Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

Pt. 872.3m (SH 658 577) – Welsh Highland Sub deletion 

There has been a deletion 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 and subsequently confirmed by a Trimble GeoXH 6000 survey, both conducted by Aled Williams. 

LIDAR image of Pt. 872.3m (SH 658 577)

The criteria for the list that this deletion 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 hill is being listed by the point (Pt. 872.3m) notation and it is adjoined to the Glyder Fawr group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with the A5 road to its north and the A4086 road to its south, and has the village of Capel Curig towards the east.

When the initial P10 sub list was completed in June 2020 this hill was listed with an estimated c 10m of drop, based on an 873m summit height and an estimated c 863m bwlch height, and therefore included as a Welsh Highland Sub when the drop value of the subs was agreed upon and revised in July 2020. 

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 Trimble GeoXH 6000 gathering data on Pt. 872.3m (SH 658 577).  Photo: Aled Williams

LIDAR analysis gave this hill under 10m of drop required for it to be classified as a Welsh Highland Sub, and as this hill had now been surveyed with the Trimble GeoXH 6000, it is this result that is being prioritised for this hill.

Therefore, the deletion of this hill from Welsh Highland Sub status is due to LIDAR analysis and subsequently confirmed by a Trimble GeoXH 6000 survey, resulting in an 872.3m summit height and an 867.0m bwlch height, with these values giving this hill 5.3m of drop, which is insufficient for it to be classified as a Welsh Highland Sub. 

 

The full details for the hill are: 

Group:  Glyder Fawr

Name:  Pt. 872.3m

OS 1:50,000 map:  115

Summit Height:  872.3m (LIDAR)

Summit Grid Reference:  SH 65867 57758 (LIDAR)

Bwlch Height:  867.0m (LIDAR)

Bwlch Grid Reference:  SH 65876 57793 (LIDAR)   

Drop:  5.3m (LIDAR) 

 

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 (July 2023)