Monday, 11 May 2020

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


Ffridd Fawr (SH 914 642) – 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 detail on contemporary Ordnance Survey maps.

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 13th May 2017.

The name the hill is listed by is Ffridd Fawr and this was derived from the Tithe map, and it is adjoined to the Mynydd Hiraethog group of hills which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the B5384 road to its north-west, the A543 road to its south and the A544 road to its east, and has the village of Llansannan towards the 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 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 list. 

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-evaluated and it was listed with an estimated c 29m of drop, based on a 317m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger map and an estimated c 288m bwlch height, with the latter based on interpolation of 10m contouring between 280m – 290m.

Extract from the Ordnance Survey 1:50,000 Landranger map

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and showed a 318m spot height on the summit area of this hill.  This spot height is also shown on Ordnance Survey data that appears on the Magic Maps website, and when coupled with the c 288m bwlch height gives this hill c 30m of drop.

Extract from the Magic Maps website

Therefore, the reclassification of this hill from Sub-Trichant status is due to detail derived from contemporary maps produced from Ordnance Survey data, resulting in a 318m summit height and a c 288m bwlch height, with these values giving this hill c 30m of drop, which is sufficient for it to be classified as a Trichant.


The full details for the hill are:

Group:  Mynydd Hiraethog

Name:  Ffridd Fawr

OS 1:50,000 map:  116

Summit Height:  318m (spot height)

Summit Grid Reference:  SH 91406 64254 (hand-held GPS via DoBIH)

Bwlch Height:  c 288m (interpolation)

Bwlch Grid Reference:  SH 91154 63416 (interpolation)

Drop:  c 30m (spot height summit and interpolated bwlch)


Myrddyn Phillips (May 2020)







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