It is invisible from the surface, but its existence has been reconstructed using geophysics and deep drilling. The Wash Igneous Complex, buried beneath the East Midlands and The Wash region of eastern England, is believed to have been a thousand times more powerful than Mount Etna.
A study published in the “GSA Bulletin” by an international team of researchers indicates that the 65 km diameter complex had the capacity to generate super-eruptions of considerable power. Traces of these eruptions are present particularly in Scandinavia and the Baltic countries.
To determine their origin, scientists worked on rock samples from two deep boreholes. According to their estimates, the volcano is approximately 454.4 million years old.
This discovery could solve a decades-old geological puzzle. Researchers believe they have identified the origin of the Kinnekulle tephras, immense deposits of volcanic ash found from Scandinavia to Poland and Belarus.
A world very different from ours
This volcano dates back to a time when the geography of the planet was radically different from today. The English complex belonged to an arc which extended from what is now the Lake District in northern England to the Brabant massif in Belgium.
The complex obviously represents no threat today: it belongs to a tectonic system that disappeared hundreds of millions of years ago. Its study, however, makes it possible to reconstruct the existence of a major volcanic episode whose traces, long separated by hundreds of kilometers, are now beginning to be connected.
