Showing posts with label Pt. 516.9m (SN 754 620). Show all posts
Showing posts with label Pt. 516.9m (SN 754 620). Show all posts

Tuesday, 7 November 2023

Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru


Pt. 516.9m (SN 754 620) – Welsh Highland Sub reclassified to Welsh Highland P15 

There has been a reclassification 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. 

Pt. 516.9m (SN 754 620)

The criteria for the list that this reclassification 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 Aled Williams and Myrddyn Phillips

The hill is being listed by the point (Pt. 516.9m) notation and it is adjoined to the Esgair Wen group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned with a minor road to its north north-west and south, and has the small community of Pontrhydfendigaid towards the north-west and the town of Tregaron towards the west south-west.

When the original list that later became known as the Welsh Highlands – Uchafion Cymru was first compiled, this hill was not included as a Welsh Highland P15 as with no spot height adjoined to its uppermost 510m ring contour and bwlch contouring between 500m – 510m, the drop value could not be interpolated accurately to include it in this list. 

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

Since the original compilation of this list there have been a number of maps made available online.  Some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website.  Whilst others were digitally updated such as the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites.

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill it had a 517m summit spot height and a 502m bwlch spot height, with these values giving this hill 15m of drop and therefore it was included as a Welsh Highland P15. 

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map

The hill was subsequently surveyed with the Trimble GeoXH 6000, resulting in a 516.3m summit height and a 501.4m bwlch height.  However, as the area of the bwlch is situated in conifer plantation it was decided to use an interpolated height and position from OS Maps.  This mapping gave contour intervals at 5m and showed a small 500m ring contour where the 502m spot height appears on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website, data were collected from near this position resulting in a 501.4m height, but when doing so the authors were aware that land to the north-east was judged slightly higher and this is what the 5m contouring on the OS Maps website indicated.  Therefore, the hill was listed with an estimated c 14m of drop, resulting in its reclassification to Welsh Highland Sub status. 

Extract from the interactive mapping that was hosted on the OS Maps website

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. 

LIDAR image of Pt. 516.9m (SN 754 620)

Therefore, the reclassification of this hill from Welsh Highland Sub status is due to a LIDAR analysis, resulting in a 516.9m summit height and a 501.0m bwlch height, with these values giving this hill 15.8m of drop, which is sufficient for it to be reinstated and classified as a Welsh Highland P15. 

 

The full details for the hill are: 

Group:  Esgair Wen

Name:  Pt. 516.9m

OS 1:50,000 map:  146, 147

Summit Height:  516.9m (LIDAR)

Summit Grid Reference:  SN 75493 62086 (LIDAR)

Bwlch Height:  501.0m (LIDAR)

Bwlch Grid Reference:  SN 75576 61971 (LIDAR)   

Drop:  15.8m (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 (November 2023)

  

Saturday, 13 October 2018

Mapping Mountains – Hill Reclassifications – Welsh Highlands - Uchafion Cymru


THIS HILL HAS SUBSEQUENTLY BEEN RECLASSIFIED TO WELSH HIGHLAND P15 STATUS


Pt. 516.3m (SN 755 621) – Uchaf reclassified to 500m Sub- Uchaf

There has been a reclassification to the listing of Yr Uchafion due to a survey conducted with the Trimble GeoXH 6000 and analysis of bwlch contouring on OS Maps, with the criteria for this list being.

Yr Uchafion – This is the draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height that have a minimum 15m of drop, accompanying the main Yr Uchafion list are three categories of sub hills, with this hill being reclassified from an Uchaf to a 500m Sub-Uchaf, with the criteria for this sub category being all Welsh hills at or above 500m in height that have 14m or more and below 15m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams with the introduction to the list being published on Mapping Mountains in November 2015.

Pt. 516.3m (SN 755 621)

As the authors do not know an appropriate name for the hill it is being listed by the point (Pt. 516.3m) notation and prior to the Trimble GeoXH 6000 survey this hill was listed with 15m of drop, based on the 517m summit and 502m bwlch spot heights that appear on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website

The hill is situated in the Elenydd group of hills which are placed in the Mid and West Wales Region (Region B, Sub-Region B2).  The hill is positioned in relatively remote land for Wales and has the small community of Pontrhydfendigaid towards the north-west and Tregaron towards the west south-west.

As the hill is a part of designated open access land it can be approached from any direction, however for those wishing to do so the hill is immersed in a conifer plantation although its high point is relatively easy to reach via a forest ride.

The reclassification of this hill is reliant upon the survey result produced by the Trimble GeoXH 6000 and interpolation of bwlch contouring on the OS Maps website.  This mapping gives contour intervals at 5m and shows a small 500m ring contour where the 502m spot height appears on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website, data were collected from near this position resulting in a 501.4m height, but when doing so the authors were aware that land to the north-east was judged to be slightly higher and this is what the 5m contouring on OS Maps indicate, and therefore the hill is being listed with a 516.3m summit height and an interpolated bwlch height of c 502m, with these values giving this hill c 14m of drop, which is insufficient for continued Uchaf staus.


Extract from OS Maps

The full details for the hill are:

Group:  Elenydd

Summit Height:  516.3m (converted to OSGM15)

Name:  Pt. 516.3m

OS 1:50,000 map:  146, 147

Summit Grid Reference:  SN 75504 62132  
 
Drop:  c 14m


The Trimble GeoXH 6000 gathering data at the summit of Pt. 516.3m

For the additions, deletions and reclassifications to Yr Uchafion / The Welsh 500m P15s reported on Mapping Mountains please consult the following Change Registers:










Myrddyn Phillips and Aled Williams (October 2018)



Sunday, 16 September 2018

Mapping Mountains – Trimble Surveys – Esgair Wen


25.06.18  Bryn y Crofftau (SN 748 634), Carn Fflur (SN 746 623), Pt. 512.8m (SN 747 620), Pt. 516.9m (SN 754 620), Pt. 526.8m (SN 745 611), Grug Crofftau (SN 750 612) and Llethr Brith (SN 756 614)

Bryn y Crofftau (SN 748 634)

The Yr Uchafion list of Welsh P15 hills over 500m in height opens up a number of places amongst the hills, where their P30 counterparts aren’t necessarily well represented and the land to the south-east of Pontrhydfendigaid is one such place.

I’d only visited the hills in this area once before and on that day found a number of forest rides  and tracks not marked on the 1:25,000 Explorer map, with the forest rides giving relatively easy access to a number of 500m P15 summits, albeit with the underfoot conditions being rather tough.  Since that day the Ordnance Survey Interactive Coverage Map hosted on the Geograph website is now available online and this map shows many spot heights applicable to these hills that do not appear on any other publicly available map, resulting in summit relocations and new Uchaf hills.  It was this area that Aled suggested we should visit and he had plotted a route between seven hills and supplied aerial maps and grid references and I then added a number of other grid references if we had the opportunity to extend the walk.  

We met in the outskirts of Machynlleth and took one car to Ystrad-fflur (Strata Florida) where we set off walking at just before 8.30am, even at this hour the heat pervaded the land and with a forecast for 30º temperatures in the country we knew it was going to be a very hot few hours on the hill.

Following a track in to the lower grasslands of the Elenydd the land resembled southern France or parts of Spain, with blue skies above and all-pervading heat cascading down with dry and dusted pathways.

Heading to the hills

Finding our route to the forest track

Our first planned hill was Bryn y Crofftau which is listed as a Pedwar, to get to it we needed to find the forest track that I had used as my descent route when last on these hills.  Our inward route led to beautiful mixed woodland and eventually down on a minor track to the main forest track which forever gained height and brought us to a clearing to our north-east, which gave access to Bryn y Crofftau.

The gap in the trees leading to the summit of Bryn y Crofftau

Leaving the forest track a narrow path led down to a boggy area and continued through thick rough summer grass toward the summit, even at this stage I began to wilt through the heat, it was debilitating and even more so with the realisation of what land we were planning on visiting and the underfoot conditions we would encounter, however Aled had brought the remains of last night’s Chinese take-away and two spare ribs shared between us seemed to rejuvenate me whilst the Trimble gathered its allotted summit data.

Heading toward the summit of Bryn y Crofftau

Gathering data at the summit of Bryn y Crofftau

Retracing our route back to the forest track it then led us up to large swathes of land that had been felled of conifers and which thankfully had not been replanted.  Our next hill was Carn Fflur and its ancient large cairn; now clear of forestry this vantage point gives excellent extended views.  The ancient cairn measures 25 metres in diameter and two data sets were taken, one from its rim and the other from its hollowed centre, during data collection the heat beat down.

Carn Fflur (SN 746 623)

Gathering data at the summit of Carn Fflur

The connecting bwlch between this and our next hill was again clear of forestry and the customary data set was taken before we made our way to the summit of a 513m map heighted hill that is listed as an Uchaf and only just misses out on Pellennig status.

Pt. 512.8m (SN 747 620) from the slopes of Carn Fflur

Gathering data at the critical bwlch of Pt. 512.8m

As data were gathered from its high point I was wilting under the intensity of heat which was proving merciless, and worried on how much more my body could take as I’ve experienced a number of unpleasant incidents either on the hill in Britain or whilst trekking abroad where severe heat has caused my body to succumb in a complete and unwelcome way.

Gathering data at the summit of Pt. 512.8m (SN 747 620)

Our next hill was immersed in forestry and we wanted to survey its summit and connecting bwlch, this hill is only given a single ring contour on contemporary Ordnance Survey maps but has 15m of drop on the Interactive Coverage Map hosted on the Geograph website, and it was one of the hills I had not visited during my previous bagging raid.

Pt. 516.9m (SN 754 620) proved a hot and difficult hill to reach its summit

Leaving the summit of the 513m map heighted hill we re-joined the forest track for a short distance before entering a land of high soft tussocks and bog that led beside the conifers to a forest ride that led up and intersected with another ride, I was now almost on my last legs and needed to stop frequently, hunched over gasping for breath in the incessant heat, I did not feel good at all.

The forest ride leading to the summit of Pt. 516.9m (SN 754 620)

We eventually reached the high point of the wide forest ride and I set the Trimble up to gather data and joined Aled in the shade, getting here was like stumbling in to a trap, and one where I did not know if I had sufficient energy levels to get myself out of.  Thankfully we were on the summit of this hill for about 30 minutes which gave me time to recover.

Gathering data on the summit area of Pt. 516.9m (SN 754 620)

During the walk we had been plagued by copious amounts of horse flies, flies and masses of midges that were buzzing us in swarms and whilst sitting next to Aled in the shade as the Trimble beeped away gathering its latest data set I looked at my scratched and torn legs as flies feasted on my blood, there were so many of them that it hardly served purpose to flap them away, as more only descended, I then felt a stinging sensation at the back of my left leg that increased in intensity to the point that I started flapping about; I had been sitting in a nest of red ants and they had defended their territory injecting their toxic alkaloid venom, they had my notice and I stood up quickly and left them to their nest as my leg turned red and itched in a most unusual and uncomfortable way.

Once data were stored and the Trimble packed away Aled wanted us to survey the hill’s connecting bwlch, which led us down to a land were few could have ever ventured in to, it was prehistoric in nature with trees covered in shining mosses highlighted in the flashes of sunlight that penetrated the canopy, the floor of this land consisted of bulbous mosses and pine needles which had probably laid undisturbed ever since the forestry was last planted, it was wondrous to be in such a place.  We used the Trimble as a hand-held device to zero in to where the spot height appears on the map and then judged where the best and most convenient spot to gather data was positioned.  During data gathering I rested and slowly regained strength and a willingness to continue living.

Immersed in the conifer plantation


A land of mosses where few could have visited since the forestry was last replanted

Aled navigated us out of the conifers and back on to the forest ride that we had used to gain the hill’s high point, we then regained height back to the forest track that was now beginning to take on the mantle of a long lost friend.

Back on the forest track looking toward the hill we had just visited

Four hills had now been surveyed and we had another three that we hoped to Trimble, this meant pushing further south in to the ever wilder landscape that constitutes the high Elenydd.  We now had two bylchau to survey before our fifth summit, the next point being the critical bwlch adjoined to our third hill; Pt. 513m.  Aled had looked at the 5m contours on OS Maps and the lowest point on the hill to hill traverse at this next bwlch is not at the end of the forest track where the 497m spot height appears on contemporary Ordnance Survey maps.  To get to the critical bwlch we followed a narrow path on the crest of a small ridge that proved delightful to walk after an hour or so immersed in thick conifer plantation.

One of the best parts of the walk heading toward the critical bwlch of Pt. 512.8m

I hoped at this stage that I would be able to complete the walk as I had major doubts only an hour or so earlier, and realised that the rest at the summit and bwlch of the last hill, with both being in shade had helped tremendously.

Pt. 526.8m (SN 745 611) now confirmed as a new Uchaf and Pellennig hill (and subsequently deleted due to LIDAR bwlch analysis)

We chose the set-up position for the Trimble at the bwlch and sat in shade whilst it collected data, Aled now found that the clump of soft undergrowth he was sitting in was infested in another ants nest, they were all over the land as were an incessant plague of flies that followed us for hours buzzing our heads and feeding on my scratched and bloodied legs.

Gathering data at the critical bwlch of Pt. 512.8m

The next bwlch was one of the more important to survey as it is adjoined to Grug Crofftau which is listed with 28m of drop and therefore is a candidate for P30 Twmpau and Dewey status.  When Aled led us in to the bog infested bwlch using the Trimble to zero in on where LIDAR places its critical point to lie, I followed willingly with part of my strength regained.

As I sat in shade beside a dried bog listening to the quiet beeps of the Trimble as it gathered individual data points, I rested, my body felt as if it had been hammered by the heat but I would not have been anywhere else at that very moment in time, as there was a fulfilling element to this walk and the land it took us in to.  During data collection Aled headed off to visit Garn Gron to the west which rose above us with grassed sides that had thankfully never been forested.

Gathering data at the critical bwlch of Grug Crofftau

I closed the Trimble down and excited the confines of the bog and forest laden bwlch at the same moment that Aled headed down from the hill, we were now out of the vast forest on its southern periphery and used the boundary fence to make progress toward our next hill which is currently unclassified but is a candidate for both Uchaf and Pellennig status.

Out of the forestry to its south

The boundary fence led toward a large bog which was thankfully relatively dry and once over it we continued back in to felled forestry and up the southern slopes of the next hill which is given a map height of 527m.

I slowly made progress up its southern slopes, following Aled, there was now a realisation that we were going to complete the walk and hopefully all remaining surveys.  Thankfully the hill’s summit is now free of forestry and as the Trimble gathered its summit data I sat with Aled and ate an apple, the only thing we were now worried about was running out of water, we had both brought extra bottles but their contents were being slowly sipped and there was still a long way to go.

Heading toward the summit of Pt. 526.8m (SN 745 611)


Gathering data at the summit of Pt. 526.8m (SN 745 611)

The next point to survey was the connecting bwlch to this 527m map heighted summit and interpolation placed it amongst or close to a small patch of remaining Scots pine forest, again the Trimble took us to this position and the allotted data gathered.

Exciting the trees a path of sorts through thick soft tussocks amongst patches of bog led us stumbling toward a fire break which would take us to the summit of Grug Crofftau.

Leaving the Scots pine wood


The forest ride leading toward the summit of Grug Crofftau

The high point of Grug Crofftau is close to a wide forest ride and about five rows of trees in to the forest, miraculously the Trimble attained its 0.1m accuracy level before data should be logged relatively quickly considering its position and gathered the all-important summit data without any form of objection.  We were now nearing the end of our surveying objectives but still had a long way to walk before reaching the awaiting car at Ystrad-fflur (Strata Florida).

Gathering data at the summit of Grug Crofftau

We excited the upper part of Grug Crofftau using another forest ride to take us down to the next bwlch which was positioned close to the waters of Llyn Crugnant, which is a wildly situated lake positioned in the grasslands of the Elenydd.  As the Trimble gathered data from the bwlch we both sat on tree stumps trying to recover from what was proving to be quite an ordeal of sun drenched and wild walking.

Llyn Crugnant

Only one survey remained and that was the summit of Llethr Brith, and thankfully a path led from the northern end of the bwlch that had just been surveyed to a forest ride that took us toward its high point which yet again was implanted firmly amongst the conifers.  It took a long time before the Trimble was activated and as we waited for ten minutes of data to be gathered swarms of midges and flies descended on us.

Gathering data at the summit of Llethr Brith

The summit of LLethr Brith was the last of 14 surveys taken during the day; I had visited seven summits and Aled eight, with Garn Gron being the extra one.  The land we had visited was uncompromising to say the least and the conditions severe with intense heat, and yet we had completed all that we had set off to do.  All that remained was the walk out, first down the continuation of the forest ride which brought us back to the forest track, I celebrated and knelt on the ground and kissed the gravel.

Reaching the forest track was like encountering an old friend.  Photo: Aled Williams

However, it was still a long walk out down the forest track where it intersected another which brought us down toward Hafod-newydd.  Walking down the green track toward this house the sun slowly ebbed behind hill ridges to our west as conifers rose skyward and took on a blackened hue accentuated by subline and gentle greens of fern and moss at their base.  Day was turning to night as dusk brought gentleness to this land.

The forest at dusk


Sunset

By the time we reached Hafod-newydd I was desperate to rest and started to wilt at an alarming rate, beyond the track continued downward, now out of the forestry toward a stream and a bridge that would if we had of continued, bring us to the narrow road taking us back to my car, but by this stage I was again almost done in, and when I saw a car on the track that was in the process of doing what looked like a seven point turn I gathered my last remaining strength and started shouting ‘hello’ and running toward the vehicle.  The driver kindly stopped his seven point turn and we tried to communicate, unfortunately he was almost deaf and only picked up certain words, thankfully those of 13 hours on the hill, exhausted, need water and please can we have a lift, seemed to do the trick and within a few minutes Aled was sitting in the back of the car with Henry the dog and I was sitting in the front with Denis, our saviour and driver.

Denis; our driver and saviour and his dog Henry

Denis had saved us another 40 minute walk back on the track and road, this I suspect would have been too much for me and I do not know how on earth I could have done it.  He dropped us off close to my car and we shook hands, what an absolutely lovely person he proved to be. 

I arrived home about midnight and was soon in bed feeling completely exhausted but also extremely happy at what we had accomplished during the day.  


Postscript:

Since the survey of 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 for some of these hills being prioritised over that produced by the Trimble GeoXH 6000.


      

Survey Result:



Bryn y Crofftau

Summit Height:  447.3m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 74807 63477 (Trimble GeoXH 6000)

Bwlch Height:  411.5m (LIDAR)

Bwlch Grid Reference:  SN 74705 63091 (LIDAR)

Drop:  35.8m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  8.01% (Trimble GeoXH 6000 summit and LIDAR bwlch)





Carn Fflur

Summit Height:  501.3m (converted to OSGM15)

Summit Grid Reference:  SN 74626 62354

Bwlch Height:  480.6m (converted to OSGM15)

Bwlch Grid Reference:  SN 74694 62297

Drop:  20.7m

Dominance:  4.14%





Pt. 512.8m

Summit Height:  512.8m (converted to OSGM15)

Summit Grid Reference:  SN 74759 62033

Bwlch Height:  493.9m (converted to OSGM15)

Bwlch Grid Reference:  SN 74659 61518

Drop:  18.9m

Dominance:  3.69%





Pt. 516.9m

Summit Height:  516.9m (LIDAR)

Summit Grid Reference:  SN 75493 62086 (LIDAR)

Bwlch Height:  501.0m (LIDAR)

Bwlch Grid Reference:  SN 75576 61971 (LIDAR)

Drop:  15.8m (LIDAR) (Welsh Highland P15 reclassified to Welsh Highland Sub) (Welsh Highland Sub reclassified to Welsh Highland P15) 

Dominance:  3.06% (LIDAR)





Pt. 526.8m

Summit Height:  526.8m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 74595 61119 (Trimble GeoXH 6000)

Bwlch Height:  512.0m (LIDAR)

Bwlch Grid Reference:  SN 74980 61422 (LIDAR)

Drop:  14.8m (Trimble GeoXH 6000 summit and LIDAR bwlch) (Welsh Highland P15 addition) (Welsh Highland P15 reclassified to Welsh Highland Sub) (Pellennig addition) (Pellennig deletion) 

Dominance:  2.82% (Trimble GeoXH 6000 summit and LIDAR bwlch)

Remoteness:  2.700km (Pellennig addition)






Summit Height:  533.3m (converted to OSGM15)

Summit Grid Reference:  SN 75031 61257

Bwlch Height:  504.3m (converted to OSGM15)

Bwlch Grid Reference:  SN 74415 61043

Drop:  29.0m

Dominance:  5.43%





Llethr Brith

Summit Height:  527.6m (converted to OSGM15)

Summit Grid Reference:  SN 75675 61410

Bwlch Height:  508.9m (converted to OSGM15)

Bwlch Grid Reference:  SN 75366 61428

Drop:  18.7m

Dominance:  3.55%