A map shows the ozone hole above Antarctica in September, when it was the size of North America. The ozone protects the Earth from the sun's ultraviolet rays.

North America is dripping—with sizable blobs of rock sinking from the underside of the continent, beneath the U.S. Midwest, into the Earth's mantle below.. This is the conclusion of researchers ...

A map showing seismic speed in Earth’s crust at 125 miles (201 km) depth across the continental U.S. and portions of Central America and Canada. The North American craton (outlined in black ...

Those measurements, Hua says, suggest that in this area, North America’s craton is dripping downward into the mantle in a way he and his colleagues didn’t expect and couldn’t quite explain.