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 1^st 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)