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

Coedcae Mawr (ST 036 958) – Trichant reclassified to Sub-Trichant

There has been a reclassification 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 initially confirmed by Joe Nuttall who produced a summit analysis programme using LIDAR, and then by LIDAR analysis initially conducted by Jim Bloomer and subsequently by Myrddyn Phillips. 

LIDAR image of Coedcae Mawr (ST 036 958)

The criteria for the list that this reclassification 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. 

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

The name the hill is listed by is Coedcae Mawr and this was derived from the Tithe map, and it is adjoined to the Cymoedd Morgannwg group of hills, which are situated in the central part of South Wales (Region C, Sub-Region C2), and it is encircled by minor roads with the A4233 road further to its west and the A4059 road and the A470 road further to its east, and has the town of Pontypridd towards the south-east. 

When the original 300m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was included in the main P30 list with an estimated summit height of c 360m. 

When the P30 lists were standardised, and interpolated heights and drop values also included, this hill was listed with an estimated c 44m of drop based on the estimated c 360m summit height and an estimated c 316m bwlch height, with both heights based on interpolation of 10m contouring that appear on the Ordnance Survey 1:25,000 Explorer map.  With its adjacent hill positioned at ST 041 961 listed with a 354m summit height based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map. 

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

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

Both summits have now been analysed via LIDAR.  The result produced by LIDAR analysis gives this hill a 361.4m summit height and as this is lower than the 363.0m adjacent summit positioned at ST 04179 96153, their respective bylchau are swapped.

Therefore, the reclassification of this hill to Sub-Trichant status is due to LIDAR analysis, resulting in a 361.4m summit height and a 333.3m bwlch height, with these values giving this hill 28.1m of drop, which is insufficient for it to be classified as a Trichant.

 

The full details for the hill are: 

Group:  Cymoedd Morgannwg 

Name:  Coedcae Mawr 

OS 1:50,000 map:  170

Summit Height:  361.4m (LIDAR)                                                           

Summit Grid Reference:  ST 03647 95811 (LIDAR) 

Bwlch Height:  333.3m (LIDAR) 

Bwlch Grid Reference:  ST 03865 96007 (LIDAR) 

Drop:  28.1m (LIDAR)

 

Myrddyn Phillips (December 2020)