Mapping Mountains – Hill Reclassifications – The Fours – The 400m Hills of England

Almsworthy Common (SS 841 420) – Sub-Four exclusion

There has been an exclusion from the listing of the The Fours – The 400m Hills of England, with the summit height, col height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Almsworthy Common (SS 841 420)

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

The Fours – The 400m Hills of England - English hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main list is a sub list entitled the Sub-Fours, the criteria for which are all English hills at or above 400m and below 500m in height that have 15m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available to download in Google Doc format from the Mapping Mountains site.

The Fours - The 400m Hills of England by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Almsworthy Common, and it is adjoined to the Dunkery Beacon group of hills, which are situated in the counties of Somerset and Devon, and it is positioned encircled by minor roads with the the B3223 road and the B3224 road farther to its south, and has the village of Porlock towards the north-east.

When the Introduction to the first group of hills for the updated and revised listing of the The Fours – The 400m Hills of England was published by Mapping Mountains on the 10^th September 2022, it was announced that the accompanying sub lists were being revised with the two 390m categories dispensed with and the criteria and name of the 400m Sub-Fours revised.  The one accompanying sub list is now named the Sub-Fours with its criteria being all English hills 400m and above and below 500m in height that have 15m and more and below 30m of drop.

Prior to this revision this hill was listed with an estimated c 16m of drop, based on the 453m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 437m col height, based on interpolation of 10m contouring between 430m – 440m. 

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

However, it was not until 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.

Therefore, the exclusion of this hill from Sub-Four status is due to LIDAR analysis, resulting in a 453.8m summit height and a 439.1m col height, with these values giving this hill 14.7m of drop, which is insufficient for it to be classified as a Sub-Four. 

 

The full details for the hill are:

Group:  Dunkery Beacon

Name:  Almsworthy Commom

OS 1:50,000 map:  181

Summit Height:  453.1m (LIDAR)

Summit Grid Reference:  SS 84151 42008 (LIDAR)

Col Height:  439.1m (LIDAR)

Col Grid Reference:  SS 83776 42521 (LIDAR)

Drop:  14.7m (LIDAR)

 

For the additions, deletions and reclassifications to The Fours – The 400m Hills of England reported on Mapping Mountains since the December 2013 publication of the 1^st edition of this list by Europeaklist please consult the following Change Registers:

 

The Fours

 

Sub-Fours

 

Myrddyn Phillips and Aled Williams (July 2026)                

Mapping Mountains – Significant Height Revisions – The 500-Metre Tops of England and Wales – Deweys

Rhobell Ganol (SH 785 274) 

There has been a Significant Height Revision to a hill that is listed in the The 500-Metre Tops of England and Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Aled Williams. 

LIDAR image of Rhobell Ganol (SH 785 274)

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

The 500-Metre Tops of England and Wales are affectionately known after their hill list compiler; Michael Dewey.  This list mixes metric and imperial height in its criteria to bookend up to the 2000ft height band and takes in all hills in England, Isle of Man and Wales that are 500m and above and below 2000ft (609.6m) in height that have 30m minimum drop. 

Mountain tables by Michael Dewey

Michael Dewey died on the 5^th November 2022.  His wife; Gillian wished for this list to be carried on and made provision for it to be co-authored by Myrddyn Phillips.  Michael will always be the compiler and originator, it’s just that he’s now got a co-author to safeguard and carry this list on.

The name the hill is listed by is Rhobell Ganol and it is adjoined to the Arenig Fawr group of hills, which are situated in the central part of North Wales, and it is positioned with a minor road to its north, the A470 road to its west and the A494 road to its east, and has the small community of Rhyd-y-main towards the south south-east.

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

When the original list of Deweys appeared in the Mountain tables book published by Constable in 1995, this hill was listed with a non-interpolated summit height of 520+m, based on the uppermost 520m ring contour 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

Since the original publication 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 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.

One of the mapping resources now available online is the Magic Maps website which hosts an interactive map originated from Ordnance Survey data.  This mapping has a 522m summit spot height applied to the southerly top that matches the summit position given the hill by LIDAR analysis. 

Extract from the interactive mapping hosted on the Magic Maps website

Another of the mapping resources now available online is the WalkLakes website which hosts an interactive map originated from the Ordnance Survey Open Data programme.  This map has many spot heights not on other publicly available maps and gives a 522m spot height to a northerly top positioned at SH 78603 27533. 

Extract from the interactive mapping hosted on the WalkLakes website

However, it was not until 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. 

LIDAR summit image of Rhobell Ganol (SH 785 274)

LIDAR analysis gives the summit of this hill as 524.8m positioned at SH 78578 27406, 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 524.8m and this was derived from LIDAR analysis, this is 4.8m higher than the originally listed summit height of 520+m, which was based on the non-interpolated uppermost 520m ring contour that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and 2.8m higher than the spot heights that appear on the Magic Maps interactive map and the interactive mapping hosted on the WalkLakes website. 

 

The full details for the hill are:

Group:  Arenig Fawr

Name:  Rhobell Ganol

OS 1:50,000 map:  124

Summit Height (New Height):  524.8m (LIDAR)

Summit Grid Reference:  SH 78578 27406 (LIDAR)  

Bwlch Height:  485.7m (LIDAR)

Bwlch Grid Reference:  SH 78549 26977 (LIDAR)

Drop:  39.1m (LIDAR)

 

Myrddyn Phillips (July 2026)

  

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)