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: 

Cae Cenfas Ucha (SN 751 118) – Welsh P15 addition 

Lletwith (SN 865 405) – Sub-Trichant addition 

Cae Pen y Cefn (SH 532 377) – 30-99m Sub-Twmpau addition 

Porfa Bwlch (SN 987 491) – 200m Sub-Twmpau deletion 

Bryn Hywel (SH 515 417) – 100m Sub-Twmpau deletion

Geirth Mawr (SH 535 393) – 30-99m Twmpau reclassified to 30-99m Sub-Twmpau

Pt. 152.7m (SH 510 416) – 100m Sub-Twmpau addition

Cefn Gwrhyd (SN 737 096) – Welsh P15 addition

Dinas (SH 498 378) – 30-99m Sub-Twmpau deletion

 

 

Significant Height Revisions: 

Cefn y Coed (SH 667 172) – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales 

Cae Cenfas Ucha (SN 751 118) – Welsh P15s

 

 

Summit Relocations: 

Bryn y Beaudy (SH 507 404) – 100m Twmpau

Cae Pen y Cefn (SH 532 377) – 30-99m Twmpau

Cefn y Coed (SH 667 172) – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales 

Cae Cenfas Ucha (SN 751 118) – Welsh P15s

Cae Tri Cornel (SN 974 499) – 200m Twmpau

Moelfre (SN 326 361) – Y Trichant - The 300m Hills of Wales

Crug y Gorllwyn (SN 321 340) – Y Trichant - The 300m Hills of Wales

The Head (SM 731 046) – 30-99m Twmpau, Y Trechol – The Dominant Hills of Wales and Y Pellennig - The Remotest Hills of Wales

 

Significant Name Changes: 

Home Warren (SO 115 289) – 200m Twmpau

Llandefaelog Tre'r Graig (SO 116 304) – 200m Twmpau

Lletwith (SN 865 405) – Y Trichant - The 300m Hills of Wales

Bryn y Beaudy (SH 507 404) – 100m Twmpau

Llan Ucha Nantgwared (SN 878 316) – Y Trichant - The 300m Hills of Wales

Cae Pen y Cefn (SH 532 377) – 30-99m Twmpau

Cefn y Coed (SH 667 172) – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Cae Cenfas Ucha (SN 751 118) – Welsh P15s

Coed Abergwynant (SH 677 178) – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Cae Tri Cornel (SN 974 499) – 200m Twmpau

Mapping Mountains – Summit Relocations – 30-99m Twmpau, Y Trechol – The Dominant Hills of Wales and Y Pellennig – The Remotest Hills of Wales

The Head (SM 731 046) 

There has been a Summit Relocation to a hill that is listed in the 30-99m Twmpau, Y Trechol – The Dominant Hills of Wales and Y Pellennig – The Remotest Hills of Wales, with the summit height and its location, the drop, dominance, remoteness and status of the hill prompted by detail produced by Joe Nuttall in his surface analysis programme (JNSA). 

The criteria for the three listings that this summit relocation 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

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

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 The Head, 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 on the island of Skokholm which is positioned to the south-west of the Pembrokeshire coast.

When the original 30-99m 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 55m summit height positioned at SM 730 047, with an accompanying note stating; Height from 1:10000 map, details from David Purchase.

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 56m summit height and drop, based on interpolation of its largest 55m uppermost contour positioned at SM 72969 04698.  The summit position was subsequently and slightly amended to SM 72970 04701 from detail that appeared on the Hill Bagging website. 

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

However, it was not until Joe Nuttall developed his surface analysis programme that the details of this hill could be analysed via the OS Terrain product.  The height produced by the surface analysis programme is 55.0m and this is positioned at SM 73112 04672, 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 judged to be 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 height produced by the surface analysis programme developed by Joe Nuttall is 55.0m and is positioned at SM 73112 04672, 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 positioned to a different 55m contour and approximately 42 metres eastward from where the previously listed summit is positioned. 

 

The full details for the hill are: 

Group:  Garn Fawr

Name:  The Head

OS 1:50,000 map:  157

Summit Height:  55.0m (JNSA)

Summit Grid Reference (New Position):  SM 73112 04672 (JNSA)

Bwlch Height:  N/A (island)

Bwlch Grid Reference:  N/A (island)

Drop:  55.0m (JNSA)

Dominance:  100.00% (island)

Remoteness:  5.21km (JNSA)

 

Myrddyn Phillips and Aled Williams (May 2024)

 

  

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Dinas (SH 498 378) – 30-99m Sub-Twmpau deletion 

There has been a deletion 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 Dinas (SH 498 378)

The criteria for the list that this deletion 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 listed by is Dinas, 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 south, and has the town of Cricieth surrounding it.

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 20m of drop, based on the 43m 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 23m bwlch height, based on interpolation of 5m contouring between 20m – 25m. 

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 deletion of this hill from 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 43.3m summit height and a 25.5m bwlch height, with these values giving this hill 17.9m of drop, which is insufficient for it to be classified as a 30-99m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Moel Hebog 

Name:  Dinas 

OS 1:50,000 map:  123

Summit Height:  43.3m (LIDAR) 

Summit Grid Reference:  SH 49838 37808 (LIDAR)               

Bwlch Height:  25.5m (LIDAR) 

Bwlch Grid Reference:  SH 49941 37839 (LIDAR) 

Drop:  17.9m (LIDAR) 

 

Myrddyn Phillips (May 2024)

 

 

  

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

Crug y Gorllwyn (SN 321 340) 

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 Crug y Gorllwyn (SN 321 340)

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 listed by is Crug y Gorllwyn, and it is adjoined to the Mynydd Pencarreg group of hills, which are situated in the south-western part of South Wales (Region B, Sub-Region B1), and it is positioned with minor roads to its north, west and south, and the B4333 road to its east, and has the town of Castell Newydd Emlyn (Newcastle Emlyn) towards the north.

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 Hills to be surveyed sub list with a summit height of 326m, based on the spot height adjoined to a triangulation pillar positioned at SN 32185 34085 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

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 28m of drop, based on the 326m summit spot height and the 298m 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.

LIDAR analysis gives the highest ground on this hill as 327.5m positioned at SN 32249 34121 and SN 32258 34125.  However, this is a part of a covered reservoir and protocols dictate that as this is deemed a relatively recent man-made construct such ground is discounted from the height of a hill. 

LIDAR summit image of Crug y Gorllwyn (SN 321 340)

The height produced by LIDAR analysis to the summit of this hill is 326.2m positioned at SN 32186 34079, and this position in relation to covered reservoir 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 326.2m and this is positioned at SN 32186 34079, this position is beside the triangulation pillar and is approximately 63 metres south-westward from the high point of the covered reservoir. 

 

The full details for the hill are:

Group:  Mynydd Pencarreg 

Name:  Crug y Gorllwyn 

OS 1:50,000 map:  145

Summit Height:  326.2m (LIDAR)                                                           

Summit Grid Reference (New Position):  SN 32186 34079 (LIDAR)                                        

Bwlch Height:  297.1m (LIDAR) 

Bwlch Grid Reference:  SN 32843 35432 (LIDAR) 

Drop:  29.1m (LIDAR) 

 

Myrddyn Phillips (May 2024) 

Mapping Mountains – Hill Reclassifications – 100m Twmpau

 

100m Twmpau – Hill Reclassifications

The 100m Twmpau (an acronym for thirty welsh metre prominences and upward) are the Welsh hills at or above 100m and below 20om in height that have a minimum drop of 30m.  Accompanying the main P30 list is a sub list entitled the 100m Sub-Twmpau with the qualification to 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.

The list is authored by Myrddyn Phillips and the posts that have appeared on Mapping Mountains detailing the additions, reclassifications and deletions to the main P30 list and the sub list appear below presented chronologically in receding order.

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Parc y Lan (SN 454 156) – 100m Sub-Twmpau addition (84th reclassification)

Summit Relocations post for Parc y Lan

Significant Name Changes post for Parc y Lan

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 Parc y Lan (SN 454 156)

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.  The list is authored by Myrddyn Phillips, 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 now listed by is Parc y Lan 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 the A48 road to its north and the B4306 road to its south-west, and has the town of Caerfyrddin (Carmarthen) towards the north-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.

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 26m of drop, based on the 148m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 122m 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. 

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 148.5m summit height and a 123.7m bwlch height, with these values giving this hill 24.9m of drop, which is sufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Sylen 

Name:  Parc y Lan 

OS 1:50,000 map:  159

Summit Height:  148.5m (LIDAR) 

Summit Grid Reference:  SN 45458 15666 & SN 45457 15664 (LIDAR) 

Bwlch Height:  123.7m (LIDAR) 

Bwlch Grid Reference:  SN 46262 16790 (LIDAR) 

Drop:  24.9m (LIDAR) 

 

Myrddyn Phillips (December 2024)

 

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Graig y Barcut (SN 546 027) – 100m Sub-Twmpau reclassified to 100m Twmpau (83rd reclassification)

Summit Relocations post for Graig y Barcut

Significant Name Changes post for Graig y Barcut

There has been confirmation of a reclassification 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 Graig y Barcut (SN 546 027)

The criteria for the list that this reclassification 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 now listed by is Graig y Barcut 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, west and east, and the A4138 road to its south, and has the town of Pontarddulais towards the east.

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for the main P30 list.

When 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 32m of drop, based on the 104m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 72m bwlch height, based on interpolation of 5m contouring between 70m – 75m. 

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

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill it had a 72m bwlch spot height, and when coupled with the 104m summit spot height, these values gave this hill 32m of drop.

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 reclassification of this hill from 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 104.0m summit height and a 71.8m bwlch height, with these values giving this hill 32.2m of drop, which is sufficient for it to be classified as a 100m Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Sylen 

Name:  Graig y Barcut 

OS 1:50,000 map:  159

Summit Height:  104.0m (LIDAR) 

Summit Grid Reference:  SN 54698 02770 (LIDAR) 

Bwlch Height:  71.8m (LIDAR) 

Bwlch Grid Reference:  SN 54693 03117 (LIDAR) 

Drop:  32.2m (LIDAR) 

 

Myrddyn Phillips (October 2024)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Comin Gwauncaegurwen (SN 738 129) – 100m Sub-Twmpau addition (82nd reclassification)

Significant Height Revisions post for Comin Gwauncaegurwen

Significant Name Changes post for Comin Gwauncaegurwen

 

There has been 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 Comin Gawuncaegurwen (SN 738 129)

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 Comin Gwauncaegurwen and this was derived from the Tithe map with the language protocol also instigated, 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 west and a minor road to its south-east, and has the village of Brynaman towards the west north-west. 

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

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 with no significant contours of note on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map it was difficult to know whether any hill of note existed. 

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

Since the original publication of the Welsh P30 lists on Geoff Crowder’s v-g.me website there have been a number of 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 were 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, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites.

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 an uppermost 200m ring contour 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.

Therefore, the addition of this hill to 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 196.6m summit height and a 174.7m bwlch height, with these values giving this hill 21.8m 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:  Comin Gwauncaegurwen 

OS 1:50,000 map:  160

Summit Height:  196.6m (LIDAR) 

Summit Grid Reference:  SN 73812 12929 (LIDAR) 

Bwlch Height:  174.7m (LIDAR) 

Bwlch Grid Reference:  SN 73776 13436 (LIDAR) 

Drop:  21.8m (LIDAR) 

 

Myrddyn Phillips (September 2024)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pant y Brwynog (SN 548 037) – 100m Sub-Twmpau addition (81st reclassification)

Significant Height Revisions post for Pant y Brwynog

Summit Relocations post for Pant y Brwynog

Significant Name Changes post for Pant y Brwynog

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 Pant y Brwynog (SN 548 037)

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 now listed by is Pant y Brwynog 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-east, west and south, and the A476 road farther to its west, the A4138 road to its south-east and the M4 motorway farther to its east, and has the town of Pontarddulais towards the east.

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 27m of drop, based on the 130m 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 103m bwlch height, based on interpolation of 5m contouring between 100m – 105m. 

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 127.65m summit height and a 102.6m bwlch height, with these values giving this hill 25.0m of drop, which is sufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Sylen 

Name:  Pant y Brwynog 

OS 1:50,000 map:  159

Summit Height:  127.65m (LIDAR) 

Summit Grid Reference:  SN 54886 03732 (LIDAR) 

Bwlch Height:  102.6m (LIDAR) 

Bwlch Grid Reference:  SN 54795 03991 (LIDAR)

Drop:  25.0m (LIDAR) 

 

Myrddyn Phillips (August 2024)

 

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Poll Carn (SM 952 244) – 100m Sub-Twmpau addition (80th reclassification)

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 - 100m Twmpau

Y Faerdre (SH 783 794) – 100m Sub-Twmpau addition (79th reclassification)

Significant Name Changes post for Y Faerdre

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 Y Faerdre (SH 783 794)

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 now listed by is Y Faerdre and this was derived from the Ordnance Survey Draft Surveyors Map, and it is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned with the A546 road to its west and the B5115 road to its east, and has the town of Deganwy encircling it on three sides.

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 22m of drop, based on an estimated c 105m summit height and an estimated c 83m bwlch height, with both heights based on interpolation of 5m contouring 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 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 103.4m summit height and an 80.6m bwlch height, with these values giving this hill 22.8m of drop, which is sufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Hiraethog 

Name:  Y Faerdre 

OS 1:50,000 map:  115

Summit Height:  103.4m (LIDAR) 

Summit Grid Reference:  SH 78310 79461 (LIDAR) 

Bwlch Height:  80.6m (LIDAR) 

Bwlch Grid Reference:  SH 78227 79478 (LIDAR) 

Drop:  22.8m (LIDAR) 

 

Myrddyn Phillips (July 2024)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Obelisg Bryn Pydew (SH 805 789) – 100m Sub-Twmpau addition (78th reclassification)

Significant Name Changes post for Obelisg Bryn Pydew

There has been 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 Obelisg Bryn Pydew (SH 805 789)

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 now listed by is Obelisg Bryn Pydew and this was derived from online sources with the language protocol also in use, and it is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned encircled by minor roads, with the A470 road farther to its west and the A55 road farther to its south-east, and has the town of Llandudno towards the north-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.

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 19m of drop, based on an estimated c 121m summit height and an estimated c 102m bwlch height, with both heights based on interpolation of 5m contouring that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage 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.

Therefore, the addition of this hill to 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 121.1m summit height and a 99.3m bwlch height, with these values giving this hill 21.8m of drop, which is sufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Hiraethog 

Name:  Obelisg Bryn Pydew 

OS 1:50,000 map:  116

Summit Height:  121.1m (LIDAR) 

Summit Grid Reference:  SH 80506 78913 (LIDAR) 

Bwlch Height:  99.3m (LIDAR) 

Bwlch Grid Reference:  SH 80687 79013 (LIDAR) 

Drop:  21.8m (LIDAR) 

 

Myrddyn Phillips (July 2024)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pt. 112.3m (SH 807 793) – 100m Sub-Twmpau deletion (77th reclassification)

There has been a deletion from 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 Pt. 112.3m (SH 807 793)

The criteria for the list that this deletion 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. 112.3m) 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 Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned encircled by minor roads, with the A470 road farther to its west and the A55 road farther to its south-east, and has the town of Llandudno towards the north-west.

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the Hills to be surveyed sub list with a non-interpolated c 120m summit height.

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 25m of drop, based on an estimated c 123m summit height and an estimated c 98m bwlch height, with the summit height based on interpolation of the uppermost 120m ring contour that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map. 

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

Since the original publication of the Welsh P30 lists on Geoff Crowder’s v-g.me website there have been a number of 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 were 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, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites.

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 for this hill it has a 112m summit spot height. 

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.

Therefore, the deletion of this hill from 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 112.3m summit height and a 98.6m bwlch height, with these values giving this hill 13.8m of drop, which is insufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Hiraethog 

Name:  Pt. 112.3m 

OS 1:50,000 map:  116

Summit Height:  112.3m (LIDAR) 

Summit Grid Reference:  SH 80726 79335 (LIDAR) 

Bwlch Height:  98.6m (LIDAR) 

Bwlch Grid Reference:  SH 80692 79102 (LIDAR) 

Drop:  13.8m (LIDAR) 

 

Myrddyn Phillips (June 2024)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pen y Dinas (SH 779 829) – 100m Sub-Twmpau deletion (76th reclassification)

There has been a deletion from 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 Pen y Dinas (SH 779 829)

The criteria for the list that this deletion 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 Pen y Dinas, and it is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned encircled by minor roads, and has the town of Llandudno 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. 

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 20m of drop, based on an estimated c 126m summit height and an estimated c 106m bwlch height, with both heights based on interpolation of 5m contouring 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 deletion of this hill from 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 124.6m summit height and a 104.8m bwlch height, with these values giving this hill 19.8m of drop, which is insufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Hiraethog 

Name:  Pen y Dinas 

OS 1:50,000 map:  115

Summit Height:  124.6m (LIDAR) 

Summit Grid Reference:  SH 77916 82951 (LIDAR) 

Bwlch Height:  104.8m (LIDAR) 

Bwlch Grid Reference:  SH 77817 83069 (LIDAR) 

Drop:  19.8m (LIDAR) 

 

Myrddyn Phillips (June 2024)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Craig Rofft (SH 776 831) – 100m Sub-Twmpau deletion (75th reclassification)

There has been a deletion from 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 Craig Rofft (SH 776 831)

The criteria for the list that this deletion 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 now listed by is Craig Rofft and this was derived from the Ordnance Survey series of Six-Inch maps, and it is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned encircled by minor roads, and has the town of Llandudno towards the south-east.

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 20m of drop, based on the 168m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 148m bwlch height, based on interpolation of 5m contouring that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage 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.

Therefore, the deletion of this hill from 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 167.6m summit height and a 147.9m bwlch height, with these values giving this hill 19.7m of drop, which is insufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Hiraethog 

Name:  Craig Rofft 

OS 1:50,000 map:  115

Summit Height:  167.6m (LIDAR) 

Summit Grid Reference:  SH 77614 83198 (LIDAR) 

Bwlch Height:  147.9m (LIDAR) 

Bwlch Grid Reference:  SH 77400 83151 (LIDAR) 

Drop:  19.7m (LIDAR) 

 

Myrddyn Phillips (June 2024)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Fallw (SH 785 792) – 100m Sub-Twmpau reclassified to 30-99m Sub-Twmpau (74th reclassification)

There has been a reclassification from the list of 100m Twmpau 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 Fallw (SH 785 792)

The criteria for the two listings that this reclassification 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

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 Fallw and this was derived from the Tithe map, and it is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned with the A546 road to its south-west and B5115 road to its south-east, and has the town of Deganwy towards the north-west.

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the Hills to be surveyed sub list with a non-interpolated c 100m summit height.

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 22m of drop, based on an estimated c 100m summit height and an estimated c 78m bwlch height, with both heights based on interpolation of 5m contouring that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

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 97m 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.

Therefore, the reclassification of this hill from 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 98.75m summit height and a 76.9m bwlch height, with these values giving this hill 21.9m of drop, and as it is below 100m in height this is sufficient for it to be classified as a 30-99m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Hiraethog 

Name:  Fallw 

OS 1:50,000 map:  115

Summit Height:  98.75m (LIDAR) 

Summit Grid Reference:  SH 78522 79260 (LIDAR) 

Bwlch Height:  76.9m (LIDAR) 

Bwlch Grid Reference:  SH 78350 79527 (LIDAR) 

Drop:  21.9m (LIDAR) 

 

Myrddyn Phillips (June 2024)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Creigiau Cochion (SH 756 835) – 100m Sub-Twmpau addition (73rd reclassification)

Significant Name Changes post for Creigiau Cochion

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 Creigiau Cochion (SH 756 835)

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 now listed by is Creigiau Cochion and this was derived from the Ordnance Survey series of Six-Inch maps, and it is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned encircled by minor roads, and has the town of Llandudno towards the south-east.

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 20m of drop, based on an estimated c 182m summit height and an estimated c 162m bwlch height, with both heights based on interpolation of 5m contouring 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 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 181.8m summit height and a 161.25m bwlch height, with these values giving this hill 20.6m of drop, which is sufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Hiraethog 

Name:  Creigiau Cochion 

OS 1:50,000 map:  115

Summit Height:  181.8m (LIDAR) 

Summit Grid Reference:  SH 75610 83571 (LIDAR) 

Bwlch Height:  161.25m (LIDAR) 

Bwlch Grid Reference:  SH 76066 83355 (LIDAR) 

Drop:  20.6m (LIDAR) 

 

Myrddyn Phillips (June 2024)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pt. 152.7m (SH 510 416) – 100m Sub-Twmpau addition (72nd reclassification)

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 Pt. 152.7m (SH 510 416)

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. 152.7m) 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 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 A487 road to its north, the B4411 road to its west, the A497 road to its south and a minor road to its east, and has the town of Cricieth 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.

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 20m of drop, based on the 153m summit spot height and the 133m 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. 

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 152.7m summit height and a 131.8m bwlch height, with these values giving this hill 20.9m of drop, which is sufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Moel Hebog 

Name:  Pt. 152.7m 

OS 1:50,000 map:  124

Summit Height:  152.7m (LIDAR) 

Summit Grid Reference:  SH 51049 41671 & SH 51051 41671 (LIDAR) 

Bwlch Height:  131.8m (LIDAR) 

Bwlch Grid Reference:  SH 51301 41590 (LIDAR) 

Drop:  20.9m (LIDAR) 

 

Myrddyn Phillips (May 2024)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Bryn Hywel (SH 515 417) – 100m Sub-Twmpau deletion (71st reclassification)

There has been a deletion from 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 Bryn Hywel (SH 515 417)

The criteria for the list that this deletion 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 Bryn Hywel, 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 minor roads to its west and south, the A487 road to its north-east, the B4411 road farther to its west and the A497 road farther to its south, and has the town of Cricieth 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 mistakenly included in the main P30 list.

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 reclassified to 100m Sub-Twmpau status and listed with an estimated c 21m of drop, based on the 159m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 138m bwlch height, based on interpolation of 10m contouring between 130m – 140m. 

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 deletion of this hill from 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 158.7m summit height and a 139.6m bwlch height, with these values giving this hill 19.1m of drop, which is insufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Moel Hebog 

Name:  Bryn Hywel 

OS 1:50,000 map:  124

Summit Height:  158.7m (LIDAR) 

Summit Grid Reference:  SH 51520 41737 (LIDAR) 

Bwlch Height:  139.6m (LIDAR) 

Bwlch Grid Reference:  SH 51674 41306 & SH 51675 41305 (LIDAR) 

Drop:  19.1m (LIDAR) 

 

Myrddyn Phillips (May 2024)