Mapping Mountains – Significant Height Revisions – Welsh Highlands – Uchafion Cymru

Llechwedd Du (SH 893 446) 

There has been a Significant Height Revision to a hill that is listed in the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted for the Welsh Highlands – Uchafion Cymru list authored by Aled Williams and Myrddyn Phillips. 

LIDAR image of Llechwedd Du (SH 893 446)

The criteria for the list that this height revision 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 Myrddyn Phillips and Aled Williams

The name the hill is listed by is Llechwedd Du 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 A2), and is positioned with the A4212 road to its south and the B4501 road to its east, and has the town of Y Bala towards the south south-east and the village of Cerrigydrudion towards the north-east. 

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

When the original list that later became known as the Welsh Highlands – Uchafion Cymru was first compiled, this hill was included as a Welsh Highland Sub with 14m of drop, based on the 509m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and the 495m bwlch spot height that appears on the Ordnance Survey 1:25,000 Explorer map. 

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

The details for this hill were re-assessed when the OS Maps website became available online.  This is the replacement for OS Get-a-map and had contours at 5m intervals which were consistently more accurate compared to the 5m contours that sometimes appeared on Ordnance Survey 1:25,000 Explorer maps and the online Vector Map Local.  This re-assessment resulted in its reclassification to Welsh Highland P15 status and listed with an estimated c 16m of drop, based on an estimated c 511m summit height from interpolation of the 510m uppermost contour and the 495m bwlch spot height that appears on the Ordnance Survey 1:25,000 Explorer map. 

Extract from the interactive mapping hosted on the OS Maps website

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 511.4m positioned at SH 89360 44629, and 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 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.

Therefore, the new listed summit height of this hill is 511.4m and this was derived from LIDAR analysis, this is positioned at SH 89360 44629 and is 2.4m higher than its originally listed height of 509m, which was based on the summit spot height 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:  Carnedd y Filiast

Name:  Llechwedd Du

OS 1:50,000 map:  124, 125

Summit Height (New Height):  511.4m (LIDAR)

Summit Grid Reference:  SH 89360 44629 (LIDAR)

Bwlch Height:  497.1m (LIDAR)

Bwlch Grid Reference:  SH 89096 44273 (LIDAR)   

Drop:  14.3m (LIDAR) 

 

Myrddyn Phillips and Aled Williams (May 2023)

  

Mapping Mountains – Summit Relocations – The Fours – The 400m Hills of England

Bowland Knotts (SD 727 606) 

There has been confirmation of 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 Bowland Knotts (SD 727 606)

The criteria for the list that this summit relocation 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 are three categories of sub hills; the 400m Sub-Four category, the 390m Sub-Four category and the 390m Double Sub-Four category.  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 Bowland Knotts, and it is adjoined to the Ward’s Stone group of hills, which are situated in the southern Pennines, and it is positioned with a minor road to its immediate west, the B6478 road to its south-east and the A65 road to its north-east, and has the town of Settle towards the east north-east.

When the original list that later became known as The Fours – The 400m Hills of England was first compiled, the summit position of this hill was given as SD 722 603 based on the 430m map heighted triangulation pillar that appears on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map. 

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

When the 1^st edition of the The Fours was published by Europeaklist in December 2013, the summit of this hill was relocated to SD 727 606 and listed with an estimated c 86 of drop, based on an estimated c 430m summit height and an estimated c 344m col height, with both heights based on interpolation of 10m contouring that appear on the Ordnance Survey 1:25,000 Explorer map.

The following note accompanied its listing:

As there is no 430m contour ring in the vicinity of the triangulation pillar that has a flush racket height of 429.932m (highest ground in vicinity of trig is at SD 722 603) the listed summit has been relocated to the vicinity of where a c 430m contour ring is shown on the map.  Therefore the summit is relocated from the previously listed high point which appeared in the original published listing in the RHB Yahoo Group file database.  However, margin of uncertainty associated with contour lines means the ground at SD 722 603 in the vicinity of the trig is still a contender as overall high point.

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 Bowland Knotts (SD 727 606)

LIDAR analysis gives the highest ground on this hill as 430.7m positioned at SD 72767 60678, as opposed to the originally listed summit position which LIDAR gives as 430.0m positioned at SD 72207 60305, and this 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.

Therefore, the summit height produced by LIDAR analysis is 430.7m and this is positioned at SD 72767 60678.  This position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and is approximately 570 metres north-eastward from where the original listed summit is positioned.

 

The full details for the hill are:

Group:  Ward’s Stone

Name:  Bowland Knotts

OS 1:50,000 map:  98

Summit Height:  430.7m (LIDAR)

Summit Grid Reference (New Position):  SD 72767 60678 (LIDAR)

Col Height:  343.4m (LIDAR)

Col Grid Reference:  SD 71799 60697 (LIDAR)

Drop:  87.3m (LIDAR)

 

Myrddyn Phillips and Aled Williams (May 2023)

 

 

  

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

Parc y Llan (SN 101 184) 

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, bwlch height and their locations, the drop, dominance and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Parc y Llan (SN 101 184)

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

100m Twmpau – Welsh hills at or above 100m and below 200m in height that have 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. 

The 100m 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 hill is adjoined to the Mynydd Preseli group of hills, which are situated in the south-western part of South Wales (Region B, Sub-Region B1), and it is positioned with a minor road to its north-east, the B4313 road to its north-west, the A40 road to its south and the A478 road to its east, and has the town of Arberth (Narberth) towards the south.

The hill appeared in the original Welsh 100m P30 list on Geoff Crowder’s v-g.me website, under the invented and transposed name of Allt Llwyn-celyn, with an accompanying note stating; Name from buildings to the North.

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 transpose the name of a farm and add the word Allt to it.  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 777 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 Parc y Llan in the apportionments, with the details on the Tithe map appearing in the parish of Llanhuadain and in the county named as Pembroke. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the 100m Twmpau and Y Trechol – The Dominant Hills of Wales is Parc y Llan, and this was derived from the Tithe map. 

 

The full details for the hill are:

Group:  Mynydd Preseli

Name:  Parc y Llan

Previously Listed Name:  Allt Llwyn-celyn   

OS 1:50,000 map:  158

Summit Height:  109.5m (LIDAR) 

Summit Grid Reference:  SN 10115 18441 (LIDAR) 

Bwlch Height:  62.3m (LIDAR) 

Bwlch Grid Reference:  SN 11264 19419 (LIDAR) 

Drop:  47.2m (LIDAR) 

Dominance:  43.08% (LIDAR) 

 

Myrddyn Phillips (May 2023)

  

Mapping Mountains – Hill Reclassifications – Y Trichant – The 300m Hills of Wales

Pt. 344.1m (SN 662 471) – Sub-Trichant addition

There has been an addition to the list of Y Trichant – The 300m 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 Pt. 344.1m (SN 662 471)

The criteria for the list that this addition applies to are:

Y Trichant – The 300m Hills of Wales – Welsh hills at or above 300m and below 400m in height that have 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 the renaming of it appearing on Mapping Mountains on the 13^th May 2017, and the Introduction to the Mapping Mountains publication of the list appearing on the 1^st January 2022. 

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The hill is being listed by the point (Pt. 344.1m) notation as an appropriate name for it either through local enquiry and/or historic research has not been found by the author, 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 encircled by minor roads, with the B4343 road farther to its north-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 were published on Geoff Crowder’s v-g.me website, this hill was not included in the 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 with an estimated c 17m of drop, based on the 345m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 328m 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 addition of this hill to Sub-Trichant status is due to LIDAR analysis, resulting in a 344.1m summit height and a 323.3m bwlch height, with these values giving this hill 20.8m of drop, which is sufficient for it to be classified as a Sub-Trichant. 

 

The full details for the hill are: 

Group:  Esgair Wen 

Name:  Pt. 344.1m 

OS 1:50,000 map:  146

Summit Height:  344.1m (LIDAR)                                                           

Summit Grid Reference:  SN 66219 47125 (LIDAR) 

Bwlch Height:  323.3m (LIDAR) 

Bwlch Grid Reference:  SN 66507 47197 (LIDAR) 

Drop:  20.8m (LIDAR) 

 

Myrddyn Phillips (May 2023)

  

Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

Llechwedd Du (SH 893 446) – Welsh Highland P15 reclassified to Welsh Highland Sub 

There has been a reclassification to the listing of the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted for the Welsh Highlands – Uchafion Cymru list authored by Aled Williams and Myrddyn Phillips. 

LIDAR image of Llechwedd Du (SH 893 446)

The criteria for the list that this reclassification 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 Myrddyn Phillips and Aled Williams

The name the hill is listed by is Llechwedd Du 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 A2), and is positioned with the A4212 road to its south and the B4501 road to its east, and has the town of Y Bala towards the south south-east and the village of Cerrigydrudion towards the north-east. 

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

When the original list that later became known as the Welsh Highlands – Uchafion Cymru was first compiled, this hill was included as a Welsh Highland Sub with 14m of drop, based on the 509m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and the 495m bwlch spot height that appears on the Ordnance Survey 1:25,000 Explorer map. 

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

The details for this hill were re-assessed when the OS Maps website became available online.  This is the replacement for OS Get-a-map and had contours at 5m intervals which were consistently more accurate compared to the 5m contours that sometimes appeared on Ordnance Survey 1:25,000 Explorer maps and the online Vector Map Local.  This re-assessment resulted in its reclassification to Welsh Highland P15 status and listed with an estimated c 16m of drop, based on an estimated c 511m summit height from interpolation of the 510m uppermost contour and the 495m bwlch spot height that appears on the Ordnance Survey 1:25,000 Explorer map. 

Extract from the interactive mapping hosted on the OS Maps website

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 back to Welsh Highland Sub status is due to LIDAR analysis, resulting in a 511.4m summit height and a 497.1m bwlch height, with these values giving this hill 14.3m of drop, which is insufficient for it to be classified as a Welsh Highland P15. 

 

The full details for the hill are: 

Group:  Carnedd y Filiast

Name:  Llechwedd Du

OS 1:50,000 map:  124, 125

Summit Height:  511.4m (LIDAR)

Summit Grid Reference:  SH 89360 44629 (LIDAR)

Bwlch Height:  497.1m (LIDAR)

Bwlch Grid Reference:  SH 89096 44273 (LIDAR)   

Drop:  14.3m (LIDAR) 

 

For the additions, deletions and reclassifications to the Welsh Highlands – Uchafion Cymru reported on Mapping Mountains please consult the following Change Registers:

 

Welsh Highland P15s

 

Welsh Highland Subs

 

Aled Williams and Myrddyn Phillips (May 2023)