Mapping Mountains – Hill Reclassifications – The Welsh P15s

 

Y Dinas Ucha (SH 818 826) – Welsh 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 Y Dinas Ucha (SH 818 826)

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 Y Dinas Ucha and this was derived from the Tithe map, and it is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned with the coast to its immediate north-east and the B5115 road to its south-west, and has the town of Llandudno towards the west.

When the listing that became known as The Welsh P15s was being compiled, this hill was included in the main list with an estimated c 15m of drop, based on an estimated c 42m summit height and an estimated c 27m bwlch height, with both heights based on interpolation of 5m contouring. 

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 P15 status is due to LIDAR analysis, resulting in a 41.8m summit height and a 28.2m bwlch height, with these values giving this hill 13.6m 0f drop, which is insufficient for it to be classified as a Welsh P15. 

 

The full details for the hill are: 

Group:  Mynydd Hiraethog 

Name:  Y Dinas Ucha 

OS 1:50,000 map:  116

Summit Height:  41.8m (LIDAR)                                                           

Summit Grid Reference:  SH 81890 82674 (LIDAR)                                                  

Bwlch Height:  28.2m (LIDAR) 

Bwlch Grid Reference:  SH 81903 82535 (LIDAR) 

Drop:  13.6m (LIDAR) 

 

Myrddyn Phillips (December 2024)