Thursday, 28 December 2017

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


Y Gaer (SO 013 873) – Lesser Dominant deletion

There has been a deletion from the listing of Y Trechol – The Dominant Hills of Wales confirmed by a survey with the Trimble GeoXH 6000 and later substantiated by a survey with the Leica GS15, 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.

The details relating to this hill’s deletion from the Lesser Dominant list are retrospective as the confirmation was dependent upon a survey with the Trimble GeoXH 6000 which was conducted by Myrddyn Phillips on the 7th February 2014, the summit result was later substantiated by a survey with the Leica GS15 which was conducted by John Barnard, Graham Jackson and Myrddyn Phillips on the 2nd May 2014.

Prior to the survey with the Trimble GeoXH 6000 this hill was prioritised as being listed as a Lesser Dominant over its twin 308m map heighted summit of Gelli Hir which is positioned at SN 99903 88383.  The survey with the Trimble separated these twin map heighted tops and resulted in the deletion of Y Gaer, and the addition of Gelli Hir to Lesser Dominant status.

The name of the hill is Y Gaer 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 470 road and the Afon Hafren (River Severn) which is to its east, with the small community of Llandinam at the base and to the north-east of the hill and the town of Llanidloes towards the west south-west.  

As the summit of the hill is not on designated open access land permission to visit should be sought, however as a public footpath traverses this hill’s elongated and broad summit ridge in a north-east to south-west orientation and passes close to the high point of the hill, common sense should prevail and a diversion to the summit is only a short distance away.

The deletion of Y Gaer from Lesser Dominant status was confirmed by a survey with the Trimble GeoXH 6000 and the summit result was later substantiated by a survey with the Leica GS15, resulting in a summit height of 307.1m (converted to OSGM15) and a bwlch height of 215.8m (converted to OSGM15), which gives this hill 91.4m of drop and 29.74% Dominance, which is insufficient for its continued inclusion in the Lesser Dominant list.


The full details for the hill are:

Group:  Pumlumon

Name:  Y Gaer

Dominance:  29.74%

OS 1:50,000 map:  136

Summit Grid Reference:  SO 01350 87380

Summit Height:  307.1m (converted to OSGM15)

Drop Summit to Bwlch:  91.4m (converted to OSGM15)

Drop Bwlch to ODN:  215.8m 


Y Gaer (SO 013 873) is now deleted from the ranks of Lesser Dominant hills



Myrddyn Phillips (December 2017) 



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