Saturday 13 October 2018

Mapping Mountains – Hill Reclassifications – Welsh Highlands - Uchafion Cymru


THIS HILL HAS SUBSEQUENTLY BEEN RECLASSIFIED TO WELSH HIGHLAND P15 STATUS


Pt. 516.3m (SN 755 621) – Uchaf reclassified to 500m Sub- Uchaf

There has been a reclassification to the listing of Yr Uchafion due to a survey conducted with the Trimble GeoXH 6000 and analysis of bwlch contouring on OS Maps, with the criteria for this list being.

Yr Uchafion – This is the draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height that have a minimum 15m of drop, accompanying the main Yr Uchafion list are three categories of sub hills, with this hill being reclassified from an Uchaf to a 500m Sub-Uchaf, with the criteria for this sub category being all Welsh hills at or above 500m in height that have 14m or more and below 15m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams with the introduction to the list being published on Mapping Mountains in November 2015.

Pt. 516.3m (SN 755 621)

As the authors do not know an appropriate name for the hill it is being listed by the point (Pt. 516.3m) notation and prior to the Trimble GeoXH 6000 survey this hill was listed with 15m of drop, based on the 517m summit and 502m bwlch spot heights that appear on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website

The hill is situated in the Elenydd group of hills which are placed in the Mid and West Wales Region (Region B, Sub-Region B2).  The hill is positioned in relatively remote land for Wales and has the small community of Pontrhydfendigaid towards the north-west and Tregaron towards the west south-west.

As the hill is a part of designated open access land it can be approached from any direction, however for those wishing to do so the hill is immersed in a conifer plantation although its high point is relatively easy to reach via a forest ride.

The reclassification of this hill is reliant upon the survey result produced by the Trimble GeoXH 6000 and interpolation of bwlch contouring on the OS Maps website.  This mapping gives contour intervals at 5m and shows a small 500m ring contour where the 502m spot height appears on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website, data were collected from near this position resulting in a 501.4m height, but when doing so the authors were aware that land to the north-east was judged to be slightly higher and this is what the 5m contouring on OS Maps indicate, and therefore the hill is being listed with a 516.3m summit height and an interpolated bwlch height of c 502m, with these values giving this hill c 14m of drop, which is insufficient for continued Uchaf staus.


Extract from OS Maps

The full details for the hill are:

Group:  Elenydd

Summit Height:  516.3m (converted to OSGM15)

Name:  Pt. 516.3m

OS 1:50,000 map:  146, 147

Summit Grid Reference:  SN 75504 62132  
 
Drop:  c 14m


The Trimble GeoXH 6000 gathering data at the summit of Pt. 516.3m

For the additions, deletions and reclassifications to Yr Uchafion / The Welsh 500m P15s reported on Mapping Mountains please consult the following Change Registers:










Myrddyn Phillips and Aled Williams (October 2018)



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