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

The Mount (ST 258 848)

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 derived from the OS Trig Database and the bwlch height derived from interpolation of 5m contouring.

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 with 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.

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.

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 has minor roads to its north-west and north-east and the M4 motorway to its south, and is positioned between the city of Caerdydd (Cardiff) to the south-west and Casnewydd-ar-Wysg (Newport) to the north-east.

The hill originally appeared in the 100m P30 list on Geoff Crowder’s v-g.me website under a transposed name of Pen-y-lan, with an accompanying note stating; Name from buildings to the North-East.

Pen-y-lan

124m

ST253847

171

152

Name from buildings 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 farm.  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 historical 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.  The originally listed summit position of this hill has been relocated and it is the relocated summit that Ordnance Survey 1:25,000 Explorer maps name as The Mount and this name is substantiated from the Ordnance Survey series of Six-Inch maps.

Extract from the Ordnance Survey series of Six-Inch maps

Therefore, the name this hill is now listed by in the 100m Twmpau and Y Trechol – The Dominant Hills of Wales is The Mount, and this was derived from the contemporary Ordnance Survey 1:25,000 Explorer map and substantiated by the Ordnance Survey series of Six-Inch maps.

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  The Mount

Previously Listed Name:  Pen-y-lan 

OS 1:50,000 map:  171

Summit Height:  127m

Summit Grid Reference:  ST 25868 84839

Bwlch Height:  c 66m

Bwlch Grid Reference:  ST 24800 87551 

Drop:  c 61m

Dominance:  48.03%

Myrddyn Phillips (August 2019)