Mapping Mountains – Hill Reclassifications – Major Mountains of Britain and Ireland

Moel Siabod (SH 705 546) – Major addition

There has been an addition to the list of the Major Mountains of Britain and Ireland, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on contemporary Ordnance Survey maps.

Moel Siabod (SH 705 546)

The criteria for the list that this addition applies to are:

The Major Mountains of Britain and Ireland - British and Irish hills that have 600m or more of drop.  This list was first published in a downloadable leaflet format by Europeaklist in February 2010.  Its author; Mark Trengove originally listed 119 qualifying hills, with these comprising 82 hills in Scotland, 25 hills in Ireland, 7 hills in Wales, 4 hills in England and 1 hill in the Isle of Man, with a further five Scottish hills listed that fail to qualify by 10m or less of drop.

The Major Mountains of Britain and Ireland by Mark Trengove

The name the hill is listed by is Moel Siabod, and it is positioned with the A5 road to its north-east, the A4086 road to its north-west and the A498 road to its west, and has the small community of Capel Curig towards its north north-east.

When this list was originally published this hill was not included as it was documented with 595m of drop, based on the 872m summit spot height that is adjoined to a triangulation pillar and the 277m spot height that appears on the area of the bwlch on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.  However, the 277m spot height appears on a road which is above the position of the critical bwlch.

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

Since the original publication of this list there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the old Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map.

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available maps and for this hill it had a 272m bwlch spot height positioned at SH 66071 55625, and when coupled with the 872m summit spot height gave this hill 600m of drop.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website

These details and the prospective addition of this hill to the Majors were conveyed to Mark Trengove; the author of the list in January 2016.  And the addition of this hill to Major status was accepted by the list author and its new classification augmented in to the listing of the Major Mountains of Britain and Ireland in January 2016 increasing the total of qualifying hills to 120. 

The full details for the hill are:

Name:  Moel Siabod

OS 1:50,000 map:  115

OS 1:25,000 map:  18

Summit Height:  872m (trig pillar)

Summit Grid Reference:  SH 70528 54633 (trig pillar)

Bwlch Height:  272m (spot height)

Bwlch Grid Reference:  SH 66071 55625 (spot height)

Drop:  600m (trig pillar summit and spot height bwlch)

Myrddyn Phillips (April 2018)