Mapping Mountains – Summit Relocations – Y Trichant – The 300m Hills of Wales and Y Pedwarau – The 400m Hills of Wales

Banc y Gorlan (SH 922 037) and Cerrig y Tân (SH 917 039)

There has been a Twin Summit Relocation to a hill that is listed in the Y Trichant – The 300m Hills of Wales and the Y Pedwarau – The 400m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on historic and contemporary maps produced from Ordnance Survey data.

This was initiated by Joe Nuttall who produced a summit analysis programme that used LIDAR with an alternative height map (DEM) allowing identification of summits and bylchau and thereby drops.  The resulting spreadsheet that Joe produced contains over 29,600 hills.

This spreadsheet is being evaluated by a number of people, including Ronnie Bowron, who passed the details of this hill to us.

The criteria for the lists this summit relocation affects 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.

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill listed in the 390m Double Sub-Pedwar category.  The criteria for 390m Double Sub-Pedwar status being all Welsh hills at or above 390m and below 400m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams

The prioritised name the hill is listed by is Banc y Gorlan with the new twin summit listed as Cerrig y Tân, and it is adjoined to the Carnedd Wen group of hills which are situated in the southern part of North Wales (Region A, Sub-Region A4), and it is positioned with minor roads to its west and east, and the A470 road to its south, and has the village of Llanbrynmair 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 included in the Hills to be surveyed sub list that accompanied the main P30 list, and listed as Banc y Gorlan with a 396m summit height based on the spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.

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

When the 1^st edition of the Y Pedwarau was published by Europeaklist in May 2013 and the 390m sub categories included, this hill was listed with the same details as above; with a c 29m estimated drop value also given to the hill.  However, it was noted that to the north-west of this summit another 390m contour was shown on contemporary Ordnance Survey maps, this had no spot height and the summit was named Cerrig y Tân.

   

Extract from the Ordnance Survey series of Six-Inch maps

The details for this hill have been re- assessed due to Joe Nuttall’s summit analysis and Ronnie Bowron’s evaluation, with examination of the Ordnance Survey series of Six-Inch maps and mapping available on the WalkLakes website, resulting in the summit of Cerrig y Tân being listed with the same height as Banc y Gorlan.  Although not an individual summit relocation it is still worth documenting under this heading.

Extract from the WalkLakes website

The above detail comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies when the hill’s high point is in a different field, or where a number of potential summit positions are within close proximity and the highest point is not where previously given, or when it is positioned to a different feature such as in a conifer plantation, or when the high point of the hill is placed within a different map contour, or when natural ground or the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist.

Therefore, the listed summit height of this hill remains at 396m and for now the prioritised summit remains Banc y Gorlan positioned at SH 92237 03720, with the new twin summit of Cerrig y Tân positioned at SH 91785 03936.  The summit of Cerrig y Tân is not given a spot height on contemporary Ordnance Survey maps but has a 396m spot height on the WalkLakes map and a 1300ft height on the Ordnance Survey series of Six-Inch maps.

The full details for the hill are:

Group:  Carnedd Wen

Name:  Banc y Gorlan

OS 1:50,000 map:  136

Summit Height:  396m (spot height)

Summit Grid Reference:  SH 92237 03720 (spot height)

Name:  Cerrig y Tân

OS 1:50,000 map:  136

Summit Height:  396m (spot height)

Summit Grid Reference (New Twin Summit):  SH 91785 03936 (spot height)

Bwlch Height:  c 368m (interpolation)

Bwlch Grid Reference:  SH 91788 04224 (interpolation)

Drop:  c 28m (spot height summit and interpolated bwlch)

Myrddyn Phillips and Aled Williams (September 2020)