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

Pt. 464.2m (SO 133 488) – 400m Sub-Pedwar addition

There has been an addition 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 confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Pt. 464.2m (SO 133 488)

This was initiated by Joe Nuttall who produced a summit analysis programme that used LIDAR with an alternative height map (DEM) allowing identification of summits and bylchau and thereby drops.  The resulting spreadsheet that Joe produced contains over 29,600 hills.

This spreadsheet is being evaluated by a number of people, including Ronnie Bowron, who passed the details of this hill to us.

The criteria for the list that this addition 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 added to the 400m Sub-Pedwar category.  The criteria for 400m Sub-Pedwar status being all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of 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

For now the hill is being listed by the point (Pt. 464.2m) notation, and it is adjoined to the Gwaun Ceste group of hills, which are situated in the eastern part of Mid and West Wales (Region B, Sub-Region B1), and it is positioned with a minor road to its north-east, B4567 and A470 roads to its west and the B4594 road to its south, and has the village of Aberedw towards the west south-west.

When the 1^st edition of the Y Pedwarau was published by Europeaklist in May 2013, this hill was not included as it was listed with an estimated c 19m of drop, based on the 464m summit spot height and an estimated c 445m bwlch height, with the latter based on interpolation of 10m contouring between 440m – 450m that appear on the Ordnance Survey 1:25,000 Explorer map.

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. 

LIDAR summit image of Pt. 464.2m (SO 133 488)

Therefore, the confirmation of the addition of this hill to 400m Sub-Pedwar status is due to LIDAR analysis, resulting in a 464.2m summit height and a 443.4m bwlch height, with these values giving this hill 20.8m of drop which is sufficient for it to be classified as a 400m Sub-Pedwar.

The full details for the hill are:

Group:  Gwaun Ceste  

Name:  Pt. 464.2m

OS 1:50,000 map:  148

Summit Height:  464.2m (LIDAR)

Summit Grid Reference:  SO 13377 48863 (LIDAR)

Bwlch Height:  443.4m (LIDAR)

Bwlch Grid Reference:  SO 12937 48507 (LIDAR)

Drop:  20.8m (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 (October 2020)