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

Ffridd Bryn Helen (SH 967 518) – Sub-Trichant addition

There has been confirmation of 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 confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Ffridd Bryn Helen (SH 967 518)

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.

The name the hill is listed by is Ffridd Bryn Helen, and it is adjoined to the Mynydd Hiraethog group of hills which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the B4501 road to its west and the B5105 road to its south-east, and has the village of Llanfihangel Glyn Myfyr 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 that accompanied the main P30 list, as it was considered not to meet the criteria then used for this sub category. 

When 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 c 23m of drop, based on the 388m summit spot height and an estimated c 365m bwlch height, based on interpolation of bwlch contouring between 360m – 370m that appears on the Ordnance Survey 1:50,000 Landranger and 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.

Therefore, the confirmation of the addition of this hill to Sub-Trichant status is due to LIDAR analysis, resulting in a 387.5m summit height and a 363.9m bwlch height, with these values giving this hill 23.6m of drop, which is sufficient for it to be classified as a Sub-Trichant.

The full details for the hill are:

Group:  Mynydd Hiraethog

Name:  Ffridd Bryn Helen

OS 1:50,000 map:  116

Summit Height:  387.5m (LIDAR)

Summit Grid Reference:  SH 96717 51883 (LIDAR)

Bwlch Height:  363.9m (LIDAR)

Bwlch Grid Reference:  SH 96841 51697 (LIDAR)

Drop:  23.6m (LIDAR)

Myrddyn Phillips (July 2020)