Friday, 22 May 2020

Mapping Mountains – Trimble Surveys – Arenig

19.01.20  Moel Darren (SH 952 413), Foel Goch (SH 953 422), Orddu (SH 963 423), Pt. 534.1m (SH 966 419) and Pen y Cerrig Serth (SH 970 429)  

Pen y Cerrig Serth (SH 970 429)

Winter time in the uplands can give a glimpse of the hills at their best.  When snow and frost predominate and cloud inversions in flat bedded valleys add magical elements to distant views.  Today was such a day, when beautiful colour, stunning views, good company, hills and route combined to give an excellent seven hours taking in five hills with nine surveys conducted.

I met Aled in Y Bala and we soon had our cars positioned to the south of Foel Goch.  The satellite peaks radiating out from this hill give good opportunities for circular walks and we had surveyed a number of the connecting hills in October 2015.  We now wanted to visit the hills to the east of Foel Goch and combine them with its southern outlier of Moel Darren.

We gained height on a minor paved road leading past Llwyniolyn before following the continuation up valley on a muddied track.  Behind and below us the valley enclosing the Afon Dyfrdwy was bathed in mist which remained during our time on the hill.  The mists stretched out beyond Llangollen and across toward the Aran, with occasional wisps meandering up higher stream valleys only to then slowly disappear.

Leaving the muddied track close to a sheep fold we stepped across the Nant Cefn Coch which would no doubt have proved difficult to cross lower down, and followed the remains of an old wall through yellow tinged reed grass, aglow in the light from the low winter sun.  This soon brought us to a sheep track which led toward the summit of our first hill of the day; Moel Darren.

Nearing the head waters of the Nant Cefn Coch

I’d surveyed Moel Darren using a basic levelling staff in May 2004, almost sixteen years later I was back, this time with Aled and an Abney level and a Trimble.  Within a few minutes Aled had pinpointed the summit and the Trimble was set up gathering its allotted data.

As the last datum points were gathered and stored Aled headed toward the connecting bwlch to assess the lay of land, and once the equipment was closed down and packed away I stumbled my way through the tussocks to join him.  The critical point of the bwlch was not hard to determine and soon the Trimble was quietly beeping away gathering data.

Ahead of us lay the southern bulk of Foel Goch which today looked inviting.  After a steady plod uphill I joined Aled at its summit and again the Trimble was set up atop my rucksack, the measurement offset between its internal antenna and the ground at its base noted and once the 0.1m accuracy level attained before data should be logged, I set it to gather data and joined Aled who was talking to a man who had just joined us at the summit, he estimated that he’d been to the top of Foel Goch 150 times and the conditions today must have been one of the best!

Admiring the view on the way up Foel Goch

Gathering data at the summit of Foel Goch

The next point to survey was the connecting bwlch to Orddu, another hill whose drop I had surveyed with my old basic levelling staff.  This hill was the first I had surveyed for Dewey status back in March 2000, repeating the survey the following month.  I had lots of fun with this old staff, but the Trimble gives by far more accurate results and is much simpler to operate, albeit just a wee bit more expensive to purchase.

Orddu (SH 963 423)

After packing the Trimble away I slowly plodded up toward the summit of Orddu, where Aled was patiently waiting standing on the high point.  As the fifth data set of the day was gathered I looked out to the sea of mist in the valley below and across to the high Aran majestically floating above it all.

The distant high Aran

Gathering data at the summit of Orddu

The view east from the summit of Orddu

It was now decision time, should we visit the summit above the Bryn Bras ridge and combine this with Pen y Cerrig Serth, or just visit the latter.  My pace was slow and I wondered if we could visit and survey these hills before nightfall overtook us.  We assessed the time for all required surveys and the time remaining before darkness.  Deciding to visit the two hills we headed down to the next connecting bwlch to the south-east.

The bwlch of the next hill consisted of a relatively flat bedded bog with copious amounts of heather; at least today it gave a stunning backdrop of a mist enshrouded valley.  As I packed the Trimble away after the bwlch survey Aled was already waiting at the summit, it proved a slow plod to get to the top, but once the summit had been surveyed and we back-tracked to the bwlch for the continuation toward Pen y Cerrig Serth, we knew that we had sufficient time for all remaining surveys and to get down off the hill before darkness overtook us.

The main Berwyn ridge floating above the mist

Gathering data at the summit of Pt. 534.1m

Pen y Cerrig Serth

Thankfully an old path led us toward the connecting bwlch with Pen y Cerrig Serth, with it contouring its way around the eastern flank of Orddu.  The bwlch proved to be another relatively flat morass of tussocked heather and bog.  We debated its position and assessed the land from either side of an intervening fence.  Having decided on an appropriate position the Trimble was set up and gathered allotted data whilst Aled headed for the summit and I sat against the fence in the now chilled sunshine.

Gathering data at the bwlch of Pen y Cerrig Serth

Pen y Cerrig Serth was another hill I’d surveyed with my old basic levelling staff in May 2004 and I was now thankful to reach its summit, which was bathed in beauteous light as only late afternoon winter days can give.  The Trimble was soon placed at the summit gathering its ninth and last data set of the day.  Once closed down and packed away I joined Aled who was waiting beside a fence junction for our descent.

Gathering data at the summit of Pen y Cerrig Serth

It proved a good route down with succulent colour illuminating Pen y Cerrig Serth as streaks of delicate cloud massed like waves enhancing the late afternoon light.  A path of sorts led us down toward Hafotty Isaf where an old railway sleeper acted as a footbridge taking us toward our downward route.

Descending from the summit of Pen y Cerrig Serth

Late winter afternoon colour

The silhouetted Aran
Arriving at the awaiting car and taking my wellies off was blissful; all that remained was the short journey to Aled’s car.  On the way I stopped and marvelled at the sky, which was ablaze in patterned reds and scarlets as cloud waves luxuriated in colour.  The high Aran gave a silhouetted backdrop as dusk slowly descended with this last massed streak of colour before darkness overtook the land.

Survey Result:

Moel Darren 
Summit Height:  510.0m (converted to OSGM15)

Summit Grid Reference:  SH 95221 41372

Bwlch Height:  495.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 95185 41686

Drop:  14.6m (Uchaf reclassified to 500m Sub-Uchaf)

Dominance:  2.86%

Foel Goch 
Summit Height:  611.0m (converted to OSGM15)

Summit Grid Reference:  SH 95379 42292

Bwlch Height:  336.8m (converted to OSGM15, from subsequent Trimble GeoXH 6000 survey)

Bwlch Grid Reference:  SH 91716 43965

Drop:  274.2m

Dominance:  44.88%

Summit Height:  553.8m (converted to OSGM15)

Summit Grid Reference:  SH 96338 42337

Bwlch Height:  520.5m (converted to OSGM15)

Bwlch Grid Reference:  SH 95886 42428

Drop:  33.3m (Dewey and 500m Twmpau status confirmed)

Dominance:  6.01%

Pt. 534.1m
Summit Height:  534.1m (converted to OSGM15)

Summit Grid Reference:  SH 96602 41939

Bwlch Height:  513.5m (converted to OSGM15)

Bwlch Grid Reference:  SH 96429 42179

Drop:  20.6m (500m Sub-Twmpau status confirmed)

Dominance:  3.86%

Pen y Cerrig Serth 

Summit Height:  520.7m (converted to OSGM15)

Summit Grid Reference:  SH 97054 42933

Bwlch Height:  499.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 96817 42721

Drop:  20.8m (500m Sub-Twmpau addition)

Dominance:  4.00%

For details on the bwlch survey of Foel Goch

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