Unravelling the Mystery of the Mid Ocean Ridge Discover What Lies Beneath

The Mid-Atlantic Rift is an active spreading rift (Constructive plate Boundary) separating two of the largest continental plates in the world: the North American Plate and the Eurasian Plate. Although the Mid-Atlantic Ridge is mostly an underwater feature, portions of it extend above sea level, for example in Iceland. The ridge has an average spreading rate of about 2.5 centimetres per year. The Mid Atlantic Ridges are about 3 km in height above the ocean floor and 1000 to 1500 km wide, have numerous transform faults and have an axial rift valley along their length. The place where the Mid-Atlantic Ridge is best seen is at Thingvellir National Park, in southwestern Iceland. The mid-Atlantic ridge valley forms due to the movement of the tectonic plates. When two plates move apart, magma rises up resulting in basaltic volcanism and new Crust formation. Most of the spreading is under the floor of the Atlantic Ocean, and part of the longest mountain range in the world.

The Mid-Atlantic ridge was discovered in the 1950s. Its discovery led to the theory of seafloor spreading and the general acceptance of Wegener’s theory of continental drift. The Mid-Atlantic Rift (MAR) separates the North American Plate from the Eurasian Plate in the North Atlantic, and the South American Plate from the African Plate in the South Atlantic. You can see the Mid-Atlantic Ridge on the world map which is shown in red lines. The mid-Atlantic rift map is separating the north American plate from the Eurasian Plate in the north while the south American plate is with the African plate in the south.

The submarine section of the Mid-Atlantic Ridge in Iceland is known as the Reykjanes Ridge or Neovolcanic Zone. Most of the ridge system is underwater but some form land as a set of volcanic islands of varying size. Notable features are-

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The Mid-Atlantic rift valley sits atop a geologic feature known as the Mid-Atlantic Rise, which runs the length of the Atlantic Ocean. This bulge is thought to be caused by upward convective forces in the asthenosphere pushing the oceanic crust and lithosphere. This divergent boundary was first formed in the Triassic period when a series of three-armed grabens coalesced on the supercontinent Pangaea to form the ridge. Usually, only two arms of any given three-armed graben become part of a divergent plate boundary. The failed arms are called Aulacogens, and the aulacogens of the Mid-Atlantic Ridge eventually became many of the large river valleys seen along the Americas and Africa including the Mississippi River, Amazon River and Niger River. The Mid-Atlantic ridge (rift valley) is an example of a Constructive Plate boundary where plates are moving apart and making a new crust.

The mid-ocean ridge is the most extensive chain of mountains on Earth, stretching nearly 65, 000 kilometres. The massive mid-ocean ridge system is a continuous range of underwater volcanoes that wraps around the globe like seams on a baseball. Mid-ocean ridges occur along divergent plate boundaries, where a new ocean floor is created as the Earth’s tectonic plates spread apart. As the plates separate, molten magma rises to the seafloor, producing enormous basalt magma. The speed of spreading affects the shape of ridge-slower spreading rates resulting in steep, irregular topography while faster spreading rates produce much wider profiles and more gentle slopes.

Two well-studied mid-ocean ridges within the globe are the Mid-Atlantic Ridge and the East Pacific Rise. The Mid-Atlantic Ridge runs down under the Atlantic Ocean, slowly spreading at a rate of 2 to 5 centimetres per year, forming a rift valley that is about the depth and width of the Grand Canyon.

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Another, the East Pacific Rise is spreading quickly, at rates of 6 to 16 centimetres per year. Due to the fast-spreading rates, there is no rift valley in the Pacific, just a smooth volcanic summit with a crack along the crest that is much smaller than the Atlantic rift valley. Despite being such a prominent feature on our planet, much of the mid-ocean ridge system remains a mystery.

Around the 1960s, scientists mapped the Earth’s ocean floors, which revealed a seismically-active central valley, as well as a network of valleys and ridges. They also discovered that the ridge was part of a continuous system of mid-ocean ridges that extended across the entire ocean floor, connecting all the divergent boundaries around the planet.

Much like the “Pacific Ring of Fire“, the discovery of the Mid-Atlantic Ridge has helped inform our modern understanding of the world.  This discovery also led to new theories in terms of geology and planetary evolution. For instance, the theory of “seafloor spreading” was attributed to the discovery of the Mid Oceanic Ridge (MAR), as was the acceptance of continental drift and plate tectonics. It also led to the theory that all the continents were once part of the subcontinent known as “Pangaea”, which broke apart roughly 180 million years ago.

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Basically, it is responsible for the fact that the Americas have been drifting away from Africa and Eurasia for millions of years, the formation of Australia, and the collision between the Indian Subcontinent and Asia. Someday, millions of years from now the process of seafloor spreading will cause the Americas and Asia to collide, thus forming a new supercontinent- “Amasia”.

The Reykjanes Peninsula where The Mid-Atlantic Rift rises out of the Sea is the best viewable site. Reykjanes Peninsula is home to Keflavik International Airport and this is the nearest airport to reach the site.A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about 2, 600 meters (8, 500 ft) and rises about 2, 000 meters (6, 600 ft) above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a divergt plate boundary. The rate of seafloor spreading determines the morphology of the crest of the mid-ocean ridge and its width in an ocean basin.

The production of new seafloor and oceanic lithosphere results from mantle upwelling in response to plate separation. The melt rises as magma at the linear weakness betwe the separating plates, and emerges as lava, creating new oceanic crust and lithosphere upon cooling.

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The first discovered mid-ocean ridge was the Mid-Atlantic Ridge, which is a spreading cter that bisects the North and South Atlantic basins; hce the origin of the name 'mid-ocean ridge'. Most oceanic spreading cters are not in the middle of their hosting ocean basis but regardless, are traditionally called mid-ocean ridges. Mid-ocean ridges around the globe are linked by plate tectonic boundaries and the trace of the ridges across the ocean floor appears similar to the seam of a baseball. The mid-ocean ridge system thus is the longest mountain range on Earth, reaching about 65, 000 km (40, 000 mi).

The mid-ocean ridges of the world are connected and form the Ocean Ridge, a single global mid-oceanic ridge system that is part of every ocean, making it the longest mountain range in the world. The continuous mountain range is 65, 000 km (40, 400 mi) long (several times longer than the Andes, the longest contintal mountain range), and the total lgth of the oceanic ridge system is 80, 000 km (49, 700 mi) long.

Map of Marie Tharp and Bruce Heez, painted by Heinrich C. Berann (1977), showing the relief of the ocean floors with the system of mid-ocean ridges

Mid Ocean Ridge

On the ridge flanks, the depth of the seafloor (or the height of a location on a mid-ocean ridge above a base-level) is correlated with its age (age of the lithosphere where depth is measured). The depth-age relation can be modeled by the cooling of a lithosphere plate

A good approximation is that the depth of the seafloor at a location on a spreading mid-ocean ridge is proportional to the square root of the age of the seafloor.

The overall shape of ridges results from Pratt isostacy: close to the ridge axis, there is a hot, low-dsity mantle supporting the oceanic crust. As the oceanic plate cools, away from the ridge axis, the oceanic mantle lithosphere (the colder, dser part of the mantle that, together with the crust, comprises the oceanic plates) thicks, and the dsity increases. Thus older seafloor is underlain by dser material and is deeper.

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Spreading rate is the rate at which an ocean basin wids due to seafloor spreading. Rates can be computed by mapping marine magnetic anomalies that span mid-ocean ridges. As crystallized basalt extruded at a ridge axis cools below Curie points of appropriate iron-titanium oxides, magnetic field directions parallel to the Earth's magnetic field are recorded in those oxides. The oritations of the field preserved in the oceanic crust comprise a record of directions of the Earth's magnetic field with time. Because the field has reversed directions at known intervals throughout its history, the pattern of geomagnetic reversals in the ocean crust can be used as an indicator of age; giv the crustal age and distance from the ridge axis, spreading rates can be calculated.

Slow-spreading ridges such as the Mid-Atlantic Ridge have spread much less far (showing a steeper profile) than faster ridges such as the East Pacific Rise (gtle

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