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

 

Cefn Mawr (SM 978 352) 

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 LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Cefn Mawr (SM 978 352)

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 Mynydd Preseli group of hills, which are situated in the south-western part of South Wales (Region B, Sub-Region B1), and it is positioned with the B4313 road to its north, the A40 road to its west and a minor road to its south, and has the town of Abergwaun (Fishguard) towards the north-west.

The hill appeared in the original Welsh 100m P30 list on Geoff Crowder’s v-g.me website, under the invented and transposed name of Pen Cronllwyn, with an accompanying note stating; Name from buildings to the South-East.

Pen Cronllwyn

133m

SM978353

157

35

Name from buildings to the South-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.  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

As the summit of this hill comprises bounded land the details for it were examined on the Tithe map.  The term Tithe map is generally given to a map of a Welsh or English parish or township and which was prepared after the 1836 Tithe Commutation Act.  This act allowed tithes to be paid in cash rather than goods.  The Tithe maps gave names of owners and occupiers of land in each parish and importantly for place-name research they also included the name of enclosed land.  This enclosed land is usually based on a field system, however not every field is given a name, but many are and especially so in Wales. 

Extract from the Tithe map

The enclosed land where the summit of this hill is situated is given the number 324 on the Tithe map, this can be cross referenced against the apportionments; it is these apportionments that give the name of the owner or occupier of the land as well as the name of the land.  The land where the summit of this hill is situated is named as Cefn Mawr in the apportionments, with the details on the Tithe map appearing in the parish named Fishguard and in the county named as Pemroke. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the 100m Twmpau and Y Trechol – The Dominant Hills of Wales is Cefn Mawr, and this was derived from the Tithe map. 

 

The full details for the hill are:

Group:  Mynydd Preseli

Name:  Cefn Mawr

Previously Listed Name:  Pen Cronllwyn   

OS 1:50,000 map:  157

Summit Height:  133.9m (LIDAR) 

Summit Grid Reference:  SM 97857 35211 (LIDAR) 

Bwlch Height:  73.6m (LIDAR) 

Bwlch Grid Reference:  SM 97599 34681 (LIDAR) 

Drop:  60.3m (LIDAR) 

Dominance:  45.04% (LIDAR)

 

Myrddyn Phillips (March 2023)