Mapping Mountains – Significant Name Changes – 100m Twmpau and Y Trechol – The Dominant Hills of Wales

Bolton Beacon (SM 917 112) 

There has been a Significant Name Change to a hill that is listed in the 100m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill derived from detail produced by Joe Nuttall in his surface analysis progamme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Myrddyn Phillips. 

LIDAR image of Bolton Beacon (SM 917 112)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height that have 30m minimum drop, with an accompanying sub list entitled the 100m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 100m and below 200m 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 100m Twmpau by Myrddyn Phillips

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.  The list is authored by Myrddyn Phillips with the Introduction to the start of the Mapping Mountains publication of this list appearing on the 3^rd December 2015, and the list is now available in its entirety on Mapping Mountains in Google Doc format. 

Y Trechol - The Dominant Hills of Wales by Myrddyn Phillips

The hill is adjoined to the Garn Fawr group of hills, which are situated in the south-western part of South Wales (Region B, Sub-Region B1), and it is positioned encircled by minor roads, with the B4327 road farther to its north-west and the A4076 road farther to its east, and has the village of Johnston towards the east south-east.

The hill appeared in the original Welsh 30-99m P30 list on Geoff Crowder’s v-g.me website, under the transposed name of Boltonhill, with an accompanying note stating; Name from settlement to the North-East.

Boltonhill

110m

SM917112

157/158

36

Trig pillar. Name from settlement to the North-East.

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 a small community and use it for that of the hill.  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 that was hosted on the Geograph website and which was entitled the Interactive Coverage Map.  One of the historic maps now available is the Ordnance Survey One-Inch ‘Old Series’ map and it is this map that formed the basis for the change in the listed name of this hill. 

Extract from the Ordnance Survey One-Inch 'Old Series' map

The One-Inch ‘Old Series’ map was the first map that Ordnance Survey produced, and their publication culminated from the whole of Britain being surveyed between 1791 and 1874 and the detail gathered therein produced at a scale of one inch to the mile and published in sheet format between 1805 and 1874.  The One-Inch ‘Old Series’ maps for the whole of Wales are now available online; they are also available in map format as enlarged and re-projected versions to match the scale and dimensions of the Ordnance Survey 1:50,000 Landranger series and are published by Cassini.  This series of maps form another important part in the study of Welsh upland place-names and bridge the timeframe leading up to the production of the Ordnance Survey base map of the Six-Inch series, and importantly for this hill and its listed name, it is this map that uses this name and places it close to the summit of the hill.

Therefore, the name this hill is now listed by in the 100m Twmpau and Y Trechol – The Dominant Hills of Wales is Bolton Beacon, and this was derived from the Ordnance Survey One-Inch ‘Old Series’ map. 

 

The full details for the hill are:

Group:  Garn Fawr

Name:  Bolton Beacon

Previously Listed Name:  Boltonhill 

OS 1:50,000 map:  157, 158

Summit Height:  113.4m (LIDAR) 

Summit Grid Reference:  SM 91710 11288 (LIDAR) 

Bwlch Height:  66.8m (LIDAR) 

Bwlch Grid Reference:  SM 89719 12333 & SM 89721 12333 (LIDAR) 

Drop:  46.7m (LIDAR) 

Dominance:  41.13% (LIDAR) 

 

Myrddyn Phillips (September 2023)