Mapping Mountains – Summit Relocations – Y Pellennig – The Remotest Hills of Wales, The Welsh Highlands – Uchafion Cymru and 600m Twmpau

Carnedd Llechwedd Llyfn (SH 857 444) 

There has been a Summit Relocation to a hill that is listed in the Y Pellennig – The Remotest Hills of Wales, The Welsh Highlands – Uchafion Cymru and the 600m Twmpau, 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 Carnedd Llechwedd Llyfn (SH 857 444)

The criteria for the three listings 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 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

600m Twmpau - Welsh hills at or above 600m and below 700m in height with 30m minimum drop, with an accompanying sub list entitled the 600m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 600m and below 700m in height with 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 available to download in Google Doc format from Mapping Mountains. 

600m Twmpau by Myrddyn Phillips

The name the hill is listed by is Carnedd Llechwedd Llyfn and it is adjoined to the Carnedd y Filiast group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A1), and it is positioned with minor roads to its north-west and north-east, the A5 road farther to its north, the B4407 road farther to its north-west and the A4212 road to its south, and has the town of Y Bala towards the south-east.

When the original list that later became known as the The Welsh Highlands – Uchafion Cymru was first compiled, this hill was listed with an estimated c 25m of drop, based on the 643m summit spot height positioned at SH 85778 44459 that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and an estimated c 618m bwlch height, based on interpolation of 10m contouring between 600m – 610m. 

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

Since the original compilation of these lists 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.

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill it had a twin 643m summit spot height positioned at SH 85789 44665 (latterly shown on the DataMapWales) and a 618m bwlch spot height, with these values giving this hill 25m of drop and resulting in the hill being listed as a twin top. 

Extract from the DataMapWales

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 Carnedd Llechwedd Llyfn (SH 857 444)

The height produced by LIDAR analysis to the summit of this hill is 644.1m and is positioned at SH 85783 44460, whilst LIDAR gives the highest ground adjacent to where the 643m spot height appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map as 643.6m positioned at SH 85785 44677 and SH 85782 44676 and SH 85785 44674 and SH 85779 44667, 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 644.1m and this is positioned at SH 85783 44460 and this was derived from LIDAR analysis, this position approximately matches that of the spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and has resulted in the de-twinning of this hill.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Carnedd y Filiast

Name:  Carnedd Llechwedd Llyfn

OS 1:50,000 map:  124, 125

Summit Height:  644.1m (LIDAR) 

Summit Grid Reference (New Position):  SH 85783 44460 (LIDAR) 

Bwlch Height:  618.7m (LIDAR) 

Bwlch Grid Reference:  SH 86005 44925 (LIDAR) 

Drop:  25.4m (LIDAR) 

Remoteness:  2.860km

 

Myrddyn Phillips and Aled Williams (September 2026) 

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

Hound Tor (SX 628 890) – 400m Sub-Four addition

There has been an addition that is retrospective to 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 Hound Tor (SX 628 890)

The criteria for the list that this addition applies to are (prior to incorporating P15s as subs): 

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 are three categories of sub hills, with this hill being added to the 400m Sub-Four category, the criteria for which are all English 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 the 2^nd edition of the booklet containing this list was published by Mapping Mountains Publications on the 24^th April 2018.

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

The name the hill is listed by is Hound Tor and it is adjoined to the High Willhays group of hills, which are situated in the south-west of England, and it is positioned with the A30 to its north, and has the town of Okehampton towards the north-west.

When the 2^nd edition of the The Fours – The 400m Hills of England was published by Mapping Mountains Publications in April 2018, this hill was not included as it was listed with 19m of drop, based on the 495m summit spot height that appears on the contemporary Ordnance Survey 1:25,000 Explorer map and the 476m col spot height that 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 1:25,000 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 addition of this hill to 400m Sub-Four status is due to LIDAR analysis, resulting in a 495.5m summit height and a 473.7m col height, with these values giving this hill 21.8m of drop, which is sufficient for 400m Sub-Four status.

 

The full details for the hill are:

Group:  High Willhays

Name:  Hound Tor

OS 1:50,000 map:  191

Summit Height:  495.5m (LIDAR)

Summit Grid Reference:  SX 62878 89012 (LIDAR)

Col Height:  473.7m (LIDAR)

Col Grid Reference:  SX 63275 89559 (LIDAR)

Drop:  21.8m (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

 

The Fours – 400m Sub-Four

 

The Fours – 390m Sub-Four

 

The Fours – 390m Double Sub-Four

 

Myrddyn Phillips and Aled Williams (September 2026) 

Monthly Synopsis

 

Synopsis of all major changes detailed on Mapping Mountains during the last calendar month.  These can include new, confirmation and retrospective changes

 

Hill Reclassifications: 

Mynydd Margam (SS 819 888) - Pellennig deletion

Ffridd Uchaf (SH 799 668) - 100m Sub-Twmpau addition

Penllan Oat Piece (SO 103 633) - 200m Sub-Twmau addition

 

Significant Height Revisions: 

Sourton Tors (SX 543 898) - The Fours - The 400m Hills of England

Bryn Coch Ucha (SH 732 554) - The Welsh P15s

Mynydd Nodol (SH 865 393) - The Deweys

Water Hill (SX 671 812) - The Fours - The 400m Hills of England

Summit Relocations: 

Mynydd Cribau (SH 759 552) - The Welsh P15s

Significant Name Changes: 

Bryn Coch Ucha (SH 732 554) - The Welsh P15s

Pt. 428.2m (SN 731 497) - Y Pedwarau - The 400m Hills of Wales 

Mapping Mountains – Significant Name Changes – Y Pedwarau – The 400m Hills of Wales

Pt. 428.2m (SN 731 497) 

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 detail on contemporary Ordnance Survey maps, with confirmation of the status from subsequent LIDAR analysis. 

LIDAR image of Pt. 428.2m (SN 731 497) 

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, with this hill being classified as a 400m Sub-Pedwar.  The criteria for 400m Sub-Pedwar status 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 hill 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 is positioned with minor roads to its north, west, south and east, and has the village of Llanddewi Brefi towards the north-west.

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 and invented name of Carn Nant-yr-ast East Top, with an accompanying note stating; Name from hill to the West.

Carn Nant-yr-ast East Top

427m

SN732497

146/147

187

Name from hill to the West

When Myrddyn Phillips first compiled this list he 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.  His preference was to use farm names and put Pen, Bryn or Moel in front of them or as in this instance use a directional name based on supplanting the name of a near hill and adding a directional component to it.  This is not a practice that he now advocates 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. 

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

However, on occasion even when research is conducted an appropriate name for the hill may not be found, and on such occasions the listing protocol is to use the point notation, and this is the protocol adopted when Myrddyn Phillips and Aled Williams became co-authors of this list and the 1^st edition of the Y Pedwarau was published by Europeaklist in May 2013.  This hill was then listed under the point (Pt. 427m) notation with an estimated c 30m of drop, based on the 427m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 397m bwlch height, based on interpolation of 10m contouring between 390m – 400m.

Therefore, the name this hill is now listed by in the Y Pedwarau – The 400m Hills of Wales is Pt. 428.2m, and this is being used as the authors have not found an appropriate name for the hill either through historic research and/or local enquiry.

 

The full details for the hill are: 

Group:  Esgair Wen 

Name:  Pt. 428.2m 

Previously Listed Name:  Carn Nant-yr-ast East Top 

OS 1:50,000 map:  146, 147 

Summit Height:  428.2m (LIDAR) 

Summit Grid Reference:  SN 73159 49742 (LIDAR) 

Bwlch Height:  399.0m (LIDAR) 

Bwlch Grid Reference:  SN 72736 49808 & SN 72739 49810 (LIDAR) 

Drop:  29.2m (LIDAR) 

 

Myrddyn Phillips and Aled Williams (August 2026)                                                  

Mapping Mountains – Significant Name Changes – The Welsh P15s

 

Bryn Coch Ucha (SH 732 554) 

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 Bryn Coch Ucha (SH 732 554)

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 Moel Siabod group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with the A5 road to its north, the A4086 road to its north-west and the A470 road to its south, and has the village of Betws-y-coed towards the east north-east.

When the listing that became known as The Welsh P15s was being compiled, this hill was listed under the point (Pt. c 364m) notation, with an estimated c 15m of drop, based on an estimated c 364m summit height and an estimated c 349m bwlch height, with both heights based on interpolation of 10m contouring. 

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

As the summit of this hill comprises bounded land the details for it were examined on the Tithe map.  The term Tithe map is generally given to a map of a Welsh or English parish or township and which was prepared after the 1836 Tithe Commutation Act.  This act allowed tithes to be paid in cash rather than goods.  The Tithe maps gave names of owners and occupiers of land in each parish and importantly for place-name research they also included the name of enclosed land.  This enclosed land is usually based on a field system, however not every field is given a name, but many are and especially so in Wales. 

Extract from the Tithe map

The enclosed land where the summit of this hill is situated is given the number 59 on the Tithe map, this can be cross referenced against the apportionments; it is these apportionments that give the name of the owner or occupier of the land as well as the name of the land.  The land where the summit of this hill is situated is named Bryn Coch Ucha in the apportionments, with the details on the Tithe map appearing in the parish named as Llanrwst and in the county named as Caernarfonshire. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the The Welsh P15s is Bryn Coch Ucha, and this was derived from the Tithe map. 

 

The full details for the hill are: 

Group:  Moel Siabod 

Name:  Bryn Coch Ucha 

Previously Listed Name:  Pt. c 364m 

OS 1:50,000 map:  115

Summit Height:  367.2m (LIDAR)                                                           

Summit Grid Reference:  SH 73243 55426 (LIDAR)                                                  

Bwlch Height:  348.8m (LIDAR) 

Bwlch Grid Reference:  SH 73032 55281 (LIDAR) 

Drop:  18.4m (LIDAR) 

                                                           

Myrddyn Phillips (August 2026)