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

Banc (SN 721 762) – 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 derived from LIDAR analysis and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

Banc (SN 721 762)

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. 

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

The name the hill is listed by is Banc and this was derived from the Tithe map, and it is adjoined to the Elenydd group of hills which are situated in the central part of the Mid and West Wales Region (Region B, Sub-Region B2), and it is encircled by minor roads with farther afield the A4120 road to its north and the B4343 road to its east, and has the village of Pontarfynach (Devil’s Bridge) towards the east north-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. 

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 22m of drop based on the 350m summit spot height and the 328m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map.  The 350m summit spot height is now shown on the interactive mapping available on the Magic Maps website.

Extract from the Magic Maps website

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. 

LIDAR image of Banc (SN 721 762)

LIDAR analysis confirms this hill to have over 20m of drop, and as the summit has now been surveyed with the Trimble GeoXH 6000 it is this result that is being prioritised for listing purposes. 

The Trimble GeoXH 6000 gathering data at the summit of Banc

Therefore, the confirmation of the addition of this hill to Sub-Trichant status is due to LIDAR analysis and a subsequent Trimble GeoXH 6000 summit survey, resulting in a 350.9m summit height and a 329.1m bwlch height, with these values giving this hill 21.7m of drop, which is sufficient for it to be classified as a Sub-Trichant. 

 

The full details for the hill are: 

Group:  Elenydd 

Name:  Banc 

OS 1:50,000 map:  135, 147

Summit Height:  350.9 (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference:  SN 72127 76209 (Trimble GeoXH 6000) 

Bwlch Height:  329.1m (LIDAR) 

Bwlch Grid Reference:  SN 72361 75991 (LIDAR) 

Drop:  21.7m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

 

Myrddyn Phillips (May 2021)