Organic deposition commenced at Llanllwch in Zone VI at the site of a Post-glacial lake. The lake was colonized by reedswamp and succeeded by fen as the lake level was lowered. Before the end of Zone VI a flushing effect of the bog surface allowed Molinietum to develop which was replaced by Callunetum until, in Zone VIIb, probably due to increased precipitation. Sphagnum bog developed. In the raised bog peat a recurrence surface has provided a radiocarbon date of 1200 B.C. Forest destruction began in Neolithic times, and there is evidence for intensive human activity from Norman times to the present.