30-99m Twmpau – Hill Reclassifications
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Cae Pen y Cefn (SH 532 377) – 30-99m Sub-Twmpau addition (120th reclassification)
Summit Relocations post for Cae Pen y Cefn
Significant Name Changes post for Cae Pen y Cefn
There has been confirmation of an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Cae Pen y Cefn (SH 532 377) |
30-99m Twmpau by Myrddyn Phillips |
Extract from the Ordnance Survey 1:25,000 Explorer map |
The full details for the hill are:
Group: Moel Hebog
Name: Cae Pen y Cefn
OS 1:50,000 map: 124
Summit Height: 57.8m (LIDAR)
Summit Grid Reference: SH 53267 37729 (LIDAR)
Bwlch Height: 37.3m (LIDAR)
Bwlch Grid Reference: SH 53729 38357 (LIDAR)
Drop: 20.5m (LIDAR)
Myrddyn Phillips (May 2024)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Coed y Chwarel (SH 539 394) – 30-99m Sub-Twmpau addition (119th reclassification)
There has been confirmation of an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived by LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Coed y Chwarel (SH 539 394) |
30-99m Twmpau by Myrddyn Phillips |
Extract from the Ordnance Survey 1:25,000 Explorer map |
The full details for the hill are:
Group: Moel Hebog
Name: Coed y Chwarel
OS 1:50,000 map: 124
Summit Height: 58.4m (LIDAR)
Summit Grid Reference: SH 53911 39499 (LIDAR)
Bwlch Height: 34.8m (LIDAR)
Bwlch Grid Reference: SH 54045 39449 (LIDAR)
Drop: 23.6m (LIDAR)
Myrddyn Phillips (April 2024)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Carreg Waring (SH 537 390) – 30-99m Sub-Twmpau addition (118th reclassification)
Significant Name Changes post for Carreg Waring
There has been confirmation of an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived by LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Carreg Waring (SH 537 390) |
30-99m Twmpau by Myrddyn Phillips |
Extract from the Ordnance Survey 1:25,000 Explorer map |
The full details for the hill are:
Group: Moel Hebog
Name: Carreg Waring
OS 1:50,000 map: 124
Summit Height: 57.15m (LIDAR)
Summit Grid Reference: SH 53734 39025 (LIDAR)
Bwlch Height: 33.0m (LIDAR)
Bwlch Grid Reference: SH 53892 38892 (LIDAR)
Drop: 24.1m (LIDAR)
Myrddyn Phillips (April 2024)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Pen Brwsh (SM 880 396) – 30-99m Twmpau addition (117th reclassification)
There has been confirmation of an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived by LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Pen Brwsh (SM 880 396) |
The 30-99m Twmpau by Myrddyn Phillips |
Extract from the Ordnance Survey 1:25,000 Explorer map |
The full details for the hill are:
Group: Garn Fawr
Name: Pen Brwsh
OS 1:50,000 map: 157
Summit Height: 41.8m (LIDAR)
Summit Grid Reference: SM 88067 39675 (LIDAR)
Bwlch Height: 0.2m (LIDAR)
Bwlch Grid Reference: SM 88117 39673 (LIDAR)
Drop: 41.6m (LIDAR)
Myrddyn Phillips (June 2023)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Rhos Trebared (SN 173 475) – 30-99m Twmpau reclassified to 30-99m Sub-Twmpau (116th reclassification)
Significant Name Changes post for Rhos Trebared
There has been a reclassification to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived by LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Rhos Trebared (SN 173 475) |
The 30-99m Twmpau by Myrddyn Phillips |
Extract from the Ordnance Survey 1:25,000 Explorer map |
The full details for the hill are:
Group: Mynydd Bach
Name: Rhos Trebared
OS 1:50,000 map: 145
Summit Height: 70.3m (LIDAR)
Summit Grid Reference: SN 17391 47521 (LIDAR)
Bwlch Height: 40.3m (LIDAR)
Bwlch Grid Reference: SN 17728 47659 (LIDAR)
Drop: 29.9m (LIDAR)
Myrddyn Phillips (February 2023)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Allt Dan TÅ· Mawr (SN 520 228) – 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (115th reclassification)
Significant Height Revisions post for Allt Dan TÅ· Mawr
There has been confirmation of a reclassification to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Allt Dan TÅ· Mawr (SN 520 228) |
The 30-99m Twmpau by Myrddyn Phillips |
Extract from the Ordnance Survey 1:25,000 Explorer map |
The full details for the hill are:
Group: Mynydd Mallaen
Name: Allt Dan TÅ· Mawr
OS 1:50,000 map: 159
Summit Height: 72.65m (LIDAR)
Summit Grid Reference: SN 52004 22867 (LIDAR)
Bwlch Height: 39.0m (LIDAR)
Bwlch Grid Reference: SN 52223 22857 (LIDAR)
Drop: 33.7m (LIDAR)
Myrddyn Phillips (May 2022)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Pen Lan Fawr (SN 626 222) – 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (114th reclassification)
Significant Height Revisions post for Pen Lan Fawr
There has been confirmation of a reclassification 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 Pen Lan Fawr (SN 626 222) |
The 30-99m Twmpau by Myrddyn Phillips |
Extract from the Ordnance Survey 1:25,000 Explorer map |
The full details for the hill are:
Group: Mynydd Mallaen
Name: Pen Lan Fawr
OS 1:50,000 map: 159
Summit Height: 98.3m (LIDAR)
Summit Grid Reference: SN 62626 22229 (LIDAR)
Bwlch Height: 64.9m (LIDAR)
Bwlch Grid Reference: SN 61761 22561 (LIDAR)
Drop: 33.4m (LIDAR)
Myrddyn Phillips (April 2022)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Moel y Gadair (SH 521 391) – 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (113th reclassification)
Summit survey post for Moel y Gadair
Bwlch survey post for Moel y Gadair
There has been a reclassification 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 a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips.
Moel y Gadair (SH 521 391) |
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.
The 30-99m Twmpau by Myrddyn Phillips |
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 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 31m of drop, based on the 67m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 36m bwlch height based on interpolation of 10m contouring between 30m – 40m. The details for this hill were subsequently reassessed and its drop value amended to an estimated c 30m based on an estimated bwlch height of c 37m.
Extract from the Ordnance Survey 1:25,000 Explorer map |
The Trimble GeoXH 6000 gathering data at the summit of Moel y Gadair |
One of a series of surveys conducted at the bwlch on the 15th June 2015 |
With the aid of a ten figure grid reference for the bwlch position taken from the 5m contouring on the OS Maps website the bwlch of this hill was re-surveyed using the Trimble GeoXH 6000 on the 23rd February 2016, resulting in the hill being reclassified to 30-99m Sub-Twmpau status.
One of two surveys conducted at the bwlch on the 23rd February 2016 |
Initial LIDAR analysis indicated that the position of the bwlch was at SH 52007 39290, which is relatively close to where the Trimble GeoXH 6000 was placed on the survey conducted on the 23rd February 2016. LIDAR gives this position as 36.8m in height and when coupled with the 66.7m summit height, these values gave this hill 29.9m of drop.
LIDAR bwlch image with the joining of the red contour positioned on the road at SH 52007 39290 |
The initial re-assessment of LIDAR was undertaken by Aled Williams and he concluded that this hill is a natural P30, with only the height of the artificially raised road excluding it from being listed as a 30-99m Twmpau. His conclusion was that the height of the bwlch could be listed as an estimated and conservative c 36m or if using remaining natural ground; 35.8m positioned at SH 52020 39324. Either value classifies this hill as a P30.
LIDAR image of Moel y Gadair (SH 521 391) showing the various height contours used to conclude this hill is a natural P30 and its bwlch height and position |
The full details for the hill are:
Group: Moel Hebog
Name: Moel y Gadair
OS 1:50,000 map: 124
Summit Height: 66.7m (converted to OSGM15, Trimble GeoXH 6000)
Summit Grid Reference: SH 52165 39135 (Trimble GeoXH 6000)
Bwlch Height: 35.8m (LIDAR)
Bwlch Grid Reference: SH 52013 39319 (LIDAR)
Drop: 30.9m (Trimble GeoXH 6000 summit and LIDAR bwlch)
Myrddyn Phillips (March 2022)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Cefn Coch (SH 610 396) – 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (112th reclassification)
Significant Height Revisions post for Cefn Coch
Significant Name Changes post for Cefn Coch
There has been confirmation of a reclassification 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 Cefn Coch (SH 610 396) |
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.
The 30-99m Twmpau by Myrddyn Phillips |
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 Hills to be surveyed sub list, as it was considered not to meet the criteria then used for the P30 category. This hill was listed with an 81m summit height, with an accompanying note stating; 86m on 1984 1:50,000 map.
Extract from the Ordnance Survey 1:25,000 Explorer map |
The details for this hill were subsequently re-assessed as the bwlch contouring on the Ordnance Survey 1:25,000 Explorer map is between 50m – 60m, therefore according to map contouring the 48m spot height is below the position of the bwlch. This reassessment resulted in the hill being listed with an estimated c 26m of drop, based on the 81m summit spot height and an estimated c 55m bwlch height.
The details for this hill were later reassessed and the 86m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger map was favoured over that of the 81m spot height, and with the bwlch height amended to an estimated c 54m, these values gave this hill an estimated c 32m of drop.
Extract from the Ordnance Survey 1:50,000 Landranger map |
Therefore, the confirmation of the reclassification of this hill from 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in an 86.6m summit height and a 51.5m bwlch height, with these values giving this hill 35.1m of drop, which is sufficient for it to be classified as a 30-99m Twmpau.
The full details for the hill are:
Group: Moelwynion
Name: Cefn Coch
OS 1:50,000 map: 124
Summit Height: 86.6m (LIDAR)
Summit Grid Reference: SH 61030 39620 (LIDAR)
Bwlch Height: 51.5m (LIDAR)
Bwlch Grid Reference: SH 61461 39763 (LIDAR)
Drop: 35.1m (LIDAR)
Myrddyn Phillips (December 2021)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Mynydd Pant y Gaseg (SH 414 944) – 30-99m Sub-Twmpau deletion (111th reclassification)
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 detail on contemporary maps produced from Ordnance Survey data.
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.
The 30-99m Twmpau by Myrddyn Phillips |
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 Hills to be surveyed sub list, with an accompanying note stating; Height is also 80c. 1:50,000 and 1:25,000 maps differ.
Extract from the Ordnance Survey 1:25,000 Explorer map |
Extract from the Ordnance Survey 1:50,000 Landranger map |
Since publication of the P30 lists on Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the old Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage 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 maps and for this hill it had a 67m summit spot height and a 51m bwlch spot height, with these values giving this hill 16m of drop.
Therefore, the deletion of this hill from 30-99m Sub-Twmpau status is due to detail on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, resulting in a 67m summit height and a 51m bwlch height, with these values giving this hill 16m of drop, which is insufficient for it to be classified as a 30-99m Sub-Twmpau.
The full details for the hill are:
Group: Ynys Môn
Name: Mynydd Pant y Gaseg
OS 1:50,000 map: 114
Summit Height: 67m (spot height)
Summit Grid Reference: SH 41410 94459 (spot height)
Bwlch Height: 51m (spot height)
Bwlch Grid Reference: SH 41246 94369 (spot height)
Drop: 16m (spot height summit and bwlch)
Myrddyn Phillips (September 2021)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Cerrig Engan (SH 403 733) – 30-99m Sub-Twmpau addition (110th reclassification)
There has been confirmation of an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Cerrig Engan (SH 403 733) |
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.
The 30-99m Twmpau by Myrddyn Phillips |
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 72m 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 52m bwlch height based on interpolation of 5m contouring between 50m – 55m that appears on the Ordnance Survey 1:25,000 Explorer map.
Extract from the Ordnance Survey 1:25,000 Explorer map |
Therefore, the confirmation of the addition of this hill to 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 71.8m summit height and a 51.8m bwlch height, with these values giving this hill 20.0m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau.
The full details for the hill are:
Group: Ynys Môn
Name: Cerrig Engan
OS 1:50,000 map: 114, 115
Summit Height: 71.8m (LIDAR)
Summit Grid Reference: SH 40381 73301 (LIDAR)
Bwlch Height: 51.8m (LIDAR)
Bwlch Grid Reference: SH 40471 73329 (LIDAR)
Drop: 20.0m (LIDAR)
Myrddyn Phillips (September 2021)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Bwlch y Fen & Tyddyn Gwyn (SH 417 783) – 30-99m Sub-Twmpau addition (109th reclassification)
Summit Relocations post for Bwlch y Fen & Tyddyn Gwyn
Significant Name Changes post for Bwlch y Fen & Tyddyn Gwyn
There has been confirmation of an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on contemporary maps produced from Ordnance Survey data and LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Bwlch y Fen & Tyddyn Gwyn (SH 417 783) |
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.
The 30-99m Twmpau by Myrddyn Phillips |
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 21m of drop, based on the 89m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 68m bwlch height based on interpolation of 5m contouring between 65m – 70m.
Extract from the Ordnance Survey 1:25,000 Explorer map |
Therefore, the confirmation of the addition of this hill to 30-99m Sub-Twmpau status is due to detail on contemporary maps produced from Ordnance Survey data and LIDAR analysis, resulting in an 88.15m summit height and an estimated c 68m bwlch height, with these values giving this hill an estimated c 20m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau.
The full details for the hill are:
Group: Ynys Môn
Name: Bwlch y Fen & Tyddyn Gwyn
OS 1:50,000 map: 114, 115
Summit Height: 88.15m (LIDAR)
Summit Grid Reference: SH 41738 78329 (LIDAR)
Bwlch Height: c 68m (interpolation)
Bwlch Grid Reference: SH 41140 80401 (interpolation)
Drop: c 20m (LIDAR summit and interpolated bwlch)
Myrddyn Phillips (September 2021)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Dinas Fach (SM 825 226) – 30-99m Twmpau addition (108th reclassification)
There has been an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill obtained from the summit analysis programme that uses LIDAR produced by Joe Nuttall, and then by LIDAR analysis initially conducted by Jim Bloomer and subsequently by Myrddyn Phillips.
LIDAR image of Dinas Fach (SM 825 226) |
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.
The 30-99m Twmpau by Myrddyn Phillips |
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 main P30 list or the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used in either category.
Extract from the Ordnance Survey 1:50,000 Landranger map |
Extract from the Ordnance Survey 1:25,000 Explorer map |
Extract from the Magic Maps website |
Therefore, the addition of this hill to 30-99m Twmpau status is due to LIDAR analysis, resulting in a 30.45m summit height and a 0.3m bwlch height, with these values giving this hill 30.15m of drop, which is sufficient for it to be classified as a 30-99m Twmpau.
The full details for the hill are:
Group: Carn Llidi
Name: Dinas Fach
OS 1:50,000 map: 157
Summit Height: 30.45m (LIDAR)
Summit Grid Reference: SM 82559 22659 (LIDAR)
Bwlch Height: 0.3m (LIDAR)
Bwlch Grid Reference: SM 82605 22745 (LIDAR)
Drop: 30.15m (LIDAR)
Myrddyn Phillips (September 2021)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Bodowen (SH 376 669) – 30-99m Sub-Twmpau addition (107th reclassification)
Significant Name Changes post for Bodowen
There has been confirmation of an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on contemporary maps produced from Ordnance Survey data and LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Bodowen (SH 376 669) |
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.
The 30-99m Twmpau by Myrddyn Phillips |
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 23m of drop, based on the 64m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 41m 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 |
Therefore, the confirmation of the addition of this hill to 30-99m Sub-Twmpau status is due to detail on contemporary maps produced from Ordnance Survey data and LIDAR analysis, resulting in a 63.4m summit height and a 41m bwlch height, with these values giving this hill 22m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau.
The full details for the hill are:
Group: Ynys Môn
Name: Bodowen
OS 1:50,000 map: 114
Summit Height: 63.4m (LIDAR)
Summit Grid Reference: SH 37608 66991 (LIDAR)
Bwlch Height: 41m (spot height)
Bwlch Grid Reference: SH 39614 69511 (spot height)
Drop: 22m (LIDAR summit and spot height bwlch)
Myrddyn Phillips (September 2021)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Din Dryfol (SH 396 724) – 30-99m Sub-Twmpau addition (106th reclassification)
There has been confirmation of an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Din Dryfol (SH 396 724) |
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.
The 30-99m Twmpau by Myrddyn Phillips |
When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category.
After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 23m of drop, based on an estimated c 66m summit height and an estimated c 43m bwlch height, with both values based on interpolation of 5m contouring that appears on the Ordnance Survey 1:25,000 Explorer map.
Extract from the Ordnance Survey 1:25,000 Explorer map |
Therefore, the confirmation of the addition of this hill to 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 65.15m summit height and a 44.0m bwlch height, with these values giving this hill 21.1m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau.
The full details for the hill are:
Group: Ynys Môn
Name: Din Dryfol
OS 1:50,000 map: 114
Summit Height: 65.15m (LIDAR)
Summit Grid Reference: SH 39603 72469 (LIDAR)
Bwlch Height: 44.0m (LIDAR)
Bwlch Grid Reference: SH 39640 72534 (LIDAR)
Drop: 21.1m (LIDAR)
Myrddyn Phillips (September 2021)
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