Llanelli Naturalists Newsletter - January 2005 - No 71
Andrew Stevens

Leader Andrew Stevens

Llanelli Naturalists’ members were greeted by our hosts, Colin and Lin Cassidy, owners of the farm which lies on the edge of the former Ffos Las opencast coal site.  The party set off towards a boggy area which had been designated originally as a refuge for wildlife to help re-colonisation of the restored site.  It had scrubbed over with gorse and willow and was being cleared to restore it to marshy grassland.  Colin told vividly of several incidents showing how perilous the peat is for both livestock and man.  At one place he had gauged the depth of peat to be about 6 metres using drainage rods and it is possible that this was a kettle hole formed when a large chunk of ice, buried under solid glacial debris, melted.  The collapse of debris above left a pool which over time, was colonised by vegetation and filled with peat.

This area has a fascinating geological past.  During the peak of the last glaciation the whole area was covered in ice and a large glacier in the Gwendraeth Fawr valley spilled over through the Rehoboth Gap (roughly where the track to Pant-y-Gino is now).  After the ice retreated, the Cwm Mawr stream (which  flows past the Farrier’s Arms and through Stradey Woods to join the sea at Pwll) came through here.  The Trimsaran Morlais which flows into the Gwendraeth Fawr took advantage of the fractured rocks of a major fault known as the Trimsaran Disturbance to cut headwards at a faster pace and capture the headwaters of the Cwm Mawr stream west of Five Roads.  A “wind gap” was left at Pant-y-Gino with little drainage in any direction in which peat subsequently accumulated.

The vegetation was dominated by Purple Moor-grass (Molinia caerulea) with lesser components of Devil’s-bit Scabious (Succisa pratensis), Tormentil (Potentilla erecta) and Heather (Calluna vulgaris).  As the party progressed the growth became more rank and the ground underfoot wetter and more acid with the appearance of Cross-leaved Heath (Erica tetralix), Bog Asphodel (Narthecium ossifragum), Hares’-tail Cotton-grass (Eriophorum vaginatum) and Marsh St John’s wort (Hypericum elodes).  On slightly raised and drier sections, the moss Polytrichum commune and Broad Buckler-fern (Dryopteris dilatata) were present but Royal Fern (Osmunda regalis), which had been noted on a previous survey, was not re-found.  Colin told us that Dormice had been found in a small copse nearby, so it would be good if a network of suitable habitat with connecting corridors could be established across the restored opencast site.  This would reduce the chance of local extinction enabling them to spread, and perhaps even to link to the opposite flank of the Gwendraeth Fawr valley.

The way was blocked by woody growth so the party returned to the starting point and examined an adjacent field which had been grazed by sheep before it had been shut-up for hay.  A slightly drier top edge showed evidence of trampling by stock with Red Bartsia (Odonites vernus) and Daisy (Bellis perennis) getting a foothold among Eyebright (Euphrasia sp.) and Crested Dog’s-tail (Cynosurus cristatus).  For the main part, vegetation was short and thin but showed an interesting mix of acid-loving heathy plants like Heather, Lesser Skullcap (Scutellaria minor) and Heath Rush (Juncus squarrosus) forming a mosaic with those preferring more neutral soil, including Whorled Caraway (Carum verticillatum) and Meadow Thistle (Cirsium dissectum), with species such as Gipsy wort (Lycopus europaeus), in wetter parts.  Spent orchid flower-stems were evident in the sward and it was impossible to identify them with certainty, although they were likely to include Heath Spotted-orchid (Dactylorhiza maculata subsp. ericetorum).

The party looked at a further Carum meadow which appeared to have been won, in part at least, by the removal of deciduous woodland with the sward including scattered Betony (Stachys officinalis).  From here the group began to disperse, but a few remained to examine a wet acid patch in the centre of another field (probably another kettle hole) where Bog-bean (Menyanthes trifoliata) was frequent and a few plants of Marsh Speedwell (Veronica scutellata) also present.

Finally for the pub quiz night:  Where was Rehoboth?

The town is now called Rehovot in modern Israel and lies west of the southern tip of the Dead Sea.  It is mentioned in the Bible (Genesis 26:22) as a place where Isaac dug a well in the land of the Philistines during a time of famine saying  “For now the Lord hath made room for us, and we shall be fruitful in the land”.

Reference:   Bowen D.Q.  (1980).  The Llanelli Landscape: The Geology and Geomorphology.  Llanelli Borough Council.