Arenig Fawr, Merioneth - Royal Commission on the Ancient and ...

entrance to an underground level (nprn 511227), which has been exposed in one place
where a pit has collapsed (nprn 511231) (fig 18). Another, large backfilled pit (nprn
511197) was probably another, perhaps a shaft, as a path (nprn 511198) leads from it
to a large ore bin or dressing floor (nprn 511200). (The landowner has said that
underground workings were disturbed when a modern vehicle track was created.)
Other ore bins were found scattered across the hill, close to large opencast workings
(nprn 511219, 511229, 511242) (fig 19).
There are few visible remains of manganese mining at Pistyll Gwyn, where output may
never have been substantial. There are no Crown Grants that mention Pistyll Gwyn,
although according to Edward Halse, mine agent at Mynydd Nodol, manganese was
worked in the 1870s from a vein 4-5 feet wide (1.2-1.5m), with a 77.5-degree dip
(Down 1980, 51). Several small surface workings have been identified (nprn 510834-
510839), some of which may have been prospecting trenches, and a possible ore bin
(nprn 510840). Any underground workings have been obscured by backfill.
Other Industries
Llyn <strong>Arenig</strong> <strong>Fawr</strong> was adapted as a reservoir from 1830 by the Bala Water Works
Company. The dam was altered in 1864, but was altered again in the twentieth century
and is now of modern character (nprn 510707). The first pipeline was laid in 1879, but
the lines of two pipes can be traced on the ground (nprn 510698, 510699), leading to a
treatment works at Ty’n-y-cae (beyond the survey area) (Roberts 1995, 13).
There are comparatively few quarry sites within the survey area. Ample quantities of
field stone were sufficient for local building needs. Slate quarries belong to the late
nineteenth and the twentieth centuries, hoping to exploit the established market for
roofing slates. They are confined to the small areas where shale overlies igneous rocks
(nprn 510972, 510910). A quarry was begun on Ffridd y Gloddfa (nprn 510910),
probably in the early twentieth century. However it was quickly abandoned because it
did not yield slates of sufficient quality.
Opportunities for quarrying were increased after the Bala & Ffestiniog Railway was
built, a small section of which passed across the survey area. The railway was opened in
1882 and closed for traffic in 1961 – the immediate cause of its closure was the
flooding of part of the line to create Llyn Celyn reservoir. Granite quarrying near the
railway began in the last decade of the nineteenth century at Maen Grugog (nprn
511002) and at Clogwyn y Fran. The latter was massively extended in the twentieth
century and was excluded from the survey area (but see an outlying working, nprn
511246), although it is the largest of the <strong>Arenig</strong> Quarries. It was linked by tramroad
(nprn 510953) with another twentieth-century quarry site (nprn 510972), which was
extended over the road to the railway near <strong>Arenig</strong> Station. Electricity for these quarries
was provided by a generating station (nprn 510956), which stands close to the
tramroad. The brick building is now roofless and its walls are in a precarious condition.
No machinery survives, but a narrow wheelpit outside the building suggests that power
for the generator was provided by a double Pelton wheel. This was supplied by a
pipeline, of which stone piers survive (nprn 510957), and fed from two reservoirs (nprn
510958, 510959), one of which retains water. Quarrying here appears to have
outlasted the closure of the railway.
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