Mapping Mountains – Trimble Surveys – Pumlumon

30.03.21  Mynydd Tŷ’r Sais (SH 855 004), Briwnant (SH 847 017), Ffridd Pen y Graig (SH 842 018) and Pen yr Allt (SH 842 025) 

Ffridd Pen y Graig (SH 842 018)

The first true warmth of spring was savoured today, which for me is unusual as I am prone to suffer in the heat.  But winter can be oppressive with shortened day light hours and grey overbearing sky’s that during this year were only compounded by Covid restrictions, therefore the new growth and today’s warmth brought on by seasonal change highlighted a new beginning which conveniently matches many Covid restrictions recently being lifted. 

Today I wanted to visit four hills, with the first; Mynydd Tŷ’r Sais being a candidate for reclassification to P30 status.  These hills can be easily combined from the small community of Darowen and would for me, complete this block of land, as I had visited and surveyed adjacent hills to the west and also the east in recent years. 

I was parked and walking down a steep paved lane leading to Tan-llan by just past 8.30am.  I had a thin one skin jacket and gloves on as although the forecast of warn weather would quickly materialise the early morning still had a lingering chill. 

Chilled morning

Beyond Tan-llan the narrow paved lane deteriorated to a rough track, this fords a stream at its low point.  The adjacent fields were dew soaked with the sound of bleating lambs echoing through the morning mist.  The latter cloaked the hills but soon their tops emerged with just the last vestiges of mist clinging to their sides.  It was a beautiful morning to be out in this part of the world. 

Low mist still clung to the valley

I wanted to access Mynydd Tŷ’r Sais from the west; this involved the use of a private track.  Close to Rhos-Drynog farm I stood back as a number of sheep were being ushered from an adjacent field across the track to the opposing field.  The farmer who was on a quad bike pulled up and we chatted for a number of minutes.  He pointed out Maen Llwyd; an impressive standing stone that I had been close to lower on the track.  We conversed about the hills and he gave me names for a number of them.  He kindly let me continue up the track and I left after thanking him. 

Rheinallt Wigley

By now it was warming up and I had already dispensed with my thin gloves and soon afterward my jacket was packed away.  It would remain warm for the rest of the day, with later reports that Kew Gardens had recorded the warmest March day in Britain since 1968. 

The track leading to the first hill of the day

I followed the track ever upward to sheep pens and soon left it to strike up over grazing fields to a small conifer plantation, beyond which I followed the ridge fence heading up toward the top of the hill.  This hill is given a 359m spot height on contemporary Ordnance Survey 1:25,000 Explorer maps, but the summit analysis programme produced by Joe Nuttall and investigative work conducted by Ronnie Bowron indicated that its true summit is higher, and that in all likelihood its drop value exceeds 30m. 

The lower 359m spot heighted top is on the right and the higher 362.2m summit is on the left

I love surveying such hills and today the conditions were perfect with hardly a breath of breeze and with warmth this meant I could take my time and survey every point deemed necessary.  Surprisingly this consisted of only one on the summit area, with the highest point easily identified.  However its bwlch had a number of options for its critical point and I surveyed three in all, with each having undulations between.  This took just over an hour to complete, but will give confidence toward this hill’s drop value and therefore status. 

Gathering data at the summit of Mynydd Tŷ'r Sais with the lower 359m spot heighted top in the background

Leaving the bwlch I descended toward Lluest-cethingrych; an abandoned remnant when families and shepherds would use these hills from higher habitations.  The ruined house now looked down on a green track with its mature trees still shielding it from the worst of the weather.  Such places dot the upland landscape and all could tell a story of times long gone and forgotten. 

The old ruin of Lluest-cethingrych

The green track continued gravelled on the opposing banks of the Nant Tŷ’r Sais, this contoured around a hillside to the narrow paved lane east of Darowen.  On the way I stopped and smiled and took a few photos of an Argos container which shone bright sky blue in the morning’s sunshine.  It looked completely out of place amongst such beautiful and gentle countryside, but for me, it summed up one aspect why I love Wales so mush.  This country is not forensically presented where everything looks twee without a blade of grass out of place, it is lived in and all the better for such oddities. 

Looking completely out of place but still rather appealing

Ahead lay the connecting bwlch of Ffridd Pen y Graig, I’d investigated its surrounds via a Google car on my laptop and the point to survey looked as if it was submerged under a thin strip of trees that followed the valley bottom. 

Looking down on the bwlch of Ffridd Pen y Graig

I accessed the low field where the bwlch was placed via a gate and circumvented as much of the reed grass that grew near its flattest part as I could.  It was relatively easy to pinpoint the approximate position of the bwlch which was placed in a depression beside a fence and under a number of trees.  I imagined I’d be waiting for an age for the Trimble to attain the 0.1m accuracy level before data should be logged, but having set the equipment up I checked it after a couple of minutes and there was the magic number, I quickly pressed ‘Log’ and scampered away to sit on a mossed bow and waited for the allotted data to be gathered and stored. 

Gathering data at the bwlch of Ffridd Pen y Graig

After packing the Trimble away I clambered over the near fence and walked across a field before using another fence to get on to a track on the edge of forestry.  This gave me access to a steep field where the warmth battered me as I ever so slowly crept uphill, resting frequently, but height was gained and I eventually emerged beside a gate which gave access to the upper part of the hill. 

Mynydd Tŷ'r Sais (SH 855 004)

Gates and sheep paths led me up toward the summit of Briwnant; my second hill of the day.  I was glad to reach its high point.  The sky was blue and skylarks sang and the warmth gave an early summer feeling. 

Briwnant (SH 847 017)

I spent a number of minutes assessing the summit area of Briwnant and once I’d chosen the spot for Trimble placement the equipment was soon set up gathering data.  During data collection I sat and looked down on a herd of cows as they slowly wandered down the valley, conveniently away from where the next survey was going to take place. 

Gathering data at the summit of Briwnant

The next survey was at the connecting bwlch between Briwnant and Ffridd Pen y Graig and was positioned close to a fence.  I used one of the fence posts to give the Trimble a semblance of elevation and gathered the allotted data.  This process took an inordinate amount of time as I set the equipment up and closed it down on a number of occasions as the 0.1m accuracy level was not attained.  However, perseverance can be beneficial and having re-positioned it the magic number appeared and I sat below it as it quietly beeped away gathering its all-important data.  This at least gave me a well-earned rest and by the time I set off up the steepening field in front I felt almost brand new! 

Gathering data at the summit of Ffridd Pen y Graig

The summit of Ffridd Pen y Graig consists of three potential highest points.  I assessed these from a number of directions and having decided which I thought the highest set the Trimble up with its internal antenna aligned with the highest bit of mossed rock.  Before pressing ‘Log’ I stood and watched the whole upper part of the summit delicately move in motion with the breeze as it was covered in the most delightful spider webs and these ebbed in the breeze almost as if alive.  The little spiders also scampered across the yellowed outer shell of the Trimble as it gathered summit data. 

Gathering data at the bwlch of Pen yr Allt

I was nearing the end of the walk and just had one bwlch and summit to survey; this was for Pen yr Allt, a sub hill which connects to Ffridd Pen y Graig.  I spent a number of minutes assessing its connecting bwlch before choosing the spot for Trimble placement.  The summit of Pen yr Allt is covered by LIDAR, the only one to be so of the points I had surveyed during the day, because of this its position was easy to identify, but just to be on the safe side I took a second data set from a nearby small grassed hummock. 

The way back to Darowen

Once the Trimble had gathered its twelfth data set of the day I closed it down, packed it away and retraced by steps over the connecting bwlch to a public footpath and stiles as they strode out across late afternoon sun drenched fields toward the sleepy surrounds of Darowen.  It had been another good day on the hill.

 

Survey Result: 

 

Mynydd Tŷ’r Sais

Summit Height:  362.2m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SH 85514 00483 (summit relocation confirmed) 

Bwlch Height:  329.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 86220 00690

Drop:  32.2m (Sub-Trichant reclassified to Trichant)

Dominance: 8.90%

 

 

Briwnant

Summit Height:  284.2m (converted to OSGM15)

Summit Grid Reference:  SH 84709 01728 

Bwlch Height:  248.7m (converted to OSGM15)

Bwlch Grid Reference:  SH 84556 01935

Drop:  35.5m

Dominance: 12.49%

 

 

Ffridd Pen y Graig

Summit Height:  296.8m (converted to OSGM15)

Summit Grid Reference:  SH 84242 01824 

Bwlch Height:  189.5m (converted to OSGM15)

Bwlch Grid Reference:  SH 85325 01537

Drop:  107.3m

Dominance: 36.15%

 

 

Pen yr Allt

Summit Height:  266.6m (converted to OSGM15)

Summit Grid Reference:  SH 84232 02576 

Bwlch Height:  241.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 84202 02341

Drop:  24.7m (200m Sub-Twmpau addition)

Dominance: 9.26%

 

 

 

For further details please consult the Trimble Survey Spreadsheet