Mapping Mountains – Hill Reclassifications – The Welsh P15s

 

Cae Plu (SN 562 035) – Welsh Sub-P15 reclassified to Welsh P15

There has been a reclassification 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 Cae Plu (SN 562 035)

The criteria for the list that this reclassification 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 Cae Plu, and this was derived from the Tithe map, and it is adjoined to the Mynydd Sylen group of hills, which are situated in the southern part of South Wales (Region B, Sub-Region B5), and it is positioned with a minor road to its north, the A4138 road to its south and the M4 motorway to its east, and has the town of Llanelli towards the south-west.

When the listing that became known as The Welsh P15s was being compiled, this hill was included in the accompanying sub list with an estimated c 14m of drop, based on the 106m summit spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, and an estimated c 92m bwlch height based on interpolation of 5m contouring between 90m – 95m. 

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 reclassification of this hill from Welsh Sub-P15 status is due to LIDAR analysis, resulting in a 106.65m summit height and a 91.5m bwlch height, with these values giving this hill 15.15m 0f drop, which is sufficient for it to be classified as a Welsh P15. 

 

The full details for the hill are: 

Group:  Mynydd Sylen 

Name:  Cae Plu 

OS 1:50,000 map:  159

Summit Height:  106.65m (LIDAR)                                                           

Summit Grid Reference:  SN 56249 03517 (LIDAR)                                                  

Bwlch Height:  91.5m (LIDAR) 

Bwlch Grid Reference:  SN 56274 03613 (LIDAR) 

Drop:  15.15m (LIDAR) 

 

Myrddyn Phillips (January 2025)