Mapping Mountains – Hill Reclassifications – Y Pedwarau

Pt. 486m (SH 774 462) – 400m Sub-Pedwar addition

There has been an addition to the listing of Y Pedwarau due to analysis of data on the OS Maps website, which is the recent replacement for OS Get-a-map.  Y Pedwarau is the title for the list of 400m hills of Wales and takes in all Welsh hills at or above 400m and below 500m in height that have a minimum 30m of drop, the list is co-authored by Myrddyn Phillips and Aled Williams and it commenced publication on Mapping Mountains on the 30.01.17.

Llyn Conwy from Pt. 486m (SH 774 462)

Accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being added to the 400m Sub-Pedwar category.  The criteria for 400m Sub-Pedwar status are all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.

Prior to analysis of data on OS Maps this hill was listed with c 19m of drop based on the 486m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 467m based on interpolation of bwlch contouring between 460m – 470m.

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

The hill is being listed by the point (Pt. 486m) notation until an appropriate name for it can be confirmed, and it is situated in the Arenig range of hills and is placed in the Region of North Wales (Region A, Sub-Region A3).  The hill is positioned between the stream valleys of the Afon Machno to the north-west and the Afon Conwy to the south-east, with Llyn Conwy to its immediate east, and has the small community of Penmachno to its north north-east.

As the summit of the hill is a part of designated open access land it can be approached from a number of directions, with the minor road to its west giving the easiest and most convenient starting point.

The addition of Pt. 486m to 400m Sub-Pedwar status is due to the analysis of data on the OS Maps website.  This mapping gives contour intervals at 5m which has enabled the height of the bwlch to be narrowed down when compared to the 10m contour intervals given on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.  Therefore with a 486m summit spot height on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 466m (based on latest mapping), based on bwlch contouring on OS Maps between 465m – 470m, this hill is now listed with c 20m of drop, which is sufficient for it to be classified as a 400m Sub-Pedwar. 

Extract from OS Maps

The full details for the hill are:

Cardinal Hill:  Graig Goch 

Name:  Pt. 486m

Summit Height:  486m

OS 1:50,000 map:  124

Summit Grid Reference:  SH 774 462

Drop:  c 20m

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 (July 2018)