Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

Graig Fach (SH 792 249) – Welsh Highland Sub deletion 

There has been a deletion to the listing of the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Aled Williams. 

LIDAR image of Graig Fach (SH 792 249)

The criteria for the list that this deletion applies to are:

Welsh Highlands – Uchafion Cymru – Welsh hills at or above 500m in height with 15m minimum drop, with an accompanying sub list entitled the Welsh Highland Subs, the criteria for which is all Welsh hills at or above 500m in height with 10m or more and below 15m of drop.  This list is authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and the latest update relating to the list published on Mapping Mountains in January 2023.

Welsh Highlands - Uchafion Cymru by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Graig Fach and it is adjoined to the Arenig Fawr group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A2), and it is positioned with a minor road to its south south-east and the A494 road farther to its south-east, and has the small community of Rhyd-y-main towards the south south-east.

When the initial P10 sub list was completed in June 2020 this hill was listed with 10.2m of drop, based on a basic levelling survey conducted by Myrddyn Phillips on the 10.04.06, and listed with a 510m summit height and a 500m bwlch height, with an accompanying note stating that analysis of numerical data on various scales of Ordnance Survey maps give this hill an estimated c 9m of drop.  Therefore, it was included as a Welsh Highland Sub when the drop value of the subs was agreed upon and revised in July 2020. 

Extract from the Ordnance Survey 1:25,000 Explorer map 

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.

Therefore, the deletion of this hill from Welsh Highland Sub status is due to LIDAR analysis, resulting in a 511.3m summit height and a 501.4m bwlch height, with these values giving this hill 9.9m of drop, which is insufficient for it to be classified as a Welsh Highland Sub. 

 

The full details for the hill are: 

Group:  Arenig Fawr

Name:  Graig Fach

OS 1:50,000 map:  124

Summit Height:  511.3m (LIDAR)

Summit Grid Reference:  SH 79263 24920 (LIDAR)

Bwlch Height:  501.4m (LIDAR)

Bwlch Grid Reference:  SH 79277 24975 (LIDAR)   

Drop:  9.9m (LIDAR) 

 

For the additions, deletions and reclassifications to the Welsh Highlands – Uchafion Cymru reported on Mapping Mountains please consult the following Change Registers:

 

Welsh Highland P15s

 

Welsh Highland Subs

 

Aled Williams and Myrddyn Phillips (August 2023)

 

 

 

 

  

Mapping Mountains – Trimble Surveys – Pumlumon

22.02.19 & 28.03.19  Graig Fach (SN 821 930) and Y Grug (SN 840 934)

Y Grug (SN 840 934)

The last time I headed in to the northern Pumlumon range on the track past the waters of Glaslyn was in May 2016 when clear blue skies met me; today was very similar with a gentle clarity to the beckoning blue sky and the outline of distant hills on the horizon.

The track to the hills

I wanted to re-survey two hills; Graig Fach and Y Grug, as both are marginal to the P15 qualifying drop criterion for the Welsh Highlands – Uchafion Cymru list, and since my last visit Aled has analysed Y Grug via LIDAR.  Therefore I had a multitude of ten figure grid references for both hills.  But as with most hill walks, the surveying seemed periphery to just being out in such a stunning place.  The hills of the northern Pumlumon are the gems of this range and especially those gathered round the northern valleys, which dramatically sweep downward to the valley below.

As I walked past Glaslyn I stood for a few moments taking in the scene with Cadair Idris away to the north and Foel Fadian rising in yellow tinged colour accentuated by the morning light.

Glaslyn and Foel Fadian

Foel Fadian

The track led toward the northern moorland ridge of Banc Bugeilyn and nestled just beyond on the opposite side is Graig Fach.  I’d visited this hill twice before, and each time I had surveyed it, once with my old basic levelling staff and on the second visit with the Trimble.  I now wanted to check on its summit position and take a series of surveys mainly on the summit area, but if time permitted also at its bwlch.

Graig Fach is a rough hill consisting of moorland grass and heather, although a sheep track does exist which heads toward its upper section and eases passage toward its summit.  I spent over an hour on this hill taking three data sets on its summit area and two at its bwlch.  During this time a thankful cooling breeze meandered across the land as during the walk in I wondered if I was going to overheat in the unseasonably warm February weather.

Gathering data at the summit of Graig Fach

The Trimble set-up position at the summit of Graig Fach

Once all required data sets were complete I re-joined the track and reversed my inward route to where a greened track headed south-east toward the Nant Goch and Afon Clyweog.  I often find it hard to use words that give justice to the hills and the unencumbered open space they offer, and when on this greened track life seemed so simple with uncomplicated thought, just the here and now with periphery detail seemingly gone.  This to me is one of the great joys of being out amongst the hills.

The green track leading toward Y Grug

The track led to a large barn and gravelled path leading down to a sturdy footbridge crossing the Nant Goch.  The path continued up on the opposite side of the stream contouring toward a fence beside which I sat on the hillside and luxuriated myself in the unseasonal warmth, letting my mind wander and empty.

A sheep path led up close to the fence toward the summit of Y Grug which consists of small clumps of moorland grassed tussocks.  I took two data sets from the area of this hill’s summit before venturing down to its grassed connecting bwlch.

Gathering data at the summit of Y Grug

As the Trimble gathered the last of its eight data sets of the day I stood and enjoyed the scene as the slight breeze wandered across the ridge and the sun cast beautiful early spring colour.  It was good to be out.

Postscript:

As the surveyed drop for Y Grug came to 14.98m which is only 2cm below Uchaf qualification, I wanted to re-visit the hill and take further data sets from its summit and bwlch, and ideally do this on a day that was relatively warm with little breeze.  The opportunity to do so came five weeks later on the 28^th March and following the hill’s broad grassy northern ridge I headed toward its summit.  I’d come prepared as I had done before, with ten figure grid references for both summit and bwlch which were produced by Aled’s LIDAR analysis.

This was the fourth time I’d been to this hill and every visit I’d surveyed it!

The Trimble was soon positioned atop my rucksack and the measurement offset between its internal antenna and the ground below noted and away it went quietly beeping as individual datum points were gathered and stored.

The last of the five data sets taken on the summit area of Y Grug during the survey conducted on the 28.03.19

I’d brought small flags to note each survey position and spent about 50 minutes at the summit taking another five data sets to add to the two from my previous visit.

Happy with my summit endeavours I sauntered down to its connecting bwlch and placed a small flag where my eye initially positioned the critical bwlch and another flag where the ten figure grid reference produced by LIDAR places the critical bwlch, between these positions I placed another two flags, each four metres apart and spent the next 40 minutes contentedly waiting for data to be gathered and stored from these four positions.

The last of the four data sets taken on the bwlch area of Y Grug during the survey conducted on the 28.03.19

All that remained was the walk back along the northern ridge to my car and the task of processing the nine data sets just gathered.   

  

     

Survey Result:

Graig Fach

Summit Height:  513.5m (converted to OSGM15)

Summit Grid Reference:  SN 82117 93069

Bwlch Height:  498.8m (converted to OSGM15)

Bwlch Grid Reference:  SN 82314 93321

Drop:  14.7m (500m Sub-Uchaf status confirmed)

Dominance:  2.86%

Y Grug

Summit Height:  519.4m (converted to OSGM15)

Summit Grid Reference:  SN 84068 93472

Bwlch Height:  504.3m (converted to OSGM15)

Bwlch Grid Reference:  SN 83978 93757

Drop:  15.0m (Uchaf status retained)

Dominance:  2.90%

For details on the first survey of Graig Fach

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Hill Reclassifications – Yr Uchafion

Graig Fach (SN 821 931) - Uchaf reclassified to 500m Sub-Uchaf

There has been a reclassification of an Uchaf to a 500m Sub-Uchaf due to a survey conducted with the Trimble GeoXH 6000.  Yr Uchafion is the draft title for a list of the Welsh 500m P15s that takes in all hills in Wales at or above 500m that have a minimum of 15m of drop, the list is a joint compilation with Aled Williams.  Details relating to this list were published on the Mapping Mountains site in November 2015.

The hill is situated in the Pumlumon group of hills in the heartland of northern mid Wales and is positioned to the south of Foel Fadian, which is the hill’s Cardinal Hill, and between the towns of Llanidloes to its south-east and Machynlleth to its north-west.  It can be easily accessed from a minor road to its north from where a track leads toward the lake of Glaslyn; the hill is positioned just to the west of this track.  Alternatively an extended route can be devised from its south where a path can be followed above the course of the Afon Hengwm.

The name of the hill is Graig Fach (the) little rock and was surveyed over two days; on 5^th May 2016 and 22nd February 2019, both in beautiful early morning sunshine.  Graig Fach has a 514m summit spot height and bwlch contouring between 490m – 500m with a 499m spot height appearing on the Ordnance Survey enlarged mapping on the Geograph website, this latter spot height is positioned on the track and interpolation suggests that it is not positioned where the critical bwlch is situated.

The bwlch consists of moor grass and heather and two data sets were taken on both days,  whilst the summit consists of a small rock and grassy knoll with five data sets taken in all from the area of the summit, resulting in the hill only having 14.7m of drop and therefore below the 15m minimum drop value required to qualify for this list.

This now revises the total of Uchaf hills which will be updated accordingly and the hill is now listed as a 500m Sub-Uchaf.

The full details for the hill are:

Cardinal Hill:  Foel Fadian

Summit Height:  513.5m (converted to OSGM15)

Name:  Graig Fach

OS 1:50,000 map:  135, 136

Summit Grid Reference:  SN 82117 93069

Drop:  14.7m (converted to OSGM15)

The reclassifications to Yr Uchafion / The Welsh 500m P15s reported on Mapping Mountains are ills of wales as follows:

RECLASSIFIED FROM UCHAF TO SUB-UCHAF

Pt. 649.8m (SH 660 452) Uchaf reclassified to 500m Sub-Uchaf with 14.8m of drop.

Graig Fach (SN 821 931) Uchaf reclassified to 500m Sub-Uchaf with 14.5m of drop.

Graig Fach (SN 821 930) now reclassified from an Uchaf to a 500m Sub-Uchaf

For details on the survey that reclassified this hill from Uchaf to 500m Sub-Uchaf status.

Myrddyn Phillips and Aled Williams (May 2016)

Mapping Mountains – Hill Reclassifications – Y Pellennig – The Remotest Hills of Wales

Graig Fach (SN 821 930) - Pellennig deletion

There has been a deletion of a hill from the list of Y Pellennig – The Remotest Hills of Wales, due to a survey with the Trimble GeoXH 6000.  The hill is situated in the Pumlumon group in northern mid Wales and is situated between the towns of Machynlleth to its north-west and Llanidloes to its south-east with the mountain lakes of Glaslyn to its north and Bugeilyn to its south.

The name of the hill is Graig Fach and it was surveyed over two days; 5^th May 2016 and 22nd February 2019, both in beautiful early morning sunshine.  The hill can be easily accessed from the north via the track that leaves a minor road toward the lake of Glaslyn, or alternatively a longer approach to the hill is from the south-west following the path above the course of the Afon Hengwm. 

Graig Fach has a 514m summit spot height and bwlch contouring between 490m – 500m with a 499m spot height appearing on the Ordnance Survey enlarged mapping on the Geograph website, this latter spot height is positioned on the track and interpolation suggests that it is not positioned where the critical bwlch is situated.

The bwlch consists of moor grass and heather and two data sets were taken on both days,  whilst the summit consists of a small rock and grassy knoll with five data sets taken in all from the area of the summit, resulting in the hill only having 14.7m of drop and therefore below the 15m minimum drop value required to qualify for this list.  This hill is a loss to the Pellennig listing as it is one that must be seldom visited and affords good views across to the expanse of wilderness situated around Llechwedd Crin and Banc Bugeilyn.

This now brings the overall total for Y Pellennig to 167 hills for the Complete list (All Wales), with the total for the Mainland Wales list also decreasing by one to 123 hills.  The Master List will be duly updated on the Mapping Mountains site.

The full details for the hill are:

Cardinal Hill:  Foel Fadian

Summit Height:  513.5m (converted to OSGM15)

Name:  Graig Fach

OS 1:50,000 map:  135, 136

Summit Grid Reference:  SN 82117 93069

Drop:  14.7m (converted to OSGM15)

The list of additions and deletions in the Pellennig list since the 1^st edition of Y Pellennig – The Remotest Hills ills of wales of Wales was published by Europeaklist is as follows:

ADDITIONS

Pen Diban (SH 112 205)

Ynys Arw (SH 266 945)

DELETIONS

Graig Fach (SN 821 930)

Graig Fach (SN 821 930) now deleted from the Y Pellennig list

For details on the survey that deleted this hill from Pellennig status.

Myrddyn Phillips and Aled Williams (May 2016)

Mapping Mountains – Trimble Surveys – Pumlumon

05.05.16  Graig Fach (SN 821 930), Banc Bugeilyn (SN 826 924), Foel Fadian (SN 828 953) only bwlch surveyed, Bryn Llwyd (SN 835 920), Bryn yr Ŵyn (SN 839 925), Foel Twynyn (SN 840 939) and Waun Goch (SN 841 943) 

Foel Fadian (SN 828 953)

The northern Pumlumon is a land of open big sky where during spring the accompaniment of Skylarks and a grazing sheep are usually the only living creatures heard and seen.  These hills are wonderful places where moor and bog meet and sun drenched bleached hillsides are interspersed with the darkened sprig of heather.  It was to these hills I ventured today; I hadn’t been this way in a number of years but had wanted to re-visit ever since getting the Trimble as one hill in particular needed a detailed survey.

The track to the car park beside the beautiful lake of Glaslyn is now rutted and puddle laden and I would no longer take anything except for a four wheel drive vehicle down it.  As I locked my car I looked at my watch – 7.34am – a relatively early start and the slight chill set against the blue of sky was a delicious feeling, and especially so when looking south toward the continuation of the track to Glaslyn, as a track meandering in to the hill is a welcoming site, one that fulfils many dreams.

A track to the hills - a sight that fulfills many dreams

I’d come with a set plan for the day and fully realised that it may be a long one as I knew there were many surveys to conduct; 25 as it turned out, which for me and my Trimble equalled my record.

Setting off on the track brought back many memories from my previous visits, all good ones, memories can be like friends on occasion where their presence evokes the past with inner smiles and heart felt sharing’s of time gone by that is renewed with each meeting.

The first survey of the day was on the track, beside one of the many rutted puddles next to the entrance to where cars can be parked to view Glaslyn.  This point is the critical bwlch for Banc Bugeilyn.  As the Trimble gathered its data I stood and soaked in the scene as Foel Fadian leapt skyward, a hill whose summit I’d surveyed when with Eryl in January 2014 shortly after getting the Trimble, and the elongated profile of Cadair Idris filled the backdrop of mountain and moor.

Gathering data at the critical bwlch of Banc Bugeilyn

The elongated profile of Cadair Idris with the blue waters of Glaslyn as foreground

Passing Glaslyn its waters shone back with a succulent blue that matched the sky, a welcoming blue, a blue that screamed out to be noticed, a blue that foretold a good day on the hill.  I smiled at a notice close to the lake which read ‘Conditions underfoot away from the main path can be dangerous due to uneven and boggy ground and visitors should be aware of tripping or falling especially around the lake.’  This sums up the wilds of the northern Pumlumon as it can be a teense tussocky and a wee bit boggy in places.

The first hill on my surveying to do list for the day was Graig Fach, this is a forgotten lump beside the main track as it weaves its way in to the wilderness, it stands forlorn of its neighbouring higher hills, probably seldom visited but it has a beauty that comes with this, a beauty that this morning gave me a contented 50 minutes as I pottered about taking two data sets at the summit and likewise at the bwlch.  I’d only visited this hill once before, in May 2004 and it is currently listed as a Pellennig and an Uchaf, with the former based on remoteness and the latter based on a criteria of 500m minimum height and 15m minimum drop.

Surveying for summit height and position on Graig Fach with the Aran in the background

Rising above me to the south-east stood Banc Bugeilyn, a great lump of moor, heather and bog whose summit area consisted of five or six potential high points, all of which I planned on surveying.  I knew a good narrow path existed from the track to the summit, but having visited Graig Fach I did not want to double back to try and find it, so I plodded up its slopes and found a sheep track taking me in the right direction, this bi-passed a particularly large and ruddy coloured bog and led me to the steepening summit slopes.  Behind me the waters of Bugeilyn glistened in the morning’s blue skied heat with Llechwedd Crin standing invitingly steep above.

Graig Fach (SN 821 930)

Llechwedd Crin (SN 816 922) rising above the waters of Bugeilyn

Once on top I decided that at least four potential high points needed Trimbling, I eventually took data from five separate points and left happy in the knowledge that time had been spent doing this as a number of people have expressed doubt over the exact high point of this hill.

Gathering data from one of the five points surveyed for summit position and height on top of Banc Bugeilyn

Beyond Banc Bugeilyn is a drop southward in to the confines of a large and bog ridden bwlch.  This bwlch was impregnated in my memory as stretching wide and featureless.  I found that it had not changed since my last visit, I wandered to and fro assessing the land and surprisingly it wasn’t difficult to pinpoint the approximate position of the critical bwlch, this was at or between two stagnant pools.  As I stood almost ankle deep in water I set the Trimble up on top of my rucksack to give it elevation above the surrounding moor and bog, and once the 0.1m accuracy level had been attained I splashed my way a safe distance from it and tried to find relatively dry ground to stand on.

Gathering data at the critical bwlch of Foel Fadian

As the Trimble did its stuff I noticed a white Landrover on the track to my west, two people got out of it and made their way down steepening slopes, their voices carried toward me in the confined and yet open space of the bwlch, I thought it a rather comforting experience seeing another person, in this case two, a welcome addition that took my mind away from the detail catalogued for each survey that can become a slight burden on occasion.  I wondered who they were and what they were doing, they slowly inched their way down the slope and disappeared from view for evermore, their purpose and destination to remain a mystery, a metaphor for life itself as one meets / sees so many people during the years on this earth and the vast majority are unknown and will never be seen again.

After packing the Trimble away I sploshed my way across the bwlch to drier ground where a sheep track took me on to the bleached moor above the next bwlch that needed surveying.  This bwlch connects with Bryn Llwyd (this is a locally known name, used in preference to Esgair Greolen which appears on Ordnance Survey maps) and Bryn yr Ŵyn, both of which are given small uppermost 500m contour rings and no spot height on current Ordnance Survey maps.  I’d surveyed these hills on 11^th July 2000 with my old wooden staff and afterward sent the results to Michael Dewey who then included Bryn yr Ŵyn in his listing to ‘The 500-Metre Tops of England and Wales’.  I’d found on that day that the summit of Bryn yr Ŵyn was slightly higher than that of Bryn Llwyd, this was a surprise as the latter has a larger uppermost 500m ring contour on Ordnance Survey maps, the difference was only 4ft which is well within the experimental error associated with the rudimentary surveying method employed on the day.  Having the Trimble enabled me to re-survey each hill and ascertain an accurate height, and in the process confirm which is higher and also survey the drop for the hill, which I knew would be close to the minimum 30m required to qualify for Michael’s list.

I took three data sets from the bwlch, two on the hill to hill traverse and one where contour interpolation suggests the critical bwlch to be positioned.  The ground hereabouts was relatively easy to survey, and as the Trimble gathered data I luxuriated in the warmth of the day under expansive blue sky.  During this time I looked out at the valley where I planned on walking through after surveying the two summits of Bryn Llwyd and Bryn yr Ŵyn, this encloses Cors yr Ebolion, which translates as the bog of the foel, the valley stretched away in to the distance, between me and it was just moor, and more moor, a never ending wilderness where openness predominates and lost souls can never be found.

One of three surveys conducted at the bwlch for what proved to be the connecting bwlch to Bryn Llwyd and not that for Bryn yr Ŵyn

After surveying the bwlch I plodded up to the summit of Bryn Llwyd, assessed the lay of land, chose the spot to place the Trimble and set it up to gather its customary five minutes of data.  One of the joys of having the Trimble is that the surveys can form part of an extended walk, instead of purposely going out to survey a single hill, this may sound a rather unusual statement, but having the Trimble enables you to do a hill walk and survey on the way, these two ways of surveying hills are very different beasts, both have their advantages, but due to its portability and its internal antenna, accurate data that is far better than what is on a map or what can be estimated from contour interpolation can be achieved with no more than a five minute data set, it’s a wonderful bit of kit and one that has proven to be a fine addition to my hilly wanderings.

Gathering data at the summit of Bryn Llwyd

After surveying the connecting bwlch between Bryn Llwyd and Bryn yr Ŵyn I continued to the summit of the latter and proceeded to take a further three data sets, all from the same position, the resulting data can be averaged after processing.  With three bwlch and three summit data from Bryn yr Ŵyn and a data set from the summit of Bryn Llwyd I left a happy bunny and followed the edge of the conifer plantation that swamps this hill’s northern slopes down to Cors yr Ebolion.

Gathering data at the summit of Bryn yr Ŵyn

Once beside the bog I balanced over old pieces of fence post left to cross a reed infested steam and walked slowly through tussocks and bog to the safety and delights of a contouring path heading northward.  Reaching the path I tried to stop my brow from sweating and sat down on the edge of the path had a drink and a bite to eat and took my fleece coat off for the remainder of the day.  I’d been on the go for almost six hours and still had almost three hours until I got back to my car, 25 surveys takes a lot of time, you know!

The path proved a saviour and I had a memory that I’d been on it once before, it led through the mayhem of moor and bog to the Nant Ddu, where it crossed the stream and joined a track which I followed down to a large farm building.  After being in the openness of moor for a number of hours the enclosed nature of these streams where the Nant Ddu, Nant Goch and the Afon Clywedog meet was a surprisingly refreshing experience, giving a different perspective for the eye to concentrate on.  The waters rippled down small waterfalls and glistened back as the sun cast down.

The western slopes of Y Grug

A stout and relatively new footbridge crosses the stream below the large barn and a gravelled track leads up on the other side.  I followed the track as it narrowed and gained height until reaching a fence, where I diverted up to the summit of Y Grug, a 520m map heighted hill that I’d visited previously and surveyed with the old wooden staff.  By now the day’s exertions were taking their toll and as the Trimble gathered data from the summit of Y Grug I munched on an apple and spotted my car beside the road off in the distance. 

As I left the summit my right ankle began to hurt at it rubbed against my still relatively new walking boots, a problem I’ve faced ever since getting them, although unwelcome I will persevere as I’ve encountered this with previous pairs of boots and they have always bedded in over time.

The ridge of Y Grug stretches north over two other summits, both with little prominence but as I was there and as I had the Trimble I quietly surveyed each point in turn and eventually made it back on to the road just over a kilometre from where my car was parked.  I only had one survey remaining to conduct, and this was close to the road in a field and was the critical bwlch for the last summit north of Y Grug.  After packing the Trimble away I plodded back on the road to my car, it had been an excellent day on the hill with some interesting survey results anticipated.

  

Survey Result:

Graig Fach

Summit Height:  513.5m (converted to OSGM15, height from subsequent Trimble survey)

Summit Grid Reference:  SN 82117 93069 (summit position from subsequent Trimble survey)

Bwlch Height:  498.8m (converted to OSGM15, height from subsequent Trimble survey)

Bwlch Grid Reference:  SN 82314 93321 (bwlch position from subsequent Trimble survey)

Drop:  14.7m (Uchaf reclassified to 500m Sub-Uchaf and Pellennig deletion)

Dominance:  2.86% 


For details on the second Trimble survey of Graig Fach

Banc Bugeilyn

Summit Height:  550.1m (converted to OSGM15)

Summit Grid Reference:  SN 82659 92441

Bwlch Height:  476.7m (converted to OSGM15)

Bwlch Grid Reference:  SN 83158 94286

Drop:  73.3m

Dominance:  13.33%

Foel Fadian

Summit Height:  563.9m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SN 82831 95364 (from previous Trimble GeoXH 6000 survey)

Bwlch Height:  475.0m (converted to OSGM15)

Bwlch Grid Reference:  SN 82848 92131

Drop:  88.9m

Dominance:  15.76%

  

The result of the processed data for Bryn Llwyd and Bryn yr Ŵyn was of sufficient interest to warrant another survey, and therefore the following detail takes in the combined results from each survey:

Bryn Llwyd (significant name change) 

Summit Height:  501.4m (converted to OSGM15, and average of four surveys and Dewey and Uchaf status confirmed and summit relocated from Bryn yr Ŵyn [SN 83919 92571] and new Pellennig hill qualifying on distance) 

Summit Grid Reference:  SN 83574 92022

Bwlch Height:  471.2m (converted to OSGM15)

Bwlch Grid Reference:  SN 83220 91901

Drop:  30.3m (500m Twmpau status remains)

Dominance:  6.04%

Bryn yr Ŵyn

Summit Height:  499.9m (converted to OSGM15, and average of five surveys and summit relocated to Bryn Llwyd [SN 83574 92022])

Summit Grid Reference:  SN 83919 92571

Bwlch Height:  490.0m (converted to OSGM15)

Bwlch Grid Reference:  SN 83565 92279

Drop:  9.9m

Dominance:  1.99%




Foel Twymyn

Summit Height:  518.5m

Summit Grid Reference:  SN 84054 93974 (converted to OSGM15)

Bwlch Height:  c 512m (interpolation)

Bwlch Grid Reference:  SN 84081 94083 (interpolation)

Drop:  c 6m (Trimble GeoXH 6000 summit and interpolated bwlch)

Dominance:  1.25% (Trimble GeoXH 6000 summit and interpolated bwlch) 

Waun Goch

Summit Height:  520.8m (converted to OSGM15)

Summit Grid Reference:  SN 84142 94373

Bwlch Height:  508.3m (converted to OSGM15)

Bwlch Grid Reference:  SN 84324 94975

Drop:  12.5m (500m Sub-Uchaf deletion)

Dominance:  2.40% 

Post detailing the summit survey of Foel Fadian

Post detailing the second Trimble survey of Bryn Llwyd and Bryn yr Ŵyn 

For further details please consult the Trimble Survey Spreadsheet