Science Uncovers Hot Blob Beneath Appalachians, Tracing Roots to Ancient Greenland Rift

A massive hot blob of rock slowly moving beneath the Appalachian Mountains in the northeastern United States is now believed to have originated from an ancient Greenland rift, formed when Greenland and Canada separated around 80 million years ago.

This groundbreaking discovery, published in Geology by an international team of scientists, challenges the long-held belief that the phenomenon stemmed from the breakup of North America and Africa approximately 180 million years ago.

To test their hypothesis, researchers utilized a combination of existing geological data and advanced computer modeling. The simulations linked the hot blob—technically termed the Northern Appalachian Anomaly (NAA)—to a geological formation in the Labrador Sea in the North Atlantic, dating back approximately 85–80 million years.

"This thermal upwelling has long been a mysterious aspect of North American geology," said Thomas Gernon, an earth scientist from the University of Southampton, UK. "It lies beneath a region that’s been tectonically dormant for about 180 million years, so attributing it solely to the early continental breakup never fully made sense."

The NAA spans about 350 kilometers (217 miles) in width and drifts at a slow pace—approximately 20 kilometers per million years. At this rate, the mantle wave is expected to pass under New York in roughly 10 to 15 million years.

Interestingly, the researchers suggest this mantle wave plays a critical role in the continued elevation of the Appalachian Mountains. The persistent heat from the anomaly contributes to the buoyancy of the continental crust, helping to maintain and even uplift the mountain range over time—despite the region's tectonic quietude.

This study expands on earlier work by the same research group, who introduced the mantle wave theory. According to this model, blobs of hot rock rise in the Earth’s mantle in a lava-lamp-like motion when continents rift apart. These upwellings can lead to widespread geological transformations, including volcanic eruptions and mountain formation.

"Our earlier research showed that these rock drips can occur in succession, like dominoes falling, and gradually migrate over vast distances," explained Sascha Brune, a geophysicist at the GFZ Helmholtz Centre for Geosciences in Germany. "The feature beneath New England is almost certainly one of these migrating drips, born far from where it now rests."

Further investigation of the hot blob and its migratory path will help solidify its origins. In fact, the research team believes they may have already found a geological counterpart—a “mirror” anomaly—beneath north-central Greenland, also tracing back to the ancient Greenland rift and Labrador Sea.

"The idea that continental rifting can generate deep-Earth drips and circulating hot rock cells that travel thousands of kilometers inland transforms how we view continental boundaries—not just today, but throughout Earth’s environmental and geological history," said Derek Keir, a geophysicist from the University of Southampton.

This discovery opens new avenues for understanding Earth’s deep-time geology, the dynamic processes within the mantle, and their far-reaching impacts on our environment.