Midwestern Melt

The core of the U.S. may be “dripping” away

- Meghan Bartels

SOMETHING VERY STRANGE appears to be happening deep, deep underneath the U.S. Midwest and the Ohio Valley.

North America’s geological core has persisted for more than a billion years; it's what scientists call a craton, a massive block of continental rock that withstands the natural recycling system of plate tectonics. Typically scientists think of cratons as unchanging, nigh eternal. But research published in Nature Geoscience suggests that a long-lost geological plate may be siphoning molten rock from the underside of the North American craton and eroding it from below, right under our feet.

Such a scenario would not be unprecedented—scientists have evidence that the North China craton thinned dramatically millions of years ago—but it would certainly be surprising and intriguing to study in real time. “Cratons are the oldest cores of continents, so they have been sitting near Earth’s surface for billions of years,” says Claire Currie, a geophysicist at the University of Alberta, who was not involved in the new research. “They’ve persisted through time, so this is quite unusual.”