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

Pt. 480m (SH 936 523)

There has been a Summit Relocation to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales, with the summit height and its position confirmed via a spot height on the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map.

The criteria for the list this summit relocation affects are:

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height with 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being listed in the 400m Sub-Pedwar category.  The criteria for 400m Sub-Pedwar status being all Welsh hills at or above 400m and below 500m 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.

As the authors do not know an appropriate name for the hill either through local enquiry or historic research it is being listed by the point (Pt. 480m) notation, and it is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned with the A543 road to its north-west, the A5 road to its south and the B4501 road to its east, and has the village of Cerrigydrudion towards the south south-east.

When the original 400m 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 that accompanied the main P30 list, as it did not meet the criteria then used in this sub category. 

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 a 478m summit height based on the spot height positioned at SH 932 526 that appears on the Ordnance Survey 1:25,000 Explorer map.  This is also the height and position that the summit of the hill was listed in the 1^st edition of Y Pedwarau published by Europeaklist in May 2013.  However, toward the south-east of this position is another large 470m ring contour that did not possess a spot height on any publicly available map of the time.

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

Since publication of the 1^st edition of Y Pedwarau there are a number of Ordnance Survey maps now available online, one is the non-contour Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map.  This map is the recent replacement for a contoured map that had many spot heights not on any other publicly available Ordnance Survey map.  Importantly for this hill the recently available non-contour map shows a 480m spot height where the previously non-spot heighted 470m ring contour is positioned.

Extract from the Ordnance Survey non-contour Vector Map Local hosted on the Geograph website

Another resource now available online is the WalkLakes website which hosts an interactive Ordnance Survey map originated from the Ordnance Survey Open Data programme.  This map has many spot heights not on any other publicly available Ordnance Survey map and shows a 479m spot height close to where the 480m spot height appears on the non-contour Vector Map Local.

Extract from the WalkLakes website

The position of the 480m spot height comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, 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, or when the summit of the hill is in a different field compared to 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 compared to its previous listed position, or when 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.

Therefore, the new summit height for this hill is 480m and is positioned at SH 93640 52330 and appears on the non-contour Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map , this position is not given a spot height on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and is approximately 50 metres south-eastward from where the previously listed 478m summit is positioned and situated in a part of the conifer plantation that is positioned on the northern slopes of this hill.

The full details for the hill are:

Group:  Mynydd Hiraethog

Name:  Pt. 480m

OS 1:50,000 map:  116

Summit Height:  480m (spot height)

Summit Grid Reference (New Position):  SH 93640 52330 (spot height)

Bwlch Height: c 457m (interpolation)

 

Bwlch Grid Reference:  SH 92641 52999 (interpolation)

         

Drop:  c 23m

Myrddyn Phillips and Aled Williams (November 2019)