Geologists have uncovered a remarkable geological phenomenon, detailed in recent Nature Geoscience research: the ancient craton system beneath North America is gradually melting into the Earth’s mantle. This “dripping” process has created a tubelike structure beneath the Midwest United States, as old, dense rocks shift horizontally before descending into the mantle.
Cratons are ancient, stable cores of Earth’s continents, having endured for hundreds of millions of years. Despite their resilience, they are not immune to change. Mantle plumes—hot, buoyant upwellings from deep within the Earth—can distort and melt portions of the overlying crust. A similar process previously led to the thinning of the North China Craton.
Jeff Hua and his team at EarthScope developed a detailed seismic model to peer beneath North America, producing the first real-time observations of craton thinning on the continent.
This transformation is largely driven by the ongoing subduction of the Farallon Plate beneath North America, a process that has continued for over 200 million years. As the plate descends, it releases magma and volatiles, weakening the base of the craton until portions begin to drip into the mantle.
While these findings reveal profound geological activity beneath the surface, researchers emphasize that the surface remains stable. This discovery offers scientists a rare glimpse into the deep processes that shape our planet. As researcher Thorsten Becker noted, it enhances our understanding of how continents evolve and are reshaped over geological time.
