Mapping Mountains – Trimble Surveys – Carnedd Llywelyn

19.07.15  Pen yr Helgi Du (SH 697 630) and Pen Llithrig y Wrach (SH 716 623)  

Pen Llithrig y Wrach (SH 716 623)

The Carneddau offer so much as a mountain range with extended walks above 3,000ft, with secluded cymoedd and isolated mountain lakes with many circular walks taking the visitor to some of the best mountain scenery in Wales.  However, one thing that they do not have aplenty is options for scrambling.  Today our plan was to visit the best scramble the Carneddau has to offer, this is on Grib Llem which makes a direct route to the summit of Carnedd Dafydd.  Unfortunately sometimes in the hills all best plans have to be quickly re-arranged and as Ed and I arrived in Ogwen the murk clung to the westerly facing hills and the wind blew, and as heavy overnight rain had soaked these hills we decided that for today prudence was better than valour and we opted to visit Pen yr Helgi Du and Pen Llithrig y Wrach instead.  These two hills can be easily combined and if ascending to the bwlch above the Ffynnon Lludwy Reservoir a bit of hand on rock can be enjoyed on the ridge leading to the summit of Pen yr Helgi Du.

The landscape around Ogwen is impressive with many of the highest mountains in the land on display, and as we walked up the paved road to the reservoir the play of light on these hills highlighted their profile with sun occasionally emerging from behind the blanket of grey cloud, alternatively picking out detail in their rock strewn nature before the movement continued highlighting lower green pasture and giving their profile a darkened and foreboding element.  This play of light remained with us as we continued up toward the reservoir.

Looking back down the paved access road with Gallt yr Ogof and Y Foel Goch looming overhead

The darkened profile of Tryfan

And now in full majesty, a truly wonderful hill

Stunning from every angle

The lake of Ffynnon Llugwy is now used as a water supply for parts of Bangor and eastern Ynys Môn, with a series of leats feeding water to Llyn Cowlyd, it was one of these leats that we planned on following later in the day on our descent.

Ffynnon Llugwy with Carnedd Llywelyn in cloud in the background

Approaching the lake we branched right and continued on a path which became Alpine like as it gained height steeply up toward the bwlch which is named as Bwlch Eryl Farchog on the map.  This path zig zagged its way up the hillside and in many places its immediate ground was all that could be seen of it, as its gradient was so steep that one could not see its continuation from below.

The path is almost Alpine like

The expanse of Ffynnon Llugwy

Nearing the bwlch with Pen yr Helgi Du in the background

Away to our west the darkened murk continued to skim the higher Carneddau ridge and as we crested the top of the path and popped out at the bwlch a brisk wind blew, we realised that postponing our planned scramble had been a wise decision.

Once at the bwlch we assessed the land and decided where the Trimble should be placed.  As it gathered its customary five minutes of data Ed relaxed a little higher up whilst I stood below the Trimble overlooking the lake.  Once five minutes of data were collected I took a number of photographs of its set-up position and away we went heading for a dramatically looking summit cone of Pen yr Helgi Du.

The Trimble set-up position with Ed relaxing and Pen yr Helgi Du in the background

Gathering data at the critical bwlch of Pen yr Helgi Du

The ridge leading up to the summit has a path on it but with a little imagination some scrambling can be enjoyed.  I wanted to go first and have the opportunity to take photos of Ed as he worked his way up.  The scenery hereabouts was dramatic with the narrow ridge overlooking Cwn Eigiau to its north and the higher Carneddau to its west with the waters of Ffynnon Llugwy now disappearing below to its south.

Heading toward Pen yr Helgi Du

On the ridge leading up to the summit of Pen yr Helgi Du

Once at the summit I took two data sets with each one beside the remnants of a small cairn, these two high points are about 50 metres apart with the one nearest the crags overlooking Cwm Eigiau the favourite to take the accolade as this hill’s summit position.

Collecting data from the first of two points surveyed for the summit of Pen yr Helgi Du

Our next hill, Pen Llithrig y Wrach reared up in a symmetrical fashion with the easterly lands of Wales stretching beyond.  A good path led us down to its bwlch which is placed next to a ladder stile and close to a series of small puddles. 

As the Trimble struggled down to its 0.1m accuracy level before data can be logged we chatted away about all manner of stuff, and only stopped when I occasionally scampered back up to check on its slow downward progress.  Eventually the magic 0.1m appeared on its screen and I pressed ‘Log’ and re-joined Ed for another natter.

The bwlch of Pen Llithrig y Wrach

Gathering data at the critical bwlch of Pen Llithrig y Wrach

Once the Trimble had been packed away I followed Ed up the path which gains persistent height toward the summit of Pen Llithrig y Wrach.  The summit of this hill has no spot height on the current Ordnance Survey 1:25,000 and the enlarged Geograph map, whilst the 1:50,000 map has a 799m spot height which no doubt came from the 798.576m height given to the old bolt in a rock that was destroyed in July 1978 and which is catalogued in the OS Trig Database.

Pen yr Helgi Du from the ascent of Pen Llithrig y Wrach

This is an ascent I always try to do without stopping and except for a couple of quick photos where I still wobbled onward I joined Ed beside the summit cairn happy in the knowledge that I could still do so.

Ed beside the summit cairn on Pen Llithrig y Wrach

The summit of Pen Llithrig y Wrach gives excellent views down onto Llyn Cowlyd with Creigiau Gleision looming overhead.  I had a rummage around the summit cairn and found an embedded rock which proved to be the highest natural ground.  Placing a rock beside the embedded rock I aligned the Trimble’s internal antenna with the high point and joined Ed who was happily relaxing and soaking up the view.

Gathering data at the summit of Pen Llithrig y Wrach

Llyn Cowlyd

Our onward route took us down the southern ridge to the stream feeding Llyn Cowlyd, this route is steep and can be leg sapping, and as we arrived at the leat next to the stream I was thankful that we would have a couple of miles walk on relatively flat ground.

Approaching the leat

We followed the leat as it contoured around the southern ridge of Pen Llithrig y Wrach and only left it to investigate a bridleway which according to the map would give us a slightly quicker descent back toward the awaiting car.

Following the leat around the southern ridge of Pen Llithrig y Wrach

The bridleway proved boggy with a number of places where the path was a quagmire, all obstacles were overcome though, and it led us down to the A5 which we then followed up to the car.

Pen Llithrig y Wrach from the bridleway

It had been an excellent walk with Ed, and a day on the hill that was part salvaged from our initial plan.

Survey Result:

Pen yr Helgi Du

Summit Height:  832.6m (converted to OSGM15)

Summit Grid Reference:  SH 69776 63049

Bwlch Height:  747.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 69439 63342

Drop:  84.7m

Dominance:  10.18%

Pen Llithrig y Wrach

Summit Height:  798.6m (converted to OSGM15) (700m Twmpau status 

confirmed)

Summit Grid Reference:  SH 71620 62288

Bwlch Height:  618.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 70954 62637

Drop:  180.3m

Dominance:  22.57%

For further details please consult the Trimble survey spreadsheet click {here}