Atlantic Slab, Carnedd y Filiast This classic grade 3 scramble, mysteriously absent from Steve Ashton’s ‘Scrambles in Snowdonia’, is also classed as a moderate rock climb under the name of ‘The Ridge’.
The slab is at a similar angle to Little Tryfan, but about 3 times as high! Most scramblers would want to do this in roped pitches or moving together – take a selection of nuts, hexes and slings. Climbed in pitches, the scramble could take 2 – 3 hours, plus an hour for the approach and probably up to an hour for the descent by the quickest route.
Most enjoyable when completely dry, but do-able under damper conditions. Approach: Cars can be parked in a lay-by on the old Nant Ffrancon road at approx. GR 632633. Walk along the road for 50m south, cross the cattle grid and immediately turn up the grassy hillside by the stream. Continue up steeply, over a fence, and over the lip of the cwm into Cwm Graianog.
The many huge slabs of Carnedd y Filiast are now visible (mist allowing!) Atlantic Slab is the highest up along the side of the spur forming the NW wall of Cwm Graianog. Approach time, about an hour. Note the long, tall stone wall heading up the cwm to your right. There is no need to try to climb over it. Follow it up the cwm for some way until it peters out and is replaced by a broken fence. At this point you should be able to see a continuous scree slope which leads up from near the fence to the lowest corner of Atlantic Slab.
Ascend the scree carefully and make for the lowest corner of the slab. You might well find a small cairn marking the beginning of the scramble – in any case, it starts at the bottom right corner of the slab. Ascent: Initial moves, on the slab itself, are rather heathery – however, there is always plenty of clean rock, and increasing amounts the higher you get. Route finding is very straightforward – keep as much as possible to the crest of the ridge which demarcates Atlantic Slab from the lower slab to its right. Scrambling is mostly easy for the grade, pleasant and sustained and there are plenty of potential stances if you are doing it in pitches.
Occasionally there is a choice of subsidiary ridges, or the need to re-ascend the steep edge of the ridge to get back up onto the main slab / ridge. Towards the top, you can move onto easy ground on the right, or keep more out on the slab itself, with a 300 m drop under your feet! Descent:
The top of Carnedd y Filiast is 150 m NW from where the scramble ends. A good viewpoint, if there is a view. From here, all sorts of longer ways down are possible, but the most direct descent is directly down the ridge, heading NE, until well below all the other slabs – you can either then clamber back down into Cwm Graianog and when you meet the stone wall, follow it right down to the road – or continue directly down the ridge and meet the wall lower down, coming out at Tai Newyddion, a short walk from the lay-by.