Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

Pt. 590.9m (SH 776 249) – 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 conducted by Aled Williams. 

LIDAR image of Pt. 590.9m (SH 776 249)

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. 590.9m) notation 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 a minor road to its west and south south-east, with the A470 road farther to its west and the A494 road farther to its south-east, and has the town of Dolgellau towards the south-west.

When the initial P10 sub list was completed in June 2020 this hill was listed with an estimated c 9m of drop, based on the 591m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 582m bwlch height, based on interpolation of 10m contouring between 580m – 590m.  However, its status was re-evaluated on the 26.03.22 after an on-site visit and examination of updated 5m contouring and it was subsequently listed as a Welsh Highland Sub with an estimated c 10m of drop. 

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.

Therefore, the deletion of this hill from Welsh Highland Sub status is due to LIDAR analysis, resulting in a 590.9m summit height and a 581.5m bwlch height, with these values giving this hill 9.5m of drop, which is insufficient for it to be classified as a Welsh Highland Sub. 

 

The full details for the hill are: 

Group:  Arenig Fawr

Name:  Pt. 590.9m

OS 1:50,000 map:  124

Summit Height:  590.9m (LIDAR)

Summit Grid Reference:  SH 77617 24963 (LIDAR)

Bwlch Height:  581.5m (LIDAR)

Bwlch Grid Reference:  SH 77711 25065 (LIDAR)   

Drop:  9.5m (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 (August 2023)