Seahenge or Holme I is a bronze-age timber circle discovered in 1998 just off the coast of the English county of Norfolk at Holme-next-the-Sea. Its outer ring comprises a number of small split oak trunks forming a circular enclosure. Rather than being placed in individual holes, the timbers had been arranged around a circular construction trench. Their split sides faced inwards and their bark faced outwards (with one exception where the opposite is the case). One of the trunks on the south western side has a narrow Y fork in it, permitting access to the central area with another post outside, which would have prevented anyone from seeing in. The timbers were set in a depth of 1m from the contemporary ground surface although how far they continued upwards is not known. In the centre of the ring was a large inverted oak stump.

The site, presumably religious, was discovered because unusual weather conditions resulted in a lowering of the sea level of the coast for a short period. Since the entire structure had been in an anaerobic waterlogged state for several thousand years, the logs had survived with little damage. In the early Bronze Age the site was probably a saltmarsh environment, between the sea and the forest before the ocean encroached to form the modern coastline. Tidal action had scoured away overlying sediment which had built up in the intervening centuries revealing the timbers for the first time since prehistory.

Exposure to the air put the timbers at immediate risk; as the seawater which has slowly seeped into the timber over time began to drain away it left the wood to dry out and crumble. Local archaeologists from the Norfolk Archaeological Unit worked in the exhausting intertidal conditions, harassed by self-styled representatives of neo-paganism who preferred to see the site left alone to disintegrate. Many local people were also concerned at what they saw as the theft of their heritage, complaining that Seahenge would most likely be transported to London where it would be displayed out of context in the British Museum.

English Heritage arranged for the wood to be transported 50 miles to Flag Fen near Peterborough, where it was continually soaked in a wax-impregnated water to slowly (over years) replace the cellulose in the wood with wax. Transferred to Portsmouth where maritime archaeology experts at the Mary Rose Trust continued the programme at their purpose-built site. When this is complete it is hoped to recreate Seahenge near its original site, at the rebuilt Lynn Museum in King's Lynn when it opens in 2007.

It is possible to date the creation of Seahenge very accurately through dendrochronology since the rings on the trees can be correlated with other overlapping tree ring variations and the date of felling the oaks is known to have been spring or summer (2049 BC). Between 16 and 26 different trees were used in building the monument with palynological evidence suggesting they came from nearby woodland. Analysis of axe marks on the timbers indicates that at least 51 different axes were used in working the timbers. The largest axe was used to cut the central tree and not any of the other timbers. The excavators interpret each unique axe as representing a different individual, and thus it appears likely that the work was a community endeavour. Holes in the central stump indicate that it was pulled onto site by rope. Pieces of the rope were found under the stump and were made from honeysuckle stems.

Once the site was built, there is no further evidence of activity to suggest its purpose. A few centuries later, it became a focal point again with Middle and Late Bronze Age pottery having been found on the site.

Theories about the site have focused on inversion; the upside-down central tree stump and the single post turned 180 degrees from the others within the circle itself. The broad concept has been noticed in some Early Bronze Age burials. Not all the split posts can be accounted for and it has been suggested that another structure was built nearby using them.

One hundred metres east, an older ring of two concentric timber circles surrounding a hurdle lined pit containing two oak logs has also been found. Known as Holme II, it dates to the centuries before Holme I (c. 2400-2030 BC) although the two sites may have been in use together. Although also threatened with destruction by the sea, this site has been left in situ. Archaeologists have suggested that this decision by English Heritage relates to the controversy over digging Holme I.

Seahenge is so named in obvious comparison with Stonehenge and, rather like Carhenge in the United States of America, does not possess an extant henge. The contemporary ground surface associated with the monument had long since been washed away and the silt it stood in when found considerably predates the timber circle.

The Seahenge case has demonstrated several contentious subjects in the field of heritage management. Issues such as the views of local people and other interested groups compared with the aims of academia and the decisions that have to be made over what to preserve and what to leave to nature have had to be tackled by the archaeologists and government agencies connected with the site.

External links

• Pictures (http://easyweb.easynet.co.uk/~aburnham/eng/seahenge.htm)
• Conservation work at Flag Fen (http://www.flagfen.com/seahenge.htm)