Global Mid-ocean ridge system

Longest mountain range on Earth

Mountain range on seafloor
The mid-ocean ridge is a mountain range on the floor of the world's oceans. Rift valleys in the center of the mountain range runs down its spine. It sometimes reaches 1000 m (3,128 ft) above the seafloor.

Length of global mid-ocean ridge system
The entire global mid-ocean ridge system in the oceans is 80,000 km (49,700 miles ) long. It has a continuous mountain system that is 65,000 km (40,400 miles) long making it the longest mountain range on Earth.

Map of the global mid-ocean ridge system on the ocean floor, NOAA

Central rift valleys & plate movement

Rift valleys
The youngest rocks on the ocean floor are located in the rift valleys where magma pushes up the crust as it move from the upper mantle to vents on the ocean floor. The molten lava cools and forms parallel lines of basalt rocks on each side of the rift valley during an eruption.

Ocean floor movement
Each subsequent lava eruption causes the older rocks to move away from the spreading center. All across the ocean the seafloor moves from spreading ridges to subduction zones where the oceanic crust is recycled.

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Discovering and surveying the mid-ocean ridge

Surveying the ocean floors
Research ships began surveying the ocean floors in the 1950s using sonar as they traversed the oceans worldwide. A Columbia University ship, Vema, recorded information on the Atlantic Ocean seafloor. Prior surveys had shown a rise on the ocean floor but it was thought to be a small area.

Mid Atlantic Ridge
The full extent of the mountain range in the Atlantic Ocean was discovered by researchers when the data from the ship was analyzed. The submarine mountain range was named the Mid Atlantic Ridge.

Global mid-ocean system
New surveys by other ships discovered that the Mid Atlantic Ridge was in fact just one segment of the global mid ocean ridge system that is found in all the oceans on Earth.


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