Mapping Mountains – Summit Relocations – Y Pellennig – The Remotest Hills of Wales

Graig Wen (SN 786 629) 

There has been a Summit Relocation to a hill that is listed in the Y Pellennig – The Remotest 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 Graig Wen (SN 786 629)

The criteria for the list that this summit relocation applies to are:

Y Pellennig –The Remotest Hills of Wales - Welsh hills whose summit is at least 2.5km from the nearest paved public road and the hill has a minimum 15m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available as a downloadable e-booklet or print-booklet version on Mapping Mountains Publications with the up-to-date master list available on Mapping Mountains to download in Google Doc format. 

Y Pellennig - The Remotest Hills of Wales by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Graig Wen, and this was derived from local enquiry 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-west and the B4343 road farther to its north-west, and has the village of Pontrhydfendigaid also towards the north-west.

When the listing that became known as the Y Pellennig – The Remotest Hills of Wales was first compiled, this hill was listed with an estimated c 16m of drop, based on the 479m summit spot height positioned at SN 78618 62909 that appears on the Ordnance Survey 1:25,000 Explorer map, and an estimated c 463m bwlch 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.

LIDAR analysis gives the highest ground on this hill as 479.3m positioned at SN 78613 62923.  However, this is to the top of what LIDAR indicates is a raised ridge line of trees and protocols dictate that as this is deemed a relatively recent man-made construct such ground is discounted from the height of a hill. 

LIDAR summit image o Graig Wen (SN 786 629)

The summit area of this hill is intermittently covered by conifer plantation and therefore this whole area has been disturbed by man, however the height produced by LIDAR analysis to the highest centralised contour and to what could be deemed the natural summit of this hill is 479.2m and is positioned at SN 78619 62908, 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 new listed summit height of this hill is 479.2m and this is positioned at SN 78619 62908 and this was derived from LIDAR analysis, this position is approximately 15 metres south south-eastward from where the high point of the raised line of trees is positioned.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Esgair Wen

Name:  Graig Wen

OS 1:50,000 map:  146, 147

Summit Height:  479.2m (LIDAR) 

Summit Grid Reference (New Position):  SN 78619 62908 (LIDAR) 

Bwlch Height:  459.9m (LIDAR) 

Bwlch Grid Reference:  SN 78426 63149 (LIDAR) 

Drop:  19.3m (LIDAR) 

Remoteness:  3.000km

 

Myrddyn Phillips and Aled Williams (February 2026) 

Mapping Mountains – Hill Reclassifications – The Welsh P15s

 

Bryn Caniadau (SH 764 617) – Welsh Sub-P15 deletion 

There has been a deletion 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 Bryn Caniadau (SH 764 617)

The criteria for the list that this deletion 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 listed by is Bryn Caniadau, 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 with minor roads to its north-west and east, with the A5 road to its south and the B5106 road and the A470 road towards its east, and has the town of Llanrwst towards the east. 

Extract from the Ordnance Survey series of Six-Inch maps

When the listing that became known as The Welsh P15s was being compiled, this hill was included in the P14 sub list with an estimated c 14m of drop, based on an estimated c 213m summit height and an estimated c 199m 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

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 deletion of this hill from Welsh Sub-P15 status is due to LIDAR analysis, resulting in a 215.1m summit height and a 201.2m bwlch height, with these values giving this hill 13.9m 0f drop, which is insufficient for it to be classified as a Welsh Sub-P15. 

 

The full details for the hill are: 

Group:  Carnedd Llywelyn 

Name:  Bryn Caniadau 

OS 1:50,000 map:  115

Summit Height:  215.1m (LIDAR)                                                           

Summit Grid Reference:  SH 76492 61758 (LIDAR)                                                  

Bwlch Height:  201.2m (LIDAR) 

Bwlch Grid Reference:  SH 76439 61684 (LIDAR) 

Drop:  13.9m (LIDAR) 

 

Myrddyn Phillips (February 2026)

 

Mapping Mountains – Significant Height Revisions – 500m Twmpau, Y Trechol – The Dominant Hills of Wales and The Welsh Highlands – Uchafion Cymru

 

Yr Eifl (SH 364 447) 

There has been a Significant Height Revision that is retrospective to a hill that is listed in the 500m Twmpau, Y Trechol – The Dominant Hills of Wales and the The Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop, the dominance and status of the hill derived from a Leica GS15 summit survey conducted by John Barnard, Graham Jackson and Myrddyn Phillips, and LIDAR bwlch analysis conducted by Aled Williams. 

Yr Eifl (SH 364 447)

The criteria for the three 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

Y Trechol – The Dominant Hills of Wales – Welsh P30 hills whose prominence equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those additional Welsh P30 hills whose prominence is between one third and half that of their absolute height.  The list is authored by Myrddyn Phillips with the Introduction to the start of the Mapping Mountains publication of this list appearing on the 3^rd December 2015, and the list is now available in its entirety on Mapping Mountains in Google Doc format. 

Y Trechol - The Dominant Hills of Wales 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 Yr Eifl and it is adjoined to its own group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with minor roads to its north-east, the B4417 road to its south and the A499 road to its east, and has the villages of Trefor towards the north north-east and Llithfaen towards the south south-west.

When the listings of the 500m Twmpau, Y Trechol – The Dominant Hills of Wales and The Welsh Highlands – Uchafion Cymru were first compiled, this hill was listed with a summit height of 564m, based on the spot height adjoined to a triangulation pillar 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 Leica GS15 that the details for this hill could be accurately re-assessed.  Although the trig pillar is positioned on a relatively stable base it is positioned on the top of a substantial ancient cairn which consists of a multitude of individual stones and rocks and as this is considered as not being permanent in nature, it is the highest remaining natural ground on the periphery of the ancient cairn that is taken as both its listed summit height and summit position, and when compared to its originally listed summit height of 564m 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. 

Gathering data with the Leica GS15 at the listed summit position of Yr Eifl

Therefore, the new listed summit height of this hill is 560.7m and this was derived from a Leica GS15 survey, this is 3.3m lower than the originally listed summit height of 564m, which was based on the spot height adjoined to a triangulation pillar that appears on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Yr Eifl

Name:  Yr Eifl

OS 1:50,000 map:  123

Summit Height (New Height):  560.7m (converted to OSGM15, Leica GS15)

Summit Grid Reference:  SH 36482 44734 (Leica GS15)  

Bwlch Height:  129.4m (LIDAR)

Bwlch Grid Reference:  SH 45347 48678 (LIDAR)

Drop:  431.3m (Leica GS15 summit and LIDAR bwlch)

Dominance:  76.92% (Leica GS15 summit and LIDAR bwlch)

 

Myrddyn Phillips and Aled Williams (February 2026)

Mapping Mountains – Significant Name Changes – The Fours – The 400m Hills of England

Burton Howe (NZ 607 032) 

There has been a Significant Name Change based on a summit relocation to a hill that is listed in 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 Burton Howe (NZ 607 032) 

The criteria for the list that this name change 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 hill is adjoined to the Urra Moor group of hills, which are situated in the North York Moors of north-eastern England, and it is positioned with minor roads to its north and east, and the B1257 road to its west, and has the town of Stokesley towards the 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 under the name of Greenhow Moor with 17m of drop, based on the 432m summit spot height positioned at NZ 61114 02607 and the 415m col spot height that appear on the Ordnance Survey 1:25,000 Explorer map. 

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.

LIDAR analysis gives the highest ground on this hill as 432.3m positioned at NZ 60792 03254, with LIDAR giving its originally listed summit position as 432.2m positioned at NZ 61049 02611 and NZ 61062 02608 and NZ 61063 02601 and NZ 61063 02599 and NZ 61080 02598.

Therefore, the name this hill is now listed by in The Fours - The 400m Hills of England is Burton Howe and this was instigated from a summit relocation. 

 

The full details for the hill are:

Group:  Urra Moor

Name:  Burton Howe

Previously Listed Name:  Greenhow Moor

OS 1:50,000 map:  94

Summit Height:  432.3m (LIDAR)

Summit Grid Reference:  NZ 60792 03254 (LIDAR)

Col Height:  415.4m (LIDAR)

Col Grid Reference:  NZ 62245 02507 (LIDAR)

Drop:  16.9m (LIDAR)

 

Myrddyn Phillips and Aled Williams (February 2026) 

Mapping Mountains – Hill Reclassifications – Y Pedwarau – The 400m Hills of Wales

 

Crug Siarls (SN 702 483) – 390m Sub-Pedwar deletion

There has been a deletion from the listing of 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 Crug Siarls (SN 702 483)

The criteria for the list that this deletion 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 deleted from the 390m Sub-Pedwar category.  The criteria for this sub category being all Welsh hills at or above 390m and below 400m in height that have 30m minimum 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 Crug Siarls, 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 west and south, the B4343 road farther to its west, and the A482 road farther to its south-west, and has the town of Llanbedr Pont Steffan (Lampeter) towards the west.

When the original 300m height band of Welsh P30 hills compiled by Myrddyn Phillips was published on Geoff Crowder’s v-g.me website, this hill was included in the main P30 list with a 391m summit height, 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

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 with 54m of drop, based on the 391m summit spot height and the 337m 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, and these are the details giiven the hill when the 1^st edition of the Y Pedwarau, now co-authored by Myrddyn Phillips and Aled Williams was published by Europeaklist in May 2013.

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 deletion of this hill from 390m Sub-Pedwar status is due to LIDAR analysis, resulting in a 389.7m summit height and a 336.8m bwlch height, with these values giving this hill 52.9m of drop, with the summit height insufficient for it to be classified as a 390m Sub-Pedwar.                                         

 

The full details for the hill are:

Group:  Esgair Wen

Name:  Crug Sials

OS 1:50,000 map:  146, 147

Summit Height:  389.7m (LIDAR)

Summit Grid Reference:  SN 70220 48343 (LIDAR)

Bwlch Height:  336.8m (LIDAR)

Bwlch Grid Reference:  SN 69635 48220 (LIDAR)   

Drop:  52.9m (LIDAR) 

 

For the additions, reclassifications and deletions to Y Pedwarau – The 400m Hills of Wales reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers:

 

Y Pedwarau

 

Y Pedwarau – 400m Sub-Pedwarau

 

Y Pedwarau – 390m Sub-Pedwarau

 

Y Pedwarau – 390m Double Sub-Pedwarau

 

Myrddyn Phillips and Aled Williams (February 2026)