A long-standing controversy over a mysterious crater hidden under the North Sea has finally been settled. Researchers confirmed that Silverpit Crater was formed about 43 million to 46 million years ago when an asteroid or comet impacted the area.
The discovery resolves a scientific debate that has been going on for more than two decades, identifying Silver Pit as one of Earth’s relatively rare impact craters, a geological scar left when a space rock crashed into Earth at breakneck speed.
The research team, led by Dr Wisdeen Nicholson from Heriot-Watt University in Edinburgh and funded by the Natural Environment Research Council (NERC), combined advanced seismic imaging, microscopic analysis of rock samples and computer simulations to build the strongest case yet for an extraterrestrial impact. Their results were published in the journal nature communications.
Hidden crater under the North Sea
Silverpit Crater is located approximately 700 meters (2,300 feet) below the ocean floor in the southern North Sea, about 130 miles off the Yorkshire coast.
The structure has baffled geologists since it was discovered in 2002. The crater itself spans about 3 kilometers (1.9 miles) in diameter and is surrounded by a much larger ring of circular faults that spans about 20 kilometers (12 miles). Faults are cracks in rock layers that form when the Earth’s crust is stressed or moved.
Many scientists believed that the silver pits were formed by hypervelocity impacts (a term used to describe impacts involving asteroids or comets traveling at several miles per second). The crater’s circular shape, central crest, and distinctive surrounding fault pattern resembled features seen at known impact sites around the world.
Not everyone agreed.
Some researchers have proposed that this structure was formed when underground salt deposits changed over time. Some suggested it was due to volcanic activity that caused part of the ocean floor to collapse.
Disagreements became so intense that in 2009 geologists held a formal vote on the crater’s origin. earth scientist According to the magazine, most participants refused to explain the impact.
Now, the latest evidence overturns that conclusion.
New evidence reveals ancient asteroid impact
To revisit this mystery, scientists turned to newly available seismic data. Seismic imaging works similar to ultrasound scans of the Earth, allowing researchers to use reflected sound waves to create detailed images of underground rock formations.
The new images provided an unprecedented view of the crater’s internal structure.
The team also examined rock fragments taken from oil exploration wells near the site.
Dr Wisdeen Nicholson, a sedimentologist at Heriot-Watt University’s School of Energy, Earth Sciences, Infrastructure and Society, said: ‘The new seismic images provide an unprecedented view of the crater.
“Samples taken from oil wells in the area also revealed rare ‘shocked’ quartz and feldspar crystals at the same depth as the crater floor.
“We were very lucky to find these. It was a real ‘needle in a haystack’ effort. They proved the impact crater hypothesis beyond any doubt, because they have structures that can only be created by extreme impact pressures.”
Shocked minerals are considered some of the strongest evidence of an asteroid impact. The microstructures inside these crystals form only when rocks are subjected to enormous pressures that far exceed those produced by normal geological activity.
160 meter asteroid and towering tsunami
The team’s analysis shows that the object that hit the North Sea was about 160 meters (525 feet) wide and approached from the west at a shallow angle.
Although relatively small compared to the asteroid responsible for the extinction of the dinosaurs, it was still large enough to cause extraordinary destruction.
Dr Nicholson said: “Our evidence shows that a 160m wide asteroid hit the ocean floor at a low angle from the west.
“Within minutes, a 1.5-kilometer-high curtain of rock and water formed, which collapsed into the sea, creating a tsunami over 100 meters high.”
A tsunami of this magnitude would have reached more than 330 feet above sea level, higher than many modern skyscrapers.
The impact would have instantly excavated a crater and blown tons of rock, sediment, and seawater into the atmosphere.
Search for “Silver Bullet”
One of the researchers involved in the new study is Professor Gareth Collins of Imperial College London, who also weighed in on the debate over the origins of silver pits in 2009.
Collins developed a numerical model used to simulate the impact and compare its effects to the observed structure of the crater.
Professor Collins said: “I have always thought that the impact hypothesis is the simplest explanation and the one that is most consistent with observations.
“It’s extremely rewarding to finally have found the silver bullet. With our amazing new data, we can now begin the exciting work of learning more about how impacts shape the planet below the surface, something that is very difficult to do on other planets.”
Why are impact craters so rare?
Although countless asteroids and comets have impacted the Earth throughout its history, surprisingly few impact craters are visible today.
The Earth’s surface is constantly changing shape due to erosion, weathering, volcanic activity, and the slow movement of plates. Over millions of years, these processes erase many traces of ancient influences.
Dr Nicholson said: ‘Silver Pit is a rare and exceptionally preserved hypervelocity impact crater.
“These phenomena are rare because Earth is a very dynamic planet. Plate tectonics and erosion destroy almost all traces of most of these phenomena.
“About 200 impact craters have been found on land, but only about 33 have been found on the ocean floor.
“These discoveries can be used to not only understand how asteroid impacts have shaped our planet throughout history, but also to predict what will happen if there is an asteroid impact in the future.”
Joining the ranks of famous impact craters
Confirmation of the origin of the silver pit places it among a select group of known impact structures.
These include the Chicxulub crater in Mexico, which is widely associated with the mass extinction that wiped out the Nonavian dinosaurs 66 million years ago, and the Nadir crater off the coast of West Africa, another underwater impact site that was only recently identified.
With the controversy finally resolved, scientists can now use Silver Pit as a valuable natural laboratory for understanding how asteroid impacts affect both Earth and other worlds in the solar system.
This research was funded by the Natural Environment Research Council (NERC).
