Monday, 13 July 2020

Mapping Mountains – Hill Reclassifications – The Welsh Highlands – Uchafion Cymru

Waun Goch (SN 841 943) – 500m Sub-Uchaf 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 confirmed by a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips on the 5th May 2016.

Waun Goch (SN 841 943)

The criteria for the list that this deletion 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 deleted 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.

The name the hill is listed by is Waun Goch and it is adjoined to the Pumlumon group of hills, which are situated in the north-western part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with a minor road to its north and the B4518 to its east, and has the small community of Dylife towards the east.

This hill was not included as a P14 Sub in the original list of Welsh 500m P15s that later became known as Yr Uchafion and latterly as The Welsh Highlands – Uchafion Cymru, as with a c 520m summit height and bwlch contouring between 500m – 510m that appear on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, interpolation suggested that it did not have sufficient drop to be considered for P14 500m Sub-Uchaf status.

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

This hill was subsequently surveyed using a basic levelling staff on the 22nd May 2004 by Myrddyn Phillips, resulting in a 46ft / 14.0m drop value, which was sufficient for it to be classified as a 500m Sub-Uchaf.

However, as the margin of uncertainty applicable to the basic levelling method of surveying over the distance between bwlch and summit of this hill is approximately +/- 1.5m, the hill was prioritised for an accurate GNSS survey.

The Trimble GeoXH 6000 gathering data at the summit of Waun Goch

The Trimble GeoXH 6000 gathering data at the bwlch of Waun Goch

Therefore, the deletion of Waun Goch from 500m Sub-Uchaf status is due to a survey with the Trimble GeoXH 6000, resulting in a 520.8m summit height and a 508.3m bwlch height, with these values giving this hill 12.5m of drop which is insufficient for it to be retained as a 500m Sub-Uchaf.

The full details for the hill are:

Group:  Pumlumon

Name:  Waun Goch

OS 1:50,000 map:  135, 136

Summit Height:  520.8m (converted to OSGM15)

Summit Grid Reference:  SN 84142 94373

Bwlch Height:  508.3m (converted to OSGM15)

Bwlch Grid Reference:  SN 84324 94975 
Drop:  12.5m

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

Aled Williams and Myrddyn Phillips (July 2020)

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