Almost three quarters of the planet covered the seas and oceans. They represent huge sources of moisture, various components. Water evaporates, rises, forms clouds, which, in turn, are carried by air currents. Subsequently accumulated in the atmosphere the moisture again enters the seas and oceans as precipitation. So it is a cycle in nature. Of particular importance in the oceanic water. This area is the subject of study of many scholars for quite a long time.
Recently, the study of the ocean floor has acquired particular urgency. Let us further consider what it is.
Secrets of the ocean
For research use vessels with grabs, sonar, and special submarines, bathyscaphes. Most of the work is carried out on the surface of the water. For example, therefore, conducted hydroacoustic measurements. Revealing the secrets of the ocean, researchers receive critical information about the climate, the flora and fauna of ancient times. A large amount of data was obtained during the large-scale study that unfolded after the completion of world war II. This information becomes available in underwater drilling. The result of this work receive the column of rocks. In 1956 year, for example, was carried out underwater drilling. One of the columns had a length of 14.5 m (the rate of accumulation of sediment about 1 cm in 1000 years). This finding was extensively studied by the Russian scientists.
The bottom topography of the oceans
The underwater landscape is very diverse. The ocean floor is the upper part of the lithospheric plate, on which there are valleys, clefts, ridges. The main parts of the slab are:
- The continental slope.
- The deep trench.
- Oceanic plateau.
- Underwater hollows.
- Mid-ocean ridges.
In the underwater outskirts of the continent is isolated shoal, slope and the foot. The first has a lot of irregularities. It encloses the continents. On the outside of the shoals are rocky ledges. Its depth is in the range of 130 metres. The bottom topography of the oceans have been heavily influenced by glaciation. In that period the land was formed blocks of ice. The level of the ocean has dropped significantly. As a result, in the existing sections of the shoals appeared in the river deltas. These elements have survived to the present time. In addition, ice age continental boundaries emerged abrasion platform. In those areas of the shelf which was dry land at that time, were found bones of mammoths and other household items people. On the banks subjected to icing, by moving blocks were recesses hollows and depressions. These plots are located in the district of Maine, along the Alaska, Norway, in the southern part of the coast of Chile and in the Gulf of St. Lawrence.
The bottom of the ocean in this part has a number of features. In particular, it formed a well defined, distinct boundary with the shelf. In addition, in almost all places the continental slope is intersected by deep submarine canyons. Near its lower border in the Indian and Atlantic area is a surface, which is called the foot. The bottom of the Pacific ocean this area is not. The angle of slope equal to an average of 4 degrees. But in some areas it may be more of a badass. The slope differs generally stepped profile. Canyons intersecting it, can be up to 300 meters or more. The deepest is the Grand Bahamas. Its depth is five kilometers. Presumably, the canyons, and a stepped profile is formed as a result of tectonic movement. Mainland the foot is considered to be intermediate station, has a rolling slope. Its depth is 3.5 km. it contains sediment, the accumulation of which was formed by landslides and mutevelli flows. The bed of the ocean goes to a depth of 3.5-6 km. It is characterized by flat or rolling terrain. As a rule, it forms the Foundation formed by the basalts in the upper part, and the case of deep sea sediments. The latter is represented by biogenic calcareous ooze, red clay.
Some of them are of volcanic origin. As a result of wave abrasion their tops cut out. They are called guyots. The peaks are located at a distance of 1-2 kilometers to a few meters from the water surface. On the tops of the tropical zone can be formed atolls. Mountains, towering above the surface, in some areas forming Islands (SV. Elena, Hawaii, Easter, Azores). Some of them found coral structures (atolls).
Mid-ocean elevation can be up to 60 thousand km On the ridges are transverse faults. The elevation presented in the form of rock formations, the width of which is several hundred kilometers. Their height is of the order of 2-3 km, They are facing several parallel mountain ridges. The slopes down to the ocean floor with wide steps.
Along the ridges on the highest land in the center of the rift ridges cut by gorges. These areas are of particular interest. On these sites is quite high seismic activity. Daily, there happens to be a hundred earthquakes. In addition, there is a volcanic activity. The walls of the rift valleys and on the crests of ridges adjacent to it, found the deep rock of the planet.
The bottom of the ocean also form the shafts. They are represented by massive uplifts with very gentle slopes. Ramparts of the Pacific share a bed on several large basins:
- The central one.
In addition, the box cut through the fault zone. They are presented in the form of very long strips of hard fragmented DNA. From the axis of the median ridges towards the depressions starts deepening. The bottom is reduced from 2.5-3 to 5-6 m. To change sharply dissected terrain comes flat surface of the abyssal basins. The sedimentary cover becomes more powerful, increasing up to 600-1000 m in the center. Getting older and the age of the sedimentary accumulations, up to the Jurassic (top) period. In the narrow axial zones of the ridges poured lava, which built up a basalt Foundation. Sedimentary materials are gradually beginning to cover the bumps, smoothing thus the relief.
On a large scale in abyssal basins are widely distributed iron-manganese accumulations. On the margins of some continents (South America, Africa) are formed phosphates. Along the axis of the median ridges simultaneously with the appearance of basaltic rocks there is a high level of hydrothermal activity. It is associated with deposits in basaltic layer of sulphide ores. Useful components are carried into the water. Subsequently, they are deposited as metal-bearing precipitation in depressions near mid ranges. Such accumulations include basin Bowers.
They crash into the bottom of the ocean 300 meters or more. As a rule, they are distinguished by their steep sides, the tortuosity. The bottom of the canyons are fairly narrow. The most famous is the Great Bahama. Submarine canyons are very similar to the mainland of education. However, most of the first are ancient river valleys.
Life on the ocean floor is virtually nonexistent. Only a small part of the plate surface is in the photic zone. In this area the plants receive enough sunlight for photosynthesis. This euphotic territory is limited to areas along the coast, and inland seas. On the surface of the soil and its thicker inhabited by organisms, the totality of which is referred to as the benthos. At the bottom of the ocean, you can see sea urchins, shrimp, squid, octopus.