LONDON, Nov. 16 (Xinhua) -- A burial ground dating back to the seventh and ninth centuries containing more than 80 remarkably preserved coffins has been unearthed in southern England, the official agency Historic England said Wednesday.
The agency funded an archaeological dig in Norfolk leading to the discovery of rare plank-lined graves and tree-trunk coffins in a previously unknown Anglo-Saxon cemetery.
The graves are believed to be the earliest known examples from Britain, with tree ring dating now being undertaken to date the timber. They were only discovered because work to create a new lake and flood defense system meant an archaeological dig had to take place first.
Historic England said the rare discovery offers a unique opportunity to increase knowledge of early Anglo-Saxon Christian communities in Britain.
Archaeologists from the Museum of London Archaeology uncovered the important Anglo-Saxon cemetery in advance of a conservation project and fishing lake and flood defense system at Great Ryburgh in Norfolk.
Historic England said the waterlogged conditions of the river valley led to the remarkable preservation of burials that are extremely rare in the archaeological record, including plank-lined graves and tree-trunk coffins dating from the 7th-9th centuries AD.
Archaeologists say the new discovery reveals evidence it may have been the final resting place for a community of early Christians, including a timber structure thought to be a church or chapel, of which there are few examples from this period.
The team of archaeologists said Anglo-Saxon coffins seldom survive because wood decays over time. Evidence to date has largely consisted staining in the ground from decayed wood.
The 81 dug-out coffins discovered comprise oak trees split in two length-ways and hollowed out. This type of coffin was first seen in Europe in the Early Bronze Age and reappears in the early medieval period.
Although the coffins are not decorative, it would have taken considerable effort to hollow a single coffin, an estimated four man days.
The man who owns the site of the discovery, Gary Boyce, said: "It's really exciting to have such a rare and important heritage site on my land. We set out to create a lake to maximize conservation and biodiversity, to alleviate flooding in the river valley and create a new spot for anglers to fish, and along the way have revealed the hidden secrets of the area's past."
Local archaeologist Matthew Champion, who made the initial discoveries at the site, said: "This discovery is going to significantly add to our understanding of just how the settlement patterns in the river valley developed over time."
Historic England CEO, Duncan Wilson, said: "These rare and exceptionally well-preserved graves are a significant discovery which will advance our understanding of Middle-Saxon religious beliefs and rural communities."
"This cemetery has been revealed because under the current system, archaeological surveys are required before work on a sensitive site starts. This site has immense potential for revealing the story of the community who once lived there," Wilson said.