Mapping Mountains – Summit Relocations – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Pwlldu Head (SS 569 865)

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

LIDAR image of Pwlldu Head

The criteria for the two lists that this summit relocation 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 addition Welsh P30 hills whose prominence is 33.33% or more and below 50% 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.

The name of the hill is Pwlldu Head, and it is adjoined to the Gŵyr group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and it is positioned overlooking the south Wales coast, and has the village of Melin y Parc (Parkmill) towards the north-west.

As the summit of the hill is a part of open access land it can be approached from most directions, with the open access land stretching to the north-west and north north-east of the summit and public footpaths approaching this land and that of the summit from the north.

Prior to LIDAR analysis this hill was listed with 35m of drop based on the 97m height given to a triangulation pillar positioned at SS 57003 86690 and the 62m bwlch spot height that appear on the Ordnance Survey 1:25,000 Explorer map, and it is the position of the triangulation pillar that had been listed for that of the summit.

LIDAR summit image of Pwlldu Head

The summit height produced by LIDAR analysis is 97.6m at SS 56933 86561 and its position in relation to that previously given comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist, or when the summit of the hill is in a different field compared to where previously given, or when the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these relocations.

The summit height produced by LIDAR analysis is 97.6m and is positioned at SS 56933 86561, this position is not given a spot height on contemporary Ordnance Survey maps and is approximately 130 metres south south-west from where the 97m spot height adjoined to the triangulation pillar appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.  

The Ordnance Survey Interactive Coverage Map hosted on the Geograph website showing the summit position in relation to where the trig pillar is positioned

 

The full details for the hill are:

Group:  Gŵyr

Name:  Pwlldu Head

OS 1:50,000 map:  159

Summit Height:  97.6m (LIDAR)

Summit Grid Reference (new position):  SS 56933 86561 (LIDAR)

Bwlch Height:  62.2m (LIDAR)

Bwlch Grid Reference:  SS 56191 88507 (LIDAR) 

 

Drop:  35.5m (LIDAR)

Dominance:  36.32% (LIDAR)

Myrddyn Phillips (December 2018)