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

Allt Olmarch (SN 611 542) 

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 LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Allt Olmarch (SN 611 542)

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, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 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 Mynydd Bach group of hills, which are situated in the western part of South Wales (Region B, Sub-Region B1), and it is positioned with minor roads to its north and west, and the A485 road to its south-east, and has the village of Llangybi towards the south.

The hill appeared in the original Welsh 200m P30 list on Geoff Crowder’s v-g.me website, under the prioritised and transposed name of Allt Tan-y-coed, with an accompanying note stating; aka Allt Olmarch.

Allt Tan-y-coed

257m

SN612543

146

199

aka Allt Olmarch. Height from 1985 1:50000 map.

 

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 prioritise a name that appears on the contemporary Ordnance Survey 1:25,000 Explorer map without validating the land area that it applies to.  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 408 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 Olmarch Isaf farm in the apportionments, with the details on the Tithe map appearing in the parish of Betws Bledrws and in the county named as Cardigan. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the 200m Twmpau and Y Trechol – The Dominant Hills of Wales is Allt Olmarch, and this was derived from the contemporary Ordnance Survey 1:25,000 Explorer map and the land area this name applies to validated from the Tithe map. 

 

The full details for the hill are:

Group:  Mynydd Bach

Name:  Allt Olmarch

Previously Listed Name:  Allt Tan-y-coed   

OS 1:50,000 map:  146

Summit Height:  257.1m (LIDAR) 

Summit Grid Reference:  SN 61118 54276 (LIDAR) 

Bwlch Height:  168.1m (LIDAR) 

Bwlch Grid Reference:  SN 59645 54488 (LIDAR) 

Drop:  89.1m (LIDAR) 

Dominance:  34.63% (LIDAR)

 

Myrddyn Phillips (November 2022)