Mapping Mountains – Hill Reclassifications – The Welsh P15s

Pt. 27.7m (SH 252 818) – 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 Pt. 27.7m (SH 252 818)

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 hill is being listed by the point (Pt. 27.7m) notation as an appropriate name for it either through local enquiry and / or historic research has not been found by the author, and it is adjoined to the Ynys Môn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with a minor road to its immediate north-east and the A5 road to its immediate south-west, and has the town of Caergybi (Holyhead) surrounding it. 

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 the 26m 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 12m bwlch height based on interpolation of 5m contouring between 10m – 15m that appear on the Ordnance Survey 1:25,000 Explorer 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 reclassification of this hill from Welsh Sub-P15 status is due to LIDAR analysis, resulting in a 27.7m summit height and a 12.0m bwlch height, with these values giving this hill 15.7m of drop, which is sufficient for it to be included in the main list of The Welsh P15s. 

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Pt. 27.7m 

OS 1:50,000 map:  114

Summit Height:  27.7m (LIDAR)                                                           

Summit Grid Reference:  SH 25232 81874 (LIDAR) 

Bwlch Height:  12.0m (LIDAR) 

Bwlch Grid Reference:  SH 25327 81236 (LIDAR) 

Drop:  15.7m (LIDAR) 

 

Myrddyn Phillips (May 2021)