Mapping Mountains – Hill Reclassifications – The Welsh P15s

 

Graig Pen y Bont (SO 349 055) – Welsh Sub-P15 addition

There has been an addition to the list of The Welsh P15s, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Graig Pen y Bont (SO 349 055)

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

The Welsh P15s – Welsh hills with 15m minimum drop, irrespective of their height, with an accompanying sub list entitled the Welsh Sub-P15s, with the criteria for this sub category being all Welsh hills with 14m or more and below 15m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list appearing on Mapping Mountains on the 10^th May 2019. 

The Welsh P15s by Myrddyn Phillips

The name the hill is now listed by is Graig Pen y Bont, and this was derived from the Tithe map, and it is adjoined to the Ysgyryd Fawr group of hills, which are situated in the south-eastern part of South Wales (Region B, Sub-Region B4), and it is positioned with minor roads to its north and east, and the B4598 road to its west, and has the town of Brynbuga (Usk) towards the south-east.

When the listing that became known as The Welsh P15s was being compiled, this hill was not included as with an uppermost 60m contour and bwlch contouring between 50m – 60m that appear on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, it was judged not to meet the criterion for the main P15 or the accompanying P14 sub list. 

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 addition of this hill to Welsh Sub-P15 status is due to LIDAR analysis, resulting in a 70.3m summit height and a 55.9m bwlch height, with these values giving this hill 14.4m 0f drop, which is sufficient for it to be classified as a Welsh Sub-P15. 

 

The full details for the hill are: 

Group:  Ysgyryd Fawr 

Name:  Graig Pen y Bont 

OS 1:50,000 map:  161

Summit Height:  70.3m (LIDAR)                                                           

Summit Grid Reference:  SO 34901 05538 (LIDAR)                                                  

Bwlch Height:  55.9m (LIDAR) 

Bwlch Grid Reference:  SO 34994 05530 (LIDAR) 

Drop:  14.4m (LIDAR) 

 

Myrddyn Phillips (May 2025)