Mapping Mountains – Summit Relocations – The Huws – 100 great Welsh hills under 2,000ft

 

Ynys Llanddwyn (SH 385 626) 

There has been a Summit Relocation to a hill that is listed in the The Huws – 100 great Welsh hills under 2,000ft, with the summit height, bwlch height and their locations and the drop of the hill derived from a Trimble GeoXH 6000 survey and LIDAR analysis.

Ynys Llanddwyn

The criteria for the list that this summit relocation applies to are: 

The Huws – 100 great Welsh hills under 2,000ft.  Outside of each hill being less than 2,000ft (609.6m) in height this list is subjective.  However, there were a number of parameters the authors wanted to meet, these include that the hills should cover the whole length and breadth of Wales and that the list should have the fullest variety of hills, both in height, prominence, geology, history and difficulty.  The contributors to the list are Alex Cameron, John Gillham, Myrddyn Phillips, Adrian Rayner, Mark Trengove and Rob Woodall and it is available on the Haroldstreet website and on Mapping Mountains.   

The Huws - 100 great Welsh hills under 2,000ft

The name the hill is listed by is Ynys Llanddwyn, and it is a tidal island adjoined to the south-western part of Ynys Môn (Anglesey), and is positioned with the A480 road and the village of Niwbwrch (Newborough) towards the north-east. 

When the listing of The Huws was published by the Haroldstreet website and Mapping Mountains in March 2021, the summit of this hill was given to where the Lighthouse is situated at SH 38502 62500 in the south-western part of Ynys Llanddwyn and listed with a 17.4m summit height and a 6.3m bwlch height, with these values giving this summit 11.om of drop. 

LIDAR image of the south-western part of Ynys Llanddwyn

These details have been re-evaluated due to a recent visit from one of the authors, resulting in the listed summit position of this hill being relocated to beside the cross commemorating St Dwynwen which has views north-east to the high point of the island and south-west to the old Huws summit of the Lighthouse.  

The new Huws summit in centre background marked by the cross commemorating St Dwynwen with the old Huws summit incorporating the Lighthouse beyond  

Therefore, the new summit for this hill in The Huws list is positioned at SH 38579 62639, with its height listed as 20.2m.  This position is not given a spot height on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and is approximately 150 metres north-eastward from where the previously listed summit is positioned. 

 

The full details for the hill are:

Name:  Ynys Llanddwyn

OS 1:50,000 map:  114

Summit Height:  20.2m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 38579 62639 (Trimble GeoXH 6000

Bwlch Height:  11.6m (LIDAR)

Bwlch Grid Reference:  SH 38736 62748 (LIDAR) 

Drop:  8.6m (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

Alex Cameron, John Gillham, Myrddyn Phillips, Adrian Rayner, Mark Trengove and Rob Woodall (August 2021)