Scientists have identified giant bodies of sand buried deep below the North Sea—structures so vast and unusual that they are challenging long-held views about how layers beneath Earth’s surface are formed and arranged.
The formations, stretching across several kilometers (miles) in width, appear to have sunk below older and softer layers of sediment. In normal conditions, younger rocks settle on top of older ones. But in this case, the sand mounds—believed to be relatively young—have moved downward, flipping the natural order.
This reversal of layering, known as stratigraphic inversion, has been seen before but only at a much smaller scale. The newly discovered features, now named “sinkites,” are the largest of their kind ever documented.
The research team, based at the University of Manchester, collaborated with industry experts to uncover these structures using advanced seismic imaging and data from hundreds of offshore drilling sites.
Largest example of its kind alters accepted geological norms
The findings, published in the journal Communications Earth & Environment, reveal what researchers have characterized as a previously unseen natural process. “What we’ve found are structures where dense sand has sunk into lighter sediments that floated to the top of the sand,” said Professor Mads Huuse, the lead author.
Researchers believe the sinkites were formed millions of years ago, during the Late Miocene to Pliocene periods.
They suggest that underground shifts—triggered by earthquakes or sudden changes in pressure—may have caused the sand to behave like a liquid. This allowed it to slip through cracks in the seabed and settle below the softer layers, pushing those layers upward in the process.
The lighter material, made mostly of tiny marine fossils, held together by natural cracks, rose to the top and formed features now referred to as “floatites.”
Potential applications in energy and carbon storage
This unexpected underground behavior could have practical consequences. Understanding how such formations develop may help scientists predict where oil and gas could be trapped. It could also influence how and where carbon dioxide is safely stored deep underground.
“This research shows how fluids and sediments can move around in the Earth’s crust in unexpected ways,” Huuse said. “Understanding how these sinkites formed could significantly change how we assess underground reservoirs, sealing, and fluid migration.”
The team is now searching for similar formations elsewhere to test how common this process might be. While some in the scientific community remain cautious, others view the discovery as an important step forward.
The discovery of these giant bodies of sand not only opens new questions about Earth’s geological history but could also shape future efforts in energy and environmental planning.