A record-breaking drilling operation dug more than a kilometer into a seamount in the Atlantic Ocean has given scientists a treasure trove of rocks to search for clues to Earth’s inner workings.

The striking result was achieved by drilling the Atlantis Massif, a seamount located on the Mid-Atlantic Ridge, deep in the North Atlantic. Aligning a drill bit at the site, geologists drilled a 4,156-foot (1,267-meter) deep hole in the mountain and extracted an “astonishing” amount of serpentinite—metamorphic rocks that form at the deep boundaries of tectonic plates. Soil.

Despite the groundbreaking findings, this isn’t the deepest probe ever to the seafloor, and it technically didn’t dig through the Earth’s mantle. Instead, the researchers took advantage of a “tectonic window,” an area through which mantle rocks are pushed above their normal resting places, to sink a drill and remove material.

“Mantle rocks on Earth are often extremely difficult to access,” geologists wrote in a blog post. “The Atlantis Massif offers a rare advantage to access it because it consists of mantle rocks that were lifted closer to the surface by ultra-slow seafloor spreading.”

Geologists have been trying to remove large chunks of Earth’s mantle since 1961, when scientists from the Mohole Project tried to pierce the Pacific Ocean floor to reach the Mohorovicic Rift, a region where the Earth’s crust has been replaced by the mantle. Unfortunately, the project’s drilling sank before it reached just 601 feet (183 meters) below the seafloor, and the attempt was aborted. After that, a number of other attempts to drill the ocean also ended in failure.

This meant that scientists had to rely on chunks of rock ejected by volcanic eruptions to study parts of the Earth’s mantle to detect processes as diverse as volcanism and the planet’s magnetic field. surface.

Geologists from the International Oceanic Exploration Program aboard the scientific probe JOIDES Resolution began their mission in the Atlantis massif not because they wanted to extract mantle cores, but because they were looking for the origins of life on Earth. Its massive rocks contain olivine, which reacts with water in a process called serpentinization to form hydrogen, an important food source for microbial life.

But shortly after May 1, when they dug their drilling into a horizontal fault in the seafloor, the researchers extracted a record-breaking upper mantle core that stretched more than 3,280 feet (1 km) in length.

The rock was mainly peridotite, a coarse igneous rock filled with olivine and pyroxene and the most common type of rock in the upper mantle. Some signs that the rock has changed by interacting with seawater may mean that it came from the lower crust rather than the upper mantle, but scientists are looking for deeper examples, leaving their discovery beyond doubt. Within these rocks lies a wealth of information that geologists will examine to learn more about the inner workings of the Earth.

“Our scientific team believes this will be incredibly important information for the next generation of scientists,” the geologists wrote.