Mapping Mountains – Hill Reclassifications – The Welsh P15s

 

Mynydd Deulyn (SH 754 605) – Welsh Sub-P15 reclassified to Welsh P15 

There has been a reclassification to the list of 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 reclassification 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 name the hill is now listed by is Mynydd Deulyn, and this was derived from the Ordnance Survey series of Six-Inch maps, and it 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 included in the accompanying sub list 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

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 reclassification of this hill from Welsh Sub-P15 status is due to LIDAR analysis, resulting in a 334.8m summit height and a 318.4m bwlch height, with these values giving this hill 16.4m 0f drop, which is sufficient for it to be classified as a Welsh P15. 

 

The full details for the hill are: 

Group:  Carnedd Llywelyn 

Name:  Mynydd Deulyn 

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 (June 2026)

 

Mapping Mountains – Summit Relocations – Y Pedwarau – The 400m Hills of Wales

 

Pen y Rhaglan Wynt (SN 739 490) 

There has been a Summit Relocation to a hill that is 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 LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Pen y Rhaglan Wynt (SN 739 490)

The criteria for the list that this summit relocation 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, with this hill being included in the 400m Sub-Pedwar category.  The criteria for this sub category 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.

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

The name the hill is listed by is Pen y Rhaglan Wynt, and it is adjoined to the Esgair Wen group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned with minor roads to its north and south, and has the village of Llanddewibrefi towards the north-west. 

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

When the 1^st edition of the Y Pedwarau was published by Europeaklist in May 2013, this hill was listed with 26m of drop, based on the 423m summit spot height positioned at SN 73826 49110 that appears on the Ordnance Survey 1:25,000 Explorer map and the 397m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map.  This hill was listed with an accompanying note stating; Second summit of same map height at SN 739 490.  This second 423m spot height appears on the Ordnance Survey 1:50,000 Explorer map and appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

LIDAR summit image of Pen y Rhaglan Wynt (SN 739 490)

LIDAR analysis gives the highest ground on this hill as 423.4m positioned at SN 73918 49040, as opposed to LIDAR giving 423.3m positioned at SN 73823 49117, and this comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies when the high point of the hill is found to be positioned; in a different field, to a different feature such as in a conifer plantation,  within a different map contour either on Ordnance Survey maps or interactive mapping, to a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is considered a relatively recent man-made construct, or the listing of a new twin summit or de-twinning of a summit, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist.

Therefore, the height produced by LIDAR analysis to the summit of this hill is 423.4m and is positioned at SN 73918 49040.  This position is relatively close to where one of the 423m spot heights appears on the Ordnance Survey 1:50,000 Explorer map and appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map and approximately 160 metres south-eastward from where the twin map heighted spot height appears on the Ordnance Survey 1:25,000 Explorer map, resulting in the de-twinning of this hill.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Esgair Wen 

Name:  Pen y Rhaglan Wynt 

OS 1:50,000 map:  146, 147

Summit Height:  423.4m (LIDAR) 

Summit Grid Reference (New Position):  SN 73918 49040 (LIDAR) 

Bwlch Height:  397.5m (LIDAR) 

Bwlch Grid Reference:  SN 73569 49497 (LIDAR) 

Drop:  26.0m (LIDAR)

 

Myrddyn Phillips and Aled Williams (June 2026)

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

 

Chapman Barrows (SS 700 434) – 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 Chapman Barrows (SS 700 434)

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 Chapman Barrows, 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 with the A39 road to its north-west and the B3358 road to its south, and has the small community of Parracombe towards the west north-west.

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 15m of drop, based on the 480m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 465m col height, based on interpolation of 10m contouring between 460m – 470m. 

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 479.8m summit height and a 467.2m col height, with these values giving this hill 12.6m 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:  Chapman Barrows

OS 1:50,000 map:  180

Summit Height:  479.8m (LIDAR)

Summit Grid Reference:  SS 70003 43471 (LIDAR)

Col Height:  467.2m (LIDAR)

Col Grid Reference:  SS 70726 42992 (LIDAR)

Drop:  12.6m (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 (June 2026)              

Mapping Mountains – Significant Name Changes – 200m Twmpau

Rhos Swydd (SO 117 650) 

There has been a Significant Name Change to a hill that is listed in the 200m 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 Rhos Swydd (SO 117 650)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m 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. 

200m Twmpau by Myrddyn Phillips

The hill is adjoined to the Fforest Glud group of hills, which are situated in the eastern part of South Wales (Region B, Sub-Region B3), and it is positioned with a minor road to its north-west, the A44 road to its south-west and the A488 road to its south-east, and has the town of Llandrindod towards the south-west.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included in the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category.

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed under the point (Pt. c 267m) notation with an estimated c 20m of drop, based on an estimated c 267m summit height and an estimated c 247m bwlch height, with both heights based on interpolation of 10m contouring that appears on the Ordnance Survey 1:25,000 Explorer map. 

Extract from the Ordnance Survey 1:25,000 Explorer 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, and it is the series of Ordnance Survey Six-Inch maps that form the basis of 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 Rhos Swydd 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 200m Twmpau is Rhos Swydd, and this was derived from the Ordnance Survey series of Six-Inch maps. 

 

The full details for the hill are:

Group:  Fforest Glud

Name:  Rhos Swydd

Previously Listed Name:  Pt. c 267m   

OS 1:50,000 map:  148

Summit Height:  268.0m (LIDAR) 

Summit Grid Reference:  SO 11706 65038 (LIDAR) 

Bwlch Height:  244.8m (LIDAR) 

Bwlch Grid Reference:  SO 12253 65143 (LIDAR) 

Drop:  23.2m (LIDAR)

 

Myrddyn Phillips (June 2026) 

Mapping Mountains – Significant Name Changes – The Welsh P15s

Mynydd Deulyn (SH 756 608) 

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 756 608)

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 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. 382m) notation, with an estimated c 20m of drop, based on the 382m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 362m bwlch height, based on interpolation of 5m contouring between 360m – 365m that appeared on the OS Maps website. 

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. 382m 

OS 1:50,000 map:  115

Summit Height:  381.3m (LIDAR)                                                           

Summit Grid Reference:  SH 75657 60898 (LIDAR) 

Bwlch Height:  361.9m (LIDAR) 

Bwlch Grid Reference:  SH 75753 61023 (LIDAR) 

Drop:  19.4m (LIDAR) 

 

Myrddyn Phillips (June 2026)