Olive branch clue to how Minoans were wiped out

A single olive branch may have solved one of ancient history's most enduring mysteries: when and why did the great Minoan civilisation of the Mediterranean come to a sudden end?

The branch was buried during a cataclysmic volcanic eruption on the Aegean island of Thera - now known as Santorini - and scientists believe they can date the precise moment of the tree's death.

Knowing when the Thera eruption happened is important because the explsion was so powerful that it almost certainly caused the collapse of the Minoan civilisation, centred on the island of Crete, 60 miles away. Vulcanologists believe the explosion generated violent tsunamis that destroyed Crete's ports, threw thousands of tons of ash and pumice into the atmosphere and created a "nuclear winter" that led to successive crop failures in the region.

Scientists have detected ash from the explosion as far away as Greenland, the Black Sea and Egypt. They have also discovered signs of frost damage caused by the volcano on preserved plant material excavated in Ireland and California.

Walter Friedrich, of the University of Aarhus in Denmark, and his colleagues have analysed the olive branch's growth rings and combined the findings with radiocarbon dating to show the tree must have died between 1627BC and 1600BC.

"It is important to have a very precise date for the explosion because this eruption is a global time marker. If we can date it precisely we have an important tool to correlate the times of different cultures," Dr Friedrich said.

Tom Pfeiffer, a student of Dr Friedrich, discovered the olive branch buried inside a rock face formed from volcanic debris. The researchers are convinced the tree was alive when it was smothered. The scientists found 72 growth rings, including the final year's ring, inside the branch. Using radiocarbon dating, they worked out the year of the tree's death to an accuracy of 13 years each way.

The study, published in the journal Science, suggests Thera blew apart a century or so prior to the conventional date when the Minoan civilisation was thought to have gone into demise, based on evidence from archaeological objects. The scientists suggest it is highly unlikely the Minoans were able to survive the environmental impact of the eruption, which meant their civilisation ended 100 to 150 years earlier than thought. This would mean the Minoan civilisation was not contemporary with the New Kingdom of ancient Egypt - which began in the 16th century BC - as many archaeologists believed.

A separate study published in Science by Professor Sturt Manning of Cornell University in New York shows radiocarbon dating of 127 objects recovered from the Theran town of Akrotiri - which was buried by the eruption - support the findings.

Professor Colin Renfrew, a Cambridge archaeologist, said the studies appeared to provide convincing evidence to put a firm date on the eruption in Thera.