What are Mid-Ocean Ridges? Learn About Underwater Mountain Ranges

What are Mid-Ocean Ridges? Learn About Underwater Mountain Ranges
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A mid-ocean ridge is simply a mountain underwater in the ocean. They are also sometimes referred to as mid-oceanic ridges. They typically contain a rift, which is a valley, running along their spine. These rifts are created by plate tectonics, which is the large scale motions of the lithosphere on Earth. A mid-ocean ridge is created by ocean floor spreading. This process is responsible for seafloor spreading. When a seafloor is uplifted due to convection currents which cause the mantle to rise as lava emerges. Once the lava cools, new crust is created resulting in mountains under the ocean.


The world’s mid-ocean ridges form a single global system and are all connected. This makes them the world’s largest mountain range. Its total length is 49,700 miles.


New crystallized magma is constantly forming new crust for the mid-ocean ridge. At ocean ridges the crust is constantly renewing itself. Mid-ocean ridges that spread more slowly tend to have wider, larger rift valleys. An example is the Mid-Atlantic Ridge. This ridges terrain is very rugged and the rift valleys can reach widths of ten to twenty kilometers with a ridge crest relief of nearly three-thousand feet.


Mid-ocean ridges are formed by two processes. These processes include ridge-push and slab-pull. The weight of a ridge will push away the remaining tectonic plate from the ridge, particularly towards what is known as a subduction zone. This is the ridge-pull process. The slab-pull process begins at the subduction zone. When a tectonic plate’s weight is pulled below the above plate dragging the remaining plate behind it is the slab-pull process.


Mid-ocean ridges were officially discovered in the 1950’s. They were not discovered earlier because they are located deep within the ocean. When mid-ocean ridges were first discovered, scientists thought they were only in the Atlantic Ocean.

Today’s Mid-Ocean Ridges

  • Chile Rise
  • Southwest Indian Ridge
  • Southeast Indian Ridge
  • Cocos Ridge
  • Central Indian Ridge
  • East Pacific Rise
  • Reykjanes Ridge
  • Chukchi Cap
  • Pacific-Antarctic Ridge
  • Alpha Ridge
  • Mid-Atlantic Ridge
  • Explorer Ridge
  • Juan de Fuca Ridge
  • Gorda Ridge
  • Mid-Arctic Ridge (also known as the Gakkel Ridge)


Pacific Marine Environmental Laboratory. (2011). Mid-Ocean Ridges. Retrieved on April 20, 2011 from the Pacific Marine Environmental Laboratory: https://www.pmel.noaa.gov/vents/nemo/explorer/concepts/mor.html

Science Daily. (2010). Mid-Ocean Ridge. Retrieved on April 20, 2011 from Science Daily: https://www.sciencedaily.com/articles/m/mid-ocean_ridge.htm

Photo Credits

Mid-Ocean Ridge Render: Wikimedia Commons - NASA