Mapping Mountains – Trimble Surveys – Y Berwyn

19.10.16  Foel y Groes (SH 918 235), Moel y Cerrig Duon (SH 923 241), Pt. 605.7m (SH 918 257), Cefn Coch (SH 923 266), Foel y Geifr (SH 937 275), Trum y Gwragedd (SH 941 284, bwlch only) and Foel Cedig (SH 981 283, bwlch only [SH 944 273])

Moel y Cerrig Duon (SH 923 241)

Parts of the Berwyn have a reputation as being pathless heather bound wonders of torture, whilst other parts are just heather bound.  Today we encountered the former as tussocks; moor grass and heather stretched away in a sea of wilderness which is probably seldom visited except for the occasional sheep gatherer and peak bagger.

The land we visited stretches between Bwlch y Groes and Cwm Hirnant and consists of a number of 500m and 600m hills, all are bulbous affairs of heather and moor where solitude and pathless wandering is the order of the day.

I was out with Alan and we planned to survey everything we could, I met him at the high point of the road that heads from the northern extremity of Llyn Efyrnwy (Lake Vyrnwy) to Y Bala, leaving one car here we continued to Bwlch y Groes, which was where my interest in mountain surveying first cast its hold over me many a year ago when I met Dewi Jones in the car park and he told me that the Nuttall’s had missed a hill from their listing of Welsh mountains, and that he’d surveyed it as having over 15m of drop.  This chance meeting was in the late 1990’s and it led me down a rather unusual but very fulfilling surveying route that was totally unexpected.

As Alan got his autumnal wellies on I positioned the Trimble on top of my rucksack on the edge of the road beside the entrance to the large gravelled and rocky parking area at the top of Bwlch y Groes for the first of what proved to be 14 surveys of the day, this was for the critical bwlch of Moel y Cerrig Duon.

Surveying the critical bwlch of Moel y Cerrig Duon on the edge of the road at Bwlch y Groes

Once data were collected I headed up beside a fence on a narrow path which led toward the summit of Moel y Cerrig Duon, on the way is an Uchaf; Foel Groes, which is also the watershed summit of Wales, as drainage to its south flows into the Afon Dyfi (River Dovey) and Cardigan Bay, whilst drainage to its east flows into the Afon Hafren (River Severn) and the Bristol Channel and drainage to its north flows into the Afon Dyfrdwy (River Dee) and Liverpool Bay.

By the time the Trimble was being set up on the first of two potential summit positions for Foel y Groes, Alan had caught up, and as the second summit position was surveyed he headed off toward the higher summit of Moel y Cerrig Duon leaving me to survey the bwlch between.  This was the start of a system that worked extremely well with Alan heading off to find the next position to survey, leaving me to gather data with the Trimble where he had just surveyed with his Leica; this system remained with us all day.

Gathering data at the summit of Foel y Groes with (L-R) Pt. 605.7m and Moel y Cerrig Duon in the background

To our north and west the sky massed an ominous grey as dark showers broke out on the higher hills, and although the morning’s rain has ceased the thread of showers remained with us for the remainder of the walk.  The overhead conditions gave us an occasional flash of autumnal colour as deep greys of sky were highlighted by flashes of sunlight brightening an otherwise featureless and monochrome scene of mountain and moor.

When I joined Alan on the summit of Moer y Cerrig Duon his Leica was already gathering data beside the summit cairn, and once 22 minutes of data were collected he set off north-west toward a wilderness of open land that is pathless.  After the Trimble had gathered its customary five minutes of data I followed.  The going was uneven and a little tough in places, but just being there was compensation enough as I’d only joined the hills of Moel y Cerrig Duon with Foel y Geifr once before; with my Mother and her second husband; Barry, many a year ago, my memories from that day was of a great swathe of featureless tough moorland heather bashing, and the course of time has not diminished the nature of this land.

Alan beside the Leica RX1250 at the summit of Moel y Cerrig Duon

Gathering data with the Trimble GeoXH 6000 at the summit of Moel y Cerrig Duon

As I slowly stumbled my way down toward Alan who was assessing the lay of land and choosing his spot for Leica placement at the critical bwlch of Foel y Geifr, I looked toward the west as a great mass of blackened cloud enveloped the Arennig, being high when showers are breaking out is somewhat fulfilling as one can watch their course, this can sometimes be disconcerting as showers are prone to head the same way that you are going, and the going can then get rather wet, but on occasion showers can follow the course of valleys and break out either side of the hill you are on, leaving a pleasing feeling of dryness.

Alan beside the Leica RX1250 at the critical bwlch of Foel y Geifr

Foel y Geifr from its critical bwlch

Gathering data with the Trimble GeoXH 6000 at the critical bwlch of Foel y Geifr

As I joined Alan we had a quick chat before his Leica was packed away and my Trimble assembled over the same spot, next stop was the summit of a 606m map heighted Simm and Dewey, I followed Alan up the hill on pathless moor that developed in to a bed of wet peat toward the summit.  Once Alan’s Leica had gathered the customary 20 minutes of data he headed down to the next bwlch and I positioned the Trimble over the same spot and gathered five minutes of data, and then proceeded down to the next bwlch where the Leica was already in position. 

Nearing the summit of Pt. 605.7m (SH 918 257)

Approaching the summit of Pt. 605.7m (SH 918 257)

The Leica RX1250 gathering data at the summit of Pt. 605.7m

Pt. 605.7m (SH 918 257)

The Trimble GeoXH 6000 gathering data at the summit of Pt. 605.7m

The bwlch of the 606m map heighted hill was soon surveyed before I joined Alan on the summit of Cefn Coch which is listed as a Dewey with 31m of drop, this drop value is based on a rudimentary survey I conducted with Rob Woodall on the 28^th October 2001, the result was sent to Michael Dewey who then promoted Cefn Coch to his 500m list of English and Welsh hills.  Since then the Ordnance Survey enlarged mapping on the Geograoh website has become available and shows a 565m spot height at this hill’s bwlch and when coupled with its 594m summit spot height, only gives this hill 29m of map drop, which is insufficient for Dewey qualification, it will be good to finally confirm this hill’s drop value and status, as well as having another comparison of data between my old rudimentary staff and the Trimble.

Once on the summit area Alan set his Leica up on what looked like the high point and suggested that I could Trimble this point and another which looked close in height, each was separated by a small cleft of land, Alan used a Disto to sight from one to the other and confirmed that the further westerly point, where his Leica was now gathering data, was just higher.   The same procedure then took place with the Leica set up first and gathering around 20 minutes of data, and after the Trimble had gathered one set of data at the slightly lower point it was positioned at the same point as the Leica and gathered a further five minutes data set.

Alan's Leica gathering data at the summit of Cefn Coch whilst the Trimble gathers data at what proved to be a lower point

The Trimble GeoXH 6000 gathering data at the summit of Cefn Coch

The bwlch for Cefn Coch proved another wondrous affair of featureless and wild moor where few must wander.  However featureless it proved the critical point was relatively easy to pinpoint and as I joined Alan he had already assembled his Leica RX1250 and it was gathering another 20 minute data set.

Somewhere down there is Alan setting up the Leica RX1250

The Leica RX1250 gathering data at the critical bwlch of Cefn Coch

As the Trimble gathered data at the bwlch, Alan set off toward the summit of Foel y Geifr, the ground looked pathless and we hoped that a semblance of path may exist adjacent to a fence that was later joined and headed toward the last summit of the day.  It was unusual but also pleasing to be left on my own in such landscape, a rather unforgiving place of nothingness except for lingering late afternoon light, a cooling breeze and the chill of solitude and empty moor.

I found the going to the summit of Foel y Geifr to be tough, but thankfully a form of path did exist beside the fence line which strode confidentially up and across the hill.  By the time I reached the summit all I wanted to do was smile and sit down.  This summit has a trig pillar perched at its top with a number of small embedded rocks around its base, one to its north proved the highest and Leica and Trimble data were gathered.

The Leica RX1250 gathering data at the summit of Foel y Geifr

All that remained were two bylchau, the first being that of Trum y Gwragedd and the last being that of Foel Cedig.  The former was Leicaed and Trimbled and the latter just Trimbled.  The first bwlch proved another peat laden affair amongst copious amounts of moor grass and heather, and I joined Alan as the Leica gathered another data set.  As I positioned the Trimble on top of my rucksack to give it elevation above its immediate surrounds the light faded to dusk as the sun cast out from behind cloud beyond Aran Benllyn and the high Aran, giving a dramatic display of late evening light.

The high Aran

The Trimble GeoXH 6000 gathering data at the critical bwlch of Trum y Gwragedd

Last burst of sunlight

Just one survey remained and we stumbled our way down the hill to pinpoint the critical bwlch of Foel Cedig, which proved another heather and bog bound beauty.  From here it was no more than a few minutes plod up to join the high point of the road above Cwm Hirnant where my car awaited, it had been an excellent day on the hill.

 

The last survey of the day, the fourteenth, at the critical bwlch of Foel Cedig

Survey Result:

Foel y Groes

Summit Height:  580.9m (converted to OSGM15)

Summit Grid Reference:  SH 91835 23507

Bwlch Height:  560.5m (converted to OSGM15)

Bwlch Grid Reference:  SH 92028 23791

Drop:  20.4m (500m Sub-Twmpau status confirmed)

Dominance:  3.51% 

 

Moel y Cerrig Duon

Summit Height:  624.3m (converted to OSGM15, Trimble GeoXH 6000) 624.5m (Leica RX1250)

Summit Grid Reference:  SH 92349 24147

Bwlch Height:  545.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 91331 23270

Drop:  79.1m (Leica RX1250 summit and Trimble GeoXH 6000 bwlch)

Dominance:  12.66% (Leica RX1250 summit and Trimble GeoXH 6000 bwlch) 

 

Pt. 605.7m

Summit Height:  605.3m (converted to OSGM15, Trimble GeoXH 6000)  605.7m (Leica RX1250)

Summit Grid Reference:  SH 91857 25730

Bwlch Height:  558.5m (converted to OSGM15, Trimble GeoXH 6000) 558.9m (Leica RX1250)

Bwlch Grid Reference:  SH 92168 26319

Drop:  46.7m (Trimble GeoXH 6000) 46.8m (Leica RX1250)

Dominance:  7.73% (Leica RX1250 summit and bwlch)  

Cefn Coch

Summit Height:  592.6m (converted to OSGM15, Trimble GeoXH 6000) 592.9m (Leica RX1250)

Summit Grid Reference:  SH 92310 26675

Bwlch Height:  561.4m (converted to OSGM15, Trimble GeoXH 6000) 561.7m (Leica RX1250)

Bwlch Grid Reference:  SH 92501 26927

Drop:  31.2m (Trimble GeoXH 6000) 31.3m (Leica RX1250) (Dewey and 500m Twmpau status confirmed)

Dominance:  5.27% (Leica RX1250 summit and bwlch) 

  

Foel y Geifr

Summit Height:  626.0m (converted to OSGM15, Trimble GeoXH 6000) 626.2m (Leica RX1250)

Summit Grid Reference:  SH 93710 27525

Bwlch Height:  514.7m (converted to OSGM15, Trimble GeoXH 6000) 515.0m (Leica RX1250)

Bwlch Grid Reference:  SH 91823 24620

Drop:  111.3m (Trimble GeoXH 6000) 111.2m (Leica RX1250)

Dominance:  17.76% (Leica RX1250 summit and bwlch)

 

Trum y Gwragedd

Summit Height:  611.2m (converted to OSGM15, Leica 530)

Summit Grid Reference:  SH 94114 28400

Bwlch Height:  586.4m (converted to OSGM15, Trimble GeoXH 6000) 586.7m (Leica RX1250)

Bwlch Grid Reference:  SH 93945 27889

Drop:  24.5m (converted to OSGM15, Leica 530 summit and Leica RX1250 bwlch)

Dominance:  4.00% 

 

Foel Cedig

Bwlch Height:  487.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 94458 27324

Drop:  180.0m

Dominance:  26.97%




For details on the summit survey of Foel Cedig and Cyrniau Nod 

For further details please consult the Trimble Survey Spreadsheet