Bermuda, often tied to mystery and folklore, has just revealed a geological enigma that may change how we view the island’s history. A new study published in Geophysical Research Letters uncovers a massive 12.4-mile-thick structure deep beneath the oceanic crust. This unexpected find challenges our understanding of Bermuda’s formation and could explain the island’s unusual position in the Atlantic Ocean.
A Geological Oddity Beneath Bermuda
Bermuda’s unique geological features have long intrigued scientists, but a recent breakthrough has introduced an entirely new mystery. Beneath the island lies an enormous, 12.4-mile-thick layer of rock—unlike anything found elsewhere on Earth. Using advanced seismic imaging, researchers from Carnegie Science and Yale University discovered this hidden structure that lies below the oceanic crust and within the tectonic plate on which Bermuda sits. As study lead author William Frazer, a seismologist at Carnegie Science, explained,
“Typically, you have the bottom of the oceanic crust and then it would be expected to be the mantle, but in Bermuda, there is this other layer that is emplaced beneath the crust, within the tectonic plate that Bermuda sits on.”
This discovery raises questions about the island’s geological history and the processes that led to the formation of this deep rock layer. The implications for our understanding of Earth’s tectonics are profound, as such thick, dense layers have never been observed in similar contexts elsewhere.
Credit: Geophysical Research Letters
The Bermuda Oceanic Swell: An Age-Old Mystery
Bermuda’s position as an oceanic swell—where the ocean floor is unusually elevated compared to its surroundings—has puzzled scientists for years. Typically, ocean swells are associated with volcanic activity, but Bermuda’s last volcanic eruption occurred over 31 million years ago. The question then becomes: why does the swell persist without any ongoing volcanic activity?
The newly discovered rock layer could provide an answer. Researchers believe that this thick layer of rock, remnants of past volcanic activity, may be the reason why Bermuda’s oceanic swell remains elevated despite the lack of active eruptions.
“There is still this material that is left over from the days of active volcanism under Bermuda that is helping to potentially hold it up as this area of high relief in the Atlantic Ocean,” said Sarah Mazza, a geologist at Smith College, Massachusetts.
This material could be helping to support the swell, essentially preventing it from subsiding over millions of years.
This finding, published in Geophysical Research Letters, also suggests that the geological history of Bermuda is quite different from other volcanic islands, such as those found in the Pacific or Indian Oceans. Unlike those islands, Bermuda’s volcanic past may be linked to the ancient supercontinent Pangea, which began breaking apart roughly 300 million years ago, adding further complexity to the island’s history.
A Layer Like No Other
The discovery of the thick, less dense rock layer beneath Bermuda is extraordinary, not only for its size but for its unusual composition. This layer appears to have remained intact over millions of years, despite the island’s separation from active volcanic hotspots. Scientists believe that this rock is a remnant of ancient volcanic activity from a time when the island was part of a much larger landmass.
“The fact that we are in an area that was previously the heart of the last supercontinent is, I think, part of the story of why this is unique,” said Sarah Mazza.
This discovery highlights the importance of studying regions like Bermuda to understand Earth’s evolving geology.
The rock beneath Bermuda is distinct in its composition—less dense than the surrounding material—indicating that it might have originated from the mantle, possibly pushed upwards during volcanic events long ago. As scientists continue to study the region, this layer could provide clues not only about Bermuda’s past but about the forces that shaped much of Earth’s surface during the breakup of Pangea.
The Geological Significance of Bermuda’s Past
Bermuda’s geological history is unique, shaped by the island’s location at the center of what was once the supercontinent Pangea. The carbon-rich lavas found in Bermuda suggest that the island’s volcanic activity came from deep within the mantle, in stark contrast to the usual sources of volcanic islands in the Pacific and Indian Oceans. This deep mantle material could explain why Bermuda’s volcanic history is so different from other islands of its type.
The presence of this carbon-rich lava further points to the island’s ancient roots, tracing back to a time when Earth’s continents were aligned differently.
“Understanding a place like Bermuda, which is an extreme location, is important to understand places that are less extreme,” said Frazer.
He emphasizes that studying these extreme locations helps provide insight into the more typical geological processes occurring on Earth today. Bermuda, with its ancient volcanic remnants, offers a key to unlocking these broader planetary processes.