Mapping Mountains – Significant Name Changes – Y Pedwarau – The 400m Hills of Wales

Mynydd Mallaen (SN 722 455) 

There has been a Significant Name Change that is retrospective to a hill listed in 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 a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams. 

Mynydd Mallaen (SN 722 455)

The criteria for the list that this retrospective name change 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 list are five categories of sub hills; 500m Sub-Pedwarau, 500m Double Sub-Pedwarau, 400m Sub-Pedwarau, 390m Sub-Pedwarau and the 390m Double Sub-Pedwarau.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams

The hill is adjoined to the Mynydd Mallaen group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned with a minor road to its north, and has the town of Llanwrtyd towards the east.

The hill appeared in the original Welsh 400m P30 list compiled by Myrddyn Phillips and published on Geoff Crowder’s v-g.me website, under the transposed name of Crugiau Merched, with part of an accompanying note stating; aka Mynydd Mallaen.

Crugiau Merched

462m

SN722455

146/147

187

Marilyn. Clem/Yeaman. Trig pillar at 459m to the North. aka Mynydd Mallaen.

The two names of Crugiau Merched and Mynydd Mallaen are recorded on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.  The former in italicised script indicating it applies to an ancient monument, in this instance the ancient cairns that are situated on the summit area of this hill, including one positioned adjacent to/at its summit, whilst the latter name applies to the mountain itself, which is extensive. 

Extract from the Ordnance Survey 1:50,000 Landranger map

Since the original publication of the Welsh P30 lists on Geoff Crowder’s v-g.me website there have been a number of maps made available online.  Some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website.  Whilst others were digitally updated such as the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites.  Two of the historic maps now available online are the Ordnance Survey Draft Surveyors map which formed the basis for the first publicly available Ordnance Survey One-Inch ‘Old Series’ map. 

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

The One-Inch ‘Old Series’ map was the first map that Ordnance Survey produced, and their publication culminated from the whole of Britain being surveyed between 1791 and 1874 and the detail gathered therein produced at a scale of one inch to the mile and published in sheet format between 1805 and 1874.  The One-Inch ‘Old Series’ maps for the whole of Wales are now available online; they are also available in map format as enlarged and re-projected versions to match the scale and dimensions of the Ordnance Survey 1:50,000 Landranger series and are published by Cassini.  This series of maps form another important part in the study of Welsh upland place-names and bridge the time-frame leading up to the production of the Ordnance Survey base map of the Six-Inch series.  And for an Ordnance Survey map, it is this map that gives a good portrayal of the extensive nature of land the name of Mynydd Mallaen applies to. 

Extract from the Ordnance Survey One-Inch 'Old Series' map

This list is now co-authored by Myrddyn Phillips and Aled Williams and when the 1^st edition of the list was published by Europeaklist in May 2013, the prioritised listed name was changed to Mynydd Mallaen, to reflect that this is the mountain name, in preference to the name recorded for the ancient cairns situated on its summit area.

Therefore, the name this hill is now listed by in the Y Pedwarau – The 400m Hills of Wales is Mynydd Mallaen, and this was derived from a variety of Ordnance Survey maps and confirmed via local enquiry.

 

The full details for the hill are: 

Group:  Mynydd Mallaen 

Name:  Mynydd Mallaen 

Previously Listed Name:  Crugiau Merched 

OS 1:50,000 map:  146, 147 

Summit Height:  460.9m (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference:  SN 72217 45534 (Trimble GeoXH 6000) 

Bwlch Height:  259.2m (converted to OSGM15, Trimble GeoXH 6000) 

Bwlch Grid Reference:  SN 72372 46231 (Trimble GeoXH 6000) 

Drop:  201.7m (Trimble GeoXH 6000) 

 

Myrddyn Phillips and Aled Williams (December 2025)