Mapping Mountains – Significant Name Changes – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Craig Dan y Rhiw (SS 708 940)

There has been a Significant Name Change to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, its location, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Craig Dan y Rhiw

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

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m 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, with the Introduction to the Mapping Mountains publication of this list appearing on the 3^rd December 2015.

The hill is adjoined to the Fforest Fawr group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C2), and it is positioned with the Crymlyn Bog to its north-west, the Tennant Canal and the A483 road to its south, the B4290 road to its east and the M4 to its north-east, and has the town of Castell-nedd (Neath) towards its north-east.

The hill originally appeared in the 30-99m P30 list on Geoff Crowder’s v-g.me website under a partly invented, transposed and directional name of Jersey Marine Hill West Top, with an accompanying note stating; Name from district to the South-East. 

Jersey Marine Hill West Top

89m

SS708941

170

165

Name from district 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 or as in this instance transpose the name of what I presumed to be a district and add the words Hill and West Top to 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

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.  Both of these maps name a small crag on the upper southern slopes of this hill as Craig Dan y Rhiw and as it is appropriate in listing terms to use the name of a main named feature for that of the hill, it is this name that this hill is now listed by.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website

Therefore the name this hill is now listed by in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales is Craig Dan y Rhiw, and this was derived from the series of Ordnance Survey Six-Inch maps and the Ordnance Survey Vector Map Local hosted on the Geograph website, and which is entitled the Interactive Coverage Map.  With the latter mapping only becoming publicly available after the original Welsh P30 lists were published on Geoff Crowder’s v-g.me website.

The full details for the hill are:

Group:  Fforest Fawr

Name:  Craig Dan y Rhiw

Previously Listed Name:  Jersey Marine Hill West Top

 

OS 1:50,000 map:  170

Summit Height:  88.4m (LIDAR)

Summit Grid Reference:  SS 70808 94060 (LIDAR)

Bwlch Height:  50.6m (LIDAR)

Bwlch Grid Reference:  SS 70934 94360 (LIDAR) 

Drop:  37.8m (LIDAR)

Dominance:  42.73% (LIDAR)

Myrddyn Phillips (April 2019)