A peat bog, formerly a small lake, located at 485m ASL in a shallow depression on a limestone plateau.
Fieldwork on erosion features in peat cover, from 1979 (Berridge 1979-81), allied with extensive environmental sampling (Smith & Cloutman 1988), has produced bountiful and arresting evidence for Mesolithic and later activity (Barton and others 1995).

Discrete Early and Later Mesolithic artefact scatters were found around the margins of the basin, the site unusual in having been occupied in both the earlier and later phases of the period. The site also produced dated palaeoecological evidence for disturbance of the vegetation cover during this period and after.
The site was probably first visited around the mid-tenth millennium BP, the earliest artefacts found on an old soil surface or beneath its humus layer, buried under peat. Tree cover seems not to have been dense, the local woodland incorporating tracts of open ground; grazing animals may have helped maintain open conditions.
Later in the Mesolithic, from the eighth millennium BP, local heathland and open birch woodland were burnt, to encourage large game. The change to fire management played a role in the inception of peat. The lake basin would have attracted waterfowl and migratory birds and may have been a source of fish before it began to dry up and form a marsh. Hazel nuts were discovered in associated deposits.
The occupation areas, all at the east end of the lake, were represented by small scatters of artefacts made from materials which reveal contacts over some distance: beach flint (29 km away) and Greensand chert (80 km), mainly for arrowheads and butchery knives; and mudstone (100 km) for beads. Visits to the site were probably brief, though frequent, its value as a 'persistent place' being its appeal as a hunting venue.

Sources: Berridge in Archaeology in Wales 19 (1979), 11 [6]; 20 (1980), 19-20 [4]; 21 (1981), 20 [5]
Smith & Cloutman in Philosophical Transactions of the Royal Society (B) 322 (1988), 159-219
Barton and others in the Proceedings of the Prehistoric Society 61 (1995), 81-116
RCAHMW aerial coverage: AP 88-CS 270-2; 881613/10

David Leighton and John Wiles, RCAHMW, 1 April 2009