Mapping Mountains – Trimble Surveys – Moelwyn Mawr

21.01.23  Craig Stwlan (SH 667 446), Craig Ysgafn (SH 659 443) and Pt. 524.3m (SH 661 457) 

I drove up the narrow road to Tanygrisiau with trepidation, but thankfully the gritters had kept it in good condition.  In front of me were snow-covered peaks, cliffs and boulders; while behind me were the distant profiles of other snow-clad mountains commanded by the bulk of Arenig Fawr in full winter splendour.  Having parked the car, the rigid frames of winter boots were reluctantly fitted to cold feet, with crampons and a walking axe strapped to my bag in preparation for any icy ground. 

Arenig Fawr (Photo: Aled Williams)

The plan was to visit the series of rocky tops to the east of Llyn Stwlan, before contouring around the lake to Bwlch Stwlan, whereupon a traverse of Craig Ysgafn would take me to the summit of Moelwyn Mawr.  Three surveys were fitted into the walk and the absence of a companion indicated that I would have my hands full when conducting these. 

View ahead from Clogwyn yr Oen (Photo: Aled Williams)

Having scrambled up to the summit of Clogwyn yr Oen, the view ahead looked beautiful but daunting.  The powder snow was deep in places and made progress difficult as I broke trail towards Ceseiliau Moelwyn.  The Welsh Highlands Sub-Top of Clogwyn y Bustach was visited, but not surveyed given that its status within the list is secure.  Ahead stood Craig Stwlan, which I had noted as a marginal P20, as such, I knew Myrddyn Phillips would appreciate having the hill surveyed, given that it was a candidate for his 500m Sub-Twmpau list.

Clogwyn y Bustach (Photo: Aled Williams)

The summit of Craig Stwlan was first to be surveyed.  This went quickly and efficiently, no doubt benefitting from the experience of recent surveys.  The views were stunning and I could discern the path that I would take to reach Bwlch Stwlan.  The bwlch of Craig Stwlan took a bit longer to locate.  This is often dictated by the flat topography of low points, but the winter conditions doubled the challenge of the task.  Once data had been collected, I ploughed onwards through the snow, thankfully joining a set of tracks that greatly eased progress. 

Trimble atop Craig Stwlan (Photo: Aled Williams)

I then joined the path known locally as Llwybr Gaseg.  This was spectacular in the conditions, perched above the freezing waters of Llyn Stwlan and the snow plastered slopes and gullies of Moelwyn Mawr and Craig Ysgafn above.  Care was needed in places, but no ice was met.  Upon reaching Bwlch Stwlan, a splendid view of Traeth Mawr and Porthmadog opened out. 

Along Llwybr Gaseg (Photo: Aled Williams)

Bwlch Stwlan (Photo: Aled Williams)

Craig Ysgafn looked imposing from Bwlch Stwlan, but the scarcity of ice made it an easier endeavour.  The south top was visited, another Sub-Top in the Welsh Highlands list, followed by the highest summit of the ridge.  However, the focus was the northern top, which classified a marginal P10 stood a chance of being promoted to the sub-list of The Welsh Highlands list that I co-author with Myrddyn Phillips. 

Craig Ysgafn (Photo: Aled Williams)

Summit of Craig Ysgafn looking toward Moelwyn Mawr (Photo: Aled Williams)

The bwlch of the north top was found to be a snug notch in the ridge, with an airy view down a gully that led straight down to the depths of Llyn Stwlan.  The survey was completed quickly and a short climb led to the summit of the north top.  A number of rocky protuberances competed for the highest point and so the Abney level was used to identify the correct outcrop.  Three men bypassed the summit as data collected, looking a little perplexed at the beeping noises emanating from the Trimble! 

Bwlch of the north top of Craig Ysgafn (Photo: Aled Williams)

Surveying the bwlch of the north top of Craig Ysgafn (Photo: Aled Williams)

Having collected data I made my way to the base of the upper slope of Moelwyn Mawr.  A determined plod progressively took me up to the steep slope, where a surprising amount of deep snow had settled. 

Climbing Moelwyn Mawr (Photo: Aled Williams)

Summit ridge of Moelwyn Mawr (Photo: Aled Williams)

The summit ridge of Moelwyn Mawr looked airy and alpine-like, with Yr Wyddfa and its neighbouring Eryri peaks looking majestic to the north.  Below was Llyn Croesor and Bwlch Rhosydd, between which was a hillock that I had recently identified as a potential Sub-Top for the Welsh Highlands list and as such, was the third surveying objective of the day. 

Summit of Moelwyn Mawr (Photo: Aled Williams)

Yr Wyddfa (Photo: Aled Williams)

The steep descent from the summit of Moelwyn Mawr was undertaken slowly and carefully.  I had been warned from a Blaenau Ffestiniog local whom I had met on the way up Moelwyn Mawr that the snow above Rhosydd was deep.  This warning was confirmed by the appearance of a partially buried stile and fence!  However, I was yet again fortunate to follow in the footsteps of others and so quick progress was made to the shores of Llyn Croesor. 

Deep snow (Photo: Aled Williams)

The final surveying objective (Photo: Aled Williams)

On the other side of the lake stood the craggy hillock that was to be surveyed, a short but enjoyable climb led to the summit, whereupon the Trimble was placed on the highest point of outcropping rock.  The scenery was breath-taking and I felt fortunate to be out in such a wild place.  However, the serenity would soon be broken by hard surveying work! 

Surveying the summit (Photo: Aled Williams)

The bwlch of the hill was unexpectedly complex.  I quickly realised that the gap had been plugged by a dam that formerly held the north side of Llyn Croesor when operating at reservoir capacity.  Furthermore, an outflow leat consisting of earth and large slabs of rock had been built on the northern side of the dam. 

The bwlch (Photo: Aled Williams)

The dam wall (Photo: Aled Williams)

Ironically, the ice axe strapped to my bag was finally unclipped and brought into use, with the adze helping to displace snow so that a better assessment of the terraformed bwlch could be made.  Two sets of data were gathered with the Trimble; one at the bottom of the dam wall and one above the leat at the spot where remaining natural ground was identified.  However, post survey, further analysis work revealed that the natural bwlch may well be extant to the north of the wall within the leat. 

The leat (Photo: Aled Williams)

Looking back at the final hill (Photo: Aled Williams)

Once the surveying equipment was packed away, a set of snow tracks sign-posted the way to Bwlch Rhosydd and ultimately the way back to civilisation.  Before I set off, a quick glance behind my shoulder revealed beautiful cloud formations above Moelwyn Mawr, brought in from the east and heralding a change in the weather.  It had been a great day out and one no doubt to be remembered for years to come.

Clouds above Moelwyn Mawr (Photo: Aled Williams)

Walkers ascending Moelwyn Mawr (Photo: Aled Williams)

 

Moelwyn Mawr clouds (Photo: Aled Williams)

Aled Williams (January 2023)

 

Survey Result: 

 

Craig Stwlan

Summit Height:  568.4m (converted to OSGM15)

Summit Grid Reference:  SH 66736 44654

Bwlch Height:  548.3m (converted to OSGM15)

Bwlch Grid Reference:  SH 66693 44717

Drop:  20.1m (500m Sub-Twmpau addition)

Dominance:  3.53%

Craig Ysgafn

Summit Height:  688.3m (converted to OSGM15)

Summit Grid Reference:  SH 65973 44394

Bwlch Height:  678.0m (converted to OSGM15)

Bwlch Grid Reference:  SH 65960 44382

Drop:  10.3m (Welsh Highland Sub addition)

Dominance:  1.49%

Pt. 524.3m

Summit Height:  524.3m (converted to OSGM15)

Summit Grid Reference:  SH 66117 45783

Bwlch Height:  513.5m (converted to OSGM15)

Bwlch Grid Reference:  SH 66131 45774

Drop:  10.7m (Welsh Highland Sub addition)

Dominance:  2.05%

 

For further details please consult the Trimble Survey Spreadsheet

 

 

  

Mapping Mountains – Trimble Surveys – Moelwyn Mawr

07.02.20  Moelwyn Mawr (SH 658 448), only bwlch surveyed

The last of four bwlch surveys of the day was at the top of Bwlch y Gorddinan, which in English is known as the Crimea Pass.  This bwlch is placed at the top of the A470 road as it heads north-eastward from Blaenau Ffestiniog toward the A5 road and Betws-y-coed, and it connects to Moelwyn Mawr, which is one of the highest hills in the Moelwynion range and towers above the near town of Blaenau Ffestiniog.

Moelwyn Mawr (SH 658 448)

I hadn’t surveyed the summit of Moelwyn Mawr, although I had visited on 19 occasions.  However, I had driven over this bwlch many times, usually when heading north, but other times whilst visiting the hills connecting with Manod Mawr to the east or those connecting with Allt Fawr to the west, until today I hadn’t had the opportunity to survey it.

Prior to my visit I looked at the lay of land from the convenience of a digitised image via a Google car on my laptop and also examined the 5m contouring on the OS Maps website.  The latter implies the critical point of the bwlch is on the A road, whilst the former leaves the impression that it is positioned close to where a track leaves the road via a gate.

The bwlch of Moelwyn Mawr

By the time I arrived and parked at the gate entrance the breeze from early morning had increased in strength, but not so much as to hinder any survey.  Having spent five minutes examining the lay of land I repositioned my car nearer the gate entrance and again looked at where the stream valley came up from the confines of the Afon Gorddinan to the north and crossed the track close to the gate entrance and headed down beside the A470.  The only thing to pinpoint was its exact critical point.  This could easily be positioned in a small fenced compound beside the track.

This small patch of land consisted of scrub grass and was even in nature implying that the critical point was beside the outer fence where a number of fence posts gave the opportune convenience to place the Trimble on top, and by doing so creating a high improvised tripod with elevation for the equipment above its immediate surrounds.

Gathering data at the bwlch of Moelwyn Mawr

As I chose the fence post for Trimble placement, measured the offset between its internal antenna and the ground below, and set the equipment to gather data I looked out on the surrounding hills; Moel Siabod looked inviting as a distant bulk of a hill with a slither of road snaking its way toward it, whilst the nearer Allt Fawr shot skyward bathed in early afternoon light.  Whilst to my east lay Moel Farlwyd, which I knew had been surveyed by John Barnard and Graham Jackson in the last two days to confirm its impending Hump status.  I was tempted to survey this hill prior to their visit, but thought I’d leave it to the professionals!

Moel Siabod

Allt Fawr

As the Trimble beeped away gathering its individual datum points I stood on the opposite side of the road and waited for the allotted six minutes of data to be stored.  Once data collection was complete I closed the equipment down, packed it away and headed down from the bwlch to a convenient lay-by to change and continue toward Nantlle for the weekend’s festivities.

Survey Result:

Moelwyn Mawr

Summit Height:  770.1m (LIDAR)

Summit Grid Reference:  SH 65823 44860 (LIDAR)

Bwlch Height:  384.5m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SH 70000 48660 (Trimble GeoXH 6000)

Drop:  385.6m (LIDAR summit and Trimble GeoXH 6000 bwlch)

Dominance:  50.07% (LIDAR summit and Trimble GeoXH 6000 bwlch) 

  

For further details please consult the Trimble Survey Spreadsheet

The Definition of Prominence

The following is an extract from an on-line news report relating to Moelwyn Mawr.  It is probably the best definition of prominence ever put forward.

Moelwyn Mawr misses out on towering sequence by reduction than an inch.  A rise needs to be 2,000ft high and have a 15-metre (49ft) tallness disproportion between a limit and a land that connects it to a subsequent tip peak.

A Welsh towering has been downgraded to a towering – after blank out by reduction than an inch.

In a turn on a Hugh Grant film The Englishman Who Went Up a Hill But Came Down a Mountain, surveyors ruled that Moelwyn Mawr in Snowdonia no longer measures adult to a manners set out for summits.

Under central guidelines, a rise needs to be 2,000ft high and have a 15-metre (49ft) tallness disproportion between a limit and a land that connects it to a subsequent tip peak.

Missing out Moelwyn Mawr in Snowdonia no longer measures adult to a manners set out for summits.

But GPS record showed that while Moelwyn Mawr was a healthy 2,350ft high, it was 23 millimetres brief of a limit tallness difference.

Surveyor John Barnard pronounced they had not had information ‘as tighten as this’ before and certified ‘the locals are not going to be gratified with us’.

This exquisite description appeared on the Britain Weekly website

Some news outlets have now rectified their articles that incorrectly applied our survey to Moelwyn Mawr, these include:

BBC Wales News

The Daily Post   

Newspaper Articles about the Untimely and Incorrect Demise of Moelwyn Mawr

A number of articles have recently been published regarding the mountain status of Moelwyn Mawr.  These articles relate to a survey that John, Graham and I undertook on 16^th June this year.  The hill we surveyed is to the north of Moelwyn Mawr and it was not to Moelwyn Mawr, which with a prominence of c 385m unquestionably retains its mountain status.

The hill to the north of Moelwyn Mawr which we surveyed was included in the listing of 2,000ft mountains of Wales by John and Anne Nuttall as a basic levelling survey had given it a drop of approximately 15.2m.  When this hill was accepted into John and Ann’s list they coined the name of Moelwyn Mawr North Ridge Top for it.  Unfortunately confusion has arisen in a number of articles between what is Moelwyn Mawr and what is a Northern Ridge Top. 

Confusion has also arisen about the measurement we attained for the drop value of this hill.  We line surveyed from bwlch to summit and then from summit to bwlch and also gathered an hour’s data from both summit and bwlch with our Leica GS15.  Both surveying methods give a value of 14.77m of drop, this is insufficient for this northern top to retain its ‘mountain’ status and therefore it has been deleted from the listing of Nuttalls.

As the qualifying threshold for drop in the Nuttalls list is a minimum of 15m, our survey proved that this hill fell short by 0.23m (23cm).  Unfortunately confusion has also arisen in a number of published articles relating to this measurement as it has been reported that the hill failed to retain its ‘mountain’ status by 23mm.  This figure should of course be 23cm, an easy error to make but one of importance when dealing with the margins of measurement from a line survey.

However, where confusion can be forgiven because of the substituting of a ‘c’ to an ‘m’, it is hard to deal with poor old Moelwyn Mawr and its unsavoury oblivion as a ‘mountain’.  Part of this confusion stems from the name that has been used, in this case that of Moelwyn Mawr North Ridge Top, which for the uninitiated proved too much to comprehend.

Perhaps this is a case in point where the use of an invented name is both unsatisfactory and unnecessary as this hill has a locally known name which will be used when Aled Williams and I publish future place-name detail relating to it.

The stance that Aled and I adopt on such matters is to use the point (Pt.) notation for seemingly unnamed hills, this gives time for a hill list author to research an appropriate name for the hill, and where one is not found it leaves research open to future generations, whereas the use of an invented name has an uncanny knack of becoming endorsed within the hill bagging community, and in this instance such an invented name has caused confusion amongst some national newspapers.

Published newspaper articles relating to our survey are listed below:

Western Mail Wales Online

Daily Post

Daily Mail

Daily Mirror

The Telegraph

BBC News Wales

South Wales Evening Post