Pen Twyn Glas marks the 2,115ft apex of Tal Trwynau, a long, grassy ridge dividing the Grwyne Fechan valley from Cwm Banw to the west. This is the 'forgotten quarter' of The Black Mountains, the scene dominated by the great Waun Fach/Pen-y-Gadair-Fawr ridge to the right and Pen Cerrig-calch/Pen Allt-Mawr, across Cwm Banw, to the left as the Mam Cymru and I ascend. The silence is all consuming, the sense of anticipation that of those who know what's coming.... like a child upon Christmas Eve, so to speak.
Everything changes upon attaining the main ridge mid-way between Pen Allt-Mawr and Mynydd Llysiau, however. To be honest the summit itself is not exactly inspiring, being 'adorned' by one of the most pathetic walker's cairns you'll ever see and a fallen boundary stone that may well be old, but obviously not prehistoric. Then the view to the west and north-west materialises. Actually that's not the right word, implying a gradual revealing, whereas the stunning vista actually hits the traveller with all the metaphoric force of a freight train. Not just inspiring, but awe inspiring. Can anything look so beautiful as the Rhiangoll looks today in this light? An open question, I guess.
We consider heading either left or right along the ridge.... but frankly this will do nicely today, thank you very much. Trees soften the flanks of Cwm Nant-y-fedw below, as if planted for this very reason - but actually colonising the only sheltered areas they can find in this brutal, hostile landscape. But what of prehistoric 'stuff'? Well, there's a somewhat denuded Bronze Age cairn a little way down the slope to the left of the cwm [see misc post], this leading the eye towards the great bulk of Mynydd Troed and, beyond, Mynydd Llangorse with its hillforts, The Brecon Beacons and, why, even Y Mynydd Du. The great South Walian Bronze Age cemetery, no less.... Diverting the gaze northwards, the reason for siting Castell Dinas 'there' was never more obvious.
But, magnificent scenery aside, why would a stone-hungry TMA-er want to expend all that energy - for it's quite an ascent - for one, denuded cairn, albeit one that yielded artefacts upon investigation? The answer, I think, lies in a couple of further Coflein records which reveal that a Bronze Age arrowhead and flint (possibly Mesolithic) were found in the immediate vicinity [again see misc post]. Clearly men have been 'passing by' for millennia - whether on hunting expeditions or engaged in ritualistic rites I guess we'll never know - and it's this knowledge which, for me, adds some tangibility to the highly developed 'sense of place' we experience here, a feeling which I simply cannot put into words. It just feels 'right', you know?
Punters may march 'eyes down' along the main ridge - and quite a few do so, the muppets - but move a little to the west to the lip of the escarpment and I'll swear you wouldn't be at all surprised if a Bronze Age gentleman came up and sat down beside you. Come and 'ave a chat, my friend. Swop me Triplepoint jacket for your quiver of arrows? Right on!
So, come to Pen Twyn Glas and travel in the footsteps of the ancestors. Literally......
The mutilated cairn is located on a level area above the northwest facing slope. It is a mound roughly 10 metres across and 1.3 metres high, roughly circular in plan. It is built of portable stones measuring about 0.2 metres across. A shelter has been dug into the top of the cairn, forming a round hollow 3 metres across and 1.2 metres deep. A peculiar channel runs up the east side of the cairn and can be seen continuing along the bottom of the shelter. It is about 7 metres long and 0.5 metres wide. Where it runs up the side of the cairn it is 0.2 metres deep and full of exposed stone (the rest of the cairn, apart from the shelter, is covered with bilberry). The channel could be associated with the original design of the cairn, perhaps even a passage. A previous investigation of the cairn found a pigmy cup and burnt bones located within a primary cist.'