Mapping Mountains – Hill Reclassifications – Y Trichant – The 300m Hills of Wales

Nercwys Mountain (SJ 214 589) – Sub-Trichant addition

There has been an addition to the list of Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on contemporary maps produced from Ordnance Survey data.

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

Y Trichant – The 300m Hills of Wales – Welsh hills at or above 300m and below 400m in height that have 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant, with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list and the renaming of it appearing on Mapping Mountains on the 13th May 2017.

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The name the hill is listed by is Nercwys Mountain, and it is adjoined to the Moel y Gamelin group of hills, which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is encircled by minor roads and also has the A494 road to its north-west and the A5104 road to its south-east, and has the town of Yr Wyddgrug (Mold) towards the north north-east.

When the original 300m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was not included in the Hills to be surveyed sub list that accompanied the main P30 list, as it was considered not to meet the criteria then used for this sub category. 

After the P30 lists were standardised, and interpolated heights and drop values also included, this hill was listed with an estimated c 21m of drop based on the 378m summit spot height that is adjoined to a triangulation pillar and an estimated c 357m bwlch height, with the latter based on interpolation of 5m contouring between 355m – 360m that appear on the Ordnance Survey 1:25,000 Explorer map.

Extract from the Ordnance Survey 1:25,000 Explorer map

The details for this hill were re-assessed against the mapping on the OS Maps website.  This is the replacement for OS Get-a-map and until recent times had contours at 5m intervals which were proving consistently more accurate compared to the 5m contours that sometimes appear on the Ordnance Survey 1:25,000 Explorer map and used to appear on the online Vector Map Local.  This resulted in its bwlch height remaining the same as an estimated c 357m based on interpolation of 5m contouring between 355m – 360m.

Therefore, the addition of this hill to Sub-Trichant status is due to detail on contemporary maps produced from Ordnance Survey data, resulting in a 378m summit height and an estimated c 357m bwlch height, with these values giving this hill an estimated c 21m of drop, which is sufficient for it to be classified as a Sub-Trichant.

The full details for the hill are:

Group:  Moel y Gamelin

Name:  Nercwys Mountain

OS 1:50,000 map:  117

Summit Height:  378m (triangulation pillar)

                                                           

Summit Grid Reference:  SJ 21444 58981 (triangulation pillar)

Bwlch Height:  c 357m (interpolation)

Bwlch Grid Reference:  SJ 21176 58854 (interpolation)

Drop:  c 21m (triangulation pillar summit and interpolated bwlch)

Myrddyn Phillips (November 2020)