Saturday 29 December 2018

Mapping Mountains – Significant Height Revisions – Y Pellennig – The Remotest Hills of Wales


Whiteford Burrows (SS 448 964)

There has been a Significant Height Revision to a hill that now appears in the Y Pellennig – The Remotest Hills of Wales list due to LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips.

LIDAR image of Whiteford Burrows

The criteria for the list that this significant height revision applies to are:

Y Pellennig – The Remotest Hills of Wales - Welsh hills whose summit is at least 2.5km from the nearest paved public road and the hill has a minimum 15m of drop, the list is a joint compilation between Myrddyn Phillips and Aled Williams and is available as a downloadable e-booklet or print-booklet version on Mapping Mountains Publications with the up-to-date master list available on the Mapping Mountains site in Google Doc format.

The name of the hill 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.

As the hill is a part of designated open access land it can be approached from any direction, for those wishing to visit the Wales Coast Path approaches the hill from the south and follows land close to the coast and heads toward Whiteford Point, and the summit of the hill is only a short distance from this long distance path.

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.  LIDAR gives a summit height of 28.3m, and this comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

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

The term Significant Height Revisions applies to any listed hill whose interpolated height and Ordnance Survey or Harvey map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000 or analysis of data produced via LIDAR, also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble or by LIDAR analysis.  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 revisions.

Therefore, this hill’s new summit height is 29.6m and this was produced by LIDAR analysis, this is 24.6m higher than the uppermost 5m contour on the Ordnance Survey 1:25,000 Explorer map, however this new height is in accordance with the 5m contouring on OS Maps. 
 
LIDAR summit image of Whiteford Burrows
ills of Wales, and are reproduced below@


The full details for the hill are:

Group:  Gŵyr

Name:  Whiteford Burrows

OS 1:50,000 map:  159

Summit Height (New 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)

Remoteness:  2.925km


Myrddyn Phillips and Aled Williams (December 2018)





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