Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

Tryfan (SH 663 593) – Welsh Highland Sub deletion 

There has been a deletion to the listing of the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Trimble GeoXH 6000 survey conducted by Aled Williams. 

Tryfan (SH 663 593) (Photo: Aled Williams)

The criteria for the list that this deletion applies to are:

Welsh Highlands – Uchafion Cymru – Welsh hills at or above 500m in height with 15m minimum drop, with an accompanying sub list entitled the Welsh Highland Subs, the criteria for which is all Welsh hills at or above 500m in height with 10m or more and below 15m of drop.  This list is authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and the latest update relating to the list published on Mapping Mountains in January 2023.

Welsh Highlands - Uchafion Cymru by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Tryfan and it is adjoined to the Glyder Fawr group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with the A5 road to its north and the A4086 road to its south, and has the village of Capel Curig towards the east south-east.

When the initial P10 sub list was completed in June 2020 this hill was not included.  Revision of the list based on basic levelling surveys conducted by Myrddyn Phillips was completed the following month and this hill was then listed with 10.0m of drop, based on a basic levelling survey conducted on the 01.05.98, and listed with a 910m summit height that appears as a spot height on the Ordnance Survey 1:25,000 Explorer map and a 900m bwlch height, based on the basic levelling survey result compared to the summit spot height.

Extract from the Ordnance Survey 1:25,000 Explorer map

Due to the marginal nature in both listed drop and the accuracy of the surveying method that this was obtained from, this hill was prioritised for a Trimble GeoXH 6000 survey and this has now taken place resulting in its deletion from sub status. 

A precarious position for a survey - Trimble attached to a dog lead and held in situ (Photo: Aled Williams)

Therefore, the deletion of this hill from Welsh Highland Sub status is due to a Trimble GeoXH 6000 survey, resulting in a 910.8m summit height and a 901.6m bwlch height, with these values giving this hill 9.2m of drop, which is insufficient for it to be classified as a Welsh Highland Sub.

 

The full details for the hill are: 

Group:  Glyder Fawr

Name:  Tryfan

OS 1:50,000 map:  115

Summit Height:  910.8m (converted to OSGM15)

Summit Grid Reference:  SH 66393 59332

Bwlch Height:  901.6m (converted to OSGM15)

Bwlch Grid Reference:  SH 66378 59359   

Drop:  9.2m 

 

For the additions, deletions and reclassifications to the Welsh Highlands – Uchafion Cymru reported on Mapping Mountains please consult the following Change Registers:

 

Welsh Highland P15s

 

Welsh Highland Subs

 

Aled Williams and Myrddyn Phillips (March 2023)