As you read this, the North American continent’s underside is dribbling away into Earth’s molten mantle. The North American craton (outlined in black dashes) has a high seismic velocity compared to its surroundings. First seismically imaged in the 1990s by study co-author Stephen Grand, the Farallon Plate has spent the last 200 million years subducting underneath North America. To test this theory, Hua and colleagues ran their computer model with and without the inclusion of the Farallon Plate. Not only that, but similar events generally stop once the Farallon Plate’s remnants sink deeper into the mantle and cease affecting the North American craton.