How It Works

Massive marine mountains

The red boundaries show the tectonic plates that make up the Earth’s crust, which are shifting and moving all the time.

The Mid-Atlantic Ridge is part of the longest mountain range in the world – these mountains just happen to be underwater. Mid-ocean ridges are a result of plate tectonics, and form due to volcanic activity in the oceanic crust. Currents in the Earth’s mantle cause magma to heat up, and it is forced through weak spots in the crust. The resulting lava cools into a new layer of crust. This pushes the plates apart and the resulting formation often has a rift, or valley, in the centre where two different plates are being pushed apart. All of these midocean ridges are connected around the world, totalling 80,000 kilometres (50,000 miles) or so in length.

The Mid-Atlantic Ridge by itself is around 10,000 kilometres (6,200 miles) long. It separates the North American tectonic plate (which also includes the Bahamas, Cuba, Greenland and parts of other countries) from the Eurasian tectonic plate. It also separates the South American tectonic plate from the African tectonic plate. Most of the mid-Atlantic plate is underwater, but some of it is actually high enough to appear above sea level. This includes a ridge that contains the island of Iceland, as well as a number of other islands.

Oceanographers and researchers have thought there was a mountain range in the ocean here since the 1870s, and it was confirmed in 1925 by sonar. It wasn’t until the Fifties, however, that we were able to fully understand the unique features hidden in the depths of the mid-Atlantic, and realised just how massive it really was. In addition to the islands, there are numerous deep trenches and valleys as well as extensive seismic activity, which is constantly altering the terrain.