Mapping Mountains – Significant Name Changes – 100m Twmpau

 

Cefn Gweirog (SN 677 935) 

There has been a Significant Name Change to a hill that is listed in the 100m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Cefn Gweirog (SN 677 935)

The criteria for the list 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.  The list is authored by Myrddyn Phillips, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

100m Twmpau by Myrddyn Phillips

The hill is adjoined to the Banc Llechwedd Mawr group of hills, which are situated in the northern part of South Wales (Region B, Sub-Region B1), and it is positioned with the A487 road to its north-west and a minor road to its south, and has the town of Machynlleth towards the north-east.

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the main P30 list under the invented and transposed name of Mynydd Cefn-gweirog, with an accompanying note stating; Name from wood to the North.

Mynydd Cefn-gweirog

170c

SN678935

135

23

Name from wood to the North

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 the name of a wood and put the word Mynydd in front of it.  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 669 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 a part of Cefn Gweirog farm in the apportionments, with the details on the Tithe map appearing in the parish named as Llanfihangel Genau’r Glyn and in the county named as Cardigan. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the 100m Twmpau is Cefn Gweirog, and this was derived from the Tithe map. 

 

The full details for the hill are:

Group:  Banc Llechwedd Mawr

Name:  Cefn Gweirog

Previously Listed Name:  Mynydd Cefn-gweirog   

OS 1:50,000 map:  135

Summit Height:  169.3m (LIDAR) 

Summit Grid Reference:  SN 67771 93522 (LIDAR) 

Bwlch Height:  126.3m (LIDAR) 

Bwlch Grid Reference:  SN 67844 93344 (LIDAR) 

Drop:  43.0m (LIDAR) 

 

Myrddyn Phillips (July 2025)