Mapping Mountains – Trimble Surveys – Y Berwyn

09.08.20  Y Garn (SJ 080 272), Y Clogydd (SJ 065 283), Moel Crynddyn (SJ 059 278), Craig Rhiwarth (SJ 058 271) and Craig Rhiwarth (SJ 054 271)  

Y Clogydd (SJ 065 283)

Today’s walk was first suggested by Aled a year or so ago and takes in hills above Llangynog, with a number of surveying objectives including putting an accurate height to Y Garn; a hill surveyed for summit position by John Barnard, Eric Hardman and myself a number of years ago, and comparing the result of my basic levelling survey for Moel Crynddyn against that produced by the Trimble GeoXH 6000.

The forecast was for warming conditions as the day progressed, and we met in the car park in the centre of the small community of Llangynog at 7.30am.  Leaving one car here for our descent we then headed through Penybontfawr and connected with minor roads and lanes above Cefn Coch to the end of the paved section of road at over 370m.

From here a fence line led uphill all the way to the summit of our first hill of the day; Y Garn.  Leaving the car we were soon in murk which covered all the higher hills east of Y Bala.  A cooling breeze gently swept across the land as we slowly ascended chatting on the way and taking frequent rests.  Thankfully the forecast heat did not appear until later in the walk and I found the whole ascent to the summit of Y Garn to be a pleasure.

The high point of our first hill is a grassed area beside the ridge fence westward from the triangulation pillar that looks down to the eastern lands when visibility is good.  Today it was still clagged in cooling mist with dew soaked grasses wetting our boots.

Gathering data at the summit of Y Garn

This was a hill I’d wanted to survey with the Trimble for a number of years and it was good to be here with Aled.  The equipment was soon set-up beeping away collecting its individual data points, by the time we’d continued our chat the Trimble had gathered and stored eleven minutes of data.  Switching it off, we continued in to the murk on a compass bearing heading north-westward to the connecting bwlch.

The bwlch proved expansive with copious amounts of tussock grass, with a few vehicle tracks on the moor crossing this way and that and the customary boggy ground pre-dominating.  I’d noted two potential positions, one where the 524m map spot height appears and another where interpolation places the critical bwlch.  Both were Trimbled.

Gathering data at the bwlch of Y Garn

I hadn’t been on these hills in a number of years and although the higher tops and their connecting ridge didn’t give us any extensive view, it was a pleasure being here wandering through rough Berwyn territory with wafts of mist, breeze blown across the land.

The next point to survey was the summit of Y Clogydd which is one of the bumps leading from Post Gwyn to Y Garn.  Aled led us to the summit and after it was surveyed, then down to its connecting bwlch.  One data set from the summit and two from the area of its bwlch were taken.

As the second bwlch data set was being gathered the mist slowly rose giving the outline of a small conifer plantation to our north-west, and peering skyward we kept thinking that blue sky was only just above.  The clear blueness of summer never materialised, but loosing height from the bwlch and finding the track leading toward the bwlch connecting with Moel Crynddyn, we were now under the mist and watching as the summit of Craig Rhiwarth slowly appeared in front of us, with the summit of Y Garn soon to be on view.

I’d surveyed Moel Crynddyn for drop in October 2007; this was toward the end of using my old basic levelling staff.  The drop was measured to be 15.0m, and both Aled and I doubted whether this hill would survive in our Welsh Highlands – Uchafion Cymru list after the Trimble data is processed.

Moel Crynddyn (SJ 059 278)

Whatever the result for Moel Crynddyn, it will not detract from the hill itself, as it is finely placed overlooking a great sweeping drop down in to Cwm Glan-hafon.  Having decided on the point to survey for its bwlch the Trimble was set up in reed grass gathering its data.

Gathering data at the bwlch of Moel Crynddyn

A vehicle track on the grassed slopes of Moel Crynddyn led from the bwlch toward its summit, which is positioned over the steep drop down to the cwm below.  As the Trimble gathered its summit data we sat looking down in to the upper reaches of the cwm as the light browned outline of a Kestrel glided across the sky.

Gathering data at the summit of Moel Crynddyn

Leaving the summit we headed down as the muggy conditions started to take their toll.  The next bwlch which connects to the higher of the Craig Rhiwarth summits had been LIDARed by Aled and is placed in forestry.  This would not be Trimbled, and we continued on a path beside a fence up toward the hill’s eastern top which is positioned on a small outcrop of rock.

Y Garn (SJ 080 272)

Heading toward the two Craig Rhiwarth tops

I now needed to rest and was thankful to sit down as the Trimble gathered its ninth data set of the day.  Its connecting bwlch had also been LIDARed by Aled, so we bi-passed this on our way to the last summit of the day; the higher of the two Craig Rhiwarth tops.

Gathering data at the lower of the two Craig Rhiwarth tops

The upper part of this hill contains the remains of an ancient Iron Age hillfort.  The structure is enclosed by a wall which is now no more than a line of tumbled rock.  According to Coflein a series of original entrances still exist and we passed through one on our descent.  Within the walled enclosure are about 170 circular structures measuring 4 – 12 metres in diameter with a number of rectangular buildings also present.  The whole site is impressive.

Gathering data at the higher of the two Craig Rhiwarth tops

The high point of the hill is positioned a few metres from a proudly constructed cairn and soon the Trimble was gathering its allotted data.  It was good to be here, high above the valley, on the summit of the last hill of the day.  Views were not expansive as the grey murk still predominated, but outlined hills and their connecting ridges were on show, giving a fulfilling end to the high part of the day’s walk.

Heading down from Craig Rhiwarth

From the summit it was a steep descent firstly back to the hill’s bwlch passing through one of the ancient entrances to the Iron Age hillfort, and then down following paths through fern in to the cwm below, before a path leading through an old oak plantation brought us on to a paved lane leading back to Llangynog.

Through the fern to the cwm below

The walk had taken over nine hours and five summits had been surveyed and in all ten data sets taken.  The distance wasn’t great, with mist and murk and high humidity as well as some rough underfoot conditions, but we had achieved everything we wanted. 

Survey Result:

Y Garn 

 

Summit Height:  607.8m (converted to OSGM15)

Summit Grid Reference:  SJ 08060 27282

Bwlch Height:  524.7m (converted to OSGM15)

Bwlch Grid Reference:  SJ 07175 27787

Drop:  83.1m

Dominance:  13.68%

Y Clogydd 

 

Summit Height:  595.6m (converted to OSGM15)

Summit Grid Reference:  SJ 06565 28373

Bwlch Height:  583.5m (converted to OSGM15)

Bwlch Grid Reference:  SJ 06425 28472

Drop:  12.2m

Dominance:  2.04%

Moel Crynddyn

  

Summit Height:  504.7m (converted to OSGM15)

Summit Grid Reference:  SJ 05942 27845

Bwlch Height:  489.7m (converted to OSGM15)

Bwlch Grid Reference:  SJ 05857 27931

Drop:  15.0m (Uchaf status retained)

Dominance:  2.97%

Craig Rhiwarth

  

Summit Height:  527.7m (converted to OSGM15)

Summit Grid Reference:  SJ 05849 27105

Bwlch Height:  513.9m (LIDAR)

Bwlch Grid Reference:  SJ 05623 27165 (LIDAR)

Drop:  13.8m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  2.62% (Trimble GeoXH 6000 summit and LIDAR bwlch)

Craig Rhiwarth 

 

Summit Height:  530.9m (converted to OSGM15)

Summit Grid Reference:  SJ 05484 27113

Bwlch Height:  462.6m (LIDAR)

Bwlch Grid Reference:  SJ 05568 27592 (LIDAR)

Drop:  68.3m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  12.87% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Arenig Fach

07.02.20  Arenig Fach (SH 820 415), only bwlch surveyed

Arenig Fach stands as a great lump of wild rock and wind-blown heathered moor.  No ascent is particularly easy, although the hill does afford solitude and expansive views.  I’d surveyed its summit in November 2016 during Steve Smith’s celebratory completion of the Nuttalls.  On that day the summit was bleakly chilled and wet.  Today for its bwlch survey the weather forecast gave settled conditions, albeit with the breeze increasing in strength during the early afternoon, as it was just before 10.00am when I pulled up and parked beside the A4212 this did not concern me.

Arenig Fach (SH 820 415)

Prior to my visit the position and height of this bwlch had been determined by LIDAR analysis conducted by Aled Williams, and it was the ten figure LIDAR grid reference that I was now reliant upon for Trimble placement.

I had inspected the land beside the A road in a Google car on my laptop and the southern roadside verge had intermittent small conifer trees on it, I hoped that its critical point would not prove to be either under or beside one of these as this may interrupt signals received by the Trimble.

The bwlch of Arenig Fach

It was only a short walk on the road to where the bwlch of Arenig Fach is situated and with the Trimble used as a hand-held device I quickly zeroed in to its critical point, which was beside one lone conifer tree.  The road at this point had been slightly raised above its moorland surrounds and if not for LIDAR, the positioning of the critical point of this bwlch may have taken an inordinate amount of time to assess.

The Trimble was soon positioned on top of my rucksack, which acts as an improvised tripod, giving it elevation above its immediate surrounds, and once the 0.1m accuracy level was attained before data should be logged, I pressed ‘Log’ and retreated across the other side of the road and waited patiently whilst six minutes of data were gathered and stored.

The Trimble set-up position at the bwlch of Arenig Fach

During this time I counted the cars that passed, three headed west toward Trawsfynydd whilst eight headed east toward Y Bala.  It wasn’t a particularly busy stretch of road on this day for this part of Wales.

Once data were gathered and stored I pressed ‘Done’, closed the equipment down, packed it away and walked the short distance back to my car and headed toward the third of four planned bwlch surveys for the day; the next survey being the bwch that connects to Carnedd Iago (SH 782 406).

Survey Result:

Arenig Fach

Summit Height:  688.9m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SH 82020 41583 (from previous Trimble GeoXH 6000 survey)

Bwlch Height:  390.6m (converted to OSGM15)

Bwlch Grid Reference:  SH 78593 38716

Drop:  298.3m

Dominance:  43.30%

  

For details on the summit survey of this hill

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Moelwyn Mawr

23.03.19  Cnicht (SH 645 466) and Pt. 690.2m (SH 647 468)

Cnicht (SH 645 466)

Cnicht is rightly considered one of the iconic mountains of Wales; it rises above the small community of Croesor in a steep pyramidal and eloquent shape.  However, this view hides its extended north-eastern ridge that descends in grassed slopes toward the tranquil surrounds of Llyn yr Adar.

Many years ago it seemed as if I almost lived on this hill having visited it already on a number of occasions, as when its north-easterly top was promoted to Nuttall status in spring 1997 it meant many more visits to its ever appealing summit to bring my Welsh Nuttall total up-to-date.  However, those times are now long gone, and it has been nine years since I last visited.

Four of us set out from the car park in Croesor and with a forecast of dry conditions with hazy sunshine the day ahead was one to enjoy.  Two of our party; Abi and Ann-Marie had Mountain Leadership qualification so any semblance of navigational skill that I may possess was happily put to one side for the day.

Heading toward the hill

As height was gained the profile of Cnicht was forever in view, with tiny figures of people on its upper slopes and summit adding perspective to the scene.  We had a number of stops enjoying the intermittent sunshine and early spring warmth, during which I took the opportunity to set off ahead slowly plodding my way up the ridge knowing that Jude, Abi and Ann-Marie would catch me up before the summit, and so they did, just before the last steep section.

The summit of Cnicht consists of a number of up thrust small rocks with the central of three our candidate for the highest and within a few minutes of arriving on the summit the Trimble was aligned with the highest bit of rock and quietly beeping away collecting its individual datum points.

Gathering data at the summit of Cnicht

During data collection the girls sat just below the summit with Ann-Marie seemingly seated on the edge of the world from the vantage point I stood at, once the last of the allotted data were gathered and stored I closed the equipment down and we headed on the continuation of the ridge to the bwlch between the main and subsidiary peak of Cnicht.

Ann-Marie perched on the edge of the world

Ann-Marie, Jude and Abi at the summit of Cnicht

This bwlch is easily identified and the Trimble was soon positioned on top of my rucksack and the offset between its internal antenna and the ground below measured and noted.  It remained there for six minutes gathering its all-important data.

The Trimble set-up position at the bwlch of the subsidiary peak of Cnicht

Moelwyn Mawr

Gathering data at the bwlch for the subsidiary peak of Cnicht

The ridge path continues north-eastward and bisects at the base of the next top, with one branch bi-passing the uphill section, whilst the other climbs through rock toward the summit of this next hill.

Jude heading toward the summit of the second hill of the day

This hill has an untidy flattish cairn signifying its summit, these few rocks were soon removed and with the ground below now exposed we could determine its very highest point, which proved to be about 0.75 of a metre from where the untidy cairn had obliterated and messed an otherwise natural scene.

Again the Trimble was placed with its internal antenna aligned with the summit and it remained in place for the next eleven minutes gathering data as the four of us sat and chatted.  During this a few people walked the ridge from Cnicht and none visited the point where the Trimble beeped away gathering its third data set of the day.

Gathering data at the subsidiary peak of Cnicht

The last survey of the day was the critical bwlch of Cnicht which is placed overlooking Llyn yr Adar.  The broad north-eastern ridge descending from Cnicht soon turns in to moor grass and its path leads direct down to this bwlch.

Within a few minutes the Trimble was placed on top of my rucksack and it was gathering its last data set of the day.  As I stood away from the equipment Canada geese skimmed across the near lake giving a backdrop with their wagh-onk call piecing an otherwise quiet scene.

Gathering data at the critical bwlch of Cnicht

All that remained was the walk back via a boggy path leading down to the abandoned workings of the Rhosydd Quarry and the continuation below the Croesor Quarry to the valley below.  Once back at the car and changed we headed south toward Cross Foxes where Ann-Marie’s husband; Mark joined us for a good meal before heading home, a great way to end the day. 

        

Survey Result:

Cnicht

Summit Height:  690.7m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SH 64545 46613

Bwlch Height:  585.7m (converted to OSGM15)

Bwlch Grid Reference:  SH 65589 47707

Drop:  105.0m

Dominance:  15.20%

Pt. 690.2m

Summit Height:  690.2m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SH 64799 46864

Bwlch Height:  670.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 64681 46742

Drop:  19.3m

Dominance:  2.79%

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Carnedd Llywelyn

31.08.18  Foel Lwyd (SH 720 723) and Tal y Fan (SH 729 726)  

Tal y Fan (SH 729 726)

Today I hoped to meet Matthew Myerscough and Michael Murray as they reached the summit of Tal y Fan, the last of 190 Welsh Nuttall summits on their continuous coast to coast walk over these hills that had taken 34 days to complete.  For more details please see their Dragon’s Back Challenge website.

I’d tried to meet Matthew and Michael 15 days ago, but heavy overnight rain meant that instead of pushing on through a part of the Berwyn, whose hills I was surveying, they had taken a day off to re-group.

To complicate matters I had arranged to meet Janet Ruth Davies; a research photographer, in Capel Curig at 4.00pm, and therefore I needed to leave the summit of Tal y Fan by 2.30pm, would Matthew and Michael be on this final summit by then, all I could do was reach the summit and wait.

As I drove up the high road toward Bwlch y Ddeufaen that heads in to the northern Carneddau, the sky shone blue, a radiant colour at this time in the morning.  The route I had planned was not long, as it only took in Foel Lwyd and Tal y Fan, but I wanted to take data from each bwlch and summit to compare against that taken by John, Graham and myself with the Leica GS15 in May 2013 when we surveyed the summit of Tal y Fan, and the following day the summit of Foel Lwyd, and by Alan Dawson who in June 2017 surveyed each summit and bwlch with his Leica RX1250.

I was walking up the continuation of the narrow road to the south of Tal y Fan by just after 10.00am and hoped to complete the surveys by 1.30pm, which would give me an hour on the summit of Tal y Fan waiting for Matthew and Michael.

A car and camper van sat resting in the early morning sun in the car park at the end of the narrow road, their occupants either on the hill or still asleep, from here a track heads toward the bwlch which is dominated by two standing stones, these sentinels have stood guard for many millennia, and although the construction of pylons that cross this bwlch is an imposition that nowadays would probably not be granted planning permission, the monoliths still stand solemnly on the passage of time.  This morning they were bathed in sunshine with yellowed gorse and purpled heather as backdrop.

Looking toward Bwlch Ddeufaen

The southerly monolith

The northerly monolith

The bwlch of Tal y Fan is positioned close to these two ancient monoliths and Alan had previously surveyed it with the Leica RX1250, I wanted to gather data from his bwlch position and also from a second position approximately 100 metres distant that OS Maps indicate is a contender for the critical bwlch.

The first position was beside a bog and realising I had plenty of time until my hoped for rendezvous I decided to gather ten minutes of data.  During this a number of people passed mainly heading over the bwlch, with one person heading south-west up toward Carnedd y Ddelw.  Once data were gathered and stored I wandered through the heather toward the second position to be surveyed, and another ten minute data set was duly gathered.

Gathering data at the critical bwlch of Tal y Fan

Leaving the bwlch I made steady progress up beside the wall leading toward the summit area of Foel Lwyd, the last time I’d visited this hill was in May 2013 with John Barnard and Graham Jackson the day after filming with BBC Breakfast on the summit of Tal y Fan, and although we worked extremely well as a team on and off the hill, I can remember disagreement in the ranks even then, on this particular day the conversation was partly based on what hills we should concentrate on surveying, as although I’d invested a great amount of time and effort in to the team as well as a substantial amount of money, the hills I either wanted to survey or suggested to survey were usually dispensed with and others favoured instead.

The summit of Foel Lwyd is situated on the southern side of a stone wall and this had to be negotiated to get to it.  Stone wall and barb wired fence climbing are two intrinsic parts of hill walking that seem to be getting more difficult with the passage of time, and this one proved no different as I sat astride the wall wondering what my next move should be!

Eventually I slithered down the wall and made my way through heather toward the small rock where the summit of Foel Lwyd is positioned.  During the morning a brisk breeze blew and so I positioned the Trimble atop my rucksack which was nestled on its back, and aligned the internal antenna of the Trimble with the high point of the hill and noted the measurement offset between it and the ground below, before pressing ‘Log’ and waiting for ten minutes of data to be gathered and stored.

Gathering data at the summit of Foel Lwyd

By now I was scouring adjacent hillsides in the faint hope of spotting Matthew and Michael, unsurprisingly the distance involved meant that even if they were walking on one of the ridges I would probably not pick them out.

Away to the north the gauged out husk of Penmaen Mawr, which in its time was an impressive hill with over 100m of prominence, and due to quarrying is now two separate P30s, stood out with Ynys Seiriol (Puffin Island) behind, with its brambled summit being a test of mind and body to reach.

The two summits of Penmaen Mawr with Ynys Seiriol in the background

Ahead the rock strewn upper slopes of Tal y Fan rose domed like out of heathered surrounds, with its trig pillar pointing skyward.  My next survey was the connecting bwlch between these two hills, this is the critical bwlch of Foel Lwyd and is placed beside the stone wall.  I found placing the Trimble on top of it to be the easiest course of action, and another data set was gathered.

Tal y Fan from Foel Lwyd

Gathering data at the bwlch area of Foel Lwyd

A path leads from the bwlch through the rocky upper slopes of Tal y Fan to the ladder style close to its trig pillar and large embedded rock which is its high point.  When I arrived there was a buzz of a radio receiver and Dave; its operator, was busy connecting with a multitude of people, we only talked briefly as I wanted solitude and a sit in the brisk sun drenched breeze.  But before doing this I wanted to gather the last data set of the walk from the high point of Tal y Fan.

Gathering data at the summit of Tal y Fan

As the Trimble gathered this last data set I sat on a rock beside the stone wall and again scoured adjacent hillsides for any sign of Matthew and Michael.  Once the Trimble had gathered and stored its allotted data I closed it down, packed it away and had a bite to eat and sat waiting.  After an hour I wondered if Matthew and Michael had already been over the summit and were now heading down to the completion of their continuous walk at the coast to the north.  By 2.15pm there was no sign of them and so I gathered up the bottle of celebratory bubbly I’d brought and which was nestled in my rucksack, taped the congratulatory note I had written to its side and positioned it at the base of the trig pillar, hoping that if they were still on their way toward Tal y Fan they would at least find it.  At 2.30pm I started my descent.

The bottle of bubbly left (and found) for Matthew and Michael

Nestled out of the breeze awaiting a continuous Welsh Nuttall completion

It is only a short distance from the summit of Tal y Fan following the path down its slopes to a ladder stile close to its connecting bwlch and then onward to the narrow lane where my car was parked.  During my descent I continued to look out toward Pen y Castell which I presumed would be Matthew and Michael’s penultimate hill and wondered if they would head in a direct route from this hill to Tal y Fan, they did not, as although I missed meeting them, they found the bottle of bubbly having arrived on the summit of Tal y Fan at 4.30pm after doubling back to Drum from Pen y Castell.  It was a shame I had missed them, and their achievement in completing a continuous traverse of the Welsh Nuttalls and in the process raising £5,000 for the Llanberis and Aberglaslyn Mountain Rescue Teams is to be applauded.

Postscript

Since visiting these hills full LIDAR coverage is now available.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height and positional data that is now freely available for England and Wales.  Consequently the numerical details for these hills have been analysed using this technique, resulting in the LIDAR height and position being prioritised for the bwlch of Foel Lwyd.

  

Survey Result:

Foel Lwyd 

Summit Height:  600.2m (converted to OSGM15, from previous Leica GS15 survey) (significant height revision)

Summit Grid Reference:  SH 72036 72323 (from previous Leica GS15 survey)

Bwlch Height:  547.2m (LIDAR)

Bwlch Grid Reference:  SH 72647 72325 (LIDAR)

Drop:  53.0m (Leica GS15 summit and LIDAR bwlch)

Dominance:  8.83% (Leica GS15 summit and LIDAR bwlch)

Tal y Fan

Summit Height:  610.0m (converted to OSGM15, average of two previous surveys by a Leica GS15 and Leica RX1250)

Summit Grid Reference:  SH 72936 72648 (from previous Leica RX1250 survey)

Bwlch Height:  420.5m (converted to OSGM15, from previous Leica RX1250 survey)

Bwlch Grid Reference:  SH 71446 71856 (from previous Leica RX1250 survey)

Drop:  189.5m (from previous Leica RX1250 survey)

Dominance:  31.07% (from previous Leica RX1250 survey)

For further details please consult the Trimble Survey Spreadsheet