Mapping Mountains – Hill Reclassifications – Y Trichant – The 300m Hills of Wales

Mynydd Fforest (SO 094 395) – Trichant addition

There has been an addition to the list of 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 detail produced by Joe Nuttall in his surface analysis progamme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Aled Williams and Myrddyn Phillips. 

Mynydd Fforest (SO 094 395)

The criteria for the list that this addition 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 name the hill is listed by is Mynydd Fforest and it is adjoined to the Mynydd Epynt group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned with a minor road to its west, south and north-east, with the A470 road farther to its east, and has the village of Erwyd (Erwood) towards the north.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included as with a summit height of 400m, based on the spot height adjoined to the triangulation pillar that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map it was included in the 400m height band of Welsh P30 hills that are now known as the Y Pedwarau – The 400m Hills of Wales. 

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

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 63m of drop, based on the 400m summit spot height and an estimated c 337m bwlch height, based on interpolation of 10m contouring between 330m – 340m.

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. 

LIDAR image of Mynydd Fforest (SO 094 395)

Therefore, the addition of this hill to Trichant status is due to LIDAR analysis, resulting in a 399.8m summit height and a 334.9m bwlch height, with these values giving this hill 65.0m of drop, with its height now sufficient for it to be classified as a Trichant. 

 

The full details for the hill are:

Group:  Mynydd Epynt 

Name:  Mynydd Fforest 

OS 1:50,000 map:  161

Summit Height:  399.8m (LIDAR) 

Summit Grid Reference:  SO 09495 39530 (LIDAR) 

Bwlch Height:  334.9m (LIDAR) 

Bwlch Grid Reference:  SO 07943 38253 (LIDAR) 

Drop:  65.0m (LIDAR) 

 

Myrddyn Phillips (August 2023)