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

Pt. 413m (SO 105 018) – 400m Sub-Pedwar reclassified to 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.

Pt. 413m (SO 105 018).  Photo image from Google 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 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 hill is being listed by the point (Pt. 413m) 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 Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and it is positioned with minor roads to its north, east and south, with the B4255 road to its south-west, the A4054 road and the A470 road further to its west and the A469 road further to its east, and has the town of Merthyr Tudful towards the north-west.

When the 1^st edition of the Y Pedwarau was published by Europeaklist in May 2013, this hill was listed as a 400m Sub-Pedwar with an estimated c 29m drop, based on the 413m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 384m bwlch height based on interpolation of 10m contouring between 380m – 390m.

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

The details for this hill were 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 re-assessment resulted in the hill being listed with an estimated c 31m of drop, based on interpolation of 5m bwlch contouring between 380m – 385m.

Extract from the OS Maps website

The details for this hill were also examined using the largest scale interactive map hosted on the Geograph website; this mapping shows a 414m spot height on the summit area of this hill and a 382m spot height on the narrow road just above where interpolation places the critical point of this hill’s bwlch.  These values have not been taken in the listed heights and drop for this hill, but are more evidence that it meets the required minimum 30m of drop to qualify for Pedwar status.

Summit extract from the interactive map hosted on the Geograph website

Bwlch extract from the interactive map hosted on the Geograph website

Therefore, the reclassification of this hill from 400m Sub-Pedwar to Pedwar status is due to re-assessment of detail on contemporary Ordnance Survey maps, resulting in a 413m summit height and an estimated c 382m bwlch height, with these values giving this hill c 31m of drop which is sufficient for it to be classified as a Pedwar.

The full details for the hill are:

Group:  Cymoedd Gwent

 

Name:  Pt. 413m

OS 1:50,000 map:  171

Summit Height:  413m (spot height)

Summit Grid Reference:  SO 10581 01800 (spot height)

Bwlch Height:  c 382m (interpolation)

Bwlch Grid Reference:  SO 11053 01910 (interpolation)

Drop:  c 31m (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 (May 2020)