At the bottom of the North Sea, buried beneath layers of sediment and fossilized sea creatures, scientists have discovered something that should not be there: giant mounds of dense sand. They seem quite literally to be the Earth’s geological layers, but flipped around. Essentially, the Earth’s insides are facing outwards.
Publishing their findings in Communications Earth & Environment, Researchers from the University of Manchester and Norwegian oil company Aker BP were scanning the seafloor with seismic imaging when they discovered massive formations called “sinkites.” They’re masses of heavy sand that had somehow sunk beneath lighter, older layers of sediment. Those lighter layers that ended up on top were referred to as “floatites.”
This phenomenon, known as stratigraphic inversion, isn’t unheard of. However, it has never been observed at this scale. There were hundreds of these things, stretching across several kilometers of seafloor.
Scientists Discovered Parts of the North Sea Seafloor Are Literally Upside Down
Typically, Earth’s layers consist of older material at the bottom and newer material at the top. But in this deep-sea inversion, seismic scans showed a bizarre reversal, with denser, younger sand layers punching through older, softer material.
Researchers suspect that this grand subterranean flip-flop occurred approximately 5.3 million years ago, around the Miocene-Pliocene boundary. Back then, a stiff upper crust of microscopic marine fossils floated over a heavier sand layer.
Earthquakes or other disturbances may have pulverized the upper layer, allowing the sand beneath to work its way down through the mess and flip the entire chunks of seafloor. Now, millions of years later, the whole thing is gently blanketed by normal seafloor sediment, covering it up like it never happened, leaving it to be revealed only by seismic imaging.
Understanding how sinkites and floatites formed could be a game-changer for carbon capture, underground storage, and maybe even oil exploration. It reveals that the seafloor is far more dynamic, unstable, and unpredictable than previously thought, and researchers already considered it unstable to begin with.
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