Mapping Mountains – Significant Height Revisions – The Welsh P15s

 

Comin Gwauncaegurwen (SN 711 123) 

There has been a Significant Height Revision 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 Comin Gwauncaegurwen (SN 711 123)

The criteria for the list that this height revision 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 Comin Gwauncaegurwen and this was derived from the Tithe map with the language protocol also used, and it is adjoined to the Mynydd Du group of hills, which are situated in the southern part of South Wales (Region B, Sub-Region B5), and it is positioned with the A4068 road to its north-east, the A4069 road to its north-west and a minor road to its south, and has the village of Brynaman towards the north. 

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

When the listing that became known as The Welsh P15s was being compiled, this hill was not included in the main P15 list or the accompanying P14 sub list, as it possessed no contours of significance on either the Ordnance Survey 1:50,000 Landranger or the 1:25,000 Explorer map. 

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

Since the initial compilation of this list started 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 mapping on the Magic Maps website.

One of the mapping resources now available online is the WalkLakes website which hosts an interactive map originated from the Ordnance Survey Open Data programme.  This map has many spot heights not on other publicly available maps and a 216m spot height is given on the summit area of this hill. 

Extract from the interactive mapping hosted on the WalkLakes 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 summit image of Comin Gawuncaegurwen (SN 711 123)

The summit height produced by LIDAR analysis is 216.6m and when compared to detail on the Ordnance Survey 1:50,000 Landranger and the 1:25,000 Explorer map, 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 216.6m and this was derived from LIDAR analysis.  This is 16.6m higher than the uppermost 200m contour on the contemporary Ordnance Survey 1:50,000 Landranger map and 26.6m higher than the uppermost 190m contour on the Ordnance Survey 1:25,000 Explorer map. 

 ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Mynydd Du 

Name:  Comin Gawuncaegurwen 

OS 1:50,000 map:  160

Summit Height (New Height):  216.6 (LIDAR)                                                           

Summit Grid Reference:  SN 71158 12343 (LIDAR) 

Bwlch Height:  196.6m (LIDAR) 

Bwlch Grid Reference:  SN 71330 12592 & SN 71332 12592 (LIDAR) 

Drop:  19.98m (LIDAR) 

 

Myrddyn Phillips (April 2024)

 

 

 

Mapping Mountains – Hill Reclassifications – 100m Twmpau

Pt. 118.2m (SN 717 303) – 100m Sub-Twmpau addition

There has been confirmation of an addition to the list of the 100m Twmpau, 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. 118.2m (SN 717 303)

The criteria for the list that this addition 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. 

100m Twmpau by Myrddyn Phillips

The hill is being listed by the point (Pt. 118.2m) 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 Mynydd Du group of hills, which are situated in the southern part of South Wales (Region B, Sub-Region B5), and it is positioned with the A40 road to its north-west and a minor road to its immediate south-east, and has the village of Llangadog towards the south south-west.

When the original 100m 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. 

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-assessed and it was listed with an estimated c 26m of drop, based on an estimated c 117m summit height and an estimated c 91m bwlch height, with both heights based on interpolation of 5m contouring that appeared 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 confirmation of the addition of this hill to 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 118.2m summit height and a 90.8m bwlch height, with these values giving this hill 27.4m of drop, which is sufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Du 

Name:  Pt. 118.2m 

OS 1:50,000 map:  146, 160

Summit Height:  118.2m (LIDAR) 

Summit Grid Reference:  SN 71731 30341 & SN 71732 30342 (LIDAR) 

Bwlch Height:  90.8m (LIDAR) 

Bwlch Grid Reference:  SN 71320 29901 (LIDAR) 

Drop:  27.4m (LIDAR) 

 

Myrddyn Phillips (April 2024) 

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

Pt. 118.9m (SN 710 294) 

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 Pt. 118.9m (SN 710 294)

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. 

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 Du group of hills, which are situated in the southern part of South Wales (Region B, Sub-Region B5), and it is positioned with the Afon Tywi (River Towy) and the A40 road to its west, the B4069 road to its east, and has the village of Llangadog 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 y Tyddyn, with an accompanying note stating; Name from farm to the North.

Allt y Tyddyn

119m

SN711294

146/160

12

Name from farm 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 words Allt y 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

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 (Pt. 118.9m) notation, and for this hill this is such an example.

Therefore, the name this hill is now listed by in the 100m Twmpau and Y Trechol – The Dominant Hills of Wales is Pt. 118.9m, and this is being used as the author has not found an appropriate name for the hill either through historic research and/or local enquiry. 

 

The full details for the hill are:

Group:  Mynydd Du

Name:  Pt. 118.9m

Previously Listed Name:  Allt y Tyddyn 

OS 1:50,000 map:  146, 160

Summit Height:  118.9m (LIDAR) 

Summit Grid Reference:  SN 71046 29411 (LIDAR) 

Bwlch Height:  69.9m (LIDAR) 

Bwlch Grid Reference:  SN 72466 30393 (LIDAR) 

Drop:  48.9m (LIDAR) 

Dominance:  41.16% (LIDAR) 

 

Myrddyn Phillips (April 2024)

  

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Carreg Waring (SH 537 390) – 30-99m Sub-Twmpau addition 

There has been confirmation of an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived by LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Carreg Waring (SH 537 390)

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

30-99m Twmpau – Welsh hills at or above 30m and below 100m in height that have 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 30m and below 100m 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. 

30-99m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Carreg Waring, and this was derived by a combination of the Ordnance Survey series of Six-Inch maps and local enquiry, and it is adjoined to the Moel Hebog 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 A497 road to its north and a minor road to its east, and has the town of Porthmadog towards the east.

When the original 30-99m 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 23m of drop, based on the 57m summit 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 an estimated c 34m bwlch height, based on interpolation of 5m contouring between 30m – 35m. 

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 confirmation of the addition of this hill to 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 57.15m summit height and a 33.0m bwlch height, with these values giving this hill 24.1m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Moel Hebog 

Name:  Carreg Waring 

OS 1:50,000 map:  124

Summit Height:  57.15m (LIDAR) 

Summit Grid Reference:  SH 53734 39025 (LIDAR)               

Bwlch Height:  33.0m (LIDAR) 

Bwlch Grid Reference:  SH 53892 38892 (LIDAR) 

Drop:  24.1m (LIDAR) 

 

Myrddyn Phillips (April 2024)

 

 

 

 

  

Mapping Mountains – Summit Relocations – Y Trichant – The 300m Hills of Wales

Llanfilo Camp (SO 113 327) 

There has been a Summit Relocation to a hill that is listed in the 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 Llanfilo Camp (SO 113 327)

The criteria for the list that this summit relocation 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 name the hill is now listed by is Llanfilo Camp and this was derived from information supplied by Coflein, and it is adjoined to the Mynydd Epynt 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 A38 road farther to its north and the B4560 road farther to its east, and has the town of Talgarth towards the east north-east.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the main P30 list with a 310m summit height adjoined to a triangulation pillar positioned at SO 11359 32761 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

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 Llanfilo Camp (SO 113 327)

LIDAR analysis gives the highest ground on this hill as 310.4m positioned at SO 11352 32709, and this in relation to the previously listed summit position which LIDAR analysis gives as 310.0m in height and positioned at SO 11351 32749 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.

Therefore, the summit height produced by LIDAR analysis is 310.4m and this is positioned at SO 11352 32709, this position is not given a spot height or a 310m contour ring on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and is approximately 40 metres southward from where the previously listed summit is positioned and importantly to a different feature; being relocated from a triangulation pillar to an ancient earthwork. 

 

The full details for the hill are:

Group:  Mynydd Epynt 

Name:  Llanfilo Camp 

OS 1:50,000 map:  161

Summit Height:  310.4m (LIDAR)                                                           

Summit Grid Reference (New Position):  SO 11352 32709 (LIDAR) 

Bwlch Height:  223.6m (LIDAR) 

Bwlch Grid Reference:  SO 09879 31998 (LIDAR) 

Drop:  86.8m (LIDAR) 

 

Myrddyn Phillips (April 2024)