Mapping Mountains – Significant Name Changes – 200m Twmpau and Y Trechol – The Dominant Hills of Wales

 

Pen y Castell (SJ 117 095) 

There has been a Significant Name Change to a hill that is listed in the 200m 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 LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Pen y Castell (SJ 117 095)

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

200m Twmpau - Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m 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. 

200m 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 Esgeiriau Gwynion group of hills, which are situated in the southern part of North Wales (Region A, Sub-Region A3), and it is positioned with a minor road to its north, the B4382 road to its south-west, the B4389 road to its east and the A495 road farther to its north, and has the town of Llanfair Caereinion towards the south south-west.

The hill appeared in the original Welsh 200m P30 list on Geoff Crowder’s v-g.me website, under the invented and transposed name of Bryn Pentre-uchaf, with an accompanying note stating; Name from buildings to the South.

Bryn Pentre-uchaf

207m

SJ117096

125

215/239

Name from buildings 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.  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 the original publication of the Welsh P30 lists on Geoff Crowder’s v-g.me website there have been a number of 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 were digitally updated such as the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites.  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 places the name of Pen y Castell close to the summit of the hill.

Therefore, the name this hill is now listed by in the 200m Twmpau and Y Trechol – The Dominant Hills of Wales is Pen y Castell, and this was derived from the Ordnance Survey One-Inch ‘Old Series’ map. 

 

The full details for the hill are:

Group:  Esgeiriau Gwynion

Name:  Pen y Castell

Previously Listed Name:  Bryn Pentre-uchaf 

OS 1:50,000 map:  125

Summit Height:  206.75m (LIDAR) 

Summit Grid Reference:  SJ 11735 09568 (LIDAR) 

Bwlch Height:  136.2m (LIDAR) 

Bwlch Grid Reference:  SJ 11431 09469 & SJ 11424 09475 (LIDAR) 

Drop:  70.5m (LIDAR) 

Dominance:  34.11% (LIDAR) 

 

Myrddyn Phillips (August 2024)