Thick Rock Layer Beneath Bermuda Explains Elevation

Scientists have uncovered a massive, unprecedented rock layer beneath the island of Bermuda, offering a key explanation for why the archipelago remains elevated above the surrounding Atlantic Ocean floor despite millions of years without volcanic activity.

The discovery, detailed in a study published in the journal Geophysical Research Letters, reveals a 12.4-mile-thick (20 kilometers) slab of low-density rock situated between the oceanic crust and the mantle, about 31 miles (50 kilometers) below the surface. Researchers from Carnegie Science and Yale University identified the structure by analyzing seismic waves from 396 distant earthquakes recorded at a station on Bermuda. These waves, which typically pass directly from the crust into the mantle, deflected unexpectedly when encountering the layer, allowing the team to map its extent and properties.

Bermuda sits atop an oceanic swell, a raised portion of the seafloor that elevates the islands roughly 1,640 feet (500 meters) above the surrounding terrain. Such swells commonly form over mantle hotspots, where hot material rises to create volcanoes and buoy up the crust, as seen in island chains like Hawaii. However, Bermuda's...