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

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

Significant Name Changes post for Bryn Pydew Obelisk

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 Bryn Pydew Obelisk (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 Bryn Pydew Obelisk and this was derived from online sources, 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:  Bryn Pydew Obelisk 

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)