Mapping Mountains – Hill Reclassifications – Y Pedwarau – The 400m Hills of Wales

Hergest Ridge (SO 246 557) – Pedwar addition

There has been an addition to the listing of the Y Pedwarau – The 400m Hills of Wales under the classification of National Top status (for details relating to the concept of National Tops see separate post), with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams. 

Hergest Ridge (SO 246 557)

The criteria for the list that this addition applies to are: 

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop.  The list is co-authored byMyrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Hergest Ridge and it is adjoined to the Gwaun Ceste group of hills, which are situated in the eastern part of Mid and West Wales (Region B, Sub-Region B1), and it is positioned with the A44 road to its north-east, the B4594 road to its west and a minor road to its south, and has the small village of Llanfair Llythynwg (Gladestry) towards the west south-west.

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

When the 1^st edition of the Y Pedwarau was published by Europeaklist in May 2013, this hill was not included as the concept of National Tops had not been devised.  The hill was subsequently analysed using contemporary Ordnance Survey maps and LIDAR for height and drop.  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 Hergest Ridge (SO 246 557) 

LIDAR analysis confirms this hill as over 400m in height, and as the summit has now been surveyed with the Trimble GeoXH 6000, it is this result that is being prioritised for listing purposes. 

The Trimble GeoXH 6000 gathering data at the summit of Hergest Ridge (SO 246 557)

Therefore, the confirmation of the addition of this hill to Pedwar status under the National Top classification is due to LIDAR analysis and a subsequent Trimble GeoXH 6000 survey, resulting in a 401.0m summit height and a 269.4m bwlch height, with these values giving this hill 131.7m of drop which is sufficient for it to be classified as a Pedwar. 

 

The full details for the hill are:

Group:  Gwaun Ceste 

Name:  Hergest Ridge

OS 1:50,000 map:  148

Summit Height:  401.0m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 24693 55769 (Trimble GeoXH 6000)

Bwlch Height:  269.5m (LIDAR)

Bwlch Grid Reference:  SO 22053 55707 (LIDAR)

Drop:  131.5m (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

For the additions, reclassifications and deletions to Y Pedwarau – The 400m Hills of Wales reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers:

 

Y Pedwarau

 

Y Pedwarau – 400m Sub-Pedwarau

 

Y Pedwarau – 390m Sub-Pedwarau

 

Y Pedwarau – 390m Double Sub-Pedwarau

 

Aled Williams and Myrddyn Phillips (October 2021)