Mapping Mountains – Hill Reclassifications – Y Pedwarau

Garth Fawr (SO 082 059) – Pedwar addition

There has been an addition to the listing of Y Pedwarau due to detail on OS Maps, which is the recent replacement for OS Get-a-map.  The Y Pedwarau is the title for the list of 400m hills of Wales and takes in all Welsh hills at and above 400m and below 500m in height that have a minimum 30m of drop, the list is a joint compilation between Myrddyn Phillips and Aled Williams and it commenced publication on Mapping Mountains on the 30.01.17.

The name of the hill is Garth Fawr and prior to analysis of contours on the OS Maps website this hill was not listed as it is a relatively recent man-made construction and is the result of waste spoil from the Ffos-y-fran opencast mine that is now considered solid and stable, therefore it does not possess any separate ring contours for the area of its summit on either the Ordnance Survey 1:50,000 Landranger or the 1:25,000 Explorer map.

Garth Fawr is situated in the Y Cymoedd – dwyreiniol range of hills and is placed in the Region of South Wales (Region C, Sub-Region C2).  The hill is positioned between the towns of Merthyr Tudful (Merthyr Tydfil) to its north-west and Rhymni (Rhymney) to its north-east and has the A 465 Heads of the Valleys Road to its north and the A 4060 road to its west.

As the summit of this hill is not a part of designated open access land permission to visit should be sought, for those wishing to do so a minor road to the south would give access to the hill.

Garth Fawr had little natural prominence and is a southerly spur of Twyn y Waun, but due to mining activity its height has increased with the 5m contour intervals on OS Maps giving it three separate uppermost 410m ring contours and a bwlch height of c 376m based on contouring between 375m – 380m, whilst LIDAR analysis conducted by Aled Williams gives the summit height as 388.0m at SO 08521 05968 and the height of the bwlch as 374.8m at SO 08618 06004.  It is apparent that the mine spoil was deposited after the measurement of LIDAR data was taken.  Therefore, as the hill is considered solid and stable these values are sufficient for it to be listed as a Pedwar with c 35m of drop.

The full details for the hill are:

Cardinal Hill:  Twyn y Waun

 

Summit Height:  410m

Name:  Garth Fawr

OS 1:50,000 map:  160

Summit Grid Reference:  SO 082 059

Drop:  c 35m

For the additions, deletions and reclassifications to the Y Pedwarau 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

Garth Fawr (SO 082 059) is now classified as a Pedwar.  Photo: Rob Woodall

Myrddyn Phillips and Aled Williams (January 2018)