a hill. Leave the road through a gate, taking a track to the left (W). The track leads to Pant Farm after 200m and then curves round to the left in front of the buildings.
Look left (SW) for a good view of the north-east face of Pen y Fan with Cwm Sere in the foreground beyond the trees. On the left is Bryn Teg ridge leading up to the prow of Cribyn. This will be your descent route. On the eastern side of this ridge is the brown scar of the Roman Road running over Bwlch ar y Fan which runs between Cribyn and Fan y Big. Looking back the way you have walked, the escarpments of the Black Mountains are visible on a clear day.
Continue on this track, leaving the buildings on your right, and climb steadily up the slope through a gap between hawthorn hedges. Bear right and then left, continuing in the direction of Cwm Sere to Croftau. Leave the house on your left, pass through the gate and a large oak on the right and keep to the left-hand side of the field to another gate where you enter Cwm Sere proper. The woodland on the far side of the stream on your left is managed by the Brecknock Wildlife Trust (see Walk 7).
Continue through yet another gate along the obvious track leading into sparse woodland and across to a gap in the tree line. Continue across the field for 300m to a line of trees in front of you. In the centre of this barrier is a gate leading to a track which bears slightly right past moss-covered ant hills and through mixed woodland of beech and hazel. Deciduous woodland attracts varied birdlife and, depending upon the time of day and season, you may see woodpeckers and owls as well as other typical woodland species.
The track is easily followed as it drops through the woods, crossing a small stream running down from the right. At the end of the woodland is the hill fence through which a gate leads out onto the hillside, opening up a magnificent view of Cribyn on the left and Pen y Fan straight in front. Drop into the stream bed and follow this upstream, encountering small waterfalls on the way towards the headwall at the end of Cwm Sere between the north faces of Pen y Fan on the right and Cribyn on the left.
Pen y Fan from Cribyn
You can expect to see dippers in the stream bed and, with luck, a buzzard wheeling overhead or a heron hunting its prey near the water. Cwm Sere was carved by ice into a U-shape but this has been altered slightly by a snowbed eating away at its western side in post-glacial times (see Walk 4) and by Nant Sere eroding away a notch in its base (see ‘Glacial origin of U-shaped valleys,’ Introduction).
Once in the basin below Cribyn strike across towards the foot of the north-east face of Pen y Fan. The sheer immensity of the north-east face of Pen y Fan can be fully appreciated from the head of the cwm.
GEOLOGY AND GEOMORPHLOGY OF PEN Y FAN
The north-east face of Pen y Fan rises some 380m (1200ft), becoming vertical near the top where the more resistant Plateau Beds form a distinctive cap to the summit. Units of the Lower Old Red Sandstone, Plateau Beds and Brownstones are well exposed in the face. The ribbed nature of the Brownstones is due to the alternation of sandstone with softer marls. The brown scars on the face of the mountain are testimony to the relentless onslaught of the elements and the processes of erosion. The most deadly of these is freezing and thawing of water in cracks in the rocks, which literally shatters the stone along existing lines of weakness. (The Brownstones are particularly well bedded and cleaved, and split apart forming regular blocks, seemingly made for constructing dry-stone walls and buildings.) Gravity then plays its part in transporting stone and soil downslope. Rainwater percolates into the ground where it is concentrated along the upper surfaces of the less permeable marly layers. Eventually it seeps out of the face, leading to erosion of the soft marls. This undermines the sandstone blocks above, leading to their collapse. This water is then concentrated in gullies, further eroding soil and rock which is then channelled to the bottom of the face, where it spreads out to form talus cones. Look out for a distinctive white, frothy stream which forms in the large gully on the right of the face after heavy rain. In snow and ice conditions, the gullies provide spectacular winter climbing routes for daring climbers using crampons and ice axes.
Ascending the steep prow of Cribyn
From the foot of Pen y Fan take the track up the headwall which goes from bottom right to top left. Crossing piles of loose stones at first, the headwall track rises at an easy angle, presenting no problems, and arrives at the unnamed col between Cribyn and Pen y Fan. The extended route to the summit of Pen y Fan leaves from here. There is also an exhilarating alternative route round the shoulder of Cribyn that may be followed from here.
Turn left (E) up the steep, eroded slope to the summit of Cribyn. The ascent of Cribyn is rewarded with an impressive panorama on a clear day, with good views to the west of the north-east face of Pen y Fan and to the east of the other Beacons valleys and ridges, Fan y Big and the Black Mountains beyond.
Descend (NNE) following the narrow prow of Cribyn. The steep descent down the nose of Cribyn can be exciting in snow and ice conditions and may well require crampons and an ice axe. Stop now and again to enjoy the views – look over into the adjacent valley of Cwm Cynwyn through which runs the Roman Road (see Walk 11) up to Bwlch ar y Fan between Cribyn and Fan y Big.
The return route heads down Bryn Teg (NNE) on a wide grassy track to a gate past a sign reading ‘Entry to National Trust Land’ (Bannau Brycheiniog – The Brecon Beacons). Follow the stony track, part of the Roman Road, which leads down to a crossroads where you take the road ahead. This leads back to the stone bridge from where you started.
Extension
Climb W along Craig Cwm Sere to the summit of Pen y Fan. The final ascent of Pen y Fan is badly eroded but the National Trust has built a zigzag path out of the Brownstones to reduce further damage. Now descend back to the unnamed col between Pen y Fan and Cribyn and rejoin Walk 5.
Alternative route
Traverse around the shoulder of Cribyn along a sheep track. This is the most exciting mountain route in the Beacons, the narrowness of the path and the steep drops giving the walker a real taste of exposure. Remember that great care must be exercised here in winter conditions where crampons and an ice axe may well be the order of the day. Look back now and again at the north-east face of Pen y Fan which dominates the skyline, making this one of the finest viewpoints in the Beacons. The final part of this traverse affords grand views of Cwm Sere and across Allt Ddu to the town of Brecon on the left. (See Walk 6 for a description of the flora of the north-west face of Cribyn). Now rejoin Walk 5 at the start of Bryn Teg.
WALK 6
Cwm Sere Ridge
| Start | Pont y Caniedydd (SO 039 244) |
| Distance | 10km (6 miles) |
| Total Ascent | 560m (1841ft) |
| Map | OL12 Western Area |
This is one of the classic ridge walks in the Beacons. The route climbs the ridge on the east side of the valley and includes ascents of Cribyn and the highest peak in the Beacons, Pen y Fan. Descent is via Cefn Cwm Llwch, the ridge on the western border of the valley. The ascents and descents in
