Thursday, 9 March 2017

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


Carreg Rhoson (SM 672 256) - Dominant addition

There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales due to detail included on the Ordnance Survey enlarged mapping hosted on the Geograph website.  This has resulted in the hill being added to the Dominant list.  With the criteria for inclusion to this 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 it was added to the list shortly after its initial compilation was completed with the date of 31st October 2012 given against its details.

Prior to this hill being listed as a P30 and its inclusion as a Dominant hill it had remained unclassified, as the uppermost 30m ring contour on the Ordnance Survey 1:25,000 Explorer map had not been spotted.

The hill is in the Pembrokeshire Islands group of hills and is placed in the Region of Mid and West Wales (Region B, Sub-Region B4) and is situated 5.175km from the nearest paved public road off the Pembrokeshire coast, and is positioned in the island chain of the Bishops and Clerks.

The name of the hill is Carreg Rhoson and this is also the name given to a number of adjacent islets, it is included as a Dominant hill as the Ordnance Survey enlarged mapping hosted on the Geograph website has greater scale and definition when compared to the smaller scaled and publicly available Ordnance Survey maps, and therefore its uppermost 30m ring contour is easier to see, and as this hill is also an island its c 30m summit height also gives it 100.00% Dominance.


The full details for the hill are:

Group:  Pembrokeshire Islands

Name:  Carreg Rhoson

Dominance:  100.00%

OS 1:50,000 map:  157

Summit Grid Reference:  SM 67235 25678

Summit Height:  c 30m

Drop Summit to Bwlch:  N/A

Drop Bwlch to ODN:  N/A 


The island chain of Carreg Rhoson with the new Dominant hill (SM 672 256) being the highest point on the right of this photograph


Myrddyn Phillips (March 2017)





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