Mapping Mountains – Hill Reclassifications – Y Trechol – The Dominant Hills of Wales

Foel Caethle (SN 606 986) – Lesser Dominant addition

There has been an addition to the list of the Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Foel Caethle (SN 606 986)

The criteria for the list that this addition applies to are:

Y Trechol - The Dominant Hills of Wales - Welsh P30 hills whose prominence  equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those additional Welsh P30 hills whose prominence is between one third and half that of their absolute height.  The list is authored by Myrddyn Phillips with the Introduction to the start of the Mapping Mountains publication of this list appearing on the 3^rd December 2015, and the list is now available in its entirety on Mapping Mountains in Google Doc format. 

Y Trechol - The Dominant Hills of Wales by Myrddyn Phillips

The name the hill is listed by is Foel Caethle and it is adjoined to the Tarren y Gesail group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), and it is positioned with a minor road to its north and the A493 road to its west and south, and has the town of Tywyn towards the north-west.

After the original 100m height band of Welsh P30 hills published on Geoff Crowder’s v-g.me website were standardised and interpolated heights and drop values also included, this hill was listed with an estimated c 53m of drop, based on the 169m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 116m bwlch height, based on interpolation of 10m contouring between 110m – 120m, with these values giving this hill 31.36% dominance. 

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 addition of this hill to Lesser Dominant status is due to LIDAR analysis, resulting in a 168.8m summit height and a 112.1m bwlch height, with these values giving this hill 56.8m of drop and 33.62% dominance, which is sufficient for Lesser Dominant status. 

 

The full details for the hill are:

Group:  Tarren y Gesail

Name:  Foel Caethle

OS 1:50,000 map:  135

Summit Height:  168.8m (LIDAR)

Summit Grid Reference:  SN 60638 98682 (LIDAR)

Bwlch Height:  112.1m (LIDAR)

Bwlch Grid Reference:  SN 60846 98530 (LIDAR)

Drop:  56.8m (LIDAR)

Dominance:  33.62% (LIDAR)

 

Myrddyn Phillips (September 2024)