Mapping Mountains – Significant Name Changes – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Bryn Glas (ST 307 902)

There has been a Significant Name Change to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, the bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Bryn Glas (ST 307 902)

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

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m 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.

Y Trechol - The Dominant Hills of Wales - Welsh P30 hills whose prominence  equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those additional Welsh P30 hills whose prominence is between one third and half that of their absolute height, with the Introduction to the Mapping Mountains publication of this list appearing on the 3^rd December 2015.

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 encircled by major roads with the A4051 to its west, A4042 to its east and the M4 motorway to its south, and has town of Castell-nedd (Neath) towards its south.  

The hill originally appeared in the 30-99m P30 list on Geoff Crowder’s v-g.me website under a partly transposed and invented name of Brynglas School, with an accompanying note stating; Name from district and school to the South.

Brynglas School

82m

ST308903

171

152

Name from district and school to the South

 

During my early hill listing I thought it appropriate to either invent a name for a hill, or use a name that appeared near to the summit of the hill on Ordnance Survey maps of the day.  My preference was to use farm names and put Pen, Bryn or Moel in front of them or as in this instance transpose the name of what I presumed to be a district and add the word School to it as the summit of this hill is situated within the grounds of the local school.  This is not a practice that I now advocate as with time and inclination place-name data can be improved either by asking local people or by examining historic documents, through this form of research an appropriate name for the hill can usually be found.

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

Since publication of these P30 lists on Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the Vector Map Local hosted on the Geograph website, and which is entitled the Interactive Coverage Map, and it is the series of Ordnance Survey Six-Inch maps that name the area taking in this hill as Bryn Glas, with this name being substantiated on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.

Extract from the series of Ordnance Survey Six-Inch maps

Therefore, the name this hill is now listed by in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales is Bryn Glas, and this was derived from contemporary Ordnance Survey maps and substantiated by the series of Ordnance Survey Six-Inch maps. 

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Bryn Glas

Previously Listed Name:  Brynglas School

 

OS 1:50,000 map:  171

Summit Height:  82.9m (LIDAR)

Summit Grid Reference:  ST 30792 90299 (LIDAR)

Bwlch Height:  36.2m (LIDAR)

Bwlch Grid Reference:  ST 30521 90857 (LIDAR)

 

Drop:  46.7m (LIDAR)

Dominance:  56.32% (LIDAR)

Myrddyn Phillips (September 2019)