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Geophysical surveys (magnetic gradiometry, magnetic susceptibility and ground resistivity) have been undertaken over the area of the Pont-y-parc leadmine (3ha centred on ST 048823) and of the associated ore processing area (0.7ha around ST 050823). Pont-y-parc was the largest of the lead mines of the Llantrisant area and documentary evidence suggests that the site had a long history of mineral exploitation, including Medieval, Tudor and 18th-19th century phases; this is borne out by the complexity of the survey results. The site lies within the "Lower Park of Clun", one of the two medieval deer parks lying to the south of Llantrisant.
To the east of the main mine workings, a series of parallel positive magnetic anomalies, possibly elongate ditched fields (although a natural origin cannot entirely be ruled out), may represent the earliest features on the site. To the north of the workings, the earliest identified feature is a leat. Cartographic evidence suggests the leat arose from the Afon Clun to the east of the surveyed site (ST 0534 8248), and followed the edge of the floodplain westwards, passing along a line now buried by the northern edge of the cemetry, and across the old Cardiff-Llantrisant road along the north side of the curtilage of the later Pont-y-parc farm. The leat is degraded adjacent to the embankment of the A4119, but reappears west of a spring interpreted as the collapsed mouth of a drainage adit constructed in 1756. The leat continues westwards as a well-developed earthwork and may bifurcate adjacent to a small platform [ST 0472 8232]. This platform (Clun Mill) has been interpreted as a Medieval corn mill (RCAHMW 1982), but it appears to have had a metallurgical function. Bloomery iron smelting slags, associated with strong magnetic anomalies, also occur along the western margin of the Pont-y-parc farm curtilage, just upslope of the lead works waste dump and leat. It is not yet clear whether this represents an in-situ bloomery site.
The lead mine has a principal series of crop workings along the top of the terrace edge, and a much less pronounced series of workings or trials over a wide area of the adjacent hilltop to the south. The main crop workings can be divided into three sections: an eastern section with deep, grass-covered, hollows including the top of a circular, stone-lined shaft, a central section in which the rock faces have been exposed, and a western section with a linear spoil dump, and which lacks the rounded hollows of the eastern, or the exposed rock faces of the central section.
The eastern section is interpreted as preserving the oldest features, with the crop workings pre-dating the necessity for the pumping shaft, previously identified as being associated with the drainage works of 1756. The spoil clearly indicates that the shaft penetrates through the Triassic conglomerates, and is excvated through a considerable thickness of the underlying Carboniferous mudrocks. Whether the adjacent crop workings are also 18th century, or whether these features are much older, cannot yet be determined.
Documentary evidence suggests the major period of exploitation was between around 1727 and 1780; it is believed that most of the large waste dump at Pont-y-parc and many of the visible workings are of this period.. The small surface workings or trials at the east end of the mine complex were dug through an area of "ridge and furrow". This agricultural regime can still be seen as faint surface features, but is very well imaged on the gradiometer survey. There is no documentary evidence for a Medieval encroachment on the deer park in this location, so this cultivation may be of 16th-17th century date.
The survey of the area adjacent to Pont y parc, marked as "lead works" on estate maps of 1774 (NLW 133414) and c.1780 (NLW 133405), shows a large dump of mining waste, probably associated with a rectangular building alongside the former course of the Afon Clun (the river was straightened to its present course proably in about 1817). The dump appears to respect the location of the leat, which bounds it to the south.
The enclosure and cottage marked on the 1774, c.1780 and 1824 (GRO D/DD B1/2) Estate Maps near the western termination of the leat (ST 0478 8227) are well-imaged by the geophysical surveys, although the associated anomalies are low-amplitude. The site of the cottage is marked by a slight platform, approximately 20m x 10m. The position of this building, well inside the former park and away from the main road, but close to the mine and with a curtilage abutting the leat and "mill", suggests that this building was associated with the mine and/or "mill". The low-amplitude anomalies suggest that it was not itself the location of industrial activities. There are no indications of buildings of 18th century date immediately adjacent to the workings, so this building might have had an administrative role. The building was removed between 1824 and 1840.
The last phase of mining on the site appears to have been a short-lived attempt to reopen the mines in 1823-7, involving reworking of the western end of the main outcrop workings, and a major refurbishment of the central section. The surviving chimney has provoked great debate as to its purpose, but the new geophysical evidence indicates that the chimney belonged to an engine house situated to its west. The position of the engine house suggests it was intended to pump a shaft within the cleared central section of the crop workings, immediately to its northwest. A curving resistivity feature running westwards from just south of the enginehouse, turning to the west of the mines and probably running back to the workings, may be evidence for tramway linking the hilltop with the workings. To the south of the enginehouse lies a building which survived until the late 20th century, and which appears to have functioned as the mine office in the early 19th century. These buildings formed a new focus to the mine and were connected to the main road by a new trackway.
Documentary evidence shows that Pont-y-parc farm was refurbished in 1836, and by the time of the 1840 Tithe Map, the field boundaries around the mine had been reorganised into the form in which they survived until recently.
The pre-18th century history of the mine remains poorly understood. The leat, with its evidence for iron smelting, certainly seems to predate the 18th century drainage adit, and the slags would suggest a pre-mid 16th century date. If the bloomery slags at Pont-y-parc are in-situ, then they also suggest 16th century or earlier activity. It is tempting to see both these as a part of the exploitation of the 1530s and 40s, when iron and lead were worked together in the park (it has been suggested that the 1540s ironworks was at Hendy Isaf, but research is suggesting that the works there may be a finery forge from the 1590s). There is the possibility, however, that the bloomery iron-making at Pont-y-parc occurred during an earlier, perhaps medieval, phase of activity.