Mapping Mountains – Summit Relocations – Y Pellennig – The Remotest Hills of Wales, Welsh Highlands – Uchafion Cymru and 900m Twmpau

 

Foel Fras (SH 696 681) 

There has been a Summit Relocation to a hill that is listed in the Y Pellennig – The Remotest Hills of Wales, Welsh Highlands – Uchafion Cymru and 900m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Leica RX1250 survey conducted by Alan Dawson. 

Foel Fras (SH 696 681) from the summit of Trwsgl (SH 663 679)

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

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.

Welsh Highlands - Uchafion Cymru by Aled Williams and Myrddyn Phillips

900m Twmpau - Welsh hills at or above 900m and below 1000m in height with 30m minimum drop, with an accompanying sub list entitled the 900m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 900m and below 1000m 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.

900m Twmpau by Myrddyn Phillips

The name the hill is listed by is Foel Fras 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 the A55 road to its north-west, the A5 road to its south-west and the B5106 and A470 roads to its east, and has the town of Bethesda towards the west south-west. 

When the original list that later became known as the Welsh Highlands – Uchafion Cymru was first compiled, this hill was listed with 58m of drop, based on the 942m summit spot height adjoined to a triangulation pillar positioned at SH 69652 68173 that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and the 884m bwlch spot height that appears on the Ordnance Survey 1:25,000 Explorer map.

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

However, the summit area of this hill is rocky and includes a number of substantial upright rock spikes.  One of the earliest Abney Level surveys to ascertain the high point of this hill was conducted in 2011 by Graham Jackson.  This survey concluded that a rock spike approximately 55 metres south-wesward of the trig pillar is the highest point of this hill. 

This rock spike was subsequently surveyed by Alan Dawson using the Leica RX1250, resulting in a 944.1m summit height positioned at SH 69611 68118, 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, 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 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.

The Leica RX1250 gathering data at the summit of Foel Fras (SH 696 681).  Photo: Alan Dawson  

Therefore, the new listed summit height of this hill is 944.1m and this is positioned at SH 69611 68118 and this was derived from a Leica RX1250 survey, this position is approximately 55 metres south-westward from where the triangulation pillar is positioned and importantly it is positioned to a different feature.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Carnedd Llywelyn

Name:  Foel Fras

OS 1:50,000 map:  115

Summit Height:  944.1m (converted to OSGM15, Leica RX1250) 

Summit Grid Reference (New Position):  SH 69611 68118 (Leica RX1250) 

Bwlch Height:  881.3m (converted to OSGM15, Leica RX1250) 

Bwlch Grid Reference:  SH 68799 66515 (Leica RX1250) 

Drop:  62.8m (Leica RX1250) 

Remoteness:  3.975km

 

Myrddyn Phillips and Aled Williams (August 2024)

 

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

Esgair Llyn Du (SN 769 620) 

There has been a Summit Relocation to a hill that is listed in the Welsh Highlands – Uchafion Cymru and 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 Aled Williams. 

Esgair Llyn Du (SN 769 620)

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

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.

Welsh Highlands - Uchafion Cymru by Aled Williams and Myrddyn Phillips

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 15m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available as a downloadable e-booklet and print-booklet version on Mapping Mountains Publications with the up-to-date master list available to download on the Mapping Mountains site 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 Esgair Llyn Du 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 a minor road to its north-west and south, and has the small community of Pontrhydfendigaid towards the north-west and the town of Tregaron towards the west south-west. 

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

When the 1^st edition of the Y Pellennig – The Remotest Hills of Wales was published by Europeaklist in April 2015, this hill was listed with 3.075km of remoteness and 20m of drop, based on the 534m summit spot height positioned at SN 767 617 and the 514m bwlch spot heights that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, with this mapping giving two positions of equal height for the bwlch. 

Extract from the interactive mapping hosted on the WalkLakes website

The Ordnance Survey Vector Map Local hosted on the Geograph website gave the higher spot height to the middle of three larger 530m map contour rings, with the southerly and middle ring contours subsequently surveyed with the Trimble GeoXH 6000.  However, the interactive mapping hosted on the WalkLakes website indicates that the most northerly of these is the higher. 

The Trimble GeoXH 6000 set-up position at the southerly of the three tops

The Trimble GeoXH 6000 set-up position at the central of the three tops

At the northerly of the three tops and the summit of Esgair Llyn Du

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. 

 

The results from these surveys are given below: 

LIDAR for northerly summit:  532.849m at SN 76930 62044 

LIDAR for central summit:  532.729m at SN 76768 61773 

Trimble GeoXH 6000 for central summit:  532.552m at SN 76770 61772 

LIDAR for southerly summit:  532.020m at SN 76691 61642 

Trimble GeoXH 6000 for southerly summit:  531.914m at SN 76691 61642 

 

The 532.8m summit height produced by LIDAR analysis and its position in relation to the previously listed summit comes within the parameters of the Summit Relocations used within this page heading, these parameters are: 

The term Summit Relocations applies to when the high point is positioned in a different field, to a different feature such as a conifer plantation, within a different map contour, a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit 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 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. 

LIDAR image of Esgair Llyn Du (SN 769 620)

LIDAR summit image of Esgair Llyn Du (SN 769 620)

Therefore, the summit height produced by LIDAR analysis is 532.8m and this is positioned at SN 76930 62044.  This position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, but a 532m spot height appears in this position on the interactive mapping hosted on the WalkLakes website and is approximately 440 metres north-eastward from where the originally listed summit is positioned and approximately 300 metres north-eastward from where the previously listed summit is positioned, resulting in its remoteness being amended from 3.075km to 2.925km.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Esgair Wen

Name:  Esgair Llyn Du

OS 1:50,000 map:  146, 147

Summit Height:  532.8m (LIDAR) 

Summit Grid Reference:  SN 76930 62044 (LIDAR) 

Bwlch Height:  513.8m (LIDAR) 

Bwlch Grid Reference:  SN 76942 61196 (LIDAR) 

Drop:  19.0m (LIDAR) 

Remoteness:  2.925 km

 

Myrddyn Phillips and Aled Williams (November 2023)

 

 

  

Mapping Mountains – Summit Relocations – 500m Twmpau and Welsh Highlands – Uchafion Cymru

Foel Fawr (SH 728 392)

There has been a Summit Relocation 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 survey conducted by Myrddyn Phillips and Aled Williams on the 19^th July 2020.

Foel Fawr (SH 728 392)

The criteria for the two listings that this summit relocation 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.

The 500m Twmpau by Myrddyn Phillips

Welsh Highlands – Uchafion Cymru – This is the revised draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height with 15m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams with the Introduction to the list being published on Mapping Mountains in November 2015 and an update relating to the list appearing on Mapping Mountains on the 19th June 2019.

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

The name the hill is listed by is Foel Fawr and it is adjoined to the Arenig Fach group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A2), and it is positioned with the B4391 road to its north, the A470 road to its west and the A4212 road to its south, and has the village of Trawsfynydd towards the south-west.

When the original list of Welsh 500m P15s that later became known as Yr Uchafion and latterly as The Welsh Highlands – Uchafion Cymru was first compiled, this hill was listed with an estimated c 41m of drop based on the 528m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and which is positioned at SH 72620 39472, and an estimated c 487m bwlch height, based on interpolation of 10m contouring between 480m - 490m.

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

Since first compilation of the Welsh 500m P15 list there have been a number of Ordnance Survey 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 are current and 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, and it was this map that showed a 528m map heighted twin summit positioned at SH 72873 39268.  The two 528m spot heights are also shown on the mapping hosted on the Magic Maps website.

Extract from the Magic Maps website

However, it was not until the survey with the Trimble GeoXH 6000 that the details for this hill could be accurately re-assessed.  The height and position for each summit is given below:

South-easterly summit:  528.611m at SH 72872 39284

North-westerly summit:  527.542m at SH 72621 39476

The above detail compared to the prioritised summit previously given 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.

Gathering data at the higher of the Foel Fawr summits

Gathering data at the lower of the Foel Fawr summits

Therefore, the summit height produced by the Trimble GeoXH 6000 survey is 528.6m and this is positioned at SH 72872 39284, this position is not given a spot height on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps, but is given a 528m spot height on the interactive mapping hosted on the Magic Maps website, and is approximately 260 metres south-eastward from where the previously listed and prioritised summit is positioned.

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Arenig Fach

Name:  Foel Fawr

OS 1:50,000 map:  124

Summit Height:  528.6m (converted to OSGM15)

Summit Grid Reference (New Position):  SH 72872 39284

  

Bwlch Height:  485.5m (converted to OSGM15)

Bwlch Grid Reference:  SH 73074 39525

Drop:  43.1m

Myrddyn Phillips and Aled Williams (October 2020)

Mapping Mountains – Summit Relocations – Yr Uchafion and 500m Twmpau

Mynydd Ton (SS 949 940)

There has been a Summit Relocation initiated by a survey with the Trimble GeoXH 6000  to the listings of Yr Uchafion and the 500m Twmpau, with the survey that resulted in this summit relocation being conducted on the 23^rd July 2016 in good, clear and sheltered conditions.

The two lists that this summit relocation affects are:

Yr Uchafion, this is the working title for a list that takes in all hills in Wales at and above 500m in height that have a minimum 15m of drop.  This list is co-authored by Myrddyn Phillips and Aled Williams.

500m Twmpau (thirty welsh metre prominences and upward), with the criteria being all Welsh hills at or above 500m and below 600m in height that have a minimum 30m of drop.  This list is authored by Myrddyn Phillips.


The survey was conducted in the range of hills known as the Y Cymoedd, these are the hills associated with the south Wales valleys.  The hill is situated between Cwm Ogwr Fawr to its west and the Rhondda Fawr valley to its east and is positioned above the towns of Treorci (Treorchy) and Treherbert to its north and Nant-y-moel, Price Town and Ogmore Vale to its south-west.

Access to the hill is relatively easy as a track leaves the A 4061 near to its high point and continues south-eastward to the north-western edge of a large conifer plantation, a path continues south-eastward adjacent to the forest boundary gaining the access point to a wide forest break which is relatively near the summit of this hill.

The name of the hill is Mynydd Ton and prior to the survey with the Trimble GeoXH 6000 the height of the hill was listed as 539m at SS 94796 93958 which is beside an ancient cairn.  This height was based on a 1,769.3ft surface height given on the Ordnance Survey Six-Inch map published in 1885.  The 539m figure was a relatively new addition to this hill’s listed height as its summit position was originally listed as ground beside its map heighted 535m triangulation pillar situated at SS 94931 94058.

The highest ground at the base of and beside the ancient cairn was surveyed with the Trimble GeoXH 6000 as being 534.2m (converted to OSGM15) high.  The processed data gave Estimated Accuracies of 5-15cm: 99.41%, with the Standard Deviation being 0.0m, and the margin of uncertainty given for the height placement of the Trimble was 0.1m.  All of the above signify that the data set was good and accurate to within the parameters of the equipment.

I had previously visited this hill in February 2003 and judged ground approximately one minute walk away from the trig pillar to be slightly higher than ground at the base of the trig pillar, and as the flush bracket adjoined to the trig pillar is given a height of 535.335m in the OS Trig Database it means that ground at its base is approximately 535m high.  This figure is dependent upon the accuracy of the flush bracket height which is given as 3^rd order.   Therefore the ground at the base of or near to the triangulation pillar is likely to be higher than that beside the ancient cairn.

Therefore the position of the relocated summit is at SS 94931 94058 and consists of ground at the base of, or near to the triangulation pillar.  This re-located summit position is at the hill’s originally listed summit and is given a 535m height on current Ordnance Survey maps and it is approximately 175 metres north-eastward from the previously listed summit position.

The full details for the hill are:

Cardinal Hill:  Werfa

Summit Height:  534.4m (converted to OSGM15)

Name:  Mynydd Ton

OS 1:50,000 map:  170

Summit Grid Reference (New Position):  SS 94931 94059 

      

Drop:  91.3m (converted to OSGM15)

The Trimble GeoXH 6000 gathering data beside the ancient cairn on Mynydd Ton, with the relocated position of the summit approximately 175 metres to the north-east and to the right of the forest break in the centre background of this photograph

For details on the survey that relocated the summit of this hill

For details on the 2nd survey of this hill

Myrddyn Phillips and Aled Williams (August 2016)