Mapping Mountains – Hill Reclassifications – Welsh Highlands - Uchafion Cymru

Foel Wyddon (SN 788 836) - Welsh Highland P15 addition

There has been an addition 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 initially derived from LIDAR analysis conducted by Aled Williams and confirmed by a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams.

Foel Wyddon (SN 788 836).  Photo: Aled Williams

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

The name the hill is listed by is Foel Wyddon and it is adjoined to the Pumlumon group of hills, which are situated in the north-western part of South Wales (Region B, Sub-Region B1), and is positioned with the A44 road to its south and east, and has the village of Ponterwyd towards the 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 Sub and therefore remained unclassified with analysis of contemporary Ordnance Survey mapping giving an estimated c 13m of drop, based on the 535m summit spot height that appears on the 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 522 bwlch height, based on interpolation of 10m contouring between 520m - 530m.   

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

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 summit and bwlch of this hill have subsequently been surveyed with the Trimble GeoXH 6000, and it is this result that is being prioritised for this hill.

The Trimble GeoXH 6000 gathering data at the summit of Foel Wyddon

The Trimble GeoXH 6000 gathering data at the bwlch of Foel Wyddon

Therefore, the addition of this hill to Welsh Highland P15 status is due to LIDAR analysis and  subsequently confirmed by a Trimble GeoXH 6000 survey, resulting in a 536.2m summit height and a 520.9m bwlch height, with these values giving this hill 15.3m of drop, which is sufficient for it to be classified as a Welsh Highland P15.  

The full details for the hill are:

Group:  Pumlumon

Name:  Foel Wyddon

OS 1:50,000 map:  135

Summit Height:  536.2m (converted to OSGM15)

Summit Grid Reference:  SN 78813 83668 

  

Bwlch Height:  520.9m (converted to OSGM15)

Bwlch Grid Reference:  SN 78783 83858

Drop:  15.3m

For the additions, deletions and reclassifications to the Welsh Highlands – Uchafion Cymru reported on Mapping Mountains please consult the following Change Registers:

The Welsh 500m P15s (Yr Uchafion)

The Welsh 500m P15s (Yr Uchafion) – 500m Subs

The Welsh 500m P15s (Yr Uchafion) – 490m Subs

The Welsh 500m P15s (Yr Uchafion) – Double Subs

Myrddyn Phillips and Aled Williams (May 2017)