According to a new study from the University of Plymouth, mainland Britain was created by the collision of three ancient land masses. For centuries, scientists have thought this region was formed from the impact of only two continental masses, Avalonia and Laurentia, more than 400 million years ago.
Based on an extensive analysis of mineral properties found in rocks across Devon and Cornwall, geologists have found evidence that a third landmass known as Armorica also contributed to the development of the British mainland.
“This is a completely new way of thinking about how Britain was formed,” said study lead author Dr. Arjan Dijkstra. “It has always been presumed that the border of Avalonia and Armorica was beneath what would seem to be the natural boundary of the English Channel. But our findings suggest that although there is no physical line on the surface, there is a clear geological boundary which separates Cornwall and south Devon from the rest of the UK.”
Dr Dijkstra and postgraduate student Callum Hatch visited 22 sites in Devon and Cornwall that were left exposed following underground volcanic eruptions and other events. Using X-ray fluorescence (XRF) spectrometry, the team performed a detailed chemical analysis on rock samples collected from each site.
Next, the experts conducted an isotopic analysis to examine the elements strontium and neodymium, which provide scientists with information about the long history of the rocks.
The experts identified a clear boundary that divides areas geologically linked to England and Wales to the north from areas that are geologically tied to France and mainland Europe to the south. According to the researchers, this could explain an abundance of tin and tungsten, which are metals commonly found in mainland Europe, in the far southwest region of England but not in the rest of the UK.
“We always knew that around 10,000 years ago you would have been able to walk from England to France,” said Dr. Dijkstra. “But our findings show that millions of years before that, the bonds between the two countries would have been even stronger. It explains the immense mineral wealth of South West England, which had previously been something of a mystery, and provides a fascinating new insight into the geological history of the UK.”
The study is published in the journal Nature Communications.
By Chrissy Sexton, Earth.com Staff Writer