Showing posts with label Bryn yr Ŵyn. Show all posts
Showing posts with label Bryn yr Ŵyn. Show all posts

Tuesday, 23 June 2020

Mapping Mountains – Hill Reclassifications – The 500-Metre Tops of England and Wales – Deweys


ADDED TO THE DEWEY LIST AS BRYN YR ŴYN (SN 839 925) WITH THE HIGHER QUALIFYING HILL NOW SUBSTANTIATED AS ESGAIR GREOLEN (SN 835 920)


Esgair Greolen (SN 835 920) – Dewey addition

This is one in a series of retrospective Hill Reclassification posts that detail hills whose status has altered in the listing of the Deweys and where I have had direct association with the status change.  These posts will tie in with a forthcoming Change Register giving detail to this list and its alterations since publication in the Mountain tables book.

Esgair Greolen (SN 835 920)

The 500-Metre Tops of England and Wales are affectionately known after their hill list compiler; Michael Dewey.  This list mixes metric and imperial height in its criteria to bookend up to the 2000ft height band and takes in all hills in England, Isle of Man and Wales that are 500m and above and below 2000ft (609.6m) in height that have 30m minimum drop.

This list formed one of a number of lists that appeared in the Mountain tables book published by Constable in 1995 and at the time of publication comprised 373 hills with 164 in England, 5 in the Isle of Man and 204 in Wales.  The Deweys have undergone extensive revision since first publication with the initial stages forming the basis of this revision given below:


1995    Mountain tables published by Constable with 373 hills listed as Deweys.

April 2000    Strider (LDWA quarterly booklet) publishes contact details for David Purchase and Myrddyn Phillips who have found and list 24 and 14 possible new 500m tops respectively.

It was expanded versions of the above two lists that formed the basis of the next publication:

25th May 2000    List of Possible 500 Metre Tops by Michael Dewey listing 44 hills.

David Purchase expands his Additional Dewey 500m Hills and Myrddyn Phillips produces lists of English 500m hills to measure and Welsh 500m hills to measure.

These lists formed the basis of the next publication:

29th June 2000    Possible/Probable 500’s by Michael Dewey listing 77 hills.  Michael adopts following protocol; if one person proposes that a top should qualify as a 500 by personal survey, and is then confirmed by a second person, it should then be promoted to the main list.

April 2002    The 500+ Tops of England and Wales – The ‘New Deweys’ published in the Strider booklet and listing 66 new qualifying hills.

25th May 2006    Rob Woodall republishes Michael’s main and possible/probable lists on the RHB Yahoo group file database. 

 
Mountain tables by Michael Dewey

The details for this addition appear below:

The name the hill is listed by in the Deweys is Esgair Greolen, and it is adjoined to the Pumlumon group of hills which are situated in the central part of Wales, and it is positioned with the A44 road to its south and the B4518 road to its east, and has the town of Machynlleth towards the north-west and Llanidloes towards the south-east.

This hill was not included in the original 1995 Constable publication, but with a small uppermost 500m ring contour and bwlch contouring between 470m – 480m that appear on the Ordnance Survey 1:25,000 Explorer map, this hill was noted as an outside possibility for a potential new Dewey.

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

The above detail was noted by Myrddyn Phillips who then conducted a basic levelling survey (BLS) of this hill on the 11th July 2000, resulting in 106½ft / 32.5m of drop, with Bryn yr Ŵyn (SN 839 925) surveyed as higher than Esgair Greolen (SN 835 920).  These details were forwarded to the list author; Michael Dewey and the hill was added to the list with the date of survey given in the Remarks column accompanying the list.

Gathering data at the summit of Esgair Greolen

Gathering data at the bwlch of Esgair Greolen

Gathering data at the summit of Bryn yr Ŵyn

As the margin of uncertainty for the BLS method of surveying over terrain such as that on this hill is approximately +/- 2m and as the resulting 32.5m of drop was near the minimum 30m qualifying drop value and as both summits only have a small uppermost 500m ring contour, this hill was prioritised for a GNSS survey, and this took place over two days; on the 5th and 13th May 2016.  The summit and bwlch of this hill were surveyed by Myrddyn Phillips using a Trimble GeoXH 6000, resulting in a 501.4m summit height for Esgair Greolen and a 499.9m summit height for Bryn yr Ŵyn and a 471.2m bwlch height, with these values giving Esgair Greolen 30.3m of drop and in the process relocating the qualifying hill to the higher summit and confirming its Dewey status.


The full details for the hill are:

Name:  Esgair Greolen

OS 1:50,000 map:  135, 136

OS 1:25,000 map:  214, 215

Summit Height:  501.4m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 83574 92022 (Trimble GeoXH 6000)

Bwlch Height:  471.2m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SN 83220 91901 (Trimble GeoXH 6000)

Drop:  30.3m (Trimble GeoXH 6000)


Myrddyn Phillips (June 2020)


Friday, 27 May 2016

Mapping Mountains – Summit Relocations – Y Pellennig, Yr Uchafion and 500m Twmpau


Bryn Llwyd (SN 835 920)  

There has been a Summit Relocation initiated by a survey with the Trimble GeoXH 6000 to the listings of Y Pellennig, Yr Uchafion and 500m Twmpau, with the survey that resulted in this summit relocation being conducted on the 5th and 13th May 2016.

The three lists that this summit relocation affects are:

Y Pellennig - The Remotest Hills of Wales, with the criteria being all hills in Wales whose summit is 2.5km or more from the nearest paved public road that have a minimum 15m of drop.  This list is co-authored by Myrddyn Phillips and Aled Williams.

Yr Uchafion, this is the working title for a list that takes in all hills in Wales at and above 500m in height that have a minimum 15m of drop.  This list is co-authored by Myrddyn Phillips and Aled Williams.

500m Twmpau (thirty welsh metre prominences and upward), with the criteria being all Welsh hills at or above 500m and below 600m in height that have a minimum 30m of drop.  This list is authored by Myrddyn Phillips.

As the hill only entered the ranks of Pellennig hills due to this survey this listing of hills is being included within this Summit Relocations heading. 

The survey was conducted in the Pumlumon range of hills over two beautiful sunny days, with the hill situated mid-way between the towns of Machynlleth to its north-west and Llanidloes to its south-east.  

The name of the hill where the summit has been re-located to is Bryn Llwyd (SN 835 920) and the name of the hill where the summit has been re-located from is Bryn yr Ŵyn (SN 839 925).  Both summits and respective bylchau were surveyed with the Trimble with their summits being connected by a bwlch that is only 9.9m below the summit height of Bryn yr Ŵyn and 11.4m below the summit height of Bryn Llwyd.

The summits of both hills possess a small uppermost 500m ring contour on Ordnance Survey maps with no adjoined spot height, with the uppermost ring contour for Bryn Llwyd being the larger.

The critical bwlch for the higher of these hills in positioned to the south-west and to my knowledge their drop has only been surveyed on three occasions, once using a basic levelling survey (BLS) method, and the other two using the Trimble GeoXH 6000.  The results from each survey appear below:


Bryn Llwyd:  summit to critical bwlch, 102.5ft (31.2m) drop (BLS), 30.3m drop (Trimble).

Bryn yr Ŵyn:  summit to connecting bwlch with Bryn Llwyd, 42.5ft (13.0m) drop (BLS), 9.9m drop (Trimble).   


I conducted the basic levelling survey in July 2000 and sent the details to Michael Dewey.  Michael assessed the information and decided to include Bryn yr Ŵyn in his list to The 500-Metre Tops of England and Wales.  The margin of uncertainly associated with the BLS method is within the error tolerance of the result, and I have wanted to re-visit and survey both hills and produce accurate absolute heights for each, ever since.  Their heights as surveyed by the Trimble GeoXH 6000 appear below:


Bryn Llwyd 501.4m (converted to OSGM15) summit at SN 83574 92022 (average of four surveys conducted over two days)

Bryn yr Ŵyn 499.9m (converted to OSGM15) summit at SN 83919 92571 (average of five surveys conducted over two days)


Therefore the position of the relocated summit is at SN 83574 92022 and it consists of grass atop an ancient mound.  The summit area and the hill itself has relatively easy underfoot conditions and consists of moor grass with a path leading from the critical bwlch to the south-west toward the connecting bwlch with Bryn yr Ŵyn.  

This re-located summit position is not given a spot height on current Ordnance Survey maps and it is approximately 660 metres south south-westward from the previously listed summit position.


The full details for the hill are:


Cardinal Hill:  Pumlumon Fawr

Summit Height:  501.4m (converted to OSGM15, and average of four summit surveys)

Name:  Bryn Llwyd

OS 1:50,000 map:  135, 136

Summit Grid Reference (New Position):  SN 83574 92022 
  
Drop:  30.3m (converted to OSGM15)


The Trimble GeoXH 6000 gathering data at the summit of Bryn Llwyd, with the summit of Bryn yr Ŵyn on the right and in the background of this photograph

For details on the 1st Trimble survey and the 2nd Trimble survey that relocated the summit of this hill.

Myrddyn Phillips and Aled Williams (May 2016)








Monday, 23 May 2016

Summit Relocations – The 500-Metre Tops of England and Wales – The Deweys


Esgair Greolen (SN 835 920)  

Michael Dewey has confirmed that the summit of Bryn yr Ŵyn (SN 83919 92571) is relocated to the higher summit of Esgair Greolen (SN 83574 92022) and therefore replaces Bryn yr Ŵyn as the hill listed in his 500-Metre Tops of England and Wales, which is affectionately known as the Deweys.



My word you’ve been busy in the Pumlumon area. Excellent work and I know it’s going to be appreciated by the people doing the Five-hundreds.  I’m pleased to accept the summit relocations of Bryn yr Ŵyn at grid reference SN 83919 9257 and Esgair Greolen at SN 83574 92022.

Michael Dewey (May 2016)




Esgair Greolen (SN 835 920) centre left of photo and Bryn yr Ŵyn (SN 839 925) on right of photo

The listing to The 500-Metre Tops of England and Wales appeared in Michael’s Mountain tables book which was published by Constable in 1995.  Since that date there have only been a few summit relocations which have resulted in replacement summits being confirmed, those affecting Wales include:


Pen y Bedw East Top (SH 784 470) replaces Pen y Bedw West Top (SH 779 469)

Cerrig Llwydion (SN 909 731) replaces Sychnentydd (SN 909 724)

Esgair Greolen (SN 835 920) replaces Bryn yr Ŵyn (SN 839 925)


Mountain tables by Michael Dewey

This summit relocation and replacement summit was confirmed by a survey conducted over two days; 05.05.16 and 13.05.16 with the Trimble GeoXH 6000.  In all five data sets were taken from the summit of Bryn yr Ŵyn and four from the summit of Esgair Greolen.  Each summit height has been averaged from these combined surveys:


Esgair Greolen 501.4m (converted to OSGM15) summit at SN 83574 92022

Bryn yr Ŵyn 499.9m (converted to OSGM15) summit at SN 83919 92571


Gathering data from the summit of Bryn yr Ŵyn

Gathering data from the summit of Esgair Greolen

If wanting more detail please consult the blog post for the 1st Trimble survey and the 2nd Trimble survey of these summits.  All details relating to each data set taken during the two days which took in these surveys are given in the Trimble Survey Spreadsheet.


Myrddyn Phillips (May 2016)





Sunday, 22 May 2016

Mapping Mountains – Trimble Surveys – Pumlumon


13.05.16  Bryn yr Ŵyn (SN 839 925), Bryn Llwyd (SN 835 920) and Fedw Ddu (SN 856 917)

Bryn Llwyd (SN 835 920) centre left of photo and Bryn yr Ŵyn (SN 839 925) on right of photo

Having visited Bryn Llwyd (this is a locally known name, used in preference to Esgair Greolen which appears on Ordnance Survey maps) and Bryn yr Ŵyn eight days ago the resulting data for each summit and the drop attained for the higher of the two was of sufficient interest that a second survey was warranted. 

I approached from the south-east from where a minor road heads south from the small community of Penffordd Las (Staylittle).  A passing place proved convenient to park with a few other such places also available near to where a track heads north toward the farm of Nant-yr-hafod.

The forecast for the day was good with sunshine and dry conditions predicted and as I walked up the track the morning’s blue sky pieced the landscape.  Just before the farm the track veers west toward the 488m map heighted summit of Fedw Ddu, and it was here that I met Gareth Griffith who came chugging around the bend with three farm dogs scampering around his vehicle.  I waved a ‘hello’ as I lifted the catch on a gate and he pulled up for a chat.

Gareth Griffith

Gareth had lived at Nant-yr-hafod for forty years and was heading up the hill to feed the sheep.  I explained where I was hoping to go and as some of this land was not a part of open access or did not have a right of way on it, I asked if he minded me using the continuation of the track, he was happy enough for me to do this and we continued our conversation, he told me that he still goes out shepherding on horseback and soon the topic of hill names was mentioned.  He proved extremely knowledgeable and rolled off name after name of the hills and streams above where he farmed.  One name in particular was of interest, it related to the hill that Ordnance Survey maps name as Esgair Greolen, which is the hill I wanted to concentrate the morning’s surveying activities on.  He knew this hill by a different name; Bryn Llwyd, and after mentioning it he said that ‘this name doesn’t appear on the map.’ 

Gareth and his dogs

As Gareth was heading up to the end of the track which is close to the summit of Fedw Ddu I asked if I could have a lift, he kindly said yes and within a couple of minutes I was happily sitting next to him in his vehicle as it chugged its way up the track.  He stopped three times to unload sheep feed and put his dogs in the cage on the trailer at the back.  Rarely do you have an opportunity to make such swift progress up a hill, and as he pulled up at the end of the track I clambered out, put my rucksack on, shook his hand and thanked him in Welsh.

Time to feed the sheep

As Gareth turned his vehicle round I waved my thanks and he disappeared down the hill, leaving me in the early morning sunshine smiling at the thought of how little energy I’d used to get so high.  Within a few minutes I was assessing the land at the bwlch of Fedw Ddu and soon had the Trimble positioned on my rucksack gathering data.

Gathering data at the critical bwlch of Fedw Ddu

Beyond this bwlch a path on the open hillside made good progress toward the summit of Bryn yr Ŵyn.  I planned to take a further two data sets from this first summit, giving five in all when combined with my previous visit, I also wanted to take three data sets from the summit of Bryn Llwyd which would make four in all when combined with those previously taken, and at least seven data sets from the area of the critical bwlch.  All accumulated summit data could be averaged to give the absolute height of each hill, whilst the bwlch data would give an evaluation of the lay of land on the hill to hill traverse, when the data were combined the higher summit would be clarified and its drop obtained.

Once on top of Bryn yr Ŵyn I quickly placed the Trimble on the same point as I had eight days previously and stood a safe distant from it and below it as the first of what proved to be a further 19 data sets were gathered from these hills.  Away to my south south-west Bryn Llwyd looked distinctly lower, as it does from almost every angle that I’ve viewed these hills from.

Gathering data at the summit of Bryn yr Ŵyn

Once a further two data sets were gathered from the summit of Bryn yr Ŵyn I walked over the moor toward Bryn Llwyd and took a further three data sets from its summit.  I placed the Trimble on the ground for two of these data sets and once on top of my rucksack.

Gathering data at the summit of Bryn Llwyd

All that remained was to gather data from the bwlch, this proved fun as a further 13 data sets were taken.  The first of which was from where contour interpolation suggests the critical bwlch to be placed on the ground, I’d taken the third bwlch data set from this position on my last visit and judged this to be visually on the downward slope of the valley to valley traverse, with the traverse from the hill to hill direction just a few metres to the north of this point.

During the remainder of my time at the bwlch I took 12 data sets on what I judged to be on the hill to hill traverse, this heads in a west to east direction.  On every bwlch data set I positioned the Trimble atop my rucksack to give it elevation above the surrounding moor and measured the offset between its internal antenna and the ground with a steel tape.  The furthest point from where I gathered bwlch data from to the west and to the east was at a point that was visually on the upward slope of the hill to hill traverse, with the remainder of the positions approximately 8-10 metres apart, and on the land that I judged to be where the low point of the hill to hill traverse was situated I took data sets five metres apart.  Each point was marked with a flag which proved ideal to visually assess the lay of land.  Once all data sets were complete I packed everything away and started the walk back toward my car.

The march of flags across the bwlch

The positions surveyed at the bwlch are indicated with flags with Bryn Llwyd in the background

Leaving the bwlch I followed a path which crests the connecting bwlch between Bryn Llwyd and Bryn yr Ŵyn and contours around the latter’s southern slopes before joining the inward path and track toward Fedw Ddu.  I’d visited this hill once before and wondered if summit data were possible to collect as its high point is immersed in a conifer plantation.

A forest break conveniently passes over where the spot height appears on the map, and I followed the moss laden ground between the trees until the up seemed to have ended and the beyond seemed to consist of down.  I aimed for a high point at the base of trees and happy that I’d visited what could be construed as the summit I positioned the Trimble to try and collect data, remarkably its 0.1m accuracy level before data should be logged was attained relatively quickly, and as it beeped away collecting its customary 300 data points I stood behind one of many conifer trees, out of sight of the equipment.

Gathering data at the summit of Fedw Ddu

After packing the Trimble away all that remained was to re-trace my inward route, this time on foot, and 6 ½ hours after setting off I arrived back at my car with 19 data points stored in the Trimble. 


  
Survey Result:

The result of the processed data for the first Trimble survey of 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 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

Drop:  9.9m

Dominance:  1.99%






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 

Dominance:  6.04%





Fedw Ddu

Summit Height:  487.7m (converted to OSGM15)

Summit Grid Reference:  SN 85672 91803

Bwlch Height:  434.8m (converted to OSGM15)

Bwlch Grid Reference:  SN 85176 91727

Drop:  52.9m

Dominance:  10.85%










Saturday, 21 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 11th 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)





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:



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%