Sunday 20 October 2019

Mapping Mountains – Hill Reclassifications – Yr Uchafion


Pt. 524.3m (SN 881 163) – 500m Sub-Uchaf reclassified to Uchaf

There has been a reclassification to a hill that is listed in the The Welsh Highlands – Uchafion Cymru, through the results of a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips on the 27th July 2019.

Pt. 524.3m (SN 881 163)

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

The Welsh Highlands – Uchafion Cymru This is the revised draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height with 15m minimum drop.  Accompanying the main list are three sub lists, these are; 500m Sub-Uchaf, 490m Sub-Uchaf and the Double Sub category, with this hill being reclassified from the 500m Sub-Uchaf category, the criteria for which are all Welsh hills at or above 500m in height with 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 and an update relating to the list appearing on Mapping Mountains on the 19th June 2019.

As an appropriate name for the hill has not been substantiated either from local enquiry or historic research it is being listed by the point (Pt. 524.3m) notation, and it is adjoined to the Fforest Fawr group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C2), and is positioned with the A4067 road to its west, and has the village of Abercraf (Abercrave) towards the south-west.

This hill was not included when the original list of Welsh 500m P15s that later became known as Yr Uchafion and latterly as The Welsh Highlands – Uchafion Cymru was compiled, as details on contemporary Ordnance Survey maps of the day indicated that it did not have the minimum of 15m of drop required to be included in this list.

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

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR analysis was conducted by Aled Williams and produced a 524.0m summit height positioned at SN 88113 16370 and a 509.4m bwlch height positioned at SN 87908 16298, giving the hill a drop of 14.6m and thereby confirming its status as a 500m Sub-Uchaf.

Gathering data at the summit of Pt. 524.3m (SN 881 163)

Gathering data at the bwlch of Pt. 524.3m

The summit and bwlch of this hill have now been surveyed by Myrddyn Phillips with the Trimble GeoXH 6000, using the LIDAR summit and bwlch grid references produced by Aled Williams as a guide.  This survey resulted in a 524.3m summit height and a 509.2m bwlch height, with these values giving this hill 15.0m of drop, which is sufficient for it to be reclassified to Uchaf status.


The full details for the hill are:

Group:  Fforest Fawr

Name:  Pt. 524.3m

OS 1:50,000 map:  160

Summit Height:  524.3m (converted to OSGM15)

Summit Grid Reference:  SN 88113 16370

Bwlch Height:  509.2m (converted to OSGM15)

Bwlch Grid Reference:  SN 87908 16298
   
Drop:  15.0m 


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










For details on the survey of this hill

Myrddyn Phillips and Aled Williams (October 2019)



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