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

Coed Llwyn Owen (SN 703 403) – 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 13^th May 2017, and the Introduction to the Mapping Mountains publication of the list appearing on the 1^st January 2022. 

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

The name the hill is listed by is Coed Llwyn Owen and it is adjoined to the Mynydd Mallaen group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned with a minor road to its and south and the A482 road farther to its south-west, and has the town of Llanymddyfri (Llandovery) towards the south-east.

When the original 300m 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. 

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

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 20m of drop, based on the 346m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 326m bwlch height, based on interpolation of 10m contouring between 320m – 330m.

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 346m summit height and an estimated c 326m bwlch height, with these values giving this hill an estimated c 20m of drop, which is sufficient for it to be classified as a Sub-Trichant. 

 

The full details for the hill are: 

Group:  Mynydd Mallaen 

Name:  Coed Llwyn Owen 

OS 1:50,000 map:  146, 147, 160

Summit Height:  346m (spot height)                                                           

Summit Grid Reference:  SN 70382 40319 (spot height) 

Bwlch Height:  c 326m (interpolation) 

Bwlch Grid Reference:  SN 70439 40313 (interpolation) 

Drop:  c 20m (spot height summit and interpolated bwlch) 

 

Myrddyn Phillips (July 2023)