Seahenge

Seahenge


Seahenge dated to spring 2050 BC

December 1, 1999 - BBC
Seahenge, the remarkable ring of oak timbers recently uncovered on a UK beach, is exactly 4,050 years old.
Scientists working with English Heritage have come up with the age by combining a number of techniques, including complex mathematics.
The researchers are so confident in their findings they are even prepared to say that the central stump of the wooden ring came from a tree which was felled or died between April and June 2050 BC. They believe the other trees used for the surrounding posts were cut down in the spring of the following year, 2049 BC.
The dating confirms the authenticity of Seahenge, which was almost certainly used as a ceremonial site in its day. Some will also regard it as further justification for the decision to remove the circle from the sands where they were found at Holme-next-the-Sea, Norfolk.
Although druid groups opposed the operation, subsequent examination of the posts has shown that the exposed wood was deteriorating much faster than anyone had suspected. If Seahenge had been left where it was built, the world would soon have lost what many now regard as the Bronze Age discovery of the decade.
Climate and growth rings
To date the central upturned stump, scientists at English Heritage resorted first to dendochronology, which matches the growth rings in wood to known historical climate data. This would normally have given a very accurate date for the tree's birth and death but this proved problematic in this case because the oak's ring patterns loosely fitted too many parts of Britain's past weather spectrum.
The team also used radiocarbon analysis, which studies the decay of natural carbon isotopes to date organic material. For accuracy, six different samples were taken. These results showed that the tree died between 2200 BC and 2000 BC. The Bayesian mathematical model can calculate and recombine probabilities contained in different data sets to produce a very narrow range of outcomes. This work showed that the tree had died sometime between April and June 2050 BC.

Reference : http://www.crystalinks.com/seahenge.html