There is much we still don’t know about the inside of our planet – but scientists recently discovered water is slowly leaking down there from the surface. It’s not a simple journey. The liquid is dripping down descending tectonic plates, before eventually reaching the core after a 2,900 kilometre journey. And while the process is slow, it has over billions of years formed a new surface between the molten metal of the outer core and the outer mantle of the Earth. In a new study, scientists at Arizona State University have said the water is triggering a chemical reaction, creating the new layer, which is “few hundred kilometres thick”. (That’s “thin” when it comes to the inner layers of the Earth.) “For years, it has been believed that material exchange between Earth's core and mantle is small. Yet, our recent high-pressure experiments reveal a different story. “We found that when water reaches the core-mantle boundary, it reacts with silicon in the core, forming silica," co-author Dr Dan Shim wrote. “This discovery, along with our previous observation of diamonds forming from water reacting with carbon in iron liquid under extreme pressure, points to a far more dynamic core-mantle interaction, suggesting substantial material exchange.” So what does it mean for all of us up on the surface? The ASU release said: “This finding advances our understanding of Earth's internal processes, suggesting a more extensive global water cycle than previously recognised. “The altered ‘film’ of the core has profound implications for the geochemical cycles that connect the surface-water cycle with the deep metallic core.” How to join the indy100's free WhatsApp channel Sign up to our free indy100 weekly newsletter Have your say in our news democracy. Click the upvote icon at the top of the page to help raise this article through the indy100 rankings.