Mapping Mountains – Significant Name Changes – 100m Twmpau

Tregrug (ST 363 974)

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 confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Tregrug (ST 363 974)

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 with 30m minimum drop, with an accompanying sub list entitled the 100 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 hill is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and it is encircled by minor roads with the Afon Wysg (River Usk) and the A449 road further to the east, and has the town of Brynbuga (Usk) towards its north north-east.

The hill originally appeared in the 100m P30 list on Geoff Crowder’s v-g.me website under the name of Llangibby Castle, which is a name that appears near the summit of this hill on contemporary Ordnance Survey 1:25,000 Explorer maps.

 

Llangibby Castle

110c

ST364974

171

152

During my early hill listing I paid little regard to name placement on the map, or the meaning of names and to what feature the name was appropriately applied to.  Therefore I prioritised names for listing purposes that I now understand are either inappropriate or where another name is viewed as being more appropriate, and as the name of Llangibby Castle refers to an inanimate object I consulted historic Ordnance Survey maps for a more appropriate Welsh name for this hill.

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.  In the case of this hill it is the series of Ordnance Survey Six-Inch maps that record the name of Tregrug, which online research substantiates as an alternate name that can be used for this hill.

Extract from the series of Ordnance Survey Six-Inch maps

Therefore the name this hill is now listed by in the 100m Twmpau is Tregrug, and this was derived from the series of Ordnance Survey Six-Inch maps and substantiated by online research. 

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Tregrug

Previously Listed Name:  Llangibby Castle

 

OS 1:50,000 map:  171

Summit Height:  109.9m (LIDAR)

Summit Grid Reference:  ST 36359 97425 (LIDAR)

Bwlch Height:  77.1m (LIDAR)

Bwlch Grid Reference:  ST 36147 97477 (LIDAR) 

Drop:  32.8m (LIDAR)

Myrddyn Phillips (August 2019)