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WALK 1

Cwm Llwch and Cefn Cwm Llwch

Start	Llwynbedw, Cwm Llwch (SO 006 246)
Distance	9.5km (6 miles)
Total Ascent	620m (2035ft)
Map	OL12 Western Area

This is a fine route into the most westerly of the northern Beacons valleys and it progresses in a southerly direction into the valley head below the north face of Corn Du – the second highest peak in the range. The walk goes up the stream in the valley floor to a corrie lake. There are good waterfall views overshadowed by the looming bulk of Corn Du. It then works its way up the right (W) ridge and so up to the summit of Corn Du. From here it continues over to the summit of Pen y Fan (the highest peak in the Beacons) and returns to the start via the ridge, Cefn Cwm Llwch. An alternative shorter route returns to the start from the obelisk below Corn Du, dropping down Pen Milan ridge on the west of the valley. The final climb to the summits is steep, as is the upper part of the descent from Pen y Fan. Route finding is straightforward in good weather, but in mist or winter conditions ability to use compass and map is important. The walk requires a reasonable degree of fitness. Points of interest include glacial geomorphology, plants and birdlife, waterfalls and lake, good panoramic views and archaeological features.

Start at the end of the car park where there is a ‘NO MOTORS’ sign. The ford and the hillside on the left of the car park is your descent. Follow the track leading into the valley, lined with beech, hawthorn, mountain ash and hazel.

The woodland on the right contains the poorly preserved earthworks of an Iron Age hill fort which is marked on the map as a dotted oval and labelled ‘Settlement’. This is a small enclosure with widely spaced ramparts. Its value as a hill fort is dubious as, although the land slopes away east to Nant Cwm Llwch, the land to the west and south rises gradually to the foot of Pen Milan.

The track soon comes to another ford across the same stream, Nant Cwm Llwch, with a wooden bridge on the left, through a second gate and then between wooded banks with fields on either side. From here there are good views into Cwm Llwch with waterfalls in the foreground and a backdrop dominated by Corn Du straight ahead and Pen y Fan on the left.

The track continues southwards between old stone walls and then detours around Cwm-llwch Cottage. Notice the abundant ferns and mosses on the sloping roof of an outhouse on the northward facing end of the cottage.

Leave the cottage on your left and skirt around the right of the farmyard by crossing over two stiles. After about 100m there are good views into Cwm Llwch, with waterfalls in the foreground and a backdrop dominated by Corn Du straight ahead and Pen y Fan on the left.

The wide open track ahead takes a direct line up a spur of land with stream courses on either side. However, this line is of little interest and avoids the superb waterfalls glimpsed earlier. Descend instead to the left and walk along the fence, which soon reaches the stream. Here a small track crosses to the left bank, although either can be followed to the waterfalls.

This is a most interesting habitat as, after the birch woodland is left behind, the banks of the stream are lined with closely grazed grassy areas where there are many different species of wild flowers, such as lousewort (Pedicularis sylvatica), bird’s-foot trefoil (Lotus corniculatus), red bartsia (Bartsia odontites) and eyebright (Euphrasia sp).

Notice that the valley slopes have a high density of hawthorn trees – a notable feature of Beacons valleys. For this reason, the number of bird species is more typically associated with woodland than an open valley. Keep a sharp lookout for tree pipit, green finch, redstart, wren, whinchat, yellowhammer and chaffinch. Even the great-spotted woodpecker has been recorded. Do not be surprised to see green woodpeckers often far from trees where they feed on ants. The falls and stream bed are good places to spot grey wagtail, heron and dipper. The valley is unusual in that there are two stream beds which have eroded the floor, leaving a raised spur of land in the centre (see ‘Geology and geomorphology of Cwm Llwch,’ Walk 3).

The hill fence crosses the stream ahead but there is a low-level stride over it just before the stream divides. The left branch of the stream is the more interesting and just ahead is an impressive waterfall. This can be climbed on the right arriving first at a small pool above the lower fall.

The falls are shaded by a mixture of hawthorn, blackthorn, ash, rowan, willow and silver birch. Most of the trees are young or have grown from previously fallen trunks. Luxuriant bryophytes and ferns thrive on damp and wet rock faces surrounding the fall. Ferns include the rare Wilson’s filmy fern (Hymenophyllum wilsonii) and Cystopteris fragilis. Bryophytes include Ulota crispa, Mnium undulatum, Hylocomium splendens, Atrichum undulatum, Neckera pumila, Fissidens taxifolius, Philanotis fontana, Hyocomium armorica, Frullania tamarisci and several others. Several ungrazed tall herb ledges can be seen to the left and right of the fall. Interesting vascular plant species include valerian (Valeriana officinalis), wild angelica (Angelica sylvestris), meadow sweet (Filipendula ulmaria), Alchemilla vulgaris, wood avens (Geum rivale) and Welsh Poppy (Mecanopsis cambrica).

Climb up the right side of the upper fall or more easily up the hill on the right of the lower fall reaching a series of smaller waterfalls from where there are magnificent views of Corn Du. Surprisingly, the flat-topped summit of Corn Du at the head of valley falsely appears higher, from this viewpoint, than its neighbour, Pen y Fan, which is on the left. When the stream starts to break up into many smaller tributaries, leave the stream to the right, striking westwards to the corrie lake of Llyn Cwm Llwch.

Flushed areas at the head of the valley are extensively covered in soft rush (Juncus effusus). Llyn Cwm Llwch is a good place to have a break and appreciate this special place (see ‘Geology and geomorphology of Cwm Llwch’; ‘Glacial origins of Llyn Cwm Llwch,’ Walk 3).

Tommy Jones obelisk, Corn Du and Pen y Fan

Take the path which leads to the right (W) up the steep slope in a zigzag, climbing steeply to the lower end of the ridge of Craig Cwm Llwch, near to the Tommy Jones Obelisk, a useful landmark in poor visibility. The path has been severely eroded into a deep gully, firstly by the passage of feet which destroyed the protective turf, and now by a combination of walkers and water. It becomes a watercourse in heavy rain.

Looking back down to the left from the obelisk is a fine view of the hummocky mounds of glacial moraine that dam the lake of Llyn Cwm Llwch.

The obelisk is a memorial to Tommy Jones, aged five, who died here in 1900 of exhaustion. He was attempting to walk alone from Cwm Llwch Farm to an army encampment at Login. It now serves as a useful landmark in poor visibility by marking a rapid descent route from Cefn Cwm Llwch to the safety of the valley below ensuring that walkers today do not suffer the same fate. The alternative route to Pen Milan leaves from here.

Follow the ridge of Craig Cwm Llwch (SE) up the steep slope to the summit of Corn Du.

From Craig Cwm Llwch you may see many species of bird and see buzzard, carrion crow and raven wheeling overhead. Ravens nest nearby on the crags of Craig Cwm Sere. You will undoubtedly see or hear meadow pipit and skylark, the commonest birds over hill grasslands. If you are especially observant you may see ring ouzel as they breed in the vicinity of the crags. This area is near to the limit of their British range.

The final 10m or so to the summit of Corn Du involves scrambling up the Plateau Beds but a stepped path leading diagonally right will avoid further damage to these loose crags. An interesting path-cum-sheep track avoids this and cuts east across the northern face of Corn Du below the crumbling cliffs of Plateau Beds to the col leading to Pen y Fan (see ‘Geology of the Brecon Beacons,’ Introduction). The crags are covered in grazed purple moor grass heath (Vaccinium). Awnless sheep’s fescue (Festuca vivipara) is the only plant species of interest. From the top of the stepped path cross left (E) to the summit of the crags overlooking Cwm Llwch.

Cefn Cwm Llwch and Llyn Cwm Llwch from Corn Du

From the cairn follow the crags (E) and descend into the col. The path swings around (ENE) and climbs along a broad track, well marked by cairns. The final one is of Bronze Age origin and leads to the trig point on the summit of Pen y Fan. Pen y Fan at 886m (2906ft) is the highest mountain in South Wales and just fails to achieve Munro status, a term given to summits over 3000ft. For a description of the mountain see ‘Geology and geomorphology of Pen y Fan,’ Walk 5).

PEN Y FAN VISTA

The summit of Pen y Fan is one of the finest vantage points in Wales. On an exceptionally clear day, Cadair Idris can just be distinguished to the north and Exmoor to the south. Fforest Fawr to the west possesses many interesting features and is a relatively unvisited part of the park. Almost due west are the cliffs of a beautiful glacial cwm, Craig Cerrig-gleisiad. To the south-west the plumes from the stacks of Port Talbot and Llandarcy can be seen on a clear day and in between these is the wide sweep of Swansea Bay which culminates in the west with the Mumbles Lighthouse.

Scramble carefully down the crags due north of the summit cairn and follow the ridge of Cefn Cwm Llwch for about 2km.

As you scramble down from the summit, look carefully at the upper surfaces of the near horizontal Plateau Beds for ripple marks. These are also present on the surfaces of rocks making up the summit. They were formed in exactly the same way as ripples are formed in the sandy beds of rivers today. Look back at the north-east face of Pen y Fan where in early spring you can see the brilliant colours of rare arctic-alpines (see ‘Flora of the north-east face of Pen y Fan,’ Walk 4).

Take a small path which leaves the main track and bears left (N) towards the pile of stones at the disused quarry of Cwar Mawr (SN018 236). From here descend west-north-west (292°) to the spur of Twyn y Dyfnant and down the steep slope to the hill fence, keeping to the right of the coniferous forestry.

Cross the fence through a gate (SN009 241) and follow the line of trees diagonally down the slope to the right. At the end of the tree line turn sharp left and drop down to the field below. An indistinct path leads directly down the field after 80m. Head for the junction of hedges to the left and continue down the slope to the ford across the stream (SN007 244) and back to the start of the walk.

Alternative route

From the obelisk turn north and follow the footpath which swings first right, left, then right again around the head of a side valley of Cwm Llwch, with steep slopes on the right. Just before the final spur of Pen Milan, the path changes into a broad green old quarry track. The hill vegetation comprises dwarf shrub heath and grass heath in which ling (Calluna) and bilberry (Vaccinium myrtillus) are common. Purple moor grass (Molinia caerulea) is abundant on flatter areas.

The route descends to the right diagonally across the valley side. This track has obviously seen heavy use in the past and, in fact, was used to transport Old Red Sandstone (see ‘Geology’ in the Introduction) from a quarry on the left, now abandoned. The softer rock was used as road infill, whereas the harder stone was used in building.

The quarry track swings sharply right and then left, descending between grassy banks and heading due north again. The path becomes ill-defined in places but eventually the fences on either side funnel the path to a gate. Pass through the gate, ford a small stream, and follow the tree-lined track to the yard with the cottage of Clwydwaunhir on the left.

Opposite the house are a small ford and a stile. Cross these and cut across some fields (SE) back to the start of the walk.