Mapping Mountains – Hill Reclassifications – Y Pedwarau – The 400m Hills of Wales

Mynydd Fforest (SO 094 395) – 400m Pedwar reclassified to 390m Sub-Pedwar

There has been a reclassification to the listing of the Y Pedwarau – The 400m 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 reclassification applies to are:

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being reclassified to the 390m Sub-Pedwar category.  The criteria for this sub category being all Welsh hills at or above 390m and below 400m in height that have 30m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams

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 400m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was included in the main P30 list 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. 

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, and these were the values this hill was listed by when the 1^st edition of the Y Pedwarau was published by Europeaklist in May 2013. 

LIDAR summit image of Mynydd Fforest (SO 094 395)

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 Pedwar 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 390m Sub-Pedwar. 

 

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)

 

For the additions, reclassifications and deletions to Y Pedwarau – The 400m Hills of Wales reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers:

 

Y Pedwarau

 

Y Pedwarau – 400m Sub-Pedwarau

 

Y Pedwarau – 390m Sub-Pedwarau

 

Y Pedwarau – 390m Double Sub-Pedwarau

 

Myrddyn Phillips and Aled Williams (July 2023)