Monday, 29 May 2017

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

Pt. 258m (SH 647 065) – Lesser Dominant addition

There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales which has resulted in this hill being added to the Lesser Welsh Dominant list.  The criteria for inclusion in this category of sub list is those Welsh P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The details relating to this hill’s inclusion as a Lesser Welsh Dominant hill are retrospective as it appeared in the Tarennydd group of hills when published on the Mapping Mountains site on the 3rd December 2016.

The hill did not appear in the original listing of Y Trechol – The Dominant Hills of Wales as bwlch contours on Ordnance Survey maps of the day implied that the drop for the hill was only c 81m, with this based on the 258m summit spot height and an estimated bwlch height of 177m based on interpolation of bwlch contouring between 170m – 180m, these values would give the hill 31.40% Dominance which is insufficient for it to qualify for this sub list.

The hill is listed in the Tarennydd group and is placed in the Region of North Wales (Region A, Sub-Region A3) with its Cardinal Hill being Foel Wyllt (SH 624 042), and it is situated with the village of Abergynolwyn to its east and it rises above Dyffryn Dysynni and the Afon Dysynni which are to its north-west.

The hill is adjacent to Craig yr Aderyn (Bird’s Rock) and makes a good small circuit with its lower heighted neighbour, with both summits situated on designated open access land and public footpaths connecting with their summits from the valleys towards the north, west and east.

The hill is being listed under the point (Pt. 258m) notation as I do not know an appropriate name for it either from local enquiry or historical research, and it qualifies for Lesser Welsh Dominant status based on the 171m bwlch spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website, this when coupled with its 258m summit spot height gives the hill 87m of drop and 33.72% Dominance.


The full details for the hill are:

Group:  Tarennydd

Name:  Pt. 258m

Dominance:  33.72%

OS 1:50,000 map:  124

Summit Grid Reference:  SH 64705 06587

Summit Height:  258m

Drop Summit to Bwlch:  87m

Drop Bwlch to ODN:  171m 

Myrddyn Phillips (May 2017)

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