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

 

Gaer Fawr (SJ 223 129) 

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 a Trimble GeoXH 6000 survey and LIDAR analysis conducted by Myrddyn Phillips.                       

Gaer Fawr (SJ 223 129)

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.  The list is authored by Myrddyn Phillips, 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 Carnedd Wen group of hills, which are situated in the southern part of North Wales (Region A, Sub-Region A2), and it is positioned with minor roads to its north and west, and the B4392 road to its south-east, and has the village of Cegidfa (Guilsfield) towards the south. 

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

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill appeared under the transposed name of Gaer-fawr Hill, which is a prominent name that appears adjacent to the summit of this hill on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.

Gaer-fawr Hill

219m

SJ224130

126

240

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, with little consideration for the meaning of the name and where it was appropriately applied to.  My preference was to use farm names and put Pen, Bryn or Moel in front of them or as in this instance transpose a prominent name that appears adjacent to the hill on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.  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.

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 that was 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.  Two of the historic maps now available online are the Ordnance Survey Draft Surveyors map which formed the basis for the first publicly available Ordnance Survey One-Inch ‘Old Series’ map, and it is these maps along with local enquiry that prompt the change in the listed name of this hill.

The Draft Surveyors maps consist of the preliminary drawings made by the Ordnance Survey surveyors between the 1780s and 1840 and formed the basis for the first publicly available One-Inch map.  They were drawn at scales of six inches to the mile for areas considered of particular military significance and down to two inches to the mile for other areas.  Fair copies were then produced from these preliminary drawings to one inch to the mile and then copper plates were prepared for printing.  The Draft Surveyors maps for the whole of Wales are now available online and they form an important part in the study of Welsh upland place-names as they bridge the time frame between the late 18^th century and the mid-19^th century when the Ordnance Survey produced their first One-Inch maps, and importantly for this hill and its listed name, it is this map that records the name Gaer Fawr adjacent to the summit of this hill. 

Extract from the Ordnance Survey Draft Surveyors 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 also this map that places the name Gaer Fawr adjacent to the summit of this hill. 

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

The intricacies of language and prioritising one in favour of another for listing a hill is fraught with complication, with originating Cymraeg names being anglicised and also originating English names being cymricised, examples such as these are more common in border country and especially so for anglicised forms.  There is no steadfast rule that fits all, but as a standard a name that has its origins in the Welsh language and where this is substantiated by either historic documentation and/or contemporary usage should be prioritised in favour of a contemporary anglicised or English version of the name.  Likewise, if a name exists where an element of it is in English and if this name applies to a hill that is situated in a Welsh speaking part of Wales it is standard practice to use a full Welsh term for the name.  It is also standard practice to use a Welsh name for a hill if another name exists that has originated in a different language.

Therefore, the name this hill is now listed by in the 200m Twmpau and Y Trechol – The Dominant Hills of Wales is Gaer Fawr and this was derived from a variety of sources including the Ordnance Survey Draft Surveyors Map and the Ordnance Survey One-Inch ‘Old Series’ map.  The Hill part of this name that appears on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map is a later addition, with local pronunciation favouring the exclusion of this word with the use of Gaefer being predominant. 

 

The full details for the hill are:

Group:  Carnedd Wen

Name:  Gaer Fawr 

Previously Listed Name:  Gaer Fawr Hill   

OS 1:50,000 map:  126

Summit Height:  217.6m (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference:  SJ 22394 12995 (Trimble GeoXH 6000)               

Bwlch Height:  138.7m (LIDAR) 

Bwlch Grid Reference:  SJ 21991 13145 (LIDAR) 

Drop:  78.9m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

Dominance:  36.26% (Trimble GeoXH 6000 summit and LIDAR bwlch) 

 

Myrddyn Phillips (July 2026)