The Atlantic Ridge, Mid-Atlantic or Mid-Atlantic Ridge is a volcanic mountain range that divides the Atlantic Ocean from North to South.
It has a length of about 15,000 kilometers that covers both the North Atlantic, from the north of Iceland, and the South Atlantic (at a point east of South South America that is located 7,200 kilometers from said subcontinent). It is part of the oceanic ridge.
The volcanic mountain range is submerged in water, so the ridge causes the surface of the Atlantic Ocean to break into several islands that can be found grouped in the middle of the sea..
Of all the islands that are located from North to South, only those of San Pedro and San Pablo have a volcanic origin, unlike Iceland, Ascensión, Tristán sa Cunha, Santa Elena and Bouvet, which are not..
It should be noted that the extension of the largest part of the Atlantic Ridge occupies some 3,000 to 5,000 meters below its surface..
From its seabed there is a long mountain chain whose peaks, sunk in the water, rise to various meters in height ranging between 1,000 and 3,000 meters.
On the other hand, the Atlantic ridge has an extension that can go wide, that is, it occupies approximately 1,500 kilometers measured from East to West.
It is well known that the Atlantic Ridge has a great cleft, that is, a deep valley that runs the entire length of its crest. Its estimated width is around 10 kilometers and its walls are authentic walls that reach a height of up to 3 kilometers.
In short, this valley forms a natural border that at the bottom of the Atlantic Ocean divides the two tectonic plates found on Earth. Its widening occurs constantly, at a rate of 3 centimeters per year.
Due to the high volcanic activity that it has within, the area in which the seabed opens tends to be nourished by its rapid rise. That is, the magma, when it rises, cools later, and later becomes a new layer that joins the ocean floor.
The Atlantic Ridge has fracture zones. The best known is the Romanche fracture, which runs from East to West. It also has discontinuities whose extension exceeds 100 kilometers in length..
The existence of the Atlantic Ridge was already sensed in the 19th century, but it could not be confirmed until the 20th century. The first clear indication of this was a find that was classified as spectacular..
It is stipulated that everything happened around the year 1853 during work for the installation of a cable across the Atlantic Ocean that would expand international communications. This was inferred three years earlier by the American oceanographer Matthew Fontaine Maury..
As has been said, the transatlantic cable was the starting step for this discovery. In order to get that cable installed correctly, it was necessary to measure the depth of the ocean.
For this, it was necessary to carry out exhaustive surveys. In these, it was noted that in the signals there was clear evidence of an underwater plateau under water, in the middle of the Atlantic Ocean. However, not much attention was paid to this particularity, so it quickly fell into oblivion..
Almost 20 years passed until a British naval expedition, led by the corvette HMS Challenger, gave new light in 1872. The oceanographic mission of the English was checking what had been found in 1853 and found, of course, that the sides of the Ocean Atlantic were shallower than its central zone.
Soundings, however, continued along the entire length of the oceanic line and this method continued longer in the remainder of the 19th century..
The nineteenth-century finds, continued by men like the Scottish naturalist Charles Wyville Thomson (1830-1882), were supplemented in 1922 by the German naval expedition in charge of the Meteor ship..
This time the sounding of the Atlantic Ocean was much more methodical. He was not just testing the waters to install telegraph cables, but made a meticulous study of the maritime area through ultrasound instruments.
Later, a team of scientists managed to find the target: a huge mountain range under the sea that crossed the entire Atlantic Ocean, with a meandering shape.
The most peculiar thing was that while the lowest peaks remained imperceptibly submerged in the water, the highest were in front of their eyes: they were the islands of the Atlantic, such as Tristán da Cunha, Ascensión and the Azores. But that was not even the half of what he was to discover.
Deeper soundings were conducted in other areas of the Atlantic Ocean in those years. Indeed, the newly found mountain range was found to pass through New Zealand and through Africa. This means that the Atlantic Ridge was not satisfied with crossing the Atlantic Ocean, but extended much further, to the Pacific Ocean..
Furthermore, scientists realized that the Transoceanic Ridge was what they had mistakenly taken to be the Central Atlantic Ridge..
In this way, the experts, in addition to making new discoveries, corrected previous ones. From the 1920s through the 1940s, explorers searched the Atlantic with methods already used to find German submarines during World War II..
This method was quite familiar to them and allowed them to correctly interpret the results of their investigations, in which they showed unmistakable signs of novelty..
After said war, the oceanographic and geological works resumed their normal activities. By then scientists knew that there were a series of radical differences between the underwater mountain ranges and those that were on the continent..
The former were a composition of pressed basalt that covered its entire structure from head to toe, quite unlike the latter, which had sedimentary rocks in their composition..
It was in the 1950s, and more specifically in 1953, when discoveries were made that can be classified as revolutionary..
The team of North American scientists, led by geologist Bruce Charles Heezen, noted that there were more landforms at the bottom of the Atlantic Ocean than initially believed. To their surprise, Heezen's group found that in the center of the Atlantic Ridge there was a very deep ravine..
This finding was key to corroborating what the previous work of Maury, the HMS Challenger team and Thomson had detected in the 19th century..
That ravine was the bottom of the ocean and its sides were nothing but its walls, which were supposedly the slopes of a giant underwater plateau.
This feature, in fact, extended throughout the entire Atlantic ridge and not just a portion of it. For this reason it was that some scientists baptized this area as the Great Cleft of the Globe.
In sum, the Atlantic Ridge was found to be longer than they had imagined, as it also passed through the Red Sea, made a detour in the coastal region of the Pacific Ocean and passed through California (particularly in its gulf, in the west coast of the United States).
The scientists did not doubt, of course, that the Great Cleft was some 60,000 kilometers long, but noted that it was discontinuous, with sections disconnected by seismic and volcanic action..
By the 1960s there were more expeditions, such as the DSDP Project in 1968 and the Mohole Project that lasted from 1961 to 1966. The latter was discontinued due to economic problems..
In both cases, something more was sought than to make a sounding along the Atlantic Ridge (whose length was already well known together with its intense volcanic and seismic activity). Hence, an approach was taken in which samples of rocks and sediment were taken..
The findings around the Atlantic Ridge did not go unnoticed, even less with the evidence revealed during the 20th century.
In the first place, the relevance of these works lies in the fact that it could be verified beyond any reasonable doubt that the theory of continental drift, postulated by Alfred Wegener, had absolute validity..
Second, the presence of the Atlantic Ridge further supported the idea that the Earth began in the shape of a supercontinent called Pangea..
After studies carried out for more than a century, it has been found that the Atlantic Ridge basically consists of a very deep valley whose shape is sinusoidal..
That is, a long meandering line that, as noted above, is interrupted in several of its sections due to the intervention of volcanoes and the underwater earthquakes so frequent in that part of the Earth. This line leaves a clear separation in the tectonic layers that are located in the continents that it crosses..
It is also worth remembering that the terrain of the Atlantic Ridge is formed by hot magma that tries to rise to the surface, but runs into ocean waters..
This causes it to end up cooling and causing a wall of hardened lava to emerge from the underwater volcanic eruption that becomes the new layer of soil on the seabed. Every year new centimeters of geological plates are added whose thickness is constantly increasing.
In addition, the Atlantic Ridge is subdivided into two branches; a northern branch, which is the North Atlantic ridge, and a southern branch, which is the South Atlantic ridge.
In the latter there is a kind of maritime trench, or rather a break, a fracture known as that of Romanche and which sinks to 7,758 meters. It is, therefore, one of the deepest underwater sites in the Atlantic Ocean..
The Atlantic Ridge begins its journey in Iceland and ends in the South Atlantic Ocean. It makes a link with South Africa through the Cape of Good Hope until it passes through the ridge of the Indian Ocean.
From there it passes to the South of Australia through the ridge of the Pacific Ocean, which is extended throughout its southern and eastern zone until it reaches the territory of Mexico, where it touches the western coast of the United States, in California..
There are secondary ridges to the Atlantic, which in turn can be transversal or parallel. Among them are the Hawaii ridge, the Pacific ridge, and the Kerguelen ridge..
Today, the ridges that maintain their tectonic activity occupy surfaces that are directly proportional to the continents with which they border.
In addition, along the route of the Atlantic Ridge there are many islands and archipelagos of volcanic origin, in total there are nine islands that are located in the middle of the Atlantic Ridge. On the North Atlantic Ridge are Iceland, San Pedro, the Azores and Jan Mayen.
For its part, the South Atlantic Ridge is made up of the islands of Bouvet, Tristán da Cunha, Gough, Santa Elena and Ascensión. In the particular case of Iceland, the Atlantic ridge passes exactly in the middle, so that it literally divides it in half.
It is worth highlighting a particularity of the Atlantic ridge that serves as a test for continental drift and therefore plate tectonics..
The fact is simple but momentous: the Romanche fracture, mentioned above, draws an imaginary horizontal line through the Equator. But the surprising thing is not that, but that the edges of the Gulf of Guinea and the northeast coast of Brazil fit together and indicate that Africa and America were continents that were once united..
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