Mapping Mountains – Trimble Surveys – Y Berwyn

13.06.14  Y Groes Fagl (SH 988 289)

Y Groes Fagl (SH 988 289)

Between the lakes of Llyn Tegid and Llyn Efyrnwy is a land of high heather moor that stretches for many miles.  The area is seldom visited except for the attentive gatherer or an occasional walker.  The hill walkers that come this way are usually baggers, those people interested in visiting the 2,000ft’s or 500m peaks that frequent the area.

The land is split by some of the highest public roads in Wales; these also give good access on to the hills.  It was the top of the road above Cwm Hirnant that John and I headed for, for today’s survey.  Graham couldn’t join us as he was getting everything prepared for a holiday with his wife; Janet, starting tomorrow.

Either side of Cwm Hirnant are a wealth of 2,000ft hills, to the immediate west is a slender heather bound ridge comprising three of these hills; Foel y Geifr, Trum y Gwragedd and Foel Goch, whilst to the east is a morass of heather bound wilderness and more 2,000ft’s.  One of these was our main objective for the day; Y Groes Fagl.  This hill is given just 50ft of ascent from its connecting bwlch with Cyrniau Nod by John and Anne Nuttall.  John and Anne are now using 15m as their drop qualification, this converts in to imperial as 49.2ft, so Y Groes Fagl is a marginal Nuttall and we planned to determine its status with a line survey.  The hill is also given 15m of drop on the Ordnance Survey enlarged Geograph map with a 644m bwlch spot height and a 659m summit spot height.

Access to the hills on the eastern side of Cwm Hirnant has been eased with the construction of a track that leaves the top of the road pass and contours around the northern face of the 2,000ft’s overlooking Cwm Bychan, before descending down in to the cwm through its conifer plantation.  The track was ploughed through the land in the late 1970’s.  This land used to be owned by Watkyn Williams-Wynn; upon his death the government took the land as death duties.  Afterwards the land commission ran the land; it was subsequently sold to the tenants in 1966/67.

The forecast for the day was good, that is if you like hot weather, I don’t particularly as I find it can sometimes completely wreck me and I end up a giggling mess strewn and poleaxed on the hillside.  As a contrast John is in his element when the weather is hot.  We set off up the track in clear heat with views west toward Arennig Fawr and the high Aran.

Arennig Fawr (SH 827 369)

The high Aran

As height was gained Cwm Bychan came in to view and in its depths the forest track that we had earlier tried to drive up to give direct access to Y Groes Fagl.  Unfortunately the first gate we encountered was padlocked which scuppered our plan and meant we would have to approach the hill from the high road pass and the previously described track.

We soon came upon Rhys Jones who had already herded his flock of sheep from a reclaimed patch of hillside and was treating each in turn to stop maggot infestation.  We stopped and chatted for ten minutes, this gave me a chance to reclaim my breath and to try and get my heart beating less than the 180 beats per minute that the hot weather was causing.  Rhys farmed this land, as did his father and grandfather before him.  This was the first of two planned stops for him as he wanted to carry on around the hillside and gather and treat the sheep further up the track before calling his day’s work done.

Rhys Jones, working the land his father, and grandfather before him had done

As the sun beat down we continued on our way toward the critical bwlch of Y Groes Fagl.  The bwlch we were aiming for is positioned near to the point of the track just before it heads downhill and in to the conifer plantation in Cwm Bychan.  As we dropped our rucksacks in the heather at the bwlch I felt a bit light headed and somewhat knackered. 

John on the track heading toward Y Groes Fagl which is somewhere beyond the horizon

The first thing to do was sit down, rest, recuperate and eat food.  Soon afterwards we had flagged three heather gully systems and determined where the critical bwlch lay.  We then proceeded up the hill with John at the level, taking and noting the readings and me at the staff.  An hour or so later and we had determined the drop value for Y Groes Fagl; 15.71m, so the hill remains a Nuttall – YYIIIPPPEEEEE!!!!!

John carrying the level and tripod between placements during the line survey

The all important calculations

I placed the Trimble GeoXH 6000 at the summit to gather ten minutes of data before we headed back down to the bwlch where John gathered ten figure grid references for the high point of each gully system.  During this I placed the Trimble at the critical bwlch, as this consisted of heather I decided to raise the Trimble off the ground, using the plastic Tupperware box that I use to insert my rehydration water bag for safe carriage in my rucksack.  The measurement offset would be taken off the processed bwlch figure.

The Trimble GeoXH 6000 gathering data at the summit of Y Groes Fagl

Using a Tupperware box as a mini-tripod at the critical bwlch of Y Groes Fagl

Once we had gathered all the necessary bwlch data we headed back up the track and in to the heather surrounding the summit of Cyrniau Nod (SH 988 279).  John wanted to determine its true summit position as two points seemed to vie for it, one near its cairn and the other a couple of hundred metres to the north.  John used the optics on the level to sight along the ridge and we placed the staff at the two high points.  The summit proved to be near to its cairn.  During this I placed the Trimble at the high point and waited for its 0.1m to be achieved before logging data, sometimes the Trimble can take an age to slowly creep down to the point where data can start to be gathered, today was such an occasion, after ten minutes of waiting I decided to close it off, as we needed to complete the summit position survey, and the sky was turning a deep shade of grey, heralding the forecast evenings rain and time dictated that we press on and get back to the car.

At the summit of Cyrniau Nod (SH 988 279)

On our way back on the track the sun was quite ferocious in parts, but the light cast by it with a deep grey sky as backdrop was stunning.  We came across Rhys again; he’d moved around the hill and was treating the second batch of sheep.  We chatted for quite some time which helped me regain my breath.  Seven hours and ten minutes after setting out we arrived back at the car, a great day on the hill, albeit a little too hot for me, just as we got our boots off the first raindrops started to fall, perfect timing. 

Homeward bound after another great day in the hills