Mapping Mountains – Summit Relocations – 30-99m Twmpau and Y Trechol - The Dominant Hills of Wales

Graig Wen (SH 397 947) 

There has been a Summit Relocation to the listing of 30-99m Twmpau (thirty welsh metre prominences and upward), with the hill also listed in Y Trechol - The Dominant Hills of Wales.  This is the first post under this heading and the summit relocation was initiated by a survey with the Trimble GeoXH 6000 with the following details being retrospective as the Trimble survey that resulted in this summit relocation was conducted on 7^th September 2014.

The survey was conducted in the north of Ynys Môn on a fine and bright day on a grouping of three excellent hills in the company of Alex Cameron, with the hill situated north-eastward of the small town of Cemaes, with the nearest major road to the hill being the A 5025 which is 1km directly south of its summit.

The name of the hill is Graig Wen, and its summit position used to be listed beside its trig pillar on a small rock outcrop at SH 398 947 which is within a small continuous 90m ring contour on current Ordnance Survey maps.

Its new summit position is approximately 80 metres westward from its trig pillar and is the top of a large boulder which is prominent when approaching the hill from the west.  This position has no uppermost 90m ring contour given it on current Ordnance Survey maps.

The full details for the hill are:

Cardinal Hill:  Mynydd Twr

Summit Height:  91.3m (converted to OSGM15, Trimble GeoXH 6000)

Name:  Graig Wen

OS 1:50,000 map:  114

Summit Grid Reference (New Position):  SH 39734 94739 (Trimble GeoXH 6000) 

  

Drop:  49.6m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

Dominance:  54.33% (Trimble GeoXH 6000 summit and LIDAR bwlch)

The Trimble GeoXH 6000 gathering data at the new summit position of Graig Wen, with the old position for the summit next to the hill's trig pillar in the background on the left of the photo

For details on the survey that relocated the summit of this hill please click {here}

Myrddyn Phillips (September 2014)