Mapping Mountains - Hill Reclassifications - 200m Twmpau

200m Twmpau – Hill Reclassifications

The 200m Twmpau (thirty welsh metre prominences and upward) are the Welsh hills at or above 200m and below 30om in height that have a minimum drop of 30m.  Accompanying the main P30 list is a sub list entitled the 200m Sub-Twmpau with the qualification to this sub category being all Welsh hills at or above 200m and below 300m 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 - 200m Twmpau

Scotland Wood (SN 758 301) – 200m Sub-Twmpau addition (82nd reclassification)

Significant Name Changes post for Scotland Wood

There has been confirmation of an addition to the list of 200m 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 Scotland Wood (SN 758 301)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m 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. 

200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Scotland Wood and this was derived from the Ordnance Survey series of Six-Inch maps, 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 encircled by minor roads with the A4069 road farther to its north-west, and has the town of Llanymddyfri (Llandovery) towards the north.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included in the accompanying 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 219m summit spot height that appears on the contemporary Ordnance Survey 1:25,000 Explorer map and an estimated c 196m bwlch height, based on interpolation of 10m contouring between 190m – 200m. 

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 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 217.4m summit height and a 195.5m bwlch height, with these values giving this hill 21.8m of drop, which is sufficient for it to be classified as a 200m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Du 

Name:  Scotland Wood 

OS 1:50,000 map:  146, 160

Summit Height:  217.4m (LIDAR) 

Summit Grid Reference:  SN 75858 30192 (LIDAR) 

Bwlch Height:  195.5m (LIDAR) 

Bwlch Grid Reference:  SN 75762 29945 (LIDAR) 

Drop:  21.8m (LIDAR) 

 

Myrddyn Phillips (April 2024)

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Comin Gwauncaegurwen (SN 721 131) – 200m Twmpau addition (81st reclassification)

Significant Height Revisions post for Comin Gwauncaegurwen

Summit Relocations post for Comin Gwauncaegurwen

Significant Name Changes post for Comin Gwauncaegurwen

There has been an addition to the list of 200m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail produced by Joe Nuttall in his surface analysis programme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Myrddyn Phillips. 

LIDAR image of Comin Gwauncaegurwen (SN721 131)

The criteria for the list that this addition applies to are:200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m 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. 

200m 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 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, the A4069 road to its west and a minor road to its south-west, and has the village of Brynaman towards the north-west.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included in the main P30 list or the accompanying 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 1:50,000 Landranger 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. 

Extract from the interactive WalkLakes 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 258m spot height is given on the summit area of this hill.  Latterly the contemporary Ordnance Survey 1:25,000 Explorer map now has an uppermost 250m contour for this hill. 

Extract from the contemporary 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 200m Twmpau status is due to LIDAR analysis, resulting in a 258.4m summit height and a 218.5m bwlch height, with these values giving this hill 39.9m of drop, which is sufficient for it to be classified as a 200m Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Du 

Name:  Comin Gwauncaegurwen 

OS 1:50,000 map:  160

Summit Height:  258.4m (LIDAR) 

Summit Grid Reference:  SN 72135 13154 (LIDAR) 

Bwlch Height:  218.5m (LIDAR) 

Bwlch Grid Reference:  SN 72505 12523 (LIDAR) 

Drop:  39.9m (LIDAR) 

 

Myrddyn Phillips (March 2024)

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Bwlchwernen Fach (SN 606 556) – 200m Sub-Twmpau addition (80th reclassification)

Summit Relocations post for Bwlchwernen Fach

Significant Name Changes post for Bwlchwernen Fach

There has been confirmation of an addition to the list of 200m 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 Bwlchwernen Fach (SN 606 556)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Bwlchwernen Fach and this was derived from the Tithe map, and it is adjoined to the Mynydd Bach group of hills, which are situated in the western part of South Wales (Region B, Sub-Region B1), and it is positioned with minor roads to its north and west, and the A485 road to its south-east, and has the village of Llanddewibrefi towards the east.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included in the accompanying 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 24m of drop, based on the 256m summit spot height that appears on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 232m bwlch height, based on interpolation of 10m contouring between 230m – 240m. 

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 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 256.35m summit height and a 230.7m bwlch height, with these values giving this hill 25.7m of drop, which is sufficient for it to be classified as a 200m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Bach 

Name:  Bwlchwernen Fach 

OS 1:50,000 map:  146

Summit Height:  256.35m (LIDAR) 

Summit Grid Reference:  SN 60699 55684 (LIDAR) 

Bwlch Height:  230.7m (LIDAR) 

Bwlch Grid Reference:  SN 60598 55268 (LIDAR) 

Drop:  25.7m (LIDAR) 

 

Myrddyn Phillips (January 2024)

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Cae Cefn (SN 547 121) – 200m Twmpau reclassified to 200m Sub-Twmpau (79th reclassification)

Significant Name Changes post for Cae Cefn

There has been a reclassification to the list of 200m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail produced by Joe Nuttall in his surface analysis programme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Myrddyn Phillips. 

LIDAR image of Cae Cefn (SN 547 121)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Cae Cefn 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 a minor road to its north and east, the B4310 road to its south-west and the A476 road to its south-east, and has the village of Cross Hands towards the east north-east.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was listed as a twin top and included in the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used for the main P30 category.

When the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and its twin status split and it was listed with an estimated c 29m of drop, based on an estimated c 227m summit height and an estimated c 198m bwlch height, with both heights based on interpolation of 10m contouring that appear on the contemporary Ordnance Survey 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.

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 227m summit spot height and with the bwlch height re-evaluated and the 197m spot height that appears on the contemporary Ordnance Survey 1:25,000 Explorer map taken as its height, these values gave this hill 30m of drop and therefore it was reclassified to 200m Twmpau status.

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 to 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 226.5m summit height and a 196.8m bwlch height, with these values giving this hill 29.7m of drop, which is insufficient for it to be classified as a 200m Twmpau.

 

The full details for the hill are: 

Group:  Mynydd Sylen 

Name:  Cae Cefn 

OS 1:50,000 map:  159

Summit Height:  226.5m (LIDAR) 

Summit Grid Reference:  SN 54711 12139 (LIDAR) 

Bwlch Height:  196.8m (LIDAR) 

Bwlch Grid Reference:  SN 54478 11503 (LIDAR) 

Drop:  29.7m (LIDAR) 

 

Myrddyn Phillips (December 2023)

 

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Cae’r Faen Mynach (SN 765 003) – 200m Sub-Twmpau reclassified to 200m Twmpau (78th reclassification)

Significant Height Revisions post for Cae'r Faen Mynach

Significant Name Changes post for Cae'r Faen Mynach

There has been a reclassification to the list of 200m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail produced by Joe Nuttall in his surface analysis programme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Myrddyn Phillips. 

LIDAR image of Cae'r Faen Mynach (SN 765 003)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Cae’r Faen Mynach and this was derived from the Tithe map, and it is adjoined to the Fan Fawr group of hills, which are situated in the southern part of South Wales (Region B, Sub-Region B5), and it is positioned with a minor road to its west, the A474 road farther to its west, the A4230 and A465 roads to its south and the A4109 road to its east, and has the village of Aberdulais towards the south-east.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used for the main P30 category.

When 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 27m of drop, based on the 234m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 207m bwlch height, based on interpolation of 10m contouring between 200m – 210m. 

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 reclassification of this hill from 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 237.6m summit height and a 207.0m bwlch height, with these values giving this hill 30.6m of drop, which is sufficient for it to be classified as a 200m Twmpau.

 

The full details for the hill are: 

Group:  Fan Fawr 

Name:  Cae’r Faen Mynach 

OS 1:50,000 map:  170

Summit Height:  237.6m (LIDAR) 

Summit Grid Reference:  SN 76549 00356 (LIDAR) 

Bwlch Height:  207.0m (LIDAR) 

Bwlch Grid Reference:  SN 75759 01169 (LIDAR) 

Drop:  30.6m (LIDAR) 

 

Myrddyn Phillips (December 2023)

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Diosgydd (SH 777 583) – 200m Sub-Twmpau addition (77th reclassification)

Significant Name Changes post for Diosgydd

There has been an addition to the list of 200m 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 Diosgydd (SH 777 583)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Diosgydd and this was derived from the Tithe map, and it is adjoined to the Carnedd Llywelyn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned encircled by minor roads, with the A5 road farther to its south-west, and has the town of Betws-y-coed towards the south-east.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included in the accompanying 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 14m of drop, based on an estimated c 221m summit height and an estimated c 207m bwlch height, with both heights based on interpolation of 10m contouring that appears on the contemporary Ordnance Survey 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.

Therefore, the addition of this hill to 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 220.85m summit height and a 200.3m bwlch height, with these values giving this hill 20.6m of drop, which is sufficient for it to be classified as a 200m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Carnedd Llywelyn 

Name:  Diosgydd 

OS 1:50,000 map:  115

Summit Height:  220.85m (LIDAR) 

Summit Grid Reference:  SH 77763 58341 (LIDAR) 

Bwlch Height:  200.3m (LIDAR) 

Bwlch Grid Reference:  SH 77620 58363 & SH 77888 58272 (LIDAR) 

Drop:  20.6m (LIDAR) 

 

Myrddyn Phillips (December 2023)

 

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Tan y Castell (SH 788 583) – 200m Sub-Twmpau addition (76th reclassification)

Significant Name Changes post for Tan y Castell

There has been confirmation of an addition to the list of 200m 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 Tan y Castell (SH 788 583)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Tan y Castell and this was derived from the Tithe map, and it is adjoined to the Carnedd Llywelyn 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 north-west and south, the A5 road to its south-west, and the B5106 road to its east, and has the town of Betws-y-coed towards the south south-east.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included in the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category.

When 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 21m of drop, based on the 253m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 232m bwlch height, based on interpolation of 10m contouring between 230m – 240m. 

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 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 252.4m summit height and a 229.9m bwlch height, with these values giving this hill 22.5m of drop, which is sufficient for it to be classified as a 200m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Carnedd Llywelyn 

Name:  Tan y Castell 

OS 1:50,000 map:  115

Summit Height:  252.4m (LIDAR) 

Summit Grid Reference:  SH 78847 58306 (LIDAR) 

Bwlch Height:  229.9m (LIDAR) 

Bwlch Grid Reference:  SH 78760 58481 (LIDAR) 

Drop:  22.5m (LIDAR) 

 

Myrddyn Phillips (November 2023)

 

 

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Tan y Castell (SH 784 580) – 200m Sub-Twmpau addition (75th reclassification)

Significant Name Changes post for Tan y Castell

There has been confirmation of an addition to the list of 200m 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 Tan y Castell (SH 784 580)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Tan y Castell and this was derived from the Tithe map, and it is adjoined to the Carnedd Llywelyn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned encircled by minor roads, with the A5 road farther to its south-west, and the B5106 road farther to its east, and has the town of Betws-y-coed towards the south-east.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included in the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this category.

When 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 29m of drop, based on the 248m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 219m bwlch height, based on interpolation of 10m contouring between 210m – 220m. 

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 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 248.7m summit height and a 220.0m bwlch height, with these values giving this hill 28.6m of drop, which is sufficient for it to be classified as a 200m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Carnedd Llywelyn 

Name:  Tan y Castell 

OS 1:50,000 map:  115

Summit Height:  248.7m (LIDAR) 

Summit Grid Reference:  SH 78439 58011 (LIDAR) 

Bwlch Height:  220.0m (LIDAR) 

Bwlch Grid Reference:  SH 78394 58095 (LIDAR) 

Drop:  28.6m (LIDAR) 

 

Myrddyn Phillips (October 2023)

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Diosgydd (SH 775 579) – 200m Sub-Twmpau reclassified to 200m Twmpau (74th reclassification)

Significant Name Changes post for Diosgydd

There has been a reclassification to the list of 200m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail produced by Joe Nuttall in his surface analysis programme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Myrddyn Phillips. 

LIDAR image of Diosgydd (SH 775 579)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Diosgydd and this was derived from the Tithe map, and it is adjoined to the Carnedd Llywelyn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned encircled by minor roads, with the A5 road farther to its south-west, and has the town of Betws-y-coed towards the south-east.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used for the main P30 category.

When 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 28m of drop, based on the 233m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 205m bwlch height, based on interpolation of 10m contouring between 200m – 210m. 

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 reclassification of this hill from 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 233.05m summit height and a 202.85m bwlch height, with these values giving this hill 30.2m of drop, which is sufficient for it to be classified as a 200m Twmpau. 

 

The full details for the hill are: 

Group:  Carnedd Llywelyn 

Name:  Diosgydd 

OS 1:50,000 map:  115

Summit Height:  233.05m (LIDAR) 

Summit Grid Reference:  SH 77503 57940 (LIDAR) 

Bwlch Height:  202.85m (LIDAR) 

Bwlch Grid Reference:  SH 77793 57796 (LIDAR) 

Drop:  30.2m (LIDAR) 

 

Myrddyn Phillips (October 2023)

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Blaen Pibydd (SN 286 337 & SN 286 336) – 200m Twmpau reclassified to 200m Sub-Twmpau (73rd reclassification)

Summit Relocations post for Blaen Pibydd

Significant Name Changes post for Blaen Pibydd

There has been a reclassification to the list of 200m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail produced by Joe Nuttall in his surface analysis progamme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Myrddyn Phillips. 

LIDAR image of Blaen Pibydd (SN 286 337 & SN 286 336)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Blaen Pibydd and this was derived from the Tithe map, 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 encircled by minor roads, with the B4299 road farther to its south-east, and has the town of Castellnewydd Emlyn (Newcastle Emlyn) towards the north north-east.

When the original 200m 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 an accompanying note stating; Included by contour configuration.

When 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 30m of drop, based on the 224m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 194m bwlch height, based on interpolation of 5m contouring between 190m – 195m.                                                               

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 reclassification of this hill to 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 223.9m summit height and a 195.0m bwlch height, with these values giving this hill 28.8m of drop, which is insufficient for it to be classified as a 200m Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Pencarreg 

Name:  Blaen Pibydd 

OS 1:50,000 map:  145

Summit Height:  223.9m (LIDAR) 

Summit Grid Reference:  SN 28692 33707 & SN 28695 33701 & SN 28696 33697 & SN 28694 33695 (LIDAR) 

Bwlch Height:  195.0m (LIDAR) 

Bwlch Grid Reference:  SN 28588 33103 (LIDAR) 

Drop:  28.8m (LIDAR) 

 

Myrddyn Phillips (September 2023)

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Lan Fanal (SN 795 343) – 200m Sub-Twmpau reclassified to 200m Twmpau (72nd reclassification)

Significant Name Changes post for Lan Fanal

There has been confirmation of a reclassification to the list of 200m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail produced by Joe Nuttall in his surface analysis progamme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Myrddyn Phillips. 

LIDAR image of Lan Fanal (SN 795 343)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Lan Fanal and this was derived from the Tithe map, 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 and a minor road to its south-west, and has the town of Llanymddyfri (Llandovery) towards the west.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used for the main P30 category.

When 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 30m of drop, based on the 238m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 208m bwlch height, based on interpolation of 10m contouring between 200m – 210m. 

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 Lan Fanal

LIDAR bwlch image of Lan Fanal

Therefore, the confirmation of the reclassification of this hill from 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 237.7m summit height and a 207.0m bwlch height, with these values giving this hill 30.7m of drop, which is sufficient for it to be classified as a 200m Twmpau.  With the bwlch height and position taken to natural ground at the base of a raised road whose critical point LIDAR gives as 207.6m in height and positioned at SN 79622 33060. 

 

The full details for the hill are: 

Group:  Mynydd Du 

Name:  Lan Fanal 

OS 1:50,000 map:  146, 160

Summit Height:  237.7m (LIDAR) 

Summit Grid Reference:  SN 79588 34329 (LIDAR) 

Bwlch Height:  207.0m (LIDAR) 

Bwlch Grid Reference:  SN 79626 33074 (LIDAR) 

Drop:  30.7m (LIDAR) 

 

Myrddyn Phillips (September 2023)

Mapping Mountains - Hill Reclassifications - 200m Twmpau

Ffridd (SH 730 035) – 200m Sub-Twmpau reclassified to 200m Twmpau (71st reclassification)

Significant Name Changes post for Ffridd

There has been a reclassification to the list of 200m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail produced by Joe Nuttall in his surface analysis progamme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Myrddyn Phillips. 

LIDAR image of Ffridd (SH 730 035)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Ffridd and this was derived from the Tithe map, and it is adjoined to the Tarren y Gesail group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), and it is positioned with the A493 road to its south and the A487 road to its east, and has the town of Machynlleth towards the south-east.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used for the main P30 category. 

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

When 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 29m of drop, based on an estimated c 253m summit height and an estimated c 224m bwlch height, with both heights based on interpolation of 10m contouring that appears on 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 reclassification of this hill from 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 254.8m summit height and a 223.7m bwlch height, with these values giving this hill 31.1m of drop, which is sufficient for it to be classified as a 200m Twmpau. 

 

The full details for the hill are: 

Group:  Tarren y Gesail 

Name:  Ffridd 

OS 1:50,000 map:  135

Summit Height:  254.8m (LIDAR) 

Summit Grid Reference:  SH 73058 03518 (LIDAR) 

Bwlch Height:  223.7m (LIDAR) 

Bwlch Grid Reference:  SH 72809 03682 (LIDAR) 

Drop:  31.1m (LIDAR) 

 

Myrddyn Phillips (August 2023)