The two burnt mounds in Coed Newydd are set either side of a minor tributary of the Lligwy river, one of which was excavated in 1912/13. A similar mound lies some 230m upstream (NPRN 406616). On the north side of the stream is a crescentic or horseshoe shaped mound about 13.7m in diameter and up to 0.6m high, open towards the stream on the south-east. A similar mound lies on the far side of the stream some 10m to the east. This is about 12.5m across and 0.7m high and is open to the north-west.

Such mounds are a product of using heated stones for boiling (food), textile processing, saunas or bathing. The discarded stones or pot boilers, were piled up in banks away from the water source. The classic crescentic mounds are usually found to be Bronze Age, although burnt stone technology and the resulting burnt mounds, persisted throughout and beyond the Roman period.
Excavation of the western mound revealed a slighly sunken rectangular clay floor about 2.9m by 1.8m, aligned towards the stream, with a few upright stones about its edges. This was interpreted at the time as a hearth, but is probably the emplacement for a water trough or tank. There were no dateable finds.

Source: Baynes in Archaeologia Cambrensis 6th series 8 (1913), 201-214
RCAHM Anglesey Inventory (1937), 137

John Wiles 12.09.07