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

Castell (SN 585 789) 

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, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

The view from the summit of Castell (SN 585 789)

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. 

The 30-99m 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 which 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 Elenydd group of hills which are situated in the central part of the Mid and West Wales Region (Region B, Sub-Region B2), and it is positioned with the coast to its west, the Afon Ystwyth to its east and the A487 road farther to its east, and has the town of Aberystwyth towards the north. 

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

The hill appeared in the original 30-99m Welsh P30 list on Geoff Crowder’s v-g.me website under the name of Y Castell, with an accompanying note stating; Name from ring and bailey at summit.

Y Castell

73m

SN585790

135

213

Name from ring and bailey at summit

 

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 historic 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 was entitled the Interactive Coverage Map, and the interactive mapping on the Magic Maps and WalkLakes websites.  Two of the historic maps now available online are the Draft Surveyors map and the Ordnance Survey One-Inch ‘Old Series’ map and it is these maps that form the basis for the compositional change in this hill’s listed name. 

The Draft Surveyor 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 shows the name as Castell, without the use of the definite article Y. 

Extract from the Ordnance Survey Draft Surveyors map

The One-Inch ‘Old Series’ map was the first map that Ordnance Survey had published and this 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 time frame 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 shows the name as Castell, without the use of the definite article Y. 

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

Therefore, the name this hill is now listed by in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales is Castell and the composition and confirmation of its name was derived from the Ordnance Survey Draft Surveyors map and the One-Inch ‘Old Series’ map. 

 

The full details for the hill are: 

Group:  Elenydd 

Name:  Castell

Previously Listed Name:  Y Castell 

OS 1:50,000 map:  135

Summit Height:  77.2m (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference:  SN 58516 78997 (Trimble GeoXH 6000) 

Bwlch Height:  42.3m (LIDAR) 

Bwlch Grid Reference:  SN 58197 78954 (LIDAR) 

Drop:  34.9m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

Dominance:  45.21% (Trimble GeoXH 6000 summit and LIDAR bwlch) 

 

Myrddyn Phillips (April 2021)