Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

Craig Yspio (SN 780 831) – 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 derived from LIDAR analysis conducted by Aled Williams and confirmed by a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

Craig Yspio (SN 780 831). (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 Craig Yspio 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 it is positioned with the A44 road to its south-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 either a Welsh Highland P15 or Welsh Highland Sub and therefore remained unclassified, as with only a relatively small uppermost 510m single ring contour and no summit or bwlch spot height, there was little map evidence available to suggest a hill existed that had a sufficient qualifying drop value. 

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

Latterly, when the initial P10 sub list was completed in June 2020, this hill was listed with an estimated c 6m of drop, based on a 513m summit height and an estimated c 507m bwlch height, the latter based on interpolation of 10m contouring between 500m – 510m. 

The interactive DataMapWales gives a better portrayal of the P15 potential of this hill

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 Craig Yspio (SN 780 831)

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 Craig Yspio

The Trimble GeoXH 6000 gathering data at the bwlch of Craig Yspio

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 517.7m summit height and a 502.4m 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:  Craig Yspio

OS 1:50,000 map:  135

Summit Height:  517.7m (converted to OSGM15)

Summit Grid Reference:  SN 78042 83130

Bwlch Height:  502.4m (converted to OSGM15)

Bwlch Grid Reference:  SN 78099 83176   

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:

 

Welsh Highland P15s

 

Welsh Highland Subs

 

Aled Williams and Myrddyn Phillips (June 2023)