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

 

Pt. 353.6m (SJ 249 539) – 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 location, the drop and status of the hill derived from detail on contemporary maps produced from Ordnance Survey data and from LIDAR analysis and a subsequent Trimble GeoXH 6000 survey  conducted by Myrddyn Phillips.

LIDAR image of Pt. 353.7m (SJ 249 539)

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 hill is being listed by the point (Pt. 353.6m) notation as an appropriate name for it either through local enquiry and / or historic research has not been found by the author, and it is adjoined to the Moel y Gamelin group of hills, which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with minor roads to its north, east and south and has the B5430 road to its west and farther afield the A525 road to its south, and has the village of Bwlchgwyn towards the east 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 Hills to be surveyed sub list that accompanied the main P30 list, as it was considered not to meet the criteria then used for the main P30 category. 

After the P30 lists were standardised, and interpolated heights and drop values also included, this hill was listed with an estimated c 31m of drop based on the 353m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger map and which is positioned at SJ 251 543 and an estimated c 322m bwlch height based on interpolation of 5m contouring that appear 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. 

LIDAR analysis resulted in the confirmation of this hill’s summit relocation and as the summit of this hill 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 Pt. 353.6m (SJ 249 539)

Therefore, the reclassification of this hill from Sub-Trichant status is due to LIDAR summit analysis and a subsequent Trimble GeoXH 6000 survey and detail on contemporary maps produced from Ordnance Survey data, resulting in a 353.6m summit height and an estimated c 322m bwlch height, with these values giving this hill an estimated c 32m of drop, which is sufficient for it to be classified as a Trichant.

 

The full details for the hill are: 

Group:  Moel y Gamelin 

Name:  Pt. 353.6m 

OS 1:50,000 map:  117

Summit Height:  353.6m (converted to OSGM15, Trimble GeoXH 6000)  

Summit Grid Reference:  SJ 24997 53989 (Trimble GeoXH 6000) 

Bwlch Height:  c 322m (interpolation) 

Bwlch Grid Reference:  SJ 24041 53999 (interpolation) 

Drop:  c 32m (Trimble GeoXH 6000 summit and interpolated bwlch) 

 

Myrddyn Phillips (January 2021)