World’s longest mountain range is mostly under water
Far beneath the ocean’s surface stretches the world’s longest mountain range. It’s one of the world’s great mysteries, barely explored beyond mapping and involved in all kinds of seismic activity.
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The zig zagging mid-ocean ridge (yes, it deserves a catchier, more majestic name) zig zags around the globe for more than 40,000 miles, making it longer than Earth’s circumference. The only place you can see it without diving way down is in Iceland. Otherwise, it edges along the tectonic plates, with peaks averaging 7,500 feet below sea level.
Scientists didn’t know about the mid-ocean ridge until the 1950s. And they’re just beginning to log data. So far, only 1% of the submerged ridge has been studied beyond mapping. Much of what we know so far comes from UK researchers who studied a small segment of the ocean bottom using seismometers. In 2016, the researchers went to Cape Verde off the west coast of Africa and set up 39 seismometer stations over a 1,000 kilometer wide segment of the mid-ocean range. A year later, they returned to retrieve their instruments and analyze the data.
What they found surprised them. “It was assumed that these gravitational forces, which are pulling down, are contributing to the spreads at the ridges,” said Matthew Agius, lead author of a study published in Nature in 2021. Instead, they saw that upwelling, not gravity, could be causing the seafloor spreading. “For the first time, we have evidence of higher temperatures in the mantle transition zone [at the Mid-Atlantic Ridge],” said Agius, as reported in Eos. “It introduces new evidence for the whole study of plate tectonics.”
Like so much of science, the exact process for creating this astounding underwater mountain range is still in the theoretical stage and will likely remain there for a while. The great depths, high cost of exploration and volatile volcanic environment work together to protect these deep ocean mysteries.