What Is the Silverpit Crater and Is It Really an Asteroid Impact?

The Short Answer

The Silverpit crater is a three-kilometre-wide impact structure buried roughly 700 metres beneath the southern North Sea, caused by a 160-metre asteroid that struck between 43 and 46 million years ago — making it the first confirmed meteorite impact crater on the UK continental shelf.

Discovery Beneath the Seafloor

In 2002, two oil-industry surveyors — Simon Stewart and Philip Allen — were reviewing seismic reflection data collected during routine petroleum exploration when they noticed something that had no business being there: a perfectly circular formation sitting about 700 metres below the seafloor, roughly 80 miles off the Yorkshire coast. No geological process they could point to had put it there. They named it Silverpit, after a nearby fishing ground, and published their findings in the journal Nature. The geological community took notice immediately — and then immediately started arguing.

The Two Decades of Debate

The central question was deceptively simple: was Silverpit the scar left by an asteroid, or was it the result of underground salt dissolution and collapse? The southern North Sea sits above thick sequences of Zechstein salt deposited roughly 250 million years ago. Salt is geologically unstable — it flows, dissolves, and when it does, the rock above can sink and crack in circular patterns that, on a seismic scan, can look suspiciously like an impact structure. Skeptics argued that Silverpit’s concentric ring faults — extending up to 20 kilometres outward from the central depression — were more consistent with salt tectonics than an extraterrestrial strike. For two decades, neither camp could land a knockout blow.

Shocked Quartz Changes Everything

The argument shifted decisively when researchers identified shocked quartz within rock samples from the Silverpit structure. Shocked quartz — also called shocked minerals or PDFs (planar deformation features) — are microscopic deformation structures inside quartz crystals that form only under the extreme pressures generated by hypervelocity impacts. We are talking about pressures exceeding 10 gigapascals, sustained for microseconds. No volcanic eruption produces them. No salt collapse produces them. They are, in the language of impact geology, a smoking gun.

Salt dissolution was effectively ruled out as the primary mechanism. The debate had a winner.

What the Impact Looked Like

At the time of impact, between 43 and 46 million years ago, this part of the world looked nothing like the grey, industrial North Sea we know today. Eocene Earth was significantly warmer, and the region was covered by a shallow tropical sea teeming with marine life. When the impactor — estimated at approximately 160 metres in diameter — hit the water and punched into the seafloor beneath, it excavated a primary crater about three kilometres wide. The energy released sent shockwaves radiating outward through the surrounding rock, creating the concentric ring fault system that extends 20 kilometres from the centre and is the structure’s most visually striking feature in seismic imagery.

The 160-metre impactor places it in a mid-range category — far smaller than the Chicxulub impactor that ended the dinosaurs, but large enough to cause catastrophic regional destruction and a significant tsunami across the shallow Eocene sea.

Why Silverpit Matters

Silverpit is scientifically significant for several reasons beyond its novelty as a UK discovery. First, it demonstrates that seismic survey data collected for petroleum exploration can be repurposed to find buried impact structures — structures that are invisible from the surface and would otherwise go undetected. Second, it raises the question of how many similar craters may be hiding beneath other sedimentary basins around the world, simply waiting for someone to look at the data differently. Third, the prolonged scientific debate it provoked is itself instructive: it illustrates how rigorously the impact hypothesis must be tested before it can be accepted, and what kinds of evidence — specifically shocked minerals — are required to settle the question.