Mapping Mountains – Hill Reclassifications – Y Pedwarau

Y Foel (SJ 012 016) – 400m Sub-Pedwar deletion

There has been a deletion to the listing of Y Pedwarau due to analysis of data on the Ordnance Survey Vector Map Local, the OS Maps website and the WalkLakes website.

The criteria for the list that this deletion applies to 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 deleted from 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.

The name of the hill is Y Foel, and it is adjoined to the Carnedd Wen group of hills, which are situated in the south-eastern part of North Wales (Region A, Sub-Region A4), and it is encircled by minor roads with the A458 further to its north and the A470 further to its south-west, and has the village of Carno towards the south-west.

Prior to the reassessment of this hill’s details it was listed with c 20m of drop based on the 414m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 394m based on bwlch contouring between 390m – 395m that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map.

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

Since publication of the 1^st edition of Y Pedwarau by Europeaklist in May 2013 there have been a number of Ordnance Survey maps made available online, one of which is housed on the OS Maps website.  This is the replacement for OS Get-a-map and has contours at 5m intervals which are proving consistently more accurate compared to the 5m contours that sometimes appear on Ordnance Survey 1:25,000 Explorer maps and the online Vector Map Local.

Extract from the OS Maps website

Another resource now available online is the WalkLakes website which houses 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 importantly for this hill shows a quarried area to the north of the summit as a depression and not an elevation.  These re-assessments resulted in the hill being listed with an estimated c 18m of drop.

Extract from the WalkLakes website

Therefore, the deletion of Y Foel from 400m Sub-Pedwar status is due to a combination of Ordnance Survey maps, including the Vector Map Local, the OS Maps website and the WalkLakes website, resulting in the hill now being listed with a 415m summit height that appears as a spot height on the Ordnance Survey non-contour Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map and on the WalkLakes website, and an estimated bwlch height of c 397m based on 5m contouring between 395m – 400m on the OS Maps website, with these values giving this hill an estimated c 18m of drop which is insufficient for continued 400m Sub-Pedwar status.

The full details for the hill are:

Group:  Carnedd Wen

 

Name:  Y Foel

OS 1:50,000 map:  136

Summit Height:  415m (Vector Map Local and WalkLakes website)

Summit Grid Reference:  SJ 01221 01629 (spot height)

Bwlch Height:  c 397m (interpolation)

Bwlch Grid Reference:  SJ 01333 01839 (interpolation)

Drop:  c 18m

For the additions, reclassifications and deletions to Y Pedwarau reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers:

Y Pedwarau

Y Pedwarau – 400m Sub-Pedwarau

Y Pedwarau – 390m Sub-Pedwarau

Y Pedwarau – 390m Double Sub-Pedwarau

Myrddyn Phillips and Aled Williams (November 2019)