Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

 

Whiteford Burrows (SS 448 964) – Double Sub-Twmpau addition 

There has been an addition to the list of Double Sub-Twmpau adjoined to the 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips. 

LIDAR image of Whiteford Burrows (SS 448 964)

The criteria for the list that this addition applies to are:

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, this height band of hills has two accompanying sub lists, the first of which is 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, and the second sub category is entitled the Double Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 20m and below 30m 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

The name the hill is listed by is Whiteford Burrows 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 Whiteford Point and the coast, and has the small community of Llanmadog towards the south. 

When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category. 

Prior to LIDAR analysis this hill was not catalogued as the uppermost contour given it on the Ordnance Survey 1:25,000 Explorer map is 5m, whilst the Ordnance Survey 1:50,000 Landranger map has no contours. 

Extract from the Ordnance Survey 1:50,000 Landranger map

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.  

Therefore, the addition of this hill to Double Sub-Twmpau status is due to LIDAR analysis, resulting in a 29.6m summit height and a 9.2m bwlch height, with these values giving this hill 20.4m of drop, which is sufficient for it to be classified as a Double Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Gŵyr

Name:  Whiteford Burrows

OS 1:50,000 map:  159

Summit Height:  29.6m (LIDAR)

Summit Grid Reference:  SS 44870 96422 (hand-held GPS)

Bwlch Height:  9.2m (LIDAR)

Bwlch Grid Reference:  SS 44631 95701 (LIDAR)   

Drop:  20.4m (LIDAR)

 

Myrddyn Phillips (August 2021)