Showing posts with label Esgair Llyn Du. Show all posts
Showing posts with label Esgair Llyn Du. Show all posts

Wednesday, 15 November 2023

Mapping Mountains – Summit Relocations – Welsh Highlands – Uchafion Cymru and Y Pellennig – The Remotest Hills of Wales


Esgair Llyn Du (SN 769 620) 

There has been a Summit Relocation to a hill that is listed in the Welsh Highlands – Uchafion Cymru and Y Pellennig – The Remotest Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Aled Williams. 

Esgair Llyn Du (SN 769 620)

The criteria for the two listings that this summit relocation 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

Y Pellennig – The Remotest Hills of Wales - Welsh hills whose summit is at least 2.5km from the nearest paved public road and the hill has 15m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available as a downloadable e-booklet and print-booklet version on Mapping Mountains Publications with the up-to-date master list available to download on the Mapping Mountains site in Google Doc format.

Y Pellennig - The Remotest Hills of Wales by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Esgair Llyn Du 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-west and south, and has the small community of Pontrhydfendigaid towards the north-west and the town of Tregaron towards the west south-west. 

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

When the 1st edition of the Y Pellennig – The Remotest Hills of Wales was published by Europeaklist in April 2015, this hill was listed with 3.075km of remoteness and 20m of drop, based on the 534m summit spot height positioned at SN 767 617 and the 514m bwlch spot heights that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, with this mapping giving two positions of equal height for the bwlch. 

Extract from the interactive mapping hosted on the WalkLakes website

The Ordnance Survey Vector Map Local hosted on the Geograph website gave the higher spot height to the middle of three larger 530m map contour rings, with the southerly and middle ring contours subsequently surveyed with the Trimble GeoXH 6000.  However, the interactive mapping hosted on the WalkLakes website indicates that the most northerly of these is the higher. 

The Trimble GeoXH 6000 set-up position at the southerly of the three tops

The Trimble GeoXH 6000 set-up position at the central of the three tops

At the northerly of the three tops and the summit of Esgair Llyn Du

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. 

 

The results from these surveys are given below: 

LIDAR for northerly summit:  532.849m at SN 76930 62044 

LIDAR for central summit:  532.729m at SN 76768 61773 

Trimble GeoXH 6000 for central summit:  532.552m at SN 76770 61772 

LIDAR for southerly summit:  532.020m at SN 76691 61642 

Trimble GeoXH 6000 for southerly summit:  531.914m at SN 76691 61642 

 

The 532.8m summit height produced by LIDAR analysis and its position in relation to the previously listed summit comes within the parameters of the Summit Relocations used within this page heading, these parameters are: 

The term Summit Relocations applies to when the high point is positioned in a different field, to a different feature such as a conifer plantation, within a different map contour, a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is considered a relatively recent man-made construct, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist. 

LIDAR image of Esgair Llyn Du (SN 769 620)

LIDAR summit image of Esgair Llyn Du (SN 769 620)

Therefore, the summit height produced by LIDAR analysis is 532.8m and this is positioned at SN 76930 62044.  This position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, but a 532m spot height appears in this position on the interactive mapping hosted on the WalkLakes website and is approximately 440 metres north-eastward from where the originally listed summit is positioned and approximately 300 metres north-eastward from where the previously listed summit is positioned, resulting in its remoteness being amended from 3.075km to 2.925km.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Esgair Wen

Name:  Esgair Llyn Du

OS 1:50,000 map:  146, 147

Summit Height:  532.8m (LIDAR) 

Summit Grid Reference:  SN 76930 62044 (LIDAR) 

Bwlch Height:  513.8m (LIDAR) 

Bwlch Grid Reference:  SN 76942 61196 (LIDAR) 

Drop:  19.0m (LIDAR) 

Remoteness:  2.925 km

 

Myrddyn Phillips and Aled Williams (November 2023)

 

 

  

Saturday, 11 November 2023

Mapping Mountains – Hill Reclassifications – 500m Twmpau


Esgair Llyn Du (SN 769 620) – 500m Sub-Twmpau deletion

There has been a deletion to the listing of the 500m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Aled Williams. 

Esgair Llyn Du (SN 769 620)

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

500m Twmpau - Welsh hills at or above 500m and below 600m in height with 30m minimum drop, with an accompanying sub list entitled the 500m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 500m and below 600m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips and is available to download in Google Doc format from Mapping Mountains. 

The 500m Twmpau by Myrddyn Phillips

The name the hill is listed by is Esgair Llyn Du 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-west and south, and has the small community of Pontrhydfendigaid towards the north-west and the town of Tregaron towards the west south-west. 

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

After the list that later became known as the 500m Twmpau was first compiled, this hill was included in the accompanying sub list with 20m of drop, based on the 534m summit spot height positioned at SN 767 617 and the 514m bwlch spot heights that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, with this mapping giving two positions of equal height for the bwlch. 

Extract from the interactive mapping hosted on the WalkLakes website

The Ordnance Survey Vector Map Local hosted on the Geograph website gave the higher spot height to the middle of three larger 530m map contour rings, with the southerly and middle ring contours subsequently surveyed with the Trimble GeoXH 6000.  However, the interactive mapping hosted on the WalkLakes website indicates that the most northerly of these is the higher. 

The Trimble GeoXH 6000 set-up position at the southerly of the three tops

The Trimble GeoXH 6000 set-up position at the middle of the three tops

At the northerly of the three tops and the summit of Esgair Llyn Du

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 Esgair Llyn Du (SN 769 620)

Therefore, the deletion of this hill from 500m Sub-Twmpau status is due to LIDAR analysis, resulting in a 532.8m summit height and a 513.8m bwlch height, with these values giving this hill 19.0m of drop, which is insufficient for it to be classified as a 500m Sub-Twmpau.

 

The full details for the hill are:

Group:  Esgair Wen

Name:  Esgair Llyn Du

OS 1:50,000 map:  146, 147

Summit Height:  532.8m (LIDAR) 

Summit Grid Reference:  SN 76930 62044 (LIDAR) 

Bwlch Height:  513.8m (LIDAR) 

Bwlch Grid Reference:  SN 76942 61196 (LIDAR) 

Drop:  19.0m (LIDAR)

 

Myrddyn Phillips (November 2023)

 

 

  

Friday, 26 May 2023

Mapping Mountains – Trimble Surveys – Esgair Wen


07.04.23  Pt. 501.5m (SN 776 629), Pt. 503.9m (SN 776 625) and Esgair Llyn Du (SN 769 620) 

Pt. 501.5m (SN 776 629)

Today involved unfinished business with a forested top positioned in the great swathe of conifer plantation that makes up the Tywi Forest.  I had visited this area once before in 2009, hence the unfinished business, and on that occasion I did a relatively long walk from one forested top to another, without the aid of knowing where the forest rides were positioned and with an Ordnance Survey 1:25,000 Explorer map that did not show the continuation of the main forest track that I used between the hills.  That day was particularly adventurous as I did not know whether each hill on my route could be joined without hours of conifer bashing.

During the walk in 2009 I visited Esgair Llyn Du, whose summit consists of a ridge aligned north to south.  I had the high point of this hill marked on the southern periphery of the ridge, which my map indicated had five separate 530m upper contour rings, with two of these relatively small.  I remember being surprised when I saw the southern section of the upper part of this hill devoid of conifers.  Or more precisely devoid of upright conifers as this section of forest had recently been felled; I quickly stumbled my way to what I thought the high point, reversed my route and continued on the main forest track to my next hill.  A few years later and a 534m spot height appeared on an online map on the next northerly 530m ring contour, necessitating a re-visit to make sure I had visited the high point of the hill.  Such re-visits are probably only the concern of a hill bagger.

The route toward Esgair Llyn Du gives options to include a number of other 500m P15 summits, all of which are included in the Welsh Highlands – Uchafion Cymru list.  And so it was appropriate that this walk was conducted in the company of Aled Williams; the co-author of this list, who being much younger and enthusiastic than me could shoot off to visit all near hills, whilst I could leisurely concentrate on the one summit; Esgair Llyn Du.

We met at Mallwyd where I left my car, with Aled driving onward toward Strata Florida and the minor road heading south-eastward that gives access to this part of the forest.  The day was set fine with fair weather cloud predicted to bubble up, but it was going to be dry and not too warm, which for the purposes of this walk was ideal.

The main forest track continued heading south-eastward, gaining height as it did so.  We stopped once or twice on our way up to Bwlch Rhyd y Meirch.  I hadn’t been out on the hill in a while and I was struck with the quietness of the land, this was only pierced by a myriad of distant bird song that gently echoed through the trees. 

Gathering data at the summit of Pt. 501.5m (SN 776 629).  (Photo Aled Williams)

It was at the bwlch that Aled left me to visit his first hill, this is marked with a 502m summit spot height and is as it was in 2009; still free of conifers with them having been felled.  As Aled visited this first hill I looked farther north-east in to some of the most remote land in Wales, with much of the immediate foreground consisting of acres of conifers, but beyond were open hills, with light and shade empathising the lay of land.  It was good to be out after having a winter break from the hills. 

Gathering data at the summit of Pt. 503.9m (SN 776 625).  (Photo: Aled Williams)

Aled had taken the Trimble to survey the summit and after re-joining me he kept it for the next hill which positioned just to the south has a 504m map summit spot height.  I’d visited both of these hills in 2009 and was happy enough to watch Aled disappear up their slopes heading toward another Trimble summit survey. 

The second hill of five that Aled visited during the day

Having waited for Aled as he ascended the first hill; this second hill gave me opportunity to slowly walk up the continuation of the forest track, which I did, with Aled catching me up near to where the summit of Esgair Llyn Du came in to view. 

Aled on the forestry track quickly catching me up

Aled had come prepared with aerial images of these hills on his mobile phone and therefore we were aware of the forest ride that follows the summit ridge of Esgair Llyn Du, all we had to do was find it and this would hopefully then give us relatively easy access to this hill’s high point. 

Esgair Llyn Du

The aerial image showed the forest ride joining the main track at a corner, however we could save a little distance by cutting the corner and stomping over ground now felled of trees, but still with the usual pitfalls of gauged out peaty channels and uneven ground.  I slowly followed Aled as he confidently strode out to find the forest ride.  Once found, we veered rightward and followed it to the first top on the ridge, this is the point I had reached in 2009.  We judged the high point to be free of trees and I proceeded to set the Trimble up to gather allotted data. 

The Trimble set-up position at the first of the Esgair Llyn Du tops 

From inside of the conifers we had a good view looking at the continuation of the forest ride to where the online map indicates the 534m spot height to be positioned.  The land farther on looked higher and therefore after the customary five minutes of data collection, the equipment was closed down and we continued northward on the forest ride.

The second top proved problematic for the Trimble and although data were attempted to be gathered the equipment beeped in frenzy when activated and soon closed itself down.  The position was enclosed, but one never knows whether accurate data will be collected as the Trimble had certainly gathered data from more enclosed positions in the past. 

The Trimble set-up position at the second of the Esgair Llyn Du tops

We debated retracing our inward route back to the main forest track, or continuing in our northward direction on the forest ride over the last of the 530m map contour rings.  Thankfully Aled persuaded me to do the latter as when on its high point we both thought this higher than the previous two.  However, each was not directly visible from the other, so we will have to wait for LIDAR to confirm which is the higher.  But 14 years after my previous visit I was happy in the knowledge I had now stood on the top of Esgair Llyn Du.  I then followed Aled as he took a direct course down through the mature conifers, aiming for the main forest track.  Such routes can become deceptive with any onward view just confined to the immediate conifers, but such routes also have a perverse beauty as few people must come such ways, and with the trees mature they at least allowed dappled light to cast light and shade down to the moss encrusted land below. 

Aled at the third of the Esgair Llyn Du tops

Heading through the trees back toward the main forest track

After making it back on to the main forest track we stopped beside a quarried pool, sat on a rock, and rested.  A few minutes later and we were back at Bwlch Rhyd y Meirch.  This was decision time for me, as two potential hills remained to visit, one of which I had not been up on my 2009 extended foray.  However, I already knew that I was content with just visiting Esgair Llyn Du and so as Aled headed farther eastward to visit the summit of Graig Wen before heading out of the forest and doubling back to the summit of Pen y Bwlch, I continued down our inward route.

I stopped occasionally to listen to the sounds of the forest, the tranquillity of which was only disturbed by three off road vehicles which were hunting out the narrower bog laden tracks.

At the junction where a green track joins the main forest track I followed it upward to the edge of the forest.  This was the route down from Pen y Bwlch; the last hill for Aled to visit.  I contemplated having a slow plod up to its summit to survey it and wait for Aled to join me, but I could remember when in 2009 this hill was my first of the day and then thinking that it had a bit more uphill than expected.  I looked up to it and thought that my continued slow wander back down the track was the order of the day. 

Pen y Bwlch

Having turned my back to the hill I continued down the forest track and was suddenly confronted by a flash of orange; a fox.  It immediately heard me and turned; I stopped and automatically reached for my camera.  It soon scampered farther down the track out of sight.  When I reached the next corner there it was, still on the track, but seeing me it soon disappeared off again and this time in to the undergrowth. 

Handsome creature

Lichen on fence post

I continued down, resting on logs at one point where we had done likewise on our ascent.  I was in no rush and more than happy with my one summit of the day.  Arriving at Aled’s car I changed and waited for him to appear, thirty minutes later and there he was, he had made good time over the other two hills. 

 

Survey Result:

 

Pt. 501.5m

Summit Height:  501.5m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 77686 62986 (Trimble GeoXH 6000)

Bwlch Height:  486m (spot height)

Bwlch Grid Reference:  SN 77925 63540 (spot height)

Drop:  16m (Trimble GeoXH 6000 summit and spot height bwlch)

Dominance:  3.10% (Trimble GeoXH 6000 summit and spot height bwlch)

 

 

Pt. 503.9m

Summit Height:  503.9m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 77606 62581 (Trimble GeoXH 6000)

Bwlch Height:  c 487m (interpolation)

Bwlch Grid Reference:  SN 77492 62497 (interpolation)

Drop:  c 17m (Trimble GeoXH 6000 summit and interpolated bwlch)

Dominance:  3.35% (Trimble GeoXH 6000 summit and interpolated bwlch)

 

 

Esgair Llyn Du

Summit Height:  532.8m (LIDAR)

Summit Grid Reference:  SN 76930 62044 (LIDAR) (summit relocation)

Bwlch Height:  513.8m (LIDAR)

Bwlch Grid Reference:  SN 76942 61196 (LIDAR)

Drop:  19.0m (LIDAR) (500m Sub-Twmpau deletion)

Dominance:  3.57% (LIDAR)

 

 

For further details please consult the Trimble Survey Spreadsheet