Cefn yr Ystrad 2010

A neglected mountain with impressive views.

Cefn yr Ystrad is the only mountain (Hewitt and Nuttall) in the southeastern branch of the Brecon Beacons. It sits at the start of the branch, and is one of the mountains whose summit is underlain by the Northern Outcrop of limestone (the outcrop also underlays the summits at the western end of the Black Mountain, and a discontinuous underlay appears on Pen Cerrig-calch in the Black Mountains). Due to its lack of proper path, and the severe damage caused by quarrying, the mountain is rarely visited. Our route follows the first part of the route in the Nuttalls guide.

• The route begins a little downstream from the Pontsticill Reservoir dam, climbing up near a junction of roads.
• Tortoiseshell butterfly.
• The path climbs up to pass under the Brecon Mountain Railway, which runs from Merthyr Tydfil to Torpantau (not Brecon).
• View over the reservoir towards the main Brecon Beacons group peaks; Corn Du (873 metres), Pen y Fan (886 metres) and Cribyn (795 metres).
• Low water levels exposing the outflow.
• The path climbs up to the final wall, where the first obvious signs of limestone appear in the form of some weathered outcrops.
• A path to the left brings Cefn yr Ystrad (617 metres) into sight.
• A very definite sign of cave; a small sink on the side of the path.
• Weathered limestone.
• The ridge running down from the main peaks to Merthyr Tydfil. It has many names on the way down; Craig Gwaun Taf, Rhiw yr Ysgyfarnog, Graig Fan Ddu, Twyn Mwyalchod, Gwaun y Pynt, Twyn Croes (452 metres), Garn Ddu (462 metres) and Cefn Cil-Sanws (461 metres). On the left are the Rhigos Mountains, topping out at Craig y Llyn (600 metres). Looking over the upper edge of the ridge are Fan Gyhirych (725 metres) and Fan Fawr (734 metres) in the Fforest Fawr group.
• The path skirts the edge of Cefn yr Ystrad. To reach the top, you simply have to pick a point in the rocky slope that seems appropriate, just after a small stream crosses the path, and the Cwm Criban stream almost touches the path.
• Above the rocks, a small limestone outcrop appears. From here, the way on is to follow the outcrop to reach the quarry.
• Below the outcrop. In the background are Corn Du, Pen y Fan, Cribyn, the indiscernible back of Fan y Bîg (719 metres), the wide moorland of Gwaun Cerrig Llwydion (754 metres), Waun Rydd (769 metres) and Allt Lwyd (654 metres).
• Sink at the outcrop. There are only two significant caves under this mountain, but given the expanse of limestone, there really should be more.
• Perhaps this is one...
• The route then reaches tracks at the edge of the immense Cwar yr Ystrad, which combines with Cwar yr Hendre and Cwar Blaen-dyffryn to create a nearly continuous 3 km long quarry, wrapping around the mountain, as much as 1 km wide (the section shown here is a little over 200 metres wide). For a while, the route takes the track skirting the right side of the quarry. Part way along, a track doubles back to the right, and a very short way along that, a little path heads to the left, climbing up onto the mountain.
• The Black Mountains group. Nearby on the left is Tor y Foel (551 metres). After that are the Black Mountains. The ones that can be distinguished are Mynydd Troed (609 metres), Waun Fach (811 metres), Pen y Gadair Fawr (800 metres), Pen Allt-mawr (719 metres) and Pen Cerrig-calch (701 metres).
• The Brecon Beacons ranges. All five groups can be seen here. On the left are the two Fforest Fawr peaks seen earlier, with Fan Brycheiniog (802 metres) in the distance between them. After that are the Brecon Beacons and Black Mountains groups (same mountains as before). Finally, on the right are the bumps of the Sugar Loaf (596 metres), The Skirrid (486 metres), Mynydd Llangatwg's lower summit (529 metres), the Blorenge (561 metres), and the top of Cefn yr Ystrad. In front of the Sugar Loaf and Skirrid are the moorland tops of Mynydd Llangynidr (551 metres) and Mynydd Llangatwg (530 metres).
• Skirting shakeholes near the summit of Cefn yr Ystrad.
• View over the heads of the South Wales Valleys, from one of the large cairns near the summit. The high points are on the left half of the picture; the Blorenge and Coety Mountain (578 metres), Mynydd James (550 metres), Mynydd Carn-y-cefn (550 metres) and Y Domen Fawr/Cefn Manmoel (504 metres).
• In the colosseum of mountains.
• Light on Gwaun Cerrig Llwydion, with its Craig y Fan Ddu buttress standing in shadow.
• The scarps of Waun Rydd.

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