Llanelli Naturalists Newsletter - December 1984
Ian Morgan

The Quartzite Outcrop (Mynydd-y-Garreg to Banc-y-llyn)

In the last Newsletter, the Carboniferous Limestone outcrop from Mynydd-y-¬Garreg (MyG) to Mynydd Llangyndeyrn (ML) was dealt with, now it is the turn of the adjacent Quartzite or 'Silica-rock' as it is known locally. The quartzite contains an extremely high percentage of Quartz (Si02) - in fact over 98%, and this purity meant that it was ideal for the production of 'firebricks' to be used for lining refractory furnaces. The major quartzite quarries are located on MyG, the only other large quarry being at Garn SN 499136 in the North-east; most quarries are disused. Previously from the largest quarry in the South-west of MyG (SN 432083) a tramway (now dismantled) carried the "silica" to Cydweli where it was made into the firebricks, The crushed quartzite was mixed with clay (which was also extract¬ed at MyG) and "milk of lime" (water and lime) to render the bricks coherent be¬fore hardening.

Where the quartzite outcrop was crossed by faults highly siliceous sands were formed due to the breaking up of the quartzite. These sands were once ex¬ploited for building purposes at Glanhiraeth (SN 433087) and Bwlch-y-llyn (SN 436092), The silica quarries were of much more importance in the past and are now in a serious state of decline - in contrast to 1939 when about 55 men wore employed on MyG (only 6 in 1975). These quartzite quarries wore opened about 1890 and during their hay-day, the silica bricks were exported as far away as Persia (Iran), the oldest quarry in the quartzite was sent down to Kidwelly by horse and cart during the turn of the century. (Much of the above historical information was obtained in conversation with the late Mr. Lewis of Four Roads, (a Past foreman of the quartzite quarries), in the summer of 1975).

The quartzite varies in quality from, bed to bed but is generally of a very high quality, and its high percentage merits the descriptive term ‘orthoquartzite’. The vegetation of the quartzite contrasts very strongly with that on the nearby limestone, and in August, it is reminiscent of the Pembrokeshire headlands with pleasing combination of the late-flowering Western Gorse (Ulex galli) and Bell Heather.    The Western Gorse is a darker yellow than the probably introduced paler-flowered and Spring flowering European Gorse (Ulex eurpeaus), which is common on disturbed soils etc, whilst the Western Gorse is more character¬istic of established western heaths and hillsides.

To the South of Graig Farm at SN 138088, a block scree of quartzite has much 'Woolly Hair Moss' Rhacomitrium lanuginosum, a distinctive plant more character-istic of mountain tops but here the ecological conditions suit it at c. 160m , in fact Pearsall, in "Mountains and Moorlands" states that it is, "the most striking of the strictly montane types of vegetation" - and here it is - at low altitude! A lichen also to be seen, and typical of acidic rocks is Rhizocarpon geographicum, which forms black-edged, lime-yellow patches on some rocks, the irregular black markings which remind, one of maps give it the specific epithet ' georgraphicum'.

In the reservoir at SN 483083 is a variant of Juncus bulbosus which forms long, thread-like masses in the deep, clear, oligotrophic water, over which flies the dragonflies Aeshna juncea and Anax imperator and some common damselflies. Adders sunbathe on the rocky slopes nearby.

Farther North near Four Roads (Pedair Heol) is a small bog, threatened by house building at SN 445054. Here is an established Marbled White colony, the butterflies frequenting bogland with species such as Sundew (Drosera rotundifolia), Bog Asphodel (Narthecium ossifragum) and Cross-leaved Heath (Erica tetralix), Stonechats occupy rough ground nearby and Goldfinches are a feature of the tall hedgerows. From the top of MyG, one can look eastwards across the broad lower Gwendraeth Fawr valley, where the numerous small and large copses, woodland proper and tree-lined hedgerows give an impression of a continuous forest rather than pastoral farmland. The "Farewell Rock", ridge described in the Own Clydach article (No. 5 in this series) can be plainly seen running parallel to MyG,

A number of farms in the Four Roads area e .g. Park y-Mynydd, Park Matho and Parc-y--llong have the prefix 'parc/k' which means 'field/meadow' rather than the normal English usage; this use of 'park' is common in Welsh-speaking North Pembrokeshire also, Parc-y-llong ('field of the boat') is a reminder of the former extent of high tides before the construction of sea defences South of Cydweli. Other place-names bear testimony to the past (and present) well-wooded nature of the southern flanks of MyG and the Gwendraeth valley - names such as Goitre-uchaf ('the upper woodland settlement'), Waun gwiail-fach ('the meadow with small saplings') and of course, the various 'coed' names e.g. Coed Mawr, Coed-bach, etc.

North-east at Crwbin Common (SN 480126), is a boggy field where a single plant of the very scarce Narrow Buckler Fern (Dryopteris carthusiana) grows amongst hundreds of the related Broad Buckler Fern (Dryopteris dilatata) and Lady Ferns (Athyrium filix-femina) - trying to re-find it is like looking for the proverbial 'needle in the haystack'! Nearby on ML are exposed great expanses of the dip slopes of the quartzite, often devoid of vegetation except for lichens and mosses. These rock faces show glacial striations (scratches), caused by boulders in the passing ice masses during the Pleistocene Ice Age. Birds typical of the acid boglands and rock outcrops of ML in summer include the Meadow Pipit, Skylark and Linnet - all common - with the scarcer Stonechat at one or two sites; the Meadow Pipit is probably the dominant host species to the Cuckoos that can often be seen and heard during the summer. Kestrels often hunt over the area and a pair of Curlews nest in one damp, rankly vegetated bog, which also holds plants such as the very attractive, glaucous-leaved Bog St John's Wort (Hyperium elodes) much Deer Grass (Trichophorum cespitosum) and the odd Royal Fern (Osmunda regalis). Finally on ML, several Bronze Age cairns can be seen by those with a trained eye; they are worth visiting (a full account is to be found in an article by A.H. Ward in the 'Carmarthen Antiquary’).

Continuing North-east along the quartzite past Mynydd Cerrig, one comes to Banc-y-¬llyn and that lake of Welsh legend, Llyn Llech Owen; this shallow lake is notable for the two types of water lily that grow there side by side, Nymphaea alba and Nymphaea lutea, the white being the commoner.    In the shallows Shoreweed, Litorella uniflora is abundant. Dragonflies to be seen are the Emperor, Golden-ringed and a strong colony of Britain's smallest dragonfly the Black Darter (Sympetrum danae), very much an upland or heathland species; the adult is all black but the immatures are an attractive combination of black and yellow. Small blue damsel¬flies flying over the water’s surface are Enallagma cyathigerum. Mallard and probably Common Sandpipers nest and the odd pair of Stonechat and Whinchat can be observed. An interesting past record is that of Black Grouse.

Lastly, a rarely-noted plant growing on heathy banks around the lake is

the upland race of Potentilla erecta, - ssp. strictissima, which is, (according to the authority on this species, A.J. Richards), "Identical with Potentilla strictissima Zimm. from the Alps", and is not uncommon above 500m in the British Isles"; but at Banc-y-llyn it grows at half this altitude. This is only the third site in Wales for this subspecies and the most southerly locality in Britain except for nearby ML, from whore it has also been confirmed.

I.K. Morgan, 17th October 1984