Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

 

Graig Fach (SH 792 249) – Welsh Highland Sub reinstatement 

There has been a reinstatement 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 a Trimble GeoXH 6000 survey conducted by Aled Williams. 

Graig Fach (SH 792 249)

The criteria for the list that this reinstatement 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

The name the hill is listed by is Graig Fach, and it is adjoined to the Arenig Fawr group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A2), and it is positioned with the A470 road to its west, a minor road to its south-east and the A494 road farther to its south-east, and has the town of Dolgellau towards the south-west. 

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

When the initial P10 sub list was completed in June 2020 this hill was listed with 10.2m of drop, based on a basic levelling survey conducted by Myrddyn Phillips on the 10.04.06, and listed with an estimated c 510m summit height and an estimate c 500m bwlch height, with an accompanying note stating that interpolation indicates an estimated c 501m bwlch height, which would mean this hill not being included as a Welsh Highland Sub.

The hill was subsequently analysed via LIDAR by Aled Williams, resulting in a 511.3m summit height and a 501.4m bwlch height, with these values giving this hill 9.9m of drop, which was insufficient for it to be classified as a Welsh Highland Sub.  However, with the drop value relatively close to the qualifying criterion of 10m this hill was prioritised for a survey with the Trimble GeoXH 6000. 

The Trimble GeoXH 6000 gathering data at the summit of Graig Fach.  Photo: Aled Williams

The Trimble GeoXH 6000 gathering data at the bwlch of Graig Fach.  Photo: Aled Williams

Therefore, the reinstatement of this hill to Welsh Highland Sub status is due to a Trimble GeoXH 6000 survey, resulting in a 511.0m summit height and a 501.0m bwlch height, with these values giving this hill 10.0m of drop, which is sufficient for it to be classified as a Welsh Highland Sub. 

 

The full details for the hill are: 

Group:  Arenig Fawr

Name:  Graig Fach          

OS 1:50,000 map:  124

Summit Height:  511.0m (converted to OSGM15)

Summit Grid Reference:  SH 79262 24920

Bwlch Height:  501.0m (converted to OSGM15)

Bwlch Grid Reference:  SH 79278 24975    

Drop:  10.0m  

 

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 (March 2025)