Mapping Mountains – Hill Reclassifications – Y Pedwarau – The 400m Hills of Wales

Pt. 427m (SN 731 497) – Pedwar reclassified to 400m Sub-Pedwar

There has been a reclassification to the listing of 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 contemporary Ordnance Survey maps.

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

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 being reclassified to 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 hill is being listed by the point (Pt. 427m) notation as an appropriate name for it either through local enquiry and / or historic research has not been found by the authors, and it is adjoined to the Elenydd group of hills, which are situated in the northern part of Mid and West Wales (Region B, Sub-Region B2), and is positioned with minor roads to its north, west, south and east, and has the village of Llanddewi Brefi towards the north-west.

When the original 400m 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, as it was considered not to meet the criteria then used for the main P30 list. 

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 an estimated c 30m of drop, based on the 427m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 397m based on interpolation of 10m contouring between 390m – 400m, and the above details were used when the hill was listed in the 1^st edition of the Y Pedwarau published by Europeaklist in May 2013.

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

Since publication of the 1^st edition of Y Pedwarau there are Ordnance Survey maps that are now also available online.  The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps; however the details for this hill remained the same as no additional spot heights appear on this map.

The details for this hill were also re-assessed when the OS Maps website became available online.  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 used to appear on the online Vector Map Local.  This latest re-assessment resulted in the hill being listed with an estimated c 29m of drop, based on interpolation of 5m bwlch contouring between 395m – 400m.

Extract from the OS Maps 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 other publicly available Ordnance Survey maps and for this hill’s summit the 427m spot height also appears in the same position as it does on the Ordnance Survey 1:25,000 Explorer map, however the bwlch contours are between 400m – 410m which if taken would give this hill a lower value that the estimated c 29m of drop.

Extract from the WalkLakes website

Therefore, the reclassification of this hill from Pedwar to 400m Sub-Pedwar status is due to re-assessment of detail on contemporary Ordnance Survey maps, resulting in a 427m summit height and an estimated c 398m bwlch height, with these values giving this hill c 29m of drop which is insufficient for continued classification as a Pedwar.

The full details for the hill are:

Group:  Elenydd 

Name:  Pt. 427m

OS 1:50,000 map:  146, 147

Summit Height:  427m (spot height)

Summit Grid Reference:  SN 73157 49745 (hand-help GPS via DoBIH)

Bwlch Height:  c 398m (interpolation)

Bwlch Grid Reference:  SN 72735 49830 (interpolation)

Drop:  c 29m (spot height summit and interpolated bwlch)

For the additions, reclassifications and deletions to Y Pedwarau – The 400m Hills of Wales 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 (February 2020)