Description

The monument consists of the remains of a gold mine, dating initially to the Roman period (1st to 4th century AD), but with further phases of activity, of which those in the later 19th and early 20th century are best attested. The main focus of the mines lies in and around a saddle on the northern slopes of a range of hills running north-east to south-west, known as Allt Ogofau to the south-west of the mines and Allt Cwmhenog to the north-east. The most obvious feature here is a large opencast working, within which the various features of the present day visitor centre are housed. This opencast is likely to be of Roman date and was originally at least 10m deeper than at present, with passages leading into underground workings at its base. Further opencast workings, trenches and adits are visible at various points along the hills to either side of the main opencast, running altogether for a total of about 1km. The early workings were fed with water by at least one and probably more aqueducts, the main one of which ran 11km down the Cothi valley from Pwll Uffern Cothi (scheduled as CM200). Various features around the mine area have been postulated as related to the use of this water for different mining and processing activities. The most obvious are two tanks at the lower end of the main aqueduct, which lie to the east of the Caio road; the waste water would have flowed away southwards from here. Crushed material which probably relates to early exploitation extends widely across the floodplain to the north-west of the workings, and the ‘Carreg Pumsaint’, a rectangular stone with hollows along its sides, is likely to have been used in the crushing process.

The modern phases of mining were focused below and to the east of the main opencast, with adits driven into the hillside at two points (later linked by a vertical internal shaft) and underground workings leading off a shaft in the main opencast area. Three different foci of processing were used; the earliest lay on the hillside to the east of the main opencast, the second in the south-eastern corner of the opencast itself, while that used in the final phase in the 1930s was constructed on the hillside to the south, near Pen-lan-wen, and reached by an incline from the shaft area. Tailings from this phase were deposited to the south of the workings and would have drained to the south-east.

The monument is of national importance for its potential to enhance our knowledge of Roman mining practices. The more recent phases are also of historical interest. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits.

The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.

Source: Cadw