Mapping Mountains – Significant Name Changes – Yr Uchafion and 500m Twmpau

Yr Allt (SO 056 162)

There has been a Significant Name Change to a hill that is listed in the Yr Uchafion and 500m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill initially determined by LIDAR analysis conducted by Aled Williams and subsequently by a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Willams on the 19^th April 2019.

Yr Allt (SO 056 162) with the Bannau Brycheiniog beyond

The criteria for the two listings that this name change applies to are:

Yr Uchafion – Welsh hills at or above 500m in height with 15m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams, with the Introduction to this list appearing on Mapping Mountains on the 4^th November 2015.

500m Twmpau – Welsh hills at or above 500m and below 600m in height with 30m minimum drop, with an accompanying sub category entitled the 500m Sub-Twmpau consisting of all Welsh hills at or above 500m and below 600m in height with 20m or more and below 30m of drop.  With the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips.

The hill is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and it is positioned with a minor road to its north-west and above the Pentwyn Reservoir to its south-west, and has the towns of Merthyr Tudful to its south and Aberhonddu (Brecon) to its north.

The hill first made an appearance in an unpublished hill list in 1985 when Tony Blackburn listed it as Pant y Creigiau in The 500 Metre Tops of England and Wales.  When this hill was first included in the listings that later became known as Yr Uchafion and the 500m Twmpau it was also listed by this same name.

Hill list authors are prone to list a hill by the name that appears nearest to its summit on contemporary Ordnance Survey maps, with little regard for the meaning of names and to what feature the name is appropriately applied to and little consideration for its local or historic confirmation.  This is not a practice that I now advocate as with time and inclination place-name information can be improved either by historic research and / or local enquiry.  In the case of this hill the name of Pant y Creigiau appears near to the summit on contemporary Ordnance Survey maps. 

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

It was during the compilation of the Yr Uchafion list that I first made place-name enquiries with local farmers, grazers and landowners, and it was during this process that the name of Yr Allt was confirmed as being appropriate for this hill.

Therefore, the name this hill is now listed by in the Yr Uchafion and the 500m Twmpau is Yr Allt and this was derived from contemporary Ordnance Survey maps and confirmed locally as appropriate.

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Yr Allt

Previously Listed Name:  Pant y Creigiau

OS 1:50,000 map:  160

Summit Height:  564.7m (converted to OSGM15)

Summit Grid Reference:  SO 05633 16201

Bwlch Height:  493.5m (converted to OSGM15)

Bwlch Grid Reference:  SO 07090 15748

Drop:  71.2m

For details on the Trimble survey of this hill

Myrddyn Phillips and Aled Williams (August 2019)