Mapping Mountains – Significant Height Revisions – Y Pellennig – The Remotest Hills of Wales and Welsh Highlands – Uchafion Cymru

 

Ysgafell Wen (SH 663 487) 

There has been a Significant Height Revision that is retrospective to a hill that is listed in the Y Pellennig – The Remotest Hills of Wales and the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Leica RX1250 survey conducted by Alan Dawson. 

LIDAR image of Ysgafell Wen (SH 663 487)

The criteria for the two listings that this height revision applies to are:

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 a minimum 15m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available as a downloadable e-booklet or print-booklet version on Mapping Mountains Publications with the up-to-date master list available on Mapping Mountains to download in Google Doc format. 

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

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 name the hill is listed by is Ysgafell Wen and it is adjoined to the Moelwyn Mawr group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A2), and it is positioned with the A498 road to its north-west, a minor road to its west and the A470 road to its east, and has the town of Blaenau Ffestiniog towards the south-east. 

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

When the original list that later became known as the Welsh Highlands – Uchafion Cymru was first compiled, this hill was listed with an estimated c 16m of drop, based on a basic levelling survey conducted by John and Anne Nuttall, with the summit height ascertained by the addition of the drop value to the 641m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

LIDAR summit image of Ysgafell Wen (SH 663 487)

However, it was not until a survey with GNSS equipment that an accurate summit height for this hill could be ascertained.  This was conducted by Alan Dawson on the 12.06.17 using a Leica RX1250, resulting in a 659.0m summit height positioned at SH 66384 48768, and this comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revisions applies to any listed hill whose interpolated height and Ordnance Survey or Harvey map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000, the Leica RX1250 or analysis of data produced via LIDAR, also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble, Leica RX1250 or by LIDAR analysis.

Therefore, the new listed summit height of this hill is 659.0m and this was derived from a Leica RX1250 survey, this is 2.0m higher than the previously listed height of c 657m, which was based on a 16m basic levelling survey conducted by John and Anne Nuttall, with the summit height ascertained by the addition of the drop value to the 641m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Moelwyn Mawr

Name:  Ysgafell Wen

OS 1:50,000 map:  115

Summit Height (New Height):  659.0m (converted to OSGM15, Leica RX1250) 

Summit Grid Reference:  SH 66384 48768 (Leica RX1250) 

Bwlch Height:  639.9m (converted to OSGM15, Leica RX1250) 

Bwlch Grid Reference:  SH 66380 48665 (Leica RX1250) 

Drop:  19.1m (Leica RX1250) 

Remoteness:  2.760km

 

Myrddyn Phillips and Aled Williams (February 2026)