Friday, 6 March 2020

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

Foel Caledeiriau (SH 838 668) – 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 13th May 2017.

The name the hill is listed by is Foel Caledeiriau and it is adjoined to the Rhos group of hills which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned with the B5113 road to its west and the A548 road to its south and its east, and has the town of Llanrwst towards the south-west.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s 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. 

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

When the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-assessed using the Ordnance Survey 1:25,000 Explorer map and the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map.  The latter mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill is had a 293m spot height on the area of the bwlch, this spot height also appears on the Magic Maps website, and when coupled with the 318m summit height that appears as a spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map gives this hill 25m of drop.

Extract from the Magic Maps website

Therefore, the addition of this hill to Sub-Trichant status is due to detail derived from contemporary maps produced from Ordnance Survey data, resulting in a 318m summit height and a 293m bwlch height, with these values giving this hill 25m of drop, which is sufficient for it to be classified as a Sub-Trichant.

The full details for the hill are:

Group:  Rhos

Name:  Foel Caledeiriau

OS 1:50,000 map:  116

Summit Height:  318m (spot height)

Summit Grid Reference:  SH 83897 66863 (spot height)

Bwlch Height:  293m (spot height)

Bwlch Grid Reference:  SH 83762 67171 (spot height)

Drop:  25m (spot heights)

Myrddyn Phillips (March 2020)

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