Rock doc: One big eruption
When I was a child, I read a lot of murder mysteries. At a young age I favored the books featuring Miss Marple by Agatha Christie. When I was a bit older I fell in love with Lord Peter Wimsey in the books by Dorothy Sayers. No matter the book, I liked to follow along as the hero of the tale put the clues together to figure out who-done-it.
So the quote from the BBC News got my attention. It was from Prof. Franck Lavigne of the Pantheon-Sorbonne University in France.
“We didn’t know the culprit at first, but we had the time of the murder and the fingerprints,” Lavigne said.
It wasn’t literally a murder that Lavigne was discussing, although many deaths may have been related to what happened. Instead, the mystery was one that hinged on geology. What’s at issue was evidence that a major volcanic eruption occurred somewhere in the world in the year 1257. The eruption was large enough its geochemical signature — or fingerprints — show up in both Arctic and Antarctic ice of medieval age.
In Europe, written records show atrocious weather hitting society hard one year later in 1258. It was cold and rainy throughout the growing season that year, with flooding replacing good harvests. In London, thousands of people were buried in mass graves, possibly due to hunger weakening the population and making it more susceptible to disease.
But where was the smoking gun, the volcano that had caused the problem? Candidates had been put forward in New Zealand, Mexico and Ecuador, but none of them quite fit the time or the specific chemical fingerprint found in the volcanic material buried in the ice.
Recently an international team of researchers announced their evidence that the Samalas Volcano on Lombok Island, Indonesia, was the culprit that caused short-lived but worldwide climate change. The team looked at several different types of evidence, including sulfur and volcanic dust traces in ice, as well as what’s found at Lombok. They also did radiocarbon dating of materials and they even checked with local written records that tell of the fall of the Lombok Kingdom in the 1200s.
“The evidence is very strong and compelling,” said Prof. Clive Oppenheimer of Cambridge University, speaking to the BBC.
Oppenheimer, Lavigne and their colleagues tied together the evidence of the far-away ice with material found in the Lombok region. They argue that about 10 cubic miles of volcanic material was hurled skyward in an enormous eruption. The smallest particles launched upward would have reached an altitude of 25 miles or more. Only such an enormous eruption would have carried volcanic materials in the quantities identified in Antarctic and Greenland ice layers. And an eruption on that scale would have made for significant climate change.
It’s not always that scientists are given a full set of clues that wrap fully around the world. But such appears to have been the case in the mystery of what happened in the year 1257.
Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.