Sunday, 16 July 2017

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

Bryn Mawr (SJ 251 190) – Lesser Dominant reclassified to Dominant

There has been a reclassification to the listing of Y Trechol – The Dominant Hills of Wales; resulting in this hill being reclassified from a Lesser Welsh Dominant to a Dominant hill.  With the criteria for inclusion to the Dominant list being those Welsh P30 hills whose prominence equal or exceed half that of their absolute height.

The details relating to this hill’s inclusion as a Dominant hill are retrospective as its reclassification was dependent upon a survey with the Trimble GeoXH 6000 which was conducted on the 8th August 2015, with its details appearing in the Carnedd Wen group of hills when published on the Mapping Mountains site on the 3rd June 2017.

Prior to this hill’s inclusion as a Dominant hill it was listed as a Lesser Welsh Dominant hill with 49.13% Dominance based on an estimated c 173m summit height and an estimated bwlch height of c 88m, which gave this hill c 85m of drop.  The bwlch height was later revised to 88m based on the spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website; this revision did not alter this hill’s Dominance value.

The hill is listed in the Carnedd Wen group and is placed in the Region of North Wales (Region A, Sub-Region A4) with its Cardinal Hill being Y Golfa (SJ 182 070), and is situated above the B 4393 road which is to its north and east and the A 483 road to its south-east, and has the Montgomery Canal to its east and the Afon Efyrnwy (River Vyrnwy) to its north, and is positioned between the small communities of Llansantffraid-ym-Mechain to the west north-west, Llanymynech to the north-east, Four Crosses to the east south-east and Ardllin (Arddleen) towards the south.

As the hill is not a part of designated open access land permission to visit should be sought, with the nearest public footpath situated to the north-east of the summit, which consists of overgrown undergrowth and trees.

The name of the hill is Bryn Mawr and it qualifies for Dominant status based on the survey with the Trimble GeoXH 6000 resulting in a summit height of 178.1m (converted to OSGM15) which when coupled with its 88m bwlch spot height gives this hill 90m of drop and 50.53% Dominance.

The full details for the hill are:

Group:  Carnedd Wen

Name:  Bryn Mawr

Dominance:  50.53%

OS 1:50,000 map:  126

Summit Grid Reference:  SJ 25117 19054

Summit Height:  178.1m (converted to OSGM15)

Drop Summit to Bwlch:  90m

Drop Bwlch to ODN:  88m 

Bryn Mawr (SJ 251 190) now reclassified to a Dominant hill

Myrddyn Phillips (July 2017)

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