Beside the Honddu
A small part of the community of Honddu Isaf to the south of Llandefaelog lies within Fforest Fawr Geopark.
The lie of the land
The community ranges in height from about 165m in the Honddu valley just north of Brecon to 450m at Ysgwydd Hwch in the north. Key hills include the flat 390m summit of Battle Hill (outside the Geopark at OS grid ref SO 015343) and the eastern flanks of Pen-y-crug. The community is of course drained by the Afon Honddu though a small area in the north-east drains into the Dulas which ultimately flows into the Wye.
Solid rocks
The underlying rocks are sandstones and mudstones which were laid down during the Devonian Period. These rocks can be seen in the sides of the Honddu gorge.
The low hills which characterize the area are formed from sandstones of the St Maughan’s Formation and mudstones of the Raglan Formation.
A major fault – the Swansea Valley Fault – runs SW to NE through the valley immediately north of Pen-y-crug.
Legacies of the Ice Ages
Surrounding hillsides are plastered with glacial till and glacio-fluvial sandsand gravels. These relate to the presence of the major Usk Valley Glacier during the ice ages.
It is thought that the River Usk formerly flowed to the north of Brecon around the back of both Pen-y-crug and Slwch Tump in the vicinity of the villages of Cradoc and Llanddew. Glacial action diverted it onto its present more southerly course.
Maps
Geology
Sheet 213 ‘Brecon’ of the British Geological Survey’s 1:50,000 map series of England and Wales gives full coverage of both the bedrock geology and superficial deposits of this part of the Community area. BGS publishes a ‘sheet explanation’ to accompany this map.
General
The following Ordnance Survey maps cover the Community:
- Landranger sheet 160 ‘Brecon Beacons’ (1:50,000 scale)
- Explorer sheet OL12 ‘Brecon Beacons National Park/Western area’ (1:25,000 scale)
Public transport
Bus services serve nearby Brecon. The nearest railway stations are 20 miles away at Llandovery, Abergavenny and Merthyr Tydfil to the west, east and south respectively.
See Traveline Cymru for bus and train services including stops, timetables and route-planning information.