Hidden Supervolcano Found Beneath England's East Coast

British Geological Survey scientists have identified the long-extinct source of Europe's vast Kinnekulle ash layer buried under The Wash.

Scientists at the British Geological Survey have identified the remains of a supervolcano centred beneath The Wash, the estuary on England's east coast, extending into Norfolk and Lincolnshire. According to the BBC, the volcano measured at least 65km (40 miles) across and erupted roughly 454 million years ago, about 200 million years before dinosaurs walked the Earth, with a force estimated at several thousand hydrogen bombs. The discovery explains a huge layer of volcanic ash spread across Norway, Sweden, the Baltic region, Belarus and Poland. Dr Tim Pharaoh, the research paper's principal author, called it a "fantastic result" that changes "our understanding of England's deep geological past" — and stressed there is no risk of it erupting again.

Supervolcanoes are normally conspicuous features, yet this one sits beneath one of England's flattest landscapes with no visible trace on the surface. Gizmodo reports that the finding, published in the GSA Bulletin, solves a decades-old geological mystery: the origin of the Kinnekulle tephra, an expansive ash layer whose source had puzzled geologists.

The breakthrough came not from new drilling but from fresh analysis of rock samples taken 80 years ago from boreholes hundreds of metres deep at North Creake in Norfolk and Claxby near Horncastle in Lincolnshire, kept in the BGS archives in Keyworth. During the Covid lockdown, scientists re-examined the samples using new equipment and techniques. Tiny zircon crystals about the width of a human hair, formed within molten magma before eruption, yielded precise uranium-lead ages: both sets formed around 454.4 million years ago, proving they came from the same volcano. The University of Oslo had obtained almost exactly the same age for the Kinnekulle tephra, suggesting the ash blew across the Tornquist Sea, then separating England and Scandinavia, and settled on the Scandinavian seafloor.

Pharaoh, drawing on 40 years at the BGS, said earlier work by University of East Anglia scientists had identified a geophysical anomaly beneath The Wash, concluded to be underlain by lighter rocks, most likely granite — a puzzle only precise ages could now solve. "Once it's gone extinct, that's it. Nobody needs to worry about the supervolcano erupting again," he told the BBC. Gizmodo notes the structure appears to be part of an extensive caldera system the researchers call the "Wash Igneous Complex," with more discoveries possible as investigation continues. University of Bristol volcanologist Prof Jenni Barclay said the work is an important step in piecing together UK geological history, with the subsurface mattering for sustainable use of resources like water and minerals.