Mapping Mountains – Significant Name Changes – Y Trichant – The 300m Hills of Wales

 

Pen Llwyn Uchel (SN 517 387) 

There has been a Significant Name Change to a hill that is listed in the Y Trichant – The 300m Hills of Wales, 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 Pen Llwyn Uchel (SN 517 387)

The criteria for the list that this name change applies to are:

Y Trichant – The 300m Hills of Wales – Welsh hills at or above 300m and below 400m in height that have 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant, with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips with the Introduction to the list and the renaming of it appearing on Mapping Mountains on the 13^th May 2017, and the Introduction to the Mapping Mountains publication of the list appearing on the 1^st January 2022. 

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The hill is adjoined to the Mynydd Pencarreg group of hills, which are situated in the south-western part of South Wales (Region B, Sub-Region B1), and it is positioned with a minor road to its immediate north, the A485 road to its west and the B4337 road to its east, and has the town of Llanybydder towards the north. 

Extract from the Ordnance Survey 1:25,000 Explorer map

The hill appeared in the original 300m height band of Welsh P30 hills published on Geoff Crowder’s v-g.me website as a twin top, under the name of Mynydd Llanllwni/Pen Llwyn-uchel, with the prioritised summit and name given to the 381m map heighted hill positioned at SN 512 383.

Mynydd Llanllwni/ Pen LLwyn-uchel

381m

SN512383

146

186

Two tops of same height.

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. 

Extract from the Ordnance Survey 1:50,000 Landranger map

The summit height produced by LIDAR analysis is 383.45m positioned at SN 51750 38783 and SN 51757 38784, with LIDAR giving 380.7m positioned at SN 51229 38380 for the old prioritised summit.

Therefore, the name this hill is now listed by in the Y Trichant – The 300m Hills of Wales is Pen Llwyn Uchel and this was derived from the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and is being used in preference to that of Mynydd Llanllwni as LIDAR has now split what were once listed as twin tops that have the same 1:25,000 Explorer map height and the individual name of Pen Llwyn Uchel is preferred to the name of Mynydd Llanllwyni which takes in both summits. 

 

The full details for the hill are: 

Group:  Mynydd Pencarreg 

Name:  Pen Llwyn Uchel 

Previously Listed Name:  Mynydd Llanllwni/Pen Llwyn-uchel 

OS 1:50,000 map:  146

Summit Height:  383.45m (LIDAR)                                                           

Summit Grid Reference:  SN 51750 38783 & SN 51757 38784 (LIDAR) 

Bwlch Height:  359.6m (LIDAR) 

Bwlch Grid Reference:  SN 52370 38728 (LIDAR) 

Drop:  23.8m (LIDAR) 

 

Myrddyn Phillips (September 2023)