Archaeological excavation at Seahenge began October 1998, under site director Mark Brennand of the Norfolk Archaeological Unit. It proved a difficult site to excavate. Sea tides restricted trial trench excavating work to between one and four hours per day. A Dendrochronological sample extracted from the stump was sent for analysis at Sheffield University. By January 1999, preliminary results indicated a Bronze Age monument. Despite projected expense, English Heritage decided full excavation would be worthwhile, because the site had begun to suffer from erosion: Sections of wood had been exposed to corrosive oxygen and salt brine after millennia protected in the mud.
