In a record-breaking geologic triumph, scientists drill a window into Earth’s mantle

Going deep beneath an underwater mountain, scientists have revealed a jackpot of new data about the most mysterious realm of our planet, writes Carolyn Y. Johnson

Aboard the Joides Resolution research vessel, team members process samples of mantle rock recovered from a more than 4,100ft-deep hole drilled into the seabed of the North Atlantic (Lesley Anderson/US Antarctic Program & IODP JRSO)

At an underwater mountain in the middle of the Atlantic Ocean, scientists have drilled nearly a mile beneath the floor and pulled up an unprecedented scientific bounty – pieces of Earth’s rocky mantle.

The record-breaking achievement has electrified geoscientists, who for decades have dreamed of punching through miles of Earth’s crust to sample the mysterious realm that makes up most of the planet. The heat-driven churn of the mantle is what fuels plate tectonics in the crust, giving rise to mountains, volcanoes and earthquakes.

The new expedition, by an ocean drilling vessel called the Joides Resolution, did not technically drill into the mantle, and the hole isn’t the deepest ever drilled beneath the ocean floor. Instead, researchers cruised to a special “tectonic window” in the North Atlantic where drills don’t have to tunnel as far to strike pay dirt. Here, the rocks of the mantle have been pushed close to the surface as the ocean floor slowly pulls apart at the nearby mid-Atlantic ridge.