Researchers have identified a massive pocket of hot rock deep beneath the Appalachian Mountains, linking it to the ancient separation of Greenland and North America 80 million years ago. This Northern Appalachian Anomaly has slowly drifted over 1,800 kilometers to its current position under New England. The discovery suggests ongoing deep-Earth processes that continue to shape the continent.
A team of scientists from the University of Southampton, the Helmholtz Centre for Geosciences in Potsdam, and the University of Florence has proposed that the Northern Appalachian Anomaly (NAA), a region of unusually warm rock spanning about 350 kilometers and located roughly 200 kilometers beneath New England, originated from rifting in the Labrador Sea between 90 and 80 million years ago.
The NAA formed near the Labrador Sea as the crust split between Canada and Greenland, then migrated southwest across the North American lithosphere at approximately 20 kilometers per million years. This movement aligns with the researchers' 'mantle wave' theory, which describes how hot, dense rock detaches from tectonic plates after continental breakups and travels like blobs in a lava lamp. The theory was a finalist for Science magazine's 2024 Breakthrough of the Year.
Lead author Tom Gernon, Professor of Earth Science at the University of Southampton, explained: "This thermal upwelling has long been a puzzling feature of North American geology. It lies beneath part of the continent that's been tectonically quiet for 180 million years, so the idea it was just a leftover from when the landmass broke apart never quite stacked up."
The study, published in Geology (2025; 53(10): 859, DOI: 10.1130/G53588.1), used geodynamic computer models, seismic tomography, and plate reconstructions to trace the anomaly's path. Co-author Sascha Brune, head of the Geodynamic Modelling Section at GFZ, noted: "These convective instabilities cause chunks of rock, several tens of kilometers thick, to slowly sink from the base of the Earth's outer layer known as the lithosphere. As the lithosphere thins, hotter mantle material rises to take its place, creating a warm region known as a thermal anomaly."
The NAA's heat may buoy the Appalachians by weakening and removing dense lithospheric roots, uplifting the mountains despite surface tectonic inactivity for 180 million years. Calculations indicate the anomaly's center could reach beneath the New York region in about 15 million years.
A similar warm anomaly likely exists beneath north-central Greenland, formed on the opposite side of the Labrador Sea. Gernon added: "Ancient heat anomalies continue to play a key role in shaping the dynamics of continental ice sheets from below." Co-author Derek Keir remarked: "The idea that rifting of continents can cause drips and cells of circulating hot rock at depth that spread thousands of kilometers inland makes us rethink what we know about the edges of continents both today and in Earth's deep past."
These findings highlight how ancient rifting influences long-term continental evolution, including uplift, erosion, and inland volcanism in stable regions.