Fforest Fawr

Fforest Fawr is the name given to an extensive upland area in the county of Powys, Wales. Formerly known as the Great Forest of Brecknock in English, it was a royal hunting area for several centuries but is now used primarily for sheep grazing, forestry, water catchment and recreation. It lies within the Brecon Beacons National Park.

The area extends from the edge of the Black Mountain in the west eastwards to the A470 Brecon to Merthyr Tydfil road, just west of the Brecon Beacons themselves. It includes the peaks of Fan Fawr (734 m), Fan Frynych (629 m), Craig Cerrig-gleisiad (629 m), Fan Llia (632 m), Fan Nedd (663 m), Fan Gyhirych (725 m), Fan Bwlch Chwyth (603 m) and Cefn Cul (562 m). Traditionally Fforest Fawr also included the peaks of Fan Hir and Fan Brycheiniog, although the modern recreational use of the name tends to be restricted to the area east of the Black Mountains of which they form a part.

The area is almost exclusively underlain by sandstones and mudstones of the Old Red Sandstone, the more resistant sandstone beds of the Brownstones Formation give rise to the major peaks.

To the south of the main peaks are two more broken north-facing scarps, that of the Carboniferous Limestone and, to its south, that of the Millstone Grit. These three suites of rock all dip southwards into the regionally important South Wales Coalfield basin.

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