Tuesday 16 October 2018

Mapping Mountains – Hill Reclassifications – Yr Uchafion


THIS HILL HAS SUBSEQUENTLY BEEN RECLASSIFIED TO WELSH HIGHLAND SUB STATUS


Pt. 526.8m (SN 745 611) – Uchaf addition

There has been an addition 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 once being a candidate for 500m Sub-Uchaf status, 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. 526.8m (SN 745 611)

As the authors do not know an appropriate name for the hill it is being listed by the point (Pt. 526.8m) notation and prior to the Trimble GeoXH 6000 survey this hill was listed with c 13m of drop, based on the 527m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 514m bwlch height based on interpolation of bwlch contouring between 510m – 520m.

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

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), and it is positioned in relatively remote land for Wales and has the small community of Pontrhydfendigaid towards the north-west and Tregaron towards the west.

As the hill is a part of designated open access land it can be approached from any direction, for those wishing to do so an approach from open hillside to the south is probably the most convenient as its eastern slopes are still immersed in conifer plantation.

The addition of this hill to Uchaf status 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 therefore narrows down the interpolated height of the bwlch, this is now estimated to be c 511m based on contouring between 510m – 515m coupled with the result of a Trimble GeoXH 6000 survey taken from near the critical bwlch, this survey produced a 511.9m height, but when doing so the authors judged land to the south-east to be lower on the hill to hill traverse, and therefore this hill is being listed with a 526.8m (converted to OSGM15) summit height and an interpolated bwlch height of c 511m, with these values giving this hill c 16m of drop, which is sufficient for Uchaf staus.

 
Extract from OS Maps

The full details for the hill are:

Group:  Elenydd

Summit Height:  526.8m (converted to OSGM15)

Name:  Pt. 526.8m

OS 1:50,000 map:  146, 147

Summit Grid Reference:  SN 74595 61119  
 
Drop:  c 16m


The Trimble GeoXH 6000 gathering data at the summit of Pt. 526.8m

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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