Dozens of landslides scar the hillsides of Fforest Fawr Geopark – this page lets slip why they happened and where they are.
Signs of past landslides can be found throughout the Old Red Sandstone hills of the Geopark. Apart from one, all the major slips have occurred within the Brownstones – the sequence of sandstones and mudstones that forms much of the upper part of the Old Red Sandstone. They all date from after the last ice age when hillsides that had been over-steepened or undercut by ice or meltwater, slumped down into the valleys.
All of the locations listed below can be found on Ordnance Survey Explorer map sheet OL12 ‘Brecon Beacons National Park; Western Area’. The British Geological Survey’s 1:50,000 scale maps 213 ‘Brecon’, 230 ‘Ammanford’ and 231 ‘Merthyr Tydfil’ provide geological coverage.
- Note that the Ordnance Survey grid references and elevations above sea level for this selection of sites are only approximate.
Landslides in the Geopark - click on map to enlarge
Blaen Taf Fawr
A triangular section of the east-facing slope above the upper reaches of the Taff has slipped, perhaps after under-cutting by the stream. Best viewed from Beacons Way en route between Pont ar Daf and Pen y Fan. Parking at Pont ar Daf at SN 987199
- Elevation: 550m / 1800ft
- Grid ref: SN 993206
Craig Cerrig-gleisiad
A major landslip – or series of landslips – whose origins are intimately connected with the glaciation of this cwm. Can be viewed in part from the A470 but a short walk into the cwm from the layby at SN 971222 gives the best views. The whole site has been designated as a national nature reserve.
- Elevation: 500m / 1600ft
- Grid ref SN 960220 – 975240
Craig y fro
Since the A470 runs right through it and there is a large parking area on its northern edge, this is the most accessible of all the landslips of the Geopark – if it’s a landslip, that is! Scientific debate continues as to whether the striking landforms seen at this spot owe their origins to ice or a slip.
- Elevation: 380m / 1250ft
- Grid ref: SN 973207
Cwm Nant Lloi
A slip just south of the pass of Bwlch Bryn-rhudd. The former Neath and Brecon Railway line passes through the middle of the slip as did the Brecon Forest Tramroad before it. It can be viewed from the A4067 Swansea road or the permissive path which follows the old railway from the pass. Park in layby at SN 867193
- Elevation: 400m
- Grid ref: SN 868188
Fan Dringarth
One of the most spectacular landslips in the whole Geopark and one of the least accessible and hence least known. The eastern side of the summit of Fan Dringarth has broken away and some of it now forms a great bulge of rocky debris looming above the Afon Dringarth at the head of Ystradfellte Reservoir. Visible from the Beacons Way as it runs along the mountain’s ridge.
- Elevation: 500m / 1600ft
- Grid ref: SN 942195 to SN 199188
Graig Fawr
Alone amongst the landslips of the National Park and Geopark, this one occurs within the mudstones and sandstones of the upper Coal Measures although landslips in these rocks are very common in the coalfield to the south. A couple of public footpaths run through the slip on the western wide of Cwm Pedol, west of Brynaman though it can be seen to advantage from the eastern side of the cwm.
- Elevation: 250m
- Grid ref: SN 695153
Dyffryn Mellte
The steep eastern side of the gorge through which the Afon Mellte flows above its confluence with the Hepste has collapsed leaving a jumble of boulders over which the woodland has spread. The jointed sandstones and weak mudstones of the ‘Marros Group’ collapsed at some unknown but distant time as they were undercut by the river. Best viewed from the path down to Sgwd y Pannwr which runs through its midst.
- Elevation: 200m
- Grid ref: SN 923104