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

Cefn Cwm Brwyno (SN 716 810) – 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 Cefn Cwm Brwyno, and it is adjoined to the Banc Llechwedd Mawr group of hills, which are situated in the northern part of South Wales (Region B, Sub-Region B1), and it is positioned with the A44 road to its north and a minor road to its south, and has the village of Ponterwyd towards the 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.

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 24m of drop, based on the 365m summit spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map and an estimated c 341m bwlch height, based on interpolation of 10m contouring between 340m – 350m. 

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

One of the mapping resources now available online is the WalkLakes website which hosts an interactive map originated from the Ordnance Survey Open Data programme.  This map has many spot heights not on other publicly available maps and the 365m spot height is also given on the summit area of this hill. 

Extract from the interactive mapping hosted on the WalkLakes website

Another of the mapping resources now available online is the Magic Maps website which hosts an interactive map originated from Ordnance Survey data.  This mapping also showed a 365m spot height on the summit area of this hill. 

Extract from the interactive mapping hosted on the Magic Maps website

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 365m summit height and an estimated c 341m bwlch height, with these values giving this hill as estimated c 24m of drop, which is sufficient for it to be classified as a Sub-Trichant. 

 

The full details for the hill are: 

Group:  Banc Llechwedd Mawr 

Name:  Cefn Cwm Brwyno 

OS 1:50,000 map:  135

Summit Height:  365m (spot height)                                                           

Summit Grid Reference:  SN 71662 81007 (spot height) 

Bwlch Height:  c 341m (interpolation) 

Bwlch Grid Reference:  SN 71773 80790 (interpolation) 

Drop:  c 24m (spot height summit and interpolated bwlch) 

 

Myrddyn Phillips (January 2023)