separate lakes, until they merged. So the primary ocean was formed. The explanation presented above was given by Otto Yulievich Schmidt, a Soviet scientist. Of course, this is a controversial hypothesis, like any other similar to it. However, no one has yet put forward a more plausible version.

Tectonic depressions

Now you know how the cavities formed. They are depressions of the earth's surface. Where are deep-sea depressions located? They are found both on land and at the bottom of the seas and oceans. Their origin is mainly tectonic. In other words, it is connected with the activity of the volcanoes of our planet. Therefore, tectonic depressions are particularly numerous. They are areas in which there is a continuous lowering of the Earth's crust due to processes occurring in the mantle (its upper part, called the asthenosphere).

Asthenosphere

The word "asthenosphere" comes from two Greek words. One of them is translated as "weak", and the second - "ball". Approximately 800-900 km is the thickness of the asthenosphere. It is the most mobile part of the Earth's surface. The asthenosphere is less dense than the lower part of the mantle. In addition, it is more elastic, since its mass is filled with molten magma, which has a deep origin. In the asthenosphere, there is regularly outflow, then condensation of the substance. Therefore, the magma moves all the time. It then goes down, then rises.

Lithosphere

The mantle reliably hides the solid, strong shell of the earth's crust, whose thickness is up to 70 km. The Earth's crust, as well as the upper part of the mantle together form a lithosphere. This name also has a Greek origin and consists of two words. The first of them is "stone", and the second is "sphere". Molten magma, which rises up from the depths, stretches (up to the rupture) the earth's crust. Most often, such gaps occur precisely in the ocean depths. Sometimes the movements of magma even lead to a change in the speed of rotation of the Earth, and hence its shape.

The lithosphere is not a homogeneous continuous cover. It consists of 13 large slabs - blocks, the thickness of which is from 60 to 100 km. All these lithospheric plates have both an oceanic and a continental crust. The largest of these are the American, Indo-Australian, Antarctic, Eurasian and Pacific.

Movement of slabs and deep basins

In the distant past, there were other outlines of the oceans and continents, which is explained by the movement of plates. Nowadays, the American and African gradually diverge. The American plate slowly floats to the Pacific, and the Eurasian plate approaches the African, Pacific and Indo-Australian.

The movements of the earth's crust due to tectonic activity were observed in all periods of the history of our planet. The cavities also formed at different times. They are characterized by different geological ages. Vulcanized and sedimentary deposits fill the ancient basins. And the youngest are clearly expressed in the relief of our planet. Therefore, it is not difficult for scientists to determine where deep-sea depressions are located.

Form of hollows

Depressions of the earth's crust can be closed both from all sides, and from most of them. Usually in diameter they reach tens and hundreds of kilometers, rarely - thousands. As a rule, their shape in relatively quiet parts of the crust of our planet is more or less round, sometimes - oval. But in the mobile belts, where deep-sea depressions are located, they have a linear form. Here they are often limited by faults.

Deepwater gutters

Depressions - not the only designation of geological objects of interest to us. Recently, pointing to them, more and more often they say "deep water gutters." The point is that this concept more accurately conveys the form of depressions of this kind. They are many in the zone, transitional between the ocean and the mainland. Especially numerous are deep-sea troughs of the Pacific Ocean. There are 16 depressions here. There are also known deep-sea trenches of the Atlantic Ocean (there are 3 of them). As for the Indian, there is only one depression.

The depth of the most significant gutters exceeds 10 thousand meters. They are in the Pacific Ocean, which is the oldest. The Mariana Trench (on the map presented above), the deepest trough of the known ones, is located right here. "The Challenger's Abyss" is what is called its deepest point. Its depth is about 11 thousand meters. This depression got its name from the Mariana Islands, located near it.

History of the study of the Mariana Trench

Scientists began to explore this object since 1875. It was then that the Challenger, a British corvette, lowered the deep-water lot into it, which determined that its depth was 8,367 m. The English in 1951 repeated their experience, but this time they used an echo sounder. The maximum depth, which he determined, was 10,863 meters. A new mark was recorded in 1957. It was established by the Russian expedition, which went to the hollow on the ship "Knight". A new record was 11 023 m. Relatively recently, in 1995 and 2011, studies were conducted that showed the following results - 10 920 and 10 994 m respectively. It is possible that the depth of the Mariana Trench is even greater.