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

Cwm Faerdy Bank (SO 078 695) – Sub-Trichant reclassified to Trichant

There has been confirmation of 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 derived from initial LIDAR analysis and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips.

Cwm Faerdy Bank (SO 078 695)

The criteria for the listing 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, 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 Cwm Faerdy Bank, and this was derived from local enquiry, and it is adjoined to the Hirddywel group of hills, which are situated in the northern part of South Wales (Region B, Sub-Region B2), and it is positioned with the Clywedog Brook to its west and the Afon Ieithon (River Ithon) to its east, and has the small community of Abaty Cwm-hir (Abbeycwmhir) towards the north-west. 

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill appeared in the accompanying Hills to be surveyed sub list as it was considered not meet the criteria then used for the main P30 list.

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 30m of drop, based on the 302m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 372m bwlch height, based on interpolation of bwlch contouring between 270m – 280m.  These details were re-examined when the Ordnance Survey Vector Map Local hosted on Geograph website and which was entitled the Interactive Coverage Map became available online and the drop value was amended to an estimated c 31m.

LIDAR image of Cwm Faerdy Bank (SO 078 695)

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.

The Trimble GeoXH 6000 gathering data at the summit of Cwm Faerdy Bank

As the summit and bwlch of this hill have now been surveyed with the Trimble GeoXH 6000, it is these details that are prioritised for this hill. 

The Trimble GeoXH 6000 gathering data at the bwlch of Cwm Faerdy Bank

Therefore, the confirmation of the reclassification of this hill from Sub-Trichant status is due to a Trimble GeoXH 6000 survey, resulting in a 302.3m summit height and a 269.9m bwlch height, with these values giving this hill 32.4m of drop, which is sufficient for it to be classified as a Trichant. 

The full details for the hill are:

Group:  Hirddywel

Name:  Cwm Faerdy Bank

OS 1:50,000 map:  136, 147

Summit Height:  302.3m (converted to OSGM15)

Summit Grid Reference:  SO 07842 69512

Bwlch Height:  269.9m (converted to OSGM15)

Bwlch Grid Reference:  SO 08304 69664

Drop:  32.4m

Myrddyn Phillips (December 2018)