Thursday, 26 May 2016

Mapping Mountains – Hill Reclassifications – Yr Uchafion

Graig Fach (SN 821 931) - Uchaf reclassified to 500m Sub-Uchaf

There has been a reclassification of an Uchaf to a 500m Sub-Uchaf due to a survey conducted with the Trimble GeoXH 6000.  Yr Uchafion is the draft title for a list of the Welsh 500m P15s that takes in all hills in Wales at or above 500m that have a minimum of 15m of drop, the list is a joint compilation with Aled Williams.  Details relating to this list were published on the Mapping Mountains site in November 2015.

The hill is situated in the Pumlumon group of hills in the heartland of northern mid Wales and is positioned to the south of Foel Fadian, which is the hill’s Cardinal Hill, and between the towns of Llanidloes to its south-east and Machynlleth to its north-west.  It can be easily accessed from a minor road to its north from where a track leads toward the lake of Glaslyn; the hill is positioned just to the west of this track.  Alternatively an extended route can be devised from its south where a path can be followed above the course of the Afon Hengwm.

The name of the hill is Graig Fach (the) little rock and was surveyed over two days; on 5th May 2016 and 22nd February 2019, both in beautiful early morning sunshine.  Graig Fach has a 514m summit spot height and bwlch contouring between 490m – 500m with a 499m spot height appearing on the Ordnance Survey enlarged mapping on the Geograph website, this latter spot height is positioned on the track and interpolation suggests that it is not positioned where the critical bwlch is situated.

The bwlch consists of moor grass and heather and two data sets were taken on both days,  whilst the summit consists of a small rock and grassy knoll with five data sets taken in all from the area of the summit, resulting in the hill only having 14.7m of drop and therefore below the 15m minimum drop value required to qualify for this list.

This now revises the total of Uchaf hills which will be updated accordingly and the hill is now listed as a 500m Sub-Uchaf.

The full details for the hill are:

Cardinal Hill:  Foel Fadian

Summit Height:  513.5m (converted to OSGM15)

Name:  Graig Fach

OS 1:50,000 map:  135, 136

Summit Grid Reference:  SN 82117 93069

Drop:  14.7m (converted to OSGM15)

The reclassifications to Yr Uchafion / The Welsh 500m P15s reported on Mapping Mountains are ills of wales as follows:


Graig Fach (SN 821 930) now reclassified from an Uchaf to a 500m Sub-Uchaf

Myrddyn Phillips and Aled Williams (May 2016)

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