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

 

Esgair Nant y Moch (SN 732 827) – 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 Esgair Nant y Moch, 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 a minor road to its north-east and the A44 road to its south, and has the village of Ponterwyd 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.

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 23m of drop, based on the 377m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 354m bwlch height, based on interpolation of 10m contouring between 350m – 360m. 

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

One of the resources recently available online is the mapping on the OS Maps website and the details for this hill were subsequently re-assessed against this mapping.  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 mapping had bwlch contouring between 350m – 355m, with interpolation placing the height of the bwlch as an estimated c 353m, with these contours also represented on other 5m contouring available online. 

Extract from online 5m contouring

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 377m summit height and an estimated c 353m 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:  Esgair Nant y Moch 

OS 1:50,000 map:  135

Summit Height:  377m (spot height)                                                           

Summit Grid Reference:  SN 73201 82748 (spot height) 

Bwlch Height:  c 353m (interpolation) 

Bwlch Grid Reference:  SN 73048 82620 (interpolation) 

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

 

Myrddyn Phillips (January 2023)