Mapping Mountains – Significant Name Changes – The Welsh P15s

 

Mynydd Deulyn (SH 754 605) 

There has been a Significant Name Change to a hill that is listed in The Welsh P15s, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Mynydd Deulyn (SH 754 605)

The criteria for the list that this name change applies to are:

The Welsh P15s – Welsh hills with 15m minimum drop, irrespective of their height, with an accompanying sub list entitled the Welsh Sub-P15s, with the criteria for this sub category being all Welsh hills with 14m or more and below 15m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list appearing on Mapping Mountains on the 10^th May 2019. 

The Welsh P15s by Myrddyn Phillips

The hill is adjoined to the Carnedd Llywelyn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned between Llyn Crafnant to its north-west and Llyn Geirionydd to its east, with the A5 road to its south, and the B5106 road, the Afon Conwy and the A470 road to its east, and has the village of Capel Curig towards the south-west and the town of Llanrwst towards the east.

When the listing that became known as The Welsh P15s was being compiled, this hill was listed under the point (Pt. 336m) notation, with an estimated c 14m of drop, based on the 336m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 322m bwlch height, based on interpolation of 10m contouring between 320m – 330m. 

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

Since the original compilation of this list 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, and it is the series of Ordnance Survey Six-Inch maps that form the basis of the change in the listed name of this hill.

The Ordnance Survey series of Six-Inch maps formed the base map Ordnance Survey used for many decades leading to the production of the 1:10,000 Series of maps, both have now been superseded by the digitised Master Map.  The series of Six-Inch maps are excellent for name placement and especially so compared to the contemporary Ordnance Survey 1:25,000 Explorer map, and it is the series of Six-Inch maps that position the name of Mynydd Deulyn to land where the summit of this hill is situated.

Extract from the Ordnance Survey series of Six-Inch maps

Therefore, the name this hill is now listed by in the The Welsh P15s is Mynydd Deulyn, and this was derived from the Ordnance Survey series of Six-Inch maps. 

 

The full details for the hill are: 

Group:  Carnedd Llywelyn 

Name:  Mynydd Deulyn 

Previously Listed Name:  Pt. 336m 

OS 1:50,000 map:  115

Summit Height:  334.8m (LIDAR)                                                           

Summit Grid Reference:  SH 75464 60544 (LIDAR)                                                  

Bwlch Height:  318.4m (LIDAR) 

Bwlch Grid Reference:  SH 75563 60655 (LIDAR) 

Drop:  16.4m (LIDAR) 

 

Myrddyn Phillips (July 2026)

 

Bugail yr Enwau – A New Blog for Welsh Upland Place-Names

 

Aled Williams has recently established a new blog called Bugail yr Enwau, which focuses on gathering upland place-names through local surveys and historical research.

https://bugailenwau.blogspot.com/

As many in the Mapping Mountains community know, Aled specialises in the upland place-names of Wales and co-authors a number of hill-lists with me, namely: The 400m Hills of Wales – Bryniau 400m Cymru, The Fours – The 400m Hills of England, and Y Pellennig – The Remotest Hills of Wales. I met up with Aled to find out more about his new blog.

Myrddyn: Hello Aled, could you tell us what your new blog is about?

Aled: For over fifteen years now, I have specialised in the cataloguing and study of place-names in the Welsh uplands. The scope of this work is extensive, covering all upland areas from Eryri in the north to Bannau Brycheiniog in the south. This blog is dedicated to this research, serving as a place to share news and information as my work develops and as it feeds into other projects and activities.

Myrddyn: Is your blog in Welsh or English?

Aled: It is bilingual. Obviously the subject matter is largely Welsh in nature, but there will be interest from monoglot English speakers, so all the articles will be available in both languages.

Myrddyn: I believe Bugail yr Enwau translates as ‘shepherd of the names’, why did you choose this name for the blog?

Aled: I wanted a Welsh name that summed up my research endeavours. Collecting upland place‑names is laborious work: like sheep, names must be gathered down from the mountain! So the name is a slightly tongue-in-cheek reference to my work in shepherding upland place-names.

Aled gathering names on Mynydd Hiraethog, June 2014 

Myrddyn: I see. So what prompted you to establish the blog?

Aled: External factors, really. Place-names have become a hot topic in Wales in recent years. There is growing concern that Welsh names are being replaced by newly invented English names or translated ones, whether house-names or topographical-names. For the latter, digital mapping and its relationship with social media is fuelling this perception, and may well be accelerating it. Various groups and organisations are actively running initiatives and projects to protect Welsh place-names, and because of my expertise in upland place-names, I am involved with the some of these activities. It’s important that people know about my work and are able to contact me for assistance. It also serves as a platform I can use for outreach.

Myrddyn: An online presence is essential these days. Do you see it as being helpful to your efforts in collecting place-names?

Aled: Absolutely. It opens up another avenue where local people can contact me directly if they have upland place‑names to safeguard or proposals for changes to official maps. A contact form has been set up for this purpose.

Myrddyn: Did I also hear that you are working with Eryri National Park to add and correct place-names on Ordnance Survey maps?

Aled: That’s right. In fact, we have already received Ordnance Survey’s acceptance relating to two names: Ysgar and Diffwys Criafol, both of which are topographical names for places located on the east side of Crib Goch; neither of which had been recorded by Ordnance Survey during the original nineteenth-century surveys that laid the foundations of their Welsh mapping. Those interested can read about it in the News section of the blog.

Myrddyn: Is obtaining Ordnance Survey acceptance on place-name changes straightforward?

Aled: No it isn’t. Cartographic changes are rightly scrutinised by Ordnance Survey, and their appropriateness must be demonstrated by compelling evidence. Without a vetting process, there is potential for all manner of erroneous or invented place-names to appear on maps. For the two names in question, the process took six months to complete and required input from Eryri National Park and the Welsh Language Commissioner. This was another reason for establishing the blog: to provide traceability and transparency on these changes, so the public know the who, what, when, and why.

Myrddyn: Will the evidence packs be posted each time an Ordnance Survey map change is accepted?

Aled: That is the intention. Posts will appear in the News section of the blog.

Myrddyn: I wish you luck with the new blog.

Aled: Thank you!

Mapping Mountains – Significant Height Revisions – 500m Twmpau and The Welsh Highlands – Uchafion Cymru

 

Mynydd Nodol (SH 865 393) 

There has been a Significant Height Revision that is retrospective to a hill that is listed in the 500m Twmpau and The Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Trimble GeoXH 6000 summit survey conducted by Myrddyn Phillips and LIDAR bwlch analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips. 

Mynydd Nodol (SH 865 393)

The criteria for the two listings that this height revision applies to are:

500m Twmpau – Welsh hills at or above 500m and below 600m in height that have 30m minimum drop, with an accompanying sub category entitled the 500m Sub-Twmpau consisting of all Welsh hills at or above 500m and below 600m in height that have 20m or more and below 30m of drop.  With the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips and is published on Mapping Mountains in Google Doc format.

500m Twmpau by Myrddyn Phillips

The Welsh Highlands – Uchafion Cymru – Welsh hills at or above 500m in height with 15m minimum drop, with an accompanying sub list entitled the Welsh Highland Subs, the criteria for which is all Welsh hills at or above 500m in height with 10m or more and below 15m of drop.  This list is authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and the latest update relating to the list published on Mapping Mountains in January 2023.

The Welsh Highlands - Uchafion Cymru by Aled Williams and Myrddyn Phillips

The name the hill is listed by is Mynydd Nodol and it is adjoined to the Arenig Fawr group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A2), and it is positioned with Llyn Celyn and the A4212 road to its north and a minor road to its south, and has the town of Y Bala towards the south-east.

When the listings of the 500m Twmpau and The Welsh Highlands – Uchafion Cymru were first compiled, this hill was listed with a summit height of 539m, based on the spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map. 

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

However, it was not until the survey with the Trimble GeoXH 6000 and LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

The Trimble GeoXH 6000 gathering data at the summit of Mynydd Nodol

The survey with the Trimble GeoXH 6000 gives the summit of this hill as 540.0m positioned at SH 86514 39339, and this comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revisions applies to any listed hill whose interpolated height and Ordnance Survey, Harvey or other interactive map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000 or other GNSS equipment or analysis of data produced via LIDAR.  Also included are hills whose summit map data is missing an uppermost ring contour when compared with the data produced by the Trimble or by LIDAR analysis.

Therefore, the new listed summit height of this hill is 540.0m and this was derived from a Trimble GeoXH 6000 survey, this is 1.0m higher than the originally listed summit height of 539m, which was based on the spot height that appears on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and importantly this height signifies that an uppermost 540m ring contour is missing from this map.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Arenig Fawr

Name:  Mynydd Nodol

OS 1:50,000 map:  124, 125

Summit Height (New Height):  540.0m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 86514 39339 (Trimble GeoXH 6000)  

Bwlch Height:  370.8m (LIDAR)

Bwlch Grid Reference:  SH 85660 39014 (LIDAR)

Drop:  169.2m (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

Myrddyn Phillips and Aled Williams (July 2026)

Topographical Regions, Sub-Regions and Groups - Revision

 

Understanding the Welsh Land-Mass

 

Our exploration of the Welsh landscape comes in many forms, with research in to upland place-names, investigations via hill walking including surveying summits and bylchau for height and position.  All of this is documented, some via personal notes, others via online access and many via the medium of hill lists.  It is the latter that requires a splitting of the land in to manageable units for ease of access and documentation. 

This land splitting is done with the aid of topography, following rivers and streams to their source.  This will be the bwlch between the listed hills.  Knowing the height of the respective bwlch and summit gives the drop value, which many hill lists rely upon for their criteria/criterion. 

Our investigations in to splitting land mass in to topographical units was published in January 2022, this concentrated on Wales and its topographical extension in to England, which we refer to as Cymru Fawr – Greater Wales. 

In the interim a similar exercise has been conducted for England and by association also for Scotland.  By including all of Britain and labelling this land area together and not separately by country has resulted in the re-labelling of the Regions and Sub-Regions for Wales as a country and Cymru Fawr – Greater Wales as a topographical land area.  It has also resulted in the re-evaluation of our Groups and their ordering. 

These revisions now appear in our January 2022 article.

All online lists affected by these revisions will be updated accordingly over time. 

A similar article for our workings relating to England will be published on the 2^nd August 2026. 

 

Aled Williams and Myrddyn Phillips (July 2026)

Mapping Mountains - Significant Name Changes - 100m Twmpau

 

100m Twmpau – Significant Name Changes

The 100m Twmpau (thirty welsh metre prominences and upward) are the Welsh hills at or above 100m and below 200m in height that have a minimum drop of 30m.  Accompanying the main P30 list is a sub list entitled the 100m Sub-Twmpau with the qualification to this sub category being all Welsh hills at or above 100m and below 200m in height with 20m or more and below 30m of drop.

The list is authored by Myrddyn Phillips and the posts that have appeared on Mapping Mountains detailing the significant name changes to the main P30 list and the sub list appear below presented chronologically in receding order.

Mapping Mountains - Significant Name Changes - 100m Twmpau

Coed Penllyn (SH 786 696) - 176th significant name change

Significant Height Revisions post for Coed Penllyn

Summit Relocations post for Coed Penllyn

There has been a Significant Name Change to a hill that is listed in the 100m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Coed Penllyn (SH 786 696)

The criteria for the list that this name change applies to are:

100m Twmpau - Welsh hills at or above 100m and below 200m in height that have 30m minimum drop, with an accompanying sub list entitled the 100m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 100m and below 200m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

100m Twmpau by Myrddyn Phillips

The hill is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned with the A470 road to its west and a minor road to its east, and has the town of Llanrwst towards the south. 

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

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the accompanying Hills to be surveyed sub list under the invented and transposed name of Pen Coed y Bortho, with an accompanying note stating; Name from wood to the West.

Pen Coed y Bortho

193m

SH786697

115

17

Height from 1989 1:50000 map. Name from wood to the West.

During my early hill listing I thought it appropriate to either invent a name for a hill, or use a name that appeared near to the summit of the hill on Ordnance Survey maps of the day, with little consideration for the meaning of the name and where it was appropriately applied to.  My preference was to use farm names and put Pen, Bryn or Moel in front of them or as in this instance transpose the name of a wood and add the word Pen to it.  This is not a practice that I now advocate as with time and inclination place-name data can be improved either by asking local people or by examining historic documents, through this form of research an appropriate name for the hill can usually be found.

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, and it is the series of Ordnance Survey Six-Inch maps coupled with the Ordnance Survey map that was hosted on the Geograph website that form the basis of the change in the listed name of this hill. 

Extract from the Ordnance Survey series of Six-Inch maps published in 1900

The Ordnance Survey series of Six-Inch maps formed the base map Ordnance Survey used for many decades leading to the production of the 1:10,000 Series of maps, both have now been superseded by the digitised Master Map.  The series of Six-Inch maps are excellent for name placement and especially so compared to the contemporary Ordnance Survey 1:25,000 Explorer map, and it is the series of Six-Inch maps that name the plantation where the summit of this hill is situated as firstly Planhigfa Penllyn in the 1900 publication and later as Penllyn Wood in the 1953 publication.

Extract from the Ordnance Survey series of Six-Inch maps published in 1953

However, it is the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map that uses the full Welsh term for this wood and names it as Coed Penllyn.

Therefore, the name this hill is now listed by in the 100m Twmpau is Coed Penllyn, and this was derived from the foundations of the name appearing on the Ordnance Survey series of Six-Inch maps and lastly with the name appearing in its full Welsh form on the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

 

The full details for the hill are:

Group:  Mynydd Hiraethog

Name:  Coed Penllyn

Previously Listed Name:  Pen Coed y Bortho 

OS 1:50,000 map:  115

Summit Height:  198.0m (LIDAR) 

Summit Grid Reference:  SH 78630 69665 (LIDAR) 

Bwlch Height:  170.9m (LIDAR) 

Bwlch Grid Reference:  SH 78892 70134 (LIDAR) 

Drop:  27.1m (LIDAR) 

 

Myrddyn Phillips (June 2026)