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

 

Foel Dryll (SH 942 379) – Sub-Trichant addition

There has been 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 detail on contemporary maps produced from Ordnance Survey data. 

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 Foel Dryll and this was derived from the Ordnance Surveys series of Six-Inch maps and it is adjoined to the Arenig group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A3), and it is positioned with the A4212 road to its west and the A494 road to its south, and has the town of Y Bala towards the south-west. 

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. 

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 20m of drop, based on the 345m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 325m bwlch height based on interpolation of 10m contouring between 320m – 330m. 

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

The details for this hill were subsequently re-assessed against the mapping on the OS Maps website.  This is the replacement for OS Get-a-map and until recent times had contours at 5m intervals which were proving consistently more accurate compared to the 5m contours that sometimes appear on the Ordnance Survey 1:25,000 Explorer map and used to appear on the online Vector Map Local.  This resulted in its bwlch height being listed as an estimated c 324m based on interpolation of 5m contouring between 320m – 325m. 

Therefore, the addition of this hill to Sub-Trichant status is due to detail on contemporary maps produced from Ordnance Survey data, resulting in a 345m summit height and an estimated c 324m bwlch height, with these values giving this hill an estimated c 21m of drop, which is sufficient for it to be classified as a Sub-Trichant. 

 

The full details for the hill are: 

Group:  Arenig 

Name:  Foel Dryll 

OS 1:50,000 map:  125

Summit Height:  345m (spot height)                                                           

Summit Grid Reference:  SH 94261 37960 (spot height) 

Bwlch Height:  c 324m (interpolation) 

Bwlch Grid Reference:  SH 94339 38162 (interpolation) 

Drop:  c 21m (spot height summit and interpolated bwlch) 

 

Myrddyn Phillips (July 2021)