Peat stratigraphy and pollen analyses distinguish two main types of peat profile, a raised bog type and a blanket bog type. Fen peat formation began in hollows (zone VI), became covered with alder-birch carr in zone VIIa, and by the beginning of zone VIIb the whole area was covered by peat. The bog system is being made up of centers of raised bog development united by blanket bog. The present vegetation is described, two types occur one with more Sphagnum magellanicum than S. papillosum in areas where there is a flushing effect and the other more typical of the greater part of the bog surface with more S. papillosum than S. magellanicum. Plants of Phragmites still growing on the bog surface are relics of previous local vegetation having been gradually restricted in their distribution on the bog surface. It is suggested that relative isolation and freedom from damage by grazing, burning and drainage has allowed this site to continue in a state of active peat accumulation.