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) 

Mapping Mountains – Trimble Surveys – Mynydd Mallaen

 

04.09.21  Mynydd Mallaen (SN 722 455) 

Mynydd Mallaen (SN 722 455)

Many years ago when compiling the original Welsh P30s I remember looking at the two dimensional map profile of Mynydd Mallaen and being amazed at the vast bulk of the hill.  To its south other P30s connect to it and one or two rogue P20s make an appearance on its plateau, but in the main its land mass just comprises one significant hill. 

This hill is complex in nature with a southerly and south-easterly broad ridge descending from its highest point, which is marked by two substantial Bronze Age barrows and an Ordnance Survey triangulation pillar.  These two broad ridges have many undulations, with the Afon Gwenlais forming the central heartland comprising many streams forming its catchment area. 

The whole hill forms the southern extremity of what I know as the Elenydd.  To its north is extensive wilderness with many hills of similar height, broken by conifer plantations, bog and streams.  To its south the land gradually descends to friendlier climes. 

The hill is enclosed by steep sides with its highest point relatively close to its connecting bwlch; which is named Bwlch-y-rhiw.  It was from this bwlch that we headed for the summit. 

Prior to the ascent we had stopped at the bwlch on our way to Aber Bronddu farm and our visit to Banc y Graig (SN 699 452) and Cnepyn Cerrig (SN 706 460), and asked permission to park adjacent to farm buildings comprising large barns.  The permission was duly granted and a detailed route to the summit given us, this matched a route Aled had spotted from aerial maps. 

Leaving the car I followed Aled on a good green quad bike track aiming for a gate and its continuation beside a fence.  The afternoon heat was building but cloud cover gave a semblance of respite.  Across the valley the steep western side of Cnepyn Cerrig stared back at us, this is covered in oak and must be a beautiful sight on a sun drenched autumnal day with colour a plenty. 

As height was gained my energy levels began to plummet, which is starting to get a concern, but I generally know my body and how to pace a taxing walk, but still, this ascent was proving tiring. 

Approaching the plateau

Eventually we left the main quad bike track and veered leftward and continued up following another track on the moor, this crested the plateau near to a rock outcrop.  Here I lay on the ground and ate a banana, rested and tried to enjoy the fact of being on this marvellous hill. 

Approaching the small rock outcrop

Nearing the small rock outcrop

From here it was only a relatively short walk to the first of the two Bronze Age cairns.  This cairn is impressive and can be seen from many a mile away.  When originally built it was 25 metres in diameter and between 4 – 5m in height.  Nowadays it has been refashioned with a modern-day cairn built of its rock to signify its high point and a channel cut through on its western side which some report to be observational in nature toward the near triangulation pillar.  The size of the cairn is similar to its original construction. 

Approaching the summit of Mynydd Mallaen

When faced by such a construction it is always difficult to choose a point to survey as the natural summit could be under the cairn and ground on its periphery would then be lower than the hill’s natural height.  We decided upon two positions to survey, the first on the highest part of the ancient cairn that was solid and stable and had grass growing on it, the second at what was deemed to be the highest part of natural ground on the periphery of the cairn.  The latter was covered in grass and bilberry, but even this was seemingly atop part of the rock forming the lower part of the cairn. 

The first of two data sets gathered at the summit of Mynydd Mallaen

During data collection Aled headed off to investigate the other large cairn which has now been hollowed out to incorporate a wind shelter.  We stayed on top for about 20 minutes collecting the two data sets, and sitting at the base of the southerly cairn, resting, eating and talking.  By the time we set off back down the hill a cloud bank had pushed in from the south giving greying skies, although these broke again as we descended. 

The second of two data sets gathered at the summit of Mynydd Mallaen

On our descent we opted for a shortened route and cut across partly rough ground to connect back with the quad bike track.  This saved quite a distance and we then followed the track back to the awaiting car. 

All that remained was to survey the bwlch, this we judged to be positioned close to where the car was parked and was at or close to one of three gates leading from the narrow lane across the near fields and past a large barn. 

Gathering data at the bwlch of Mynydd Mallaen

I set the Trimble up to gather bwlch data and wandered back to the car to change and pack my gear away.  For me it had been a tiring day on the hill, but one that was extremely rewarding both in the hills visited and surveys conducted, but also in the meeting of Irwel and Eirwyn Jones at Aber Bronddu farm.  Just the drive home remained. 

 

Survey Result: 

 

Mynydd Mallaen (significant name change)

Summit Height:  460.9m (converted to OSGM15)

Summit Grid Reference:  SN 72217 45534

Bwlch Height:  259.2m (converted to OSGM15)

Bwlch Grid Reference:  SN 72372 46231

Drop:  201.7m

Dominance:  43.76%

 

 

For further details please consult the Trimble Survey Spreadsheet