Mapping Mountains – Summit Relocations – 100m Twmpau and Y Trechol – The Dominant Hills of Wales

Cae Uchaf (SS 575 943)

There has been a Summit Relocation to a hill that is listed in the 100m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, drop and status of the hill being confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR summit image of Cae Uchaf

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 30m minimum drop, with an accompanying sub list entitled the 100m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 100m and below 200m 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.

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 addition Welsh P30 hills whose prominence is 33.33% or more and below 50% 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.

The name of the bounded land where the summit of this hill is situated is Cae Uchaf and this was derived from the Tithe map, and it is the name that this hill is now listed by.  The hill is adjoined to the Gŵyr group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and it is positioned with the B 4296 road to its east, and has the small community of Y Crwys (Three Crosses) at its base to the west south-west.

 

If wanting to visit the hill permission to do so should be sought as the summit area is not a part of designated open access land, for those wishing to do so the nearest public footpath is to the north of the summit.

Prior to LIDAR analysis this hill was listed with 70m of drop and 48.61% dominance based on the 144m summit spot height and 74m bwlch spot height that appear on the Ordnance Survey 1:25,000 Explorer map.

LIDAR bwlch image of Cae Uchaf showing the natural bwlch to be intact

The summit height produced by 1m DTM LIDAR analysis is 144.4m at SS 57511 94397 and its position in relation to that previously given comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, 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, or when the summit of the hill is in a different field compared to where previously given, or when the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these relocations.

The summit height produced by 1m DTM LIDAR analysis is 144.4m and is positioned at SS 57511 94397, this position is not given a spot height on contemporary Ordnance Survey maps and is approximately 65 metres west and in a different field from where the 144m spot height appears on the Ordnance Survey 1:25,000 Explorer map.   

Ordnance Survey Interactive Coverage Map hosted on the Geograph website showing the summit position in relation to where the 144m spot height appears

  

The full details for the hill are:

Group:  Gŵyr

Name:  Cae Uchaf

OS 1:50,000 map:  159

Summit Height:  144.4m (LIDAR)

Summit Grid Reference (new position):  SS 57511 94397 (LIDAR)

Bwlch Height:  73.4m (LIDAR, natural bwlch remains)

Bwlch Grid Reference:  SS 50983 90868 (LIDAR) 

Drop:  71.0m (LIDAR)

Dominance:  49.19% (LIDAR)

Myrddyn Phillips (November 2018)

Mapping Mountains – Summit Relocations – Y Trichant

Cefn Llanbister (SO 116 733)

There has been a Summit Relocation to a hill that is listed in the Y Trichant, and which was initiated by LIDAR analysis and confirmed by a survey with the Trimble GeoXH 6000, both of which were conducted by Myrddyn Phillips, with the latter taking place on the 03.07.18 in warm and clear conditions.

Cefn Llanbister (SO 116 733)

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

Y Trichant – Welsh hills at or above 300m and below 400m in height with 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list and its renaming appearing on Mapping Mountains on the 13^th May 2017.

The name of the hill is Cefn Llanbister and it is placed in the Beacon Hill group of hills, which are situated in the north-eastern part of Mid and West Wales (Region B, Sub-Region B1), and it is positioned with the Afon Ieithon (River Ithon) and the A 483 road to its west and the B 4356 road to its north, and has the small community of Llanbister at its base to the west of the summit.

As the summit of the hill is a part of open access land it can be approached from most directions with public footpaths accessing this land from the west and east, with the most convenient access to the hill via a track that leaves the B 4356 road just to the north of the summit.

When the original Welsh 300m P30 list was published on Geoff Crowder’s v-g.me website this hill was listed with a 373m summit height based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map, with an accompanying note stating 376m at SO GR117732 on 1986 1:50000 map.

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

Prior to LIDAR analysis and the subsequent survey with the Trimble GeoXH 6000 the listed height of this hill had been revised to 376m based on the spot height on the Ordnance Survey 1:50,000 Landranger map.

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

The summit height produced by the Trimble GeoXH 6000 survey is 377.5m (converted to OSGM15) at SO 11690 73303 and its position in relation to that previously given comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, 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, or when the summit of the hill is in a different field compared to where previously given, or when the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these relocations.

The summit height produced by the Trimble GeoXH 6000 survey is 377.5m (converted to OSGM15) and is positioned at SO 11690 73303, this position is not given a spot height on contemporary Ordnance Survey maps and is approximately 100 metres east from where the 376m spot height appears on the Ordnance Survey 1:50,000 Landranger map and 450 metres north-west from where the 373m spot height appears on the Ordnance Survey 1:25,000 Explorer map.   

The Trimble GeoXH 6000 gathering data at the summit of Cefn Llanbister which confirmed the summit relocation of this hill

The full details for the hill are:

Group:  Beacon Hill

Name:  Cefn Llanbister

OS 1:50,000 map:  136, 148

Summit Height:  377.5m (converted OSGM15)

Summit Grid Reference (new position):  SO 11690 73303

Bwlch Height:  335.3m (converted to OSGM15)

Bwlch Grid Reference:  SO 12399 74601 

 

Drop:  42.2m (converted to OSGM15)

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

Myrddyn Phillips (November 2018)

Mapping Mountains – Trimble Surveys – Cymoedd Gwent

25.08.18  Mynydd Ton (SS 949 940)  

Mynydd Ton has a convoluted history for summit placement as it was originally given to where its 535m map heighted trig pillar is situated; its summit position was then moved to an ancient cairn where a 1,769.3ft (539m) surface height is given on the series of Ordnance Survey Six-Inch maps, this latter position was surveyed using the Trimble GeoXH 6000 in July 2016 as being 534.2m in height, therefore dependent upon the flush bracket accuracy the ground at the base of the trig pillar will be higher, therefore the summit was relocated back to that of the triangulation pillar.  Today we hoped to gather data from ground beside the trig pillar and compare this against the data previously taken from beside the ancient cairn.

As Mark, Aled and I set off up the gravelled track that leaves the road junction between the A4061 and the A4107, the distinctive profile of Corn Du and Pen y Fan were silhouetted against a foreground of sparkling white wind turbines as the terraced rows of houses in Cwmparc stood bolt upright in the valley below.

The distinctive profile of Corn Du and Pen y Fan in the background with the regimented houses of Cwmparc in the valley below

Gaining height on the wide track the roads below meandered around adjacent hillsides, with the mast and wind turbines on Werfa to our west being a distinctive landmark, by now the sun was relatively low in the sky casting delicate and appealing colour on the land.

Meandering roads and wind turbines atop Werfa

Looking out toward Werfa

Leaving the track we followed a path toward the conifer plantation that swamps the eastern part of this hill, adjacent to this the path followed the forest’s perimeter fence toward a wide forest break that heads east toward the summit of the hill.  The last time I was here an abandoned 4x4 vehicle added unfortunate novelty to the scene, thankfully this has now gone but some of its remains are still scattered across the grassland of the wide forest break.

Our first port of call was the trig pillar which is relatively easy to find amongst the trees as an avenue has been cut leading to its secluded grove, and almost Narnia like it nestles in its small clearing where once open hillside would have given extensive views.

Entering the avenue of conifers leading to the secluded grove where the trig pillar is situated

The trig pillar in its secluded grove

We assessed the land at the base of the trig pillar and once the position of the high point was determined I placed the Trimble on top of the trig and took a measurement offset to the summit, we now waited for it to slowly ebb  down toward its 0.1m accuracy level.  A five minute data set was gathered from the summit and we then left through the enclosed avenue of cultivated conifers to the open forest break.

Gathering data at the summit of Mynydd Ton

As data had previously been gathered from beside the ancient cairn we opted for a second data set in the wide forest break close to the perimeter fence, we had assessed this land when heading toward the trig pillar and judged it to be slightly higher than that beside the ancient cairn.  Having walked back on the forest break from close to the trig pillar we also thought this to be close in height to that beside the trig.

Beside the ancient cairn

Therefore as Mark and Aled stood beside the perimeter fence watching the sun slowly sink in the western sky I positioned the Trimble atop its improvised tripod of my rucksack and gathered the last data set of the day.

The Trimble set-up position and the last data set of the day

Once the Trimble was packed away I joined Mark and Aled and stood and admired the scene of setting sun with the view as far as the hills of south-west England rising above the Bristol Channel.

Looking out toward the hill's of south-west England

Watching the sun set behind Werfa

To our west the mast and wind turbines on Werfa gave dimension to the hill and added detail to a scene of delicate colour that slowly unfolded from the oranged hues of a sinking sun to the pinks and mauves when light tranquilly disappears.

A myriad of colour as the sun slowly disappeared behind Werfa

It had been another enjoyable day on the hill in good company with all our bagging needs met, but it had also been a long day as after a quick stop in Brecon for chips it meant a late night for all of us, with Aled heading back to Porthmadog from Caersws where his car was parked, and Mark heading home to Mold after having a quick cup of coffee when we arrived back at my home in Welshpool.   

Survey Result:

Mynydd Ton

Summit Height:  534.4m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SS 94931 94059 (summit relocation confirmed)

Bwlch Height:  443.1m (converted to OSGM15, previously Trimbled)

Bwlch Grid Reference:  SS 93953 94456

Drop:  91.3m

Dominance:  17.08%

For details on the survey of land beside the ancient cairn on Mynydd Ton

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Significant Name Changes – 100m Twmpau and Y Trechol – The Dominant Hills of Wales

Cae Uchaf (SS 575 943)

There has been a Significant Name Change to a hill that is listed in the 100m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, drop and status of the hill being confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Cae Uchaf

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 30m minimum drop, with an accompanying sub list entitled the 100m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 100m and below 200m 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.

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 addition Welsh P30 hills whose prominence is 33.33% or more and below 50% 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.

The hill is adjoined to the Gŵyr group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and it is positioned with the B 4296 road to its east, and has the small community of Y Crwys (Three Crosses) at its base to the west south-west.

The hill originally appeared in the 100m P30 list on Geoff Crowder’s v-g.me website under the invented name of Three Crosses Hill with an accompanying note stating; Name from town to the West. 

Three Crosses Hill

144m

SS576944

159

164

Name from town to the West

  

During my early hill listing I 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.  My preference was to use farm names and put Pen, Bryn or Moel in front of them or as in this instance use a name of a village and add the word Hill to the name.  This is not a practice that I now advocate 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

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 1424 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 as Cae ucha in the apportionments, with the details on the Tithe map appearing in the parish of Llanrhidian and in the county named as Glamorgan.

Extract from the apportionments

Therefore, the name this hill is now listed by in the 100m Twmpau is Cae Uchaf, and this was derived from the Tithe map.

The full details for the hill are:

Group:  Gŵyr

Name:  Cae Uchaf

Previously Listed Name:  Three Crosses Hill 

  

OS 1:50,000 map:  159

Summit Height:  144.4m (LIDAR)

Summit Grid Reference:  SS 57511 94397 (LIDAR)

Bwlch Height:  73.4m (LIDAR, natural bwlch remains)

Bwlch Grid Reference:  SS 50983 90868 (LIDAR)

 

Drop:  71.0m (LIDAR)

Dominance:  49.19% (LIDAR)

Myrddyn Phillips (November 2018)

Mapping Mountains – Significant Height Revisions – Y Trichant

Cefn Llanbister (SO 116 733)

There has been a Significant Height Revision to a hill that is listed in the Y Trichant, and which was initiated by LIDAR analysis and followed by a survey with the Trimble GeoXH 6000 both of which were conducted by Myrddyn Phillips, with the latter taking place on the 03.07.18 in warm and clear conditions.

LIDAR image of Cefn Llanbister

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

Y Trichant – Welsh hills at or above 300m and below 400m in height with 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list and its renaming appearing on Mapping Mountains on the 13^th May 2017.

The name of the hill is Cefn Llanbister and it is placed in the Beacon Hill group of hills, which are situated in the north-eastern part of Mid and West Wales (Region B, Sub-Region B1), and it is positioned with the Afon Ieithon (River Ithon) and the A 483 road to its west and the B 4356 road to its north, and has the small community of Llanbister at its base to the west of the summit.

As the summit of the hill is a part of open access land it can be approached from most directions with public footpaths accessing this land from the west and east, with the most convenient access to the hill via a track that leaves the B 4356 road just to the north of the summit.

When the original Welsh 300m P30 list was published on Geoff Crowder’s v-g.me website this hill was listed with a 373m summit height based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map, with an accompanying note stating 376m at SO GR117732 on 1986 1:50000 map.

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

Prior to LIDAR analysis and the subsequent survey with the Trimble GeoXH 6000 the listed height of this hill had been updated to 376m based on the spot height on the Ordnance Survey 1:50,000 Landranger map.

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

The 377.5m (converted to OSGM15) summit height produced by the Trimble GeoXH 6000 is not a dramatic increase from the 376m spot height, but does come 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 or Harvey map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000 or analysis of data produced via LIDAR, also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble or by LIDAR analysis.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these revisions.

Therefore, this hill’s new summit height as surveyed with the Trimble GeoXH 6000 is 377.5m (converted to OSGM15) which is 1.5m higher than its updated height of 376m and 4.5m higher than its original listed height of 373m which appears on the Ordnance Survey 1:25,000 Explorer map.

The Trimble GeoXH 6000 gathering data at the summit of Cefn Llanbister which resulted in this hill's significant height revision

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Beacon Hill

Name:  Cefn Llanbister

OS 1:50,000 map:  136, 148

Summit Height (New height):  377.5m (converted OSGM15)

Summit Grid Reference:  SO 11690 73303

Bwlch Height:  335.3m (converted to OSGM15)

Bwlch Grid Reference:  SO 12399 74601

  

Drop:  42.2m (converted to OSGM15)

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (November 2018)