Scientists have uncovered an extraordinary secret buried 200 km (124 miles) beneath the Appalachian Mountains in North America.
It was found that a massive pocket of unusually hot rock, a geological anomaly that is not only slowly moving but may also be the reason these ancient peaks still stand tall.
This slow-moving geological remnant is called the Northern Appalachian Anomaly (NAA).
According to findings from researchers at the University of Southampton, this zone of deep heat marks the spot where Greenland and North America began to separate 80 million years ago.
Previously, the deep heat source was thought to be a leftover from when North America split from Northwest Africa 180 million years ago.
“Our research suggests it’s part of a much larger, slow-moving process deep underground that could potentially help explain why mountain ranges like the Appalachians are still standing,” said Tom Gernon, lead author and Professor of Earth Science at the University of Southampton.
“Heat at the base of a continent can weaken and remove part of its dense root, making the continent lighter and more buoyant, like a hot air balloon rising after dropping its ballast. This would have caused the ancient mountains to be further uplifted over the past few million years,” Gernon explained.
Mantle wave theory
The Northern Appalachian Anomaly is roughly 350 km (217 miles) across and lies approximately 200 km beneath New England.
The study suggests this anomaly formed about 1,800 km (1,118 miles) away, near the Labrador Sea, during the continental splitting of Canada and Greenland. This warm, unstable rock slowly journeyed southwest over tens of millions of years, covering roughly 20 km per million years.
The movement is attributed to the “mantle wave” theory.
According to the mantle wave theory, the breakup of continents causes hot, dense rock to pull away from the underside of tectonic plates gradually.
The theory suggests that when continents tear apart, dense, cold rock at the base of the tectonic plate (the lithosphere) begins to “drip” down into the hotter mantle below, much like blobs in a lava lamp.
This sinking process causes hotter material to rise in its place, creating a thermal upwelling. These rock drips can then migrate sequentially, like geological dominoes falling one after another, creating a slow-moving “mantle wave” that travels thousands of kilometers inland.
Traveling beneath continents for tens of millions of years, these slow thermal waves account for diverse geological events. These include rare volcanic eruptions that bring diamonds to the surface and uplifted land far from plate boundaries.
Passing beneath New York
Using computer models, seismic tomography, and plate reconstructions, researchers successfully traced this anomaly back to its origin: the opening of the Labrador Sea and the separation of Greenland and Canada between 90 and 80 million years ago.
The 350 km-wide anomaly has been creeping southwest across the underside of North America for tens of millions of years.
In a final, fascinating detail, the models suggest this anomaly will continue its journey, passing beneath the New York region within the next 10 to 15 million years.
Beneath north-central Greenland, researchers suggest a similar heat anomaly exists, thought to be the NAA’s geological twin, formed when the continent split.
This deep thermal feature is currently impacting ice sheet dynamics by raising temperatures at the base of the ice sheet, thereby altering its flow and melting rate.
The findings were published in the journal Geology.