Walking in the Brecon Beacons National Park

• Location
• Description
• Contents
• Introduction
• Sample Route
• Updates
• Reviews

Situated in an unspoilt area of South Wales, just north of the former coal mining valleys, the Brecon Beacons National Park is a place of beautiful and diverse landscapes. One of three national parks in Wales, more than half of its 519 square miles are over 1000ft above sea level and it boasts a rich mixture of majestic valleys, dramatic waterfalls and high mountain peaks and ridges.

The routes in this guide avoid the less interesting, more popular routes that most people frequent, and take you to wooded gorges and upland valleys that even the locals may be unaware of. All the 45 routes are circular and avoid using stretches of road wherever possible. A striking feature of the park is the number of rich and varied walks that can be found in a relatively small area, so great distances do not have to be travelled by car to sample the multitude of different landscapes and varied terrain on offer.

The park falls naturally into four geographic areas. These are (from west to east): Mynydd Du (The Black Mountain), Fforest Fawr, Brecon Beacons and the Black Mountains (Y Mynyddoedd Duon). These all have different characters making the park unique in offering such varied walking experiences.

Mynydd Du really lives up to its name, having some of the remotest upland wilderness in England and Wales. This is the area to choose when you really want to get away from it all. In contrast, Fforest Fawr (the Great Forest), a former royal hunting ground, has both friendly upland walks and deeply incised river gorges and waterfalls to rival any in the UK. The Brecon Beacons are the highest summits in the park, with Pen y Fan not quite making Munro status, being just short of 3000ft. Although this area lacks the challenges of the narrow rocky ridges of the Lake District and Snowdonia, it does provide opportunities for a real mountain expedition in exciting winter conditions. Finally, the Black Mountains, on the English border, have a softer feel to them, without the coarse and rugged Welshness of Mynydd Du.

There is also a plethora of things to see and activities for visitors of all ages and tastes, making the park a great place for families to visit. Favourite attractions for children include Dan-yr-Ogof Show Caves in the Swansea Valley, Brecon Mountain Railway at Penderyn and Big Pit National Coal Museum near Blaenavon. Picturesque market towns on the edges of the park, such as Llandovery, Brecon, Crickhowell and Abergavenny, are also great places to explore.

Geology of the Brecon Beacons
The rocks that shape the park belong to the Old Red Sandstone and were deposited some 395–345 million years ago in the Devonian period of geological time. Old Red Sandstone is a generic term which refers to a group of sedimentary rocks laid down by rivers flowing across coastal plains. Three distinct rock types, conglomerates, sands and muds, were formed from river gravels, sands and muds respectively.

South Wales lay south of the equator in latitudes which are typically occupied by deserts. Prior to this, much of Britain was affected by strong earth movements which caused uplift and sharp folding, resulting in a tract of upland (St George’s Land) which probably extended from the Midlands through central and northern Wales and into Ireland.
Flash floods washed down red muds, sands and grits along ephemeral river channels, building an extensive river flood plain. To the south was the Devonian shoreline, approximately where the Bristol Channel is now, and the warm Devonian Sea where the first fish swam. Europe at this time was drifting northward and, when it crossed the equator, the semi-arid flood plains were gradually submerged beneath tropical Carboniferous seas.

The Old Red Sandstone in the Brecon Beacons can be split on geological grounds into Lower and Upper, the Middle being missing. The Lower Old Red Sandstone comprises a group of up to 850m of red marls followed by a group of sandstones divided into two formations – the Senni Beds, some 310m of dark green chloritic layers interbedded with red, and the Brownstones, 330m of very dark red and purple sandstones. The steep craggy slopes are formed from these regularly bedded Brownstones.

A secondary escarpment is well developed on the northern ridges of Cefn Cwm Llwch, Bryn Teg and Cefn Cyff where the ridge drops steeply from the main scarp, flattens between 540 and 600m and then drops again, the steeper slopes beneath this being cut in the Senni Beds which underlie the Brownstones.

The Upper Old Red Sandstone comprises three groups of rocks. The Plateau Beds are red quartzites and conglomerates up to 33m thick which unconformably overlie the Brownstones. The summits of Corn Du and Pen y Fan are capped by an isolated outlier of some 14m of overlying, massively bedded, Plateau Beds. The second group, the Grey Grits, are unfossiliferous sandstones and conglomerates up to 200ft thick and these pass laterally eastwards into the Quartz Conglomerates which comprise red and brown sandstones, quartzites and coarse conglomerates. Further earth movements during the mid-Devonian period uplifted South Wales, resulting in renewed erosion, creating a distinct break in the geological record, and forming the distinctive ridges and valleys that walkers enjoy today.

Earth movements
Mountain building earth movements which took place at the base of the Old Red Sandstone and at the end of the Upper Palaeozoic have been named the Caledonian and Hercynian, respectively. Caledonian movements spanned a time interval of more than 100 million years, at least from latest Cambrian to post-Silurian, and were responsible for folding and faulting of rocks, resulting in geological structures aligned in a north-east–south-west direction. After these mid-Devonian movements died away, there was little mountain building until late Carboniferous times. At the end of the Coal Measures, the Brecon Beacons were on the southern flanks of a southward moving continent which eventually collided with a northward moving land mass to the south. Enormous compressive forces caused strong folding and faulting of Upper Palaeozoic rocks. The outstanding feature that resulted from these tectonic movements is the syncline of the South Wales coalfield and the regional southward tilt of the rocks of the Brecon Beacons originated as part of its northern limb. A major structure disrupts the northern rim of the coalfield and runs through the lower parts of the Waterfall Country. This is a complex fault system known as the Neath Disturbance which grew intermittently from Dinantian times, reaching its zenith in late-Carboniferous times.