Where is the longest mountain range on Earth?

Is it the Himalayas of Asia? Is it the Rocky, Appalachian, or Sierra Nevada Ranges of North America? Or maybe the Andes of South America?

Hint: If you are looking on land, you are never going to get the right answer.

The mid-ocean ridge system is a chain of mountains and valleys on the seafloor of the ocean. It forms where tectonic plates separate and spread – as this happens magma (molten rock) from the mantle erupts above the seafloor. The mid-ocean ridge mountain system is 65,000 km (40,389 miles) long.  

The mid-ocean ridge system. New ocean crust is in red. Image: Elliot Lim, CIRES, and NOAA/NCEI

Scientists go on an exciting search for hydrothermal vents

Part of the mid-ocean ridge is in the middle of the Atlantic ocean, where the North American tectonic plate meets the Eurasian tectonic plate. This part of the mid-ocean ridge is called the Mid-Atlantic Ridge.

The Mid-Atlantic Ridge is shown in light blue in the middle of the Atlantic Ocean NOAA, Public domain, via Wikimedia Commons

For many years scientists have been searching the Mid-Atlantic Ridge for special features called hydrothermal vents. A hydrothermal vent is a crack in the seabed where seawater mixes with magma (molten rock).

On March 12, 2023 a team of scientists gathered in the control room of the RV Falkor (too), an oceanographic research vessel operated by the Schmidt Ocean Institute. They watched the monitor of a camera-wielding underwater drone, or ROV, as it explored the deep sea 2,000 meters (6,600 feet) below the ship. When the screen showed a plume of black smoke, the scientists cheered.

The video showed a sprawling field of hydrothermal vents on the Puy des Folles Volcano on the Mid-Atlantic Ridge.

Some of the vents, known as “black smokers,” had formed tall “chimneys” of iron sulfide deposits. These chimneys gushed out dark, sulfurous plumes with temperatures up to about 340° Celsius (644° Fahrenheit). That temperature is hot enough to melt lead!

This high-temperature hydrothermal vent field was discovered during the expedition in the Mid-Atlantic Ridge. Image courtesy of Schmidt Ocean Institute.

Life thrives around these scorching vents

Despite the sizzling water, the newly discovered vents swarmed with life. Shrimp and other deep-sea life like crabs, mussels, anemones, fish, and gastropods are perfectly adapted to this environment.

Hydrothermal vents like these are of particular interest to scientists. These vents play a critical role in regulating global ocean chemistry by transporting heat and chemicals from the interior of the Earth. 

Also these vent systems support complex ecosystems and store vast amounts of marine genetic resources.

While there is still much to learn about hydrothermal vents, some people want to mine them for valuable minerals. 

However, scientists say that such plans should be approached with caution. Dawn Wright, a deep-sea biologist, says the work being conducted by scientists like the Falkor team is vitally important to understand the deep ocean. More knowledge is needed to understand the potential impacts of future activities like deep-sea mining. She says:  “There is still so very, very much more that we need to learn about how these ecosystems function, how nutrients are cycled among and within the vent animals, and the sheer biodiversity of these animals.”

This story has been adapted for Mongabay Kids. It is based on an article by Elizabeth Claire Alberts, published on Mongabay.com