Mapping Mountains – Hill Reclassifications – Y Trechol – The Dominant Hills of Wales

Pen y Graig Fawr (SN 773 996) – Lesser Dominant deletion

There has been a deletion from the listing of Y Trechol – The Dominant Hills of Wales initiated by a survey with the Trimble GeoXH 6000, resulting in this hill being deleted from the Lesser Dominant list. 

The criteria for this listing are:

Y Trechol – The Dominant Hills of Wales - Welsh P30s whose prominence equal or exceed half that of their absolute height, with the criteria for Lesser Dominant status being those additional Welsh P30s whose prominence is 33% or more and below 50% of their absolute height.

This hill’s deletion from Lesser Dominant status was dependent upon a survey with the Trimble GeoXH 6000 which was conducted by Myrddyn Phillips on the 29^th October 2017, with the relevant post giving the survey details appearing on Mapping Mountains on the 31^st December 2017.

Prior to the survey with the Trimble GeoXH 6000 this hill was prioritised as being listed as a Lesser Dominant over its twin 217m map heighted summit of Copa Shon which is positioned at SN 78108 99347.  The survey with the Trimble separated these twin map heighted tops and resulted in the deletion of Pen y Graig Fawr and the addition of Copa Shon to Lesser Dominant status.

The name of the hill is Pen y Graig Fawr and it is adjoined to the Pumlumon range of hills which are situated in Mid and West Wales (Region B, Sub-Region B2).  The hill overlooks the A 489 road to the north and the Afon Dulas which is to the south, with the town of Machynlleth to the west north-west. 

As the summit of the hill is not on designated open access land permission to visit should be sought, however the land to the south of the summit is a part of open access land and comes very close to the high point of the hill, because of this common sense should prevail for those wishing to visit its summit.

The deletion of Pen y Graig Fawr from Lesser Dominant status was confirmed by a survey with the Trimble GeoXH 6000, resulting in a summit height of 216.8m (converted to OSGM15) and a bwlch height of 182.4m (converted to OSGM15), and as this hill is 0.50m lower than Copa Shon (SN 781 993) it gives Pen y Graig Fawr 34.4m of drop and 15.88% Dominance, which is insufficient for its continued inclusion in the Lesser Dominant list.

The full details for the hill are:

Group:  Pumlumon

Name:  Pen y Graig Fawr

Dominance:  15.88%

OS 1:50,000 map:  135

Summit Grid Reference:  SN 77352 99601

Summit Height:  216.8m (converted to OSGM15)

Drop Summit to Bwlch:  34.4m

Drop Bwlch to ODN:  182.4m (converted to OSGM15) 

Pen y Graig Fawr (SN 773 996) is now deleted from the ranks of Lesser Dominant hills

For details on the survey that resulted in the deletion of this hill from Lesser Dominant status

Myrddyn Phillips (January 2018)