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 Penygarreg (SH 815 818) - 30-99m Sub-Twmpau addition

Obelisg Bryn Pydew (SH 805 789) - 100m Sub-Twmpau addition

March Mynydd Ucha (SO 097 282) - Welsh Sub-P15 deletion

Lan Ucha Castell Madog (SO 027 385) - 390m Double Sub-Pedwar deletion

Allt Cilhywi (SO 035 358) - Sub-Trichant reclassified to Trichant

Carreg Rhoson (SM 672 256) - 30-99m Twmpau reclassified to Double Sub-Twmpau

Trehenry Fawr (SO 097 343) - 200m Sub-Twmpau addition

Y Faerdre (SH 783 794) - 100m Sub-Twmpau addition

Mynydd Fforest (SO 086 389) - Sub-Trichant addition

Yr Allt (SN 552 024) - 30-99m Sub-Twmpau addition

Mynydd Pencarreg (SN 600 440) - Lesser Dominant deletion

Poll Carn (SM 952 244) - 100m Sub-Twmpau addition

 

 

Significant Height Revisions: 

Safle Claddu Nant y Caws (SN 468 174) & (SN 469 174) and Cae Mawr (SN 462 175) - Dual Summit Lesser Dominant and Dual Summit 100m Twmpau

March Mynydd Ucha (SO 097 282) - Welsh P15s

Y Foel Goch (SH 677 582) - Welsh Highlands - Uchafion Cymru and 800m Twmpau

Carreg Rhoson (SM 672 256) - 30-99m Twmpau and Y Pellennig - The Remotest Hills of Wales

 

 

Summit Relocations: 

Safle Claddu Nant y Caws (SN 468 174) & (SN 469 174) and Cae Mawr (SN 462 175) - Dual Summit Lesser Dominant and Dual Summit 100m Twmpau

Lan Ucha Ty'n y Wern (SN 996 423) - Y Trichant - The 300m Hills of Wales and Y Pedwarau - The 400m Hills of Wales

Coed Abergwynant (SH 677 178) - 30-99m Twmpau

Cae Gwar Allt (SN 455 133) - 100m Twmpau and Y Trechol  The Dominant Hills of Wales

Cae Eithin (SO 096 286) - Welsh P15s

Trehenry Fawr (SO 097 343) - 200m Twmpau 

 

Significant Name Changes: 

Mynydd Aberysgir (SN 981 323) - Y Trichant - The 300m Hills of Wales

Cefn Uchaf (SN 930 489) - 200m Twmpau

Obelisg Bryn Pydew (SH 805 789) - 100m Twmpau

Banc (SN 906 493) - 200m Twmpau

Y Faerdre (SH 783 794) - 100m Twmpau 

March Mynydd Ucha (SO 097 282) - Welsh P15s

Lan Ucha Ty'n y Wern (SN 996 423) - Y Trichant - The 300m Hills of Wales and Y Pedwarau - The 400m Hills of Wales

Cae Gwar Allt (SN 455 133) - 100m Twmpau and Y Trechol  The Dominant Hills of Wales 

 

Mapping Mountains – Hill Reclassifications – 100m Twmpau

 

Poll Carn (SM 952 244) – 100m Sub-Twmpau addition

There has been confirmation of an addition to the list of 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 Poll Carn (SM 952 244)

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 name the hill is listed by is Poll Carn, and it is adjoined to the Garn Fawr 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 and south, the B4330 road to its west and the A40 road to its east, and has the town of Hwlffordd (Haverfordwest) towards the south.

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.

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 23m of drop, based on the 156m summit spot height that appears on the contemporary Ordnance Survey 1:25,000 Explorer map and an estimated c 133m bwlch height, based on interpolation of 5m contouring between 130m – 135m. 

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 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 157.0m summit height and a 132.4m bwlch height, with these values giving this hill 24.6m of drop, which is sufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Garn Fawr 

Name:  Poll Carn 

OS 1:50,000 map:  157, 158

Summit Height:  157.0m (LIDAR) 

Summit Grid Reference:  SM 95211 24495 (LIDAR) 

Bwlch Height:  132.4m (LIDAR) 

Bwlch Grid Reference:  SM 95129 24514 (LIDAR) 

Drop:  24.6m (LIDAR) 

 

Myrddyn Phillips (July 2024)

 

 

 

 

Mapping Mountains – Hill Reclassifications – Y Trechol – The Dominant Hills of Wales

Mynydd Pencarreg (SN 575 432) – Lesser Dominant deletion

There has been a deletion to the list of the 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 a Trimble GeoXH 6000 summit survey conducted by Myrddyn Phillips and LIDAR bwlch analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips. 

The summit area of Mynydd Pencarreg (SN 575 432)

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

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 name the hill is listed by is Mynydd Pencarreg and it is the highest point in its own grouping of hills, which are situated in the south-western part of South Wales (Region B, Sub-Region B1), and it is positioned with the B4337 road to its south-west and the A482 road to its north-east, and has the town of Llanbedr Pont Steffan (Lampeter) towards the north. 

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

After the original 400m height band of Welsh P30 hills published on Geoff Crowder’s v-g.me website were standardised and interpolated heights and drop values also included, this hill was listed with an estimated c 138m of drop, based on the 415m summit spot height adjoined to a triangulation pillar that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 277m bwlch height, based on interpolation of 10m contouring between 270m – 280m, with these values giving this hill 33.25% dominance. 

Extract from the Ordnance Survey 1:25,000 Explorer map showing the area of the bwlch

The summit of this hill was subsequently surveyed with the Trimble GeoXH 6000, resulting in a 414.9m height and with the bwlch having been analysed via 2m LIDAR, resulting in a 276.2m height, these values gave this hill 138.7m of drop and 33.43% domiance, which was sufficient for it to be classified as a Lesser Dominant hill. 

The Trimble GeoXH 6000 gathering data at the summit of Mynydd Pencarreg

However, it was not until the latest 1m 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 bwlch image of Mynydd Pencarreg

Therefore, the deletion of this hill from Lesser Dominant status is due to LIDAR bwlch analysis coupled with the summit height derived from the Trimble GeoXH 6000 survey, resulting in a 414.9m summit height and a 276.7m bwlch height, with these values giving this hill 138.2m of drop and 33.32% dominance, which is insufficient for Lesser Dominant status. 

 

The full details for the hill are:

Group:  Mynydd Pencarreg

Name:  Mynydd Pencarreg

OS 1:50,000 map:  146

Summit Height:  414.9m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 57560 43115 (Trimble GeoXH 6000)

Bwlch Height:  276.7m (LIDAR)

Bwlch Grid Reference:  SN 60000 44090 (LIDAR)

Drop:  138.2m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  33.32% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

Myrddyn Phillips (July 2024)

 

 

 

 

  

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Yr Allt (SN 552 024) – 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 from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Yr Allt (SN 552 024)

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 Yr Allt and this was derived from the Tithe map, and it is adjoined to the Mynydd Sylen group of hills, which are situated in the southern part of South Wales (Region B, Sub-Region B5), and it is positioned with minor roads to its north and west, and the A4138 road to its south, and has the town of Llanelli towards the west south-west.

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. 

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-evaluated and it was listed with 26m of drop, based on the 97m summit spot height and the 71m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage 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 96.8m summit height and a 71.05m bwlch height, with these values giving this hill 25.75m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Sylen 

Name:  Yr Allt 

OS 1:50,000 map:  159

Summit Height:  96.8m (LIDAR) 

Summit Grid Reference:  SN 55279 02446 (LIDAR)               

Bwlch Height:  71.05m (LIDAR) 

Bwlch Grid Reference:  SN 54918 02542 (LIDAR) 

Drop:  25.75m (LIDAR) 

 

Myrddyn Phillips (July 2024)

 

  

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

Mynydd Fforest (SO 086 389) – Sub-Trichant addition

There has been confirmation of 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 Mynydd Fforest (SO 086 389)

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 name the hill is now listed by is Mynydd Fforest and this was derived from the Ordnance Survey Draft Suirveyors Map, 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 with minor roads to its west and south, and the A470 road to its east, and has the small community of Erwyd (Erwood) towards the north 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 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 20m of drop, based on the 376m summit spot height that appears on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 356m bwlch height, based on interpolation of 10m contouring between 350m – 360m. 

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 Sub-Trichant status is due to LIDAR analysis, resulting in a 375.6m summit height and a 353.55m bwlch height, with these values giving this hill 22.0m of drop, which is sufficient for it to be classified as a Sub-Trichant. 

 

The full details for the hill are: 

Group:  Mynydd Epynt 

Name:  Mynydd Fforest 

OS 1:50,000 map:  160

Summit Height:  375.6m (LIDAR)                                                           

Summit Grid Reference:  SO 08614 38958 & SO 08615 38959 (LIDAR) 

Bwlch Height:  353.55m (LIDAR) 

Bwlch Grid Reference:  SO 09049 38950 (LIDAR) 

Drop:  22.0m (LIDAR) 

 

Myrddyn Phillips (July 2024)