‘Seahenge’, at Holme-next-the-Sea in Norfolk . Here, the setting of the upturned base of a fallen oak, carefully trimmed and debarked, at the centre of an elliptical timber palisade, all but one timber of which was set with the bark to the exterior....
(From http://www.english-heritage.org.uk/publications/neolithic-and-bronze-age-landscape/199-263chapter4final.pdf )
Francis Pryor in Seahenge: a quest for life and death in Bronze Age Britain makes a point about the process of debarking of the tree stump at Seahenge and what ritual significance this may have had.
He notes other cases where posts have been debarked and also where the ground was deturfed before barrow building. He says (p249) that the processes "were essentially to do with purification and cleansing. The outer, soiled, layer was being removed to expose the purity beneath. I knew that rites of this sort are often associated with death and the spirit's journey to the next world. Was this the explanation?"
It made me think of the removal of the rough stone cortexes at Stonehenge, for similar reasons?