#https://www.indy100.com/science-tech/ocean-beneath-earth-crust-ringwoodite-2666175072

[idlescience]

Cool shit under the earth's crust post

In general, I'm not much of a geologist, but I've just discovered that there's a bunch of research focused on the water contained in the earth's crust. Research on this topic seems to have started back in the 90s (a lot of which involved a guy called Steven Jacobson). At the time they knew that the two main components of the transition zone between the earth's upper and lower mantle (Wadsleyite and ringwoodite) could likely contain water, but had no idea how much. Their crystal structure has oxygen and hydrogen-attracting properties that let them act like a sponge, trapping water within.

The problem was that these guys don't exist on the surface, so Steven and his team had to simulate the intense temperature and pressure conditions in the lab to grow samples, and then test how much water they could contain. But his estimates were crazy high, like way higher than previously thought possible, so he didn't want to publish without solid proof.

But then, the twist. They found a diamond (and as we all know diamonds are formed under pressure, specifically in a similar part of the earth's mantle), which contained a tiny amount of Ringwoodite. And the best part is that when he tested it, the water content lined up with what he'd been predicting.

More recently they've been using earthquake activity to get estimates of the actual water density in the crust based on how the seismic waves pass through the rock. And in just the transition phase alone there is likely the equivalent of THREE oceans worth of water. But there's probably water in the other layers as well, possibly up to five oceans' worth.

And one of the coolest parts of all of this? The water isn't just there, it's vital to the function of the crust and our tectonic plates, allowing the earth to cycle its water and control its temperature.