Monday, 7 December 2015

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

Pt. 68.2m (SH 383 949) - Dominant reclassified to Lesser Dominant

There has been a reclassification from the listing of Y Trechol – The Dominant Hills of Wales due to a survey with the Trimble GeoXH 6000 and which has resulted in the hill being taken out of the Dominant list and included in The Lesser Welsh Dominant list.  The hill is in the first Group to be published in this new hill list; Ynys Môn, and is situated on the northern coast of the island and positioned to the north-east of the small community of Cemaes.

This Hill Reclassifications notification has awaited the listing of Y Trechol – the Dominant Hills of Wales to begin its publication, but the survey result is retrospective as the Trimble GeoXH 6000 survey that resulted in this hill’s reclassification was conducted on the 7th September 2014 on a beautiful sunny day in the company of Alex Cameron.

The hill can be accessed from its west or east via the Wales Coast Path which goes close to its summit, with its eastern approach on this path being joined by a public footpath that gives access toward the hill from its south-east.  However, if wanting a slightly extended walk this hill can be combined with its neighbours of Dinas Gynfor (SH 391 950) and Graig Wen (SH 397 947).

The hill is unnamed on current Ordnance Survey maps and I do not know a locally known name for it or one of historical relevance and therefore the point (Pt. 68.2m) notation is being used for the hill.
The hill had been listed with 50.75% of Dominance and was therefore included in the main Dominant list.  This was based on it having a 67m summit spot height on the Ordnance Survey enlarged mapping hosted on the Geograph website and an estimated bwlch height of c 33m based on bwlch contouring between 30m – 35m, these values gave the hill a prominence of c 34m, which was enough for it to sneak into the main Dominant list.

The survey with the Trimble GeoXH 6000 resulted in a 68.2m (converted to OSGM15) summit height and a 34.2m (converted to OSGM15) bwlch height, giving this hill a Dominance of only 49.85% and confirming its reclassification from The Dominant Hills of Wales list to The Lesser Welsh Dominant list.

The full details for the hill are:

Group:  Ynys Mon

Name:  Pt. 68.2m

Dominance:  49.85% (Lesser Welsh Dominant status confirmed)

OS 1:50,000 map:  114

Summit Grid Reference:  SH 38337 94993

Summit Height:  68.2m (converted to OSGM15)

Drop Summit to Bwlch:  34.0m

Drop Bwlch to ODN:  34.2m (converted to OSGM15)  

Pt. 68.2m (SH 383 949) now reclassified to the Lesser Welsh Dominant list.

For details on the survey that resulted in this hill being reclassified to a Lesser Welsh Dominant hill please click {here}

Myrddyn Phillips (December 2015)

No comments: