Mapping Mountains – Hill Reclassifications – The Welsh P15s

 

Upper Field (SO 354 059) – Welsh Sub-P15 deletion

There has been a deletion 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 Upper Field (SO 354 059)

The criteria for the list that this deletion 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 Upper Field, 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 a minor road to its immediate south and the B4598 road to its west, and has the town of Brynbuga (Usk) towards the south south-east.

When the listing that became known as The Welsh P15s was being compiled, this hill was included in the P14 sub list with an estimated c 14m of drop, based on an estimated c 106m summit height based on interpolation of the uppermost 105m ring contour, and the 92m bwlch spot height, with both appearing on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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 Sub-P15 status is due to LIDAR analysis, resulting in an 105.4m summit height and a 93.7m bwlch height, with these values giving this hill 11.65m 0f drop, which is insufficient for it to be classified as a Welsh Sub-P15. 

 

The full details for the hill are: 

Group:  Ysgyryd Fawr 

Name:  Upper Field 

OS 1:50,000 map:  161

Summit Height:  105.4m (LIDAR)                                                           

Summit Grid Reference:  SO 35492 05982 (LIDAR)                                                  

Bwlch Height:  93.7m (LIDAR) 

Bwlch Grid Reference:  SO 35620 05997 & SO 35621 05995 (LIDAR) 

Drop:  11.65m (LIDAR) 

 

Myrddyn Phillips (May 2025)