Mapping Mountains – Hill Reclassifications – 100m Twmpau

100m Twmpau – Hill Reclassifications

The 100m Twmpau (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

Tŷ Canol (SH 471 907) – 100m Sub-Twmpau addition (35th reclassification)

Significant Name Changes post for Tŷ Canol

 

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 detail on contemporary maps produced from Ordnance Survey data. 

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. 

The 100m Twmpau by Myrddyn Phillips

The name the hill is listed by is Tŷ Canol and this was derived from the Tithe map, and it is adjoined to the Ynys Môn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is encircled by minor roads with the A5025 road farther to its west, and has the village of Pen-y-sarn towards the west 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. 

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 21m of drop, based on the 165m summit spot height and the 144m 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. 

Since the original publication of the P30 lists on Geoff Crowder’s v-g.me website and the re-assessment of this hill’s details 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 mapping on the Magic Maps website. 

Extract from the Magic Maps website

One of the mapping resources now available online is the Magic Maps website which hosts an interactive map originated from Ordnance Survey data.  This map has many spot heights not on other publicly available Ordnance Survey maps and for this hill a 166m spot height is given on the area of its summit and this is being prioritised in favour of the aforementioned 165m spot height. 

Therefore, the addition of this hill to 100m Sub-Twmpau status is due to detail on contemporary maps produced from Ordnance Survey data, resulting in a 166m summit height and a 144m bwlch height, with these values giving this hill 22m of drop which is sufficient for it to be classified as a 100m Sub-Twmpau.

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Tŷ Canol 

OS 1:50,000 map:  114

Summit Height:  166m (spot height) 

Summit Grid Reference:  SH 47141 90737 (spot height) 

Bwlch Height:  144m (spot height) 

Bwlch Grid Reference:  SH 47087 91141 (spot height) 

Drop:  22m (spot height summit and bwlch) 

 

Myrddyn Phillips (March 2021)

 

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Yr Hald (SH 456 905) – 100m Sub-Twmpau addition (34th 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 confirmed by LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Yr Hald (SH 456 905)

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. 

The 100m Twmpau by Myrddyn Phillips

The name the hill is listed by is Yr Hald and it is adjoined to the Ynys Môn 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 A5025 road to its immediate north and east, and has the village of Pen-y-sarn 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 26m of drop, based on an estimated c 105m summit height and the 79m 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 summit image of Yr Hald

Therefore, the confirmation of the addition of this hill to 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 105.8m summit height and an 80.65m bwlch height, with these values giving this hill 25.2m of drop, which is sufficient for it to be classified as a 100m Sub-Twmpau.

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Yr Hald 

OS 1:50,000 map:  114

Summit Height:  105.8m (LIDAR) 

Summit Grid Reference:  SH 45690 90596 (LIDAR) 

Bwlch Height:  80.65m (LIDAR) 

Bwlch Grid Reference:  SH 45148 90730 (LIDAR) 

Drop:  25.2m (LIDAR) 

 

Myrddyn Phillips (March 2021)

 

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Mynydd Twr (SH 214 827) – 100m Sub-Twmpau addition (33rd reclassification)

Significant Name Changes post for Mynydd Twr

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 detail on contemporary maps produced from Ordnance Survey data. 

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. 

The 100m Twmpau by Myrddyn Phillips

The name the hill is listed by is Mynydd Twr and it is adjoined to the Ynys Môn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned overlooking the coast to its north-west and has minor roads to its south and east, and has the town of Caergybi (Holyhead) 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. 

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 the 163m 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 bwlch height of c 141m based on interpolation of 5m contouring between 140m – 145m that appear on the Ordnance Survey 1:25,000 Explorer map. 

Therefore, the addition of this hill to 100m Sub-Twmpau status is due to detail on contemporary maps produced from Ordnance Survey data, resulting in a 163m summit height and an estimated c 141m bwlch height, with these values giving this hill an estimated c 22m of drop which is sufficient for it to be classified as a 100m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Mynydd Twr 

OS 1:50,000 map:  114

Summit Height:  163m (spot height) 

Summit Grid Reference:  SH 21403 82754 (spot height) 

Bwlch Height:  c 141m (interpolation) 

Bwlch Grid Reference:  SH 21513 82838 (interpolation) 

Drop:  c 22m (spot height summit and interpolated bwlch) 

 

Myrddyn Phillips (March 2021)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pen y Parc (SH 590 750) – 100m Sub-Twmpau reclassified to 100m Twmpau (32nd reclassification)

Significant Name Changes post for Pen y Parc

There has been 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 Pen y Parc (SH 590 750)

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. 

The 100m Twmpau by Myrddyn Phillips

The name the hill is listed by is Pen y Parc and this was derived from the Tithe map, and it is adjoined to the Ynys Môn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with a minor road to its north and west and has the A545 road to its south-east, and has the town of Beaumaris towards the north-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 26m of drop, based on the 114m 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 bwlch height of c 88m based on interpolation of 5m contouring between 85m – 90m that appear on the 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 reclassification of this hill from 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 113.0m summit height and an 82.8m bwlch height, with these values giving this hill 30.1m of drop, which is sufficient for it to be classified as a 100m Twmpau. 

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Pen y Parc 

OS 1:50,000 map:  114, 115

Summit Height:  113.0m (LIDAR) 

Summit Grid Reference:  SH 59003 75009 (LIDAR) 

Bwlch Height:  82.8m (LIDAR) 

Bwlch Grid Reference:  SH 58497 75660 (LIDAR) 

Drop:  30.1m (LIDAR) 

 

Myrddyn Phillips (March 2021)

 

Mapping Mountains - Hill Reclassifications - 100m Twmpau

The Knoll (ST 424 904) – 30-99m Twmpau reclassified to 100m Twmpau (31st reclassification)

Significant Height Revisions post for The Knoll

There has been a reclassification to the list of 30-99m Twmpau and 100m Twmpau, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of The Knoll (ST 424 904)

The criteria for the two listings that this reclassification 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.

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.

The name the hill is listed by is The Knoll, and it is adjoined to the Gwent Is Coed group of hills which are situated in the south-eastern part of South Wales (Region C, Sub-Region C3), and it is positioned with the A48 road to its north and the M4 motorway to its south, and has the city of Casnewydd (Newport) towards the west south-west.

When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the main P30 list and listed with a c 90m summit height, based on its uppermost 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

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 c 51m of drop, based on an estimated c 94m summit height based on interpolation of 5m contouring and a 43m bwlch spot height 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. 

LIDAR close-up image of The Knoll

Therefore, the reclassification of this hill from 30-99m Twmpau to 100m Twmpau status is due to LIDAR analysis, resulting in a 101.9m summit height and a 43.1m bwlch height, with these values giving this hill 58.7m of drop and 57.66% dominance.  With the summit height of this hill sufficient for it now to be classified as a 100m Twmpau.

The full details for the hill are:

Group:  Gwent Is Coed

Name:  The Knoll

OS 1:50,000 map:  171, 172

Summit Height:  101.9m (LIDAR)

Summit Grid Reference:  ST 42467 90424 (LIDAR)

Bwlch Height:  43.1m (LIDAR)

Bwlch Grid Reference:  ST 42135 90345 (LIDAR)

Drop:  58.7m (LIDAR)

Myrddyn Phillips (July 2020)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Coed y Bwnydd (SO 366 069) – 100m Twmpau reclassified to 200m Twmpau (30th reclassification)

Significant Name Changes post for Coed y Bwnydd

Summit Relocations post for Coed y Bwnydd

Significant Height Revisions post for Coed y Bwnydd

There has been a reclassification to the list of 100m Twmpau and 200m 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 Coed y Bwnydd (SO 366 069)

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.

100m Twmpau by Myrddyn Phillips

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.

200m Twmpau by Myrddyn Phillips

The name the hill is listed by is Coed y Bwnydd and it is adjoined to the Mynyddoedd Duon group of hills which are situated in the eastern part of South Wales (Region C, Sub-Region C3), and it is positioned with the Afon Wysg (River Usk) and the B4598 road to its west, the A40 road to its north and the A449 road to its east, and has the village of Raglan towards the east north-east and the town of Brynbuga (Usk) towards the south 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 included in the main P30 list under the name of Clytha Hill and listed with a 196m summit height, based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map at SO 368 069.

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 is entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and gives a second 196m spot height on the summit area of this hill and positioned at SO 367 069.  This additional 196m spot height also appears on Ordnance Survey data available on the Magic Maps website.

Extract from the Magic Maps 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. 

The reclassification of this hill from 100m Twmpau status is due to LIDAR analysis, resulting in a 201.4m summit height and a 59.4m bwlch height, with these values giving this hill 142.0m of drop.  With the 201.4m summit height taken to the remains of an embankment which forms a part of an ancient hill fort which qualifies under the criteria used within this list and its height is sufficient for it to be classified as a 200m Twmpau.

The full details for the hill are:

Group:  Mynyddoedd Duon

Name:  Coed y Bwnydd

OS 1:50,000 map:  161

Summit Height:  201.4m (LIDAR)

Summit Grid Reference:  SO 36613 06919 (LIDAR)

Bwlch Height:  59.4m (LIDAR)

Bwlch Grid Reference:  SO 39308 08901 (LIDAR)

Drop:  142.0m (LIDAR)

Myrddyn Phillips (January 2020)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Cae Cefn (ST 059 748) – 100m Twmpau deletion (29th reclassification)

Significant Name Changes post for Cae Cefn

Significant Height Revisions post for Cae Cefn

There has been a deletion of a hill that was listed in the 100m Twmpau, with the summit height and its location confirmed by a Leica GS15 survey conducted by John Barnard, Graham Jackson and Myrddyn Phillips which took place on the 4^th November 2013, and the bwlch height and its location, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Cae Cefn (ST 059 748)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name the hill is now listed as is Cae Cefn and this derived from the Tithe map, and it is adjoined to the Bro Morgannwg group of hills, which are situated in the southern part of South Wales (Region C, Sub-Region C2), and it is positioned with the A48 road to its south-east and minor roads to its west, north and east, and has the city of Caerdydd (Cardiff) towards the east and the town of Y Bont-faen (Cowbridge) to the west.

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

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was listed with a 140m summit height based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map.  However, as the 140m spot height is placed at the top of a covered reservoir and as these structures are considered recent man-made constructs and as Tair Onnen vied for being the higher hill, both hills were surveyed using a Leica GS15, resulting in:

Cae Cefn (ST 05910 74886):  136.2m (natural ground at base of covered reservoir)

Tair Onnen (ST 03660 73979):  137.3m

When LIDAR became available the details for these two hills were re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.  The LIDAR summit details are given below:

Cae Cefn (ST 05915 74885):  136.4m (natural ground at base of covered reservoir)

Tair Onnen (ST 03661 73979):  137.4m 

  

The Leica GS15 gathering data at the summit of Cae Cefn

Therefore, the deletion of Cae Cefn from 100m Twmpau status is due to a Leica GS15 summit survey, resulting in a 136.2m summit height taken to natural ground at the base of the man-made covered reservoir as opposed to the 137.3m summit height for Tair Onnen, and a 116.25m bwlch height from LIDAR analysis, with these values giving Cae Cefn 19.9m of drop which is insufficient for this hill to be classified as a 100m Twmpau.

The full details for the hill are:

Group:  Bro Morgannwg

Name:  Cae Cefn

OS 1:50,000 map:  170

Summit Height:  136.2m (Leica GS15)

Summit Grid Reference:  ST 05910 74886 (Leica GS15)

Bwlch Height:  116.25m (LIDAR)

Bwlch Grid Reference:  ST 04273 74542 (LIDAR)

Drop:  19.9m (Leica GS15 summit and LIDAR bwlch)

Myrddyn Phillips (October 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Tair Onnen (ST 036 739) – 100m Twmpau addition (28th reclassification)

There has been an addition to a hill that is now listed in the 100m Twmpau, with the summit height and its location confirmed by a Leica GS15 survey conducted by John Barnard, Graham Jackson and Myrddyn Phillips which took place on the 4^th November 2013.

LIDAR image of Tair Onnen (ST 036 739)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the hill is Tair Onnen, and it is adjoined to the Bro Morgannwg group of hills, which are situated in the southern part of South Wales (Region C, Sub-Region C2), and it is positioned with the A48 road to its north and minor roads to its south, and has the town of Y Bont-faen (Cowbridge) towards the west and the city of Caerdydd (Cardiff) towards the east.

Extract from the Ordnance Survey 1:25,000 Explorer 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 either the main P30 or accompanying Hills to be surveyed sub list as with a 137m summit height adjoined to its triangulation pillar it was deemed lower than Cae Cefn (ST 059 748) which has a 140m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map.  However, as the 140m spot height is to the top of a covered reservoir and as these structures are considered recent man-made constructs the two hills were subsequently surveyed using a Leica GS15 resulting in the following details.

Cae Cefn (ST 05910 74886):  136.2m (natural ground at base of covered reservoir)

Tair Onnen (ST 03660 73979):  137.3m

Gathering data with the Leica GS15 at the summit of Tair Onnen

When LIDAR became available the details for these two hills were re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.  The LIDAR summit details are given below:

Cae Cefn (ST 05915 74885):  136.4m (natural ground at base of covered reservoir)

Tair Onnen (ST 03661 73979):  137.4m

  

Therefore, the addition of Tair Onnen to 100m Twmpau status is due to a Leica GS15 survey, resulting in a 137.3m summit height as opposed to the 136.2m summit height for Cae Cefn which was taken to natural ground at the base of the man-made covered reservoir, and with an estimated bwlch height of c 67m, these values give Tair Onnen c 70m of drop which is sufficient for this hill to be classified as a 100m Twmpau.

The full details for the hill are:

Group:  Bro Morgannwg

Name:  Tair Onnen

OS 1:50,000 map:  170

Summit Height:  137.3m (Leica GS15)

Summit Grid Reference:  ST 03660 73979 (Leica GS15)

Bwlch Height:  c 67m

Bwlch Grid Reference:  ST 01235 77663

Drop:  c 70m

Myrddyn Phillips (September 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Twyn y Cryn (SO 325 008) – 100m Sub-Twmpau reclassified to 100m Twmpau (27th reclassification)

Significant Name Changes post for Twyn y Cryn

Summit Relocations post for Twyn y Cryn

There has been confirmation of a reclassification to a hill that is listed in the 100m 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 Twyn y Cryn (SO 325 008)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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 Twyn y Cryn, and it is adjoined to the Cefn yr Ystrad group of hills, which are situated in the southern part of South Wales (Region B, Sub-Region B5), and it is positioned with the A4042 road to the west and the A472 road to the north, and has the town of Pont-y-pŵl (Pontypool) towards its west and Brynbuga (Usk) towards its 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 that accompanied the main P30 list, as it did not meet the criteria then used in this list. 

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 35m of drop, based on an estimated c 147m summit height and an estimated c 112m bwlch height, with both heights based on interpolation of 10m contouring between 110m - 120m that appears on the Ordnance Survey 1:25,000 Explorer map.

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 became available online; and which is entitled the Interactive Coverage Map.  This mapping has additional spot heights not available on any other form of Ordnance Survey publicly available map, although no additional spot heights are given for this hill, this mapping does have contours at 5m intervals for this hill with bwlch contouring between 110m – 115m with an estimated bwlch height of c 112m and an uppermost summit contour of c 145 with an estimated summit height of c 147m, with these values confirming the interpolated values given this hill based on detail from the Ordnance Survey 1:25,000 Explorer map.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph 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 confirmation of the reclassification of this hill from 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 148.3m summit height and a 113.0m bwlch height, with these values giving this hill 35.3m of drop which is sufficient for it to be classified as a 100m Twmpau.

The full details for the hill are:

Group:  Cefn yr Ystrad

Name:  Twyn y Cryn

OS 1:50,000 map:  171

Summit Height:  148.3m (LIDAR)

Summit Grid Reference:  SO 32531 00891 (LIDAR)

Bwlch Height:  113.0m (LIDAR)

Bwlch Grid Reference:  SO 32392 01153 (LIDAR)

Drop:  35.3m (LIDAR)

Myrddyn Phillips (September 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Bryn Bach (SS 903 875) – 100m Sub-Twmpau reclassified to 100m Twmpau (26th reclassification)

Significant Name Changes post for Bryn Bach

Significant Height Revisions post for Bryn Bach

Summit Relocations post for Bryn Bach

There has been confirmation of a reclassification to a hill that is listed in the 100m 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 Bryn Bach

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the hill is Bryn Bach, and this was derived from the Ordnance Survey One-Inch ‘Old Series’ map and it is this name that the hill is now listed by, and it is adjoined to the Cymoedd Morgannwg group of hills, which are situated in the central part of South Wales (Region C, Sub-Region C2), and is positioned with the A4063 road and the Afon Llynfi to its south-west and the A4064 road and the Afon Garw to its south-east, and has the small community of Betws 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 included in the Hills to be surveyed sub list that accompanied the main P30 list, as it did not meet the criteria then used in this list. 

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 an estimated summit height of c 164m and an estimated bwlch height of c 133m, with both heights based on interpolation of 10m contouring on the Ordnance Survey 1:25,000 Explorer map.

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 became available online; this mapping is entitled the Interactive Coverage Map.  This mapping gives a 164m summit spot height and as it has 5m contour intervals it enabled a better assessment for an interpolated value for the height of the bwlch.  It also has a 133m spot height at a junction of roads at the area of this hill’s bwlch, with interpolation favouring a different position for the critical bwlch and an estimated height of c 133m, with these values giving this hill c 31m of drop.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph 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.  

The confirmation of the reclassification of Bryn Bach to 100m Twmpau status is due to LIDAR analysis, resulting in a 167.0m summit height and a 135.2m bwlch height, with these values giving this hill 31.9m of drop which is sufficient for it to be classified as a 100m Twmpau.

The full details for the hill are:

Group:  Cymoedd Morgannwg

Name:  Bryn Bach

OS 1:50,000 map:  170

Summit Height:  167.0m (LIDAR)

Summit Grid Reference:  SS 90364 87531 (LIDAR)

Bwlch Height:  135.2m (LIDAR)

Bwlch Grid Reference:  SS 90511 87849 (LIDAR)

Drop:  31.9m (LIDAR)

Myrddyn Phillips (June 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Garth Wood (ST 119 825) – 100m Sub-Twmpau reclassified to 100m Twmpau (25th reclassification)

There has been confirmation of a reclassification to a hill that is listed in the 100m Twmpau, with the summit height and its location confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Garth Wood

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the hill is Garth Wood, and it is adjoined to the Cymoedd Morgannwg group of hills, which are situated in the central part of South Wales (Region C, Sub-Region C2), and as its name implies the summit area and northern part of the hill comprises woodland, whilst its southern land forms a part of the Taffs Well Quarry, and it is encircled by a variety of roads with the A4054 and A470 to its east, the M4 to its south and minor roads to its north, east and south, and has the city of Caerdydd (Cardiff) towards its 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 included in the main P30 list with an accompanying note stating Included by contour configuration, and given a summit height of 179m which appears as a spot height on the Ordnance Survey 1:50,000 Landranger map.  Therefore, this hill was only listed as a P30 through an estimated bwlch height based on interpolation of contours, however due to the quarry workings the contours at the bwlch are not continuous on contemporary Ordnance Survey maps of the day. 

When this list was re-assessed and the sub-list standardised, with also inclusion of interpolated heights and drop values in the main P30 and sub-list this hill was listed with an estimated c 30m of drop based on the 179m summit spot height and an estimated bwlch height of c 149m based on interpolation of 10m contouring on the Ordnance Survey 1:50,000 Landranger map which showed a continuous 150m ring contour connecting to higher ground.  However, the same 150m ring contour remained broken on the 1:25,000 Explorer map.  

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

The drop value for this hill was re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website became available online; this mapping is entitled the Interactive Coverage Map.  Although this mapping has the same 5m contour intervals as the 1:25,000 Explorer map its scale is greatly enlarged giving the opportunity for better interpolation.  This resulted in Garth Wood being reclassified to 100m Sub-Twmpau status with an estimated c 28m of drop based on an estimated bwlch height of c 151m.  

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website

This area was re-examined when the OS Maps website became available online.  This is the replacement for OS Get-a-map and has contours at 5m intervals and for the majority of land comprising old mine and quarry workings it shows present day continuous contours, as opposed to the broken contours on the 1:25,000 Explorer map and the Vector Map Local hosted on the Geograph website.  Importantly this map shows the bwlch contours for this hill between 145m – 150m with the estimated height of the bwlch being c 149m.

Extract from the OS Maps 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. 

LIDAR summit image of Garth Wood

As LIDAR only covers the summit area for this hill its bwlch height remains estimated based on interpolation of the OS Maps 5m contouring.  Therefore, the confirmation of the reclassification of Garth Wood to 100m Twmpau status is due to LIDAR summit analysis and interpolation of OS Maps bwlch contouring, resulting in a 179.9m summit height and an estimated c 149m bwlch height, with these values giving this hill c 31m of drop which is sufficient for it to be reinstated as a 100m Twmpau.

The full details for the hill are:

Group:  Cymoedd Morgannwg

Name:  Garth Wood

OS 1:50,000 map:  171

Summit Height:  179.9m (LIDAR)

Summit Grid Reference:  ST 11990 82531 (LIDAR)

Bwlch Height:  c 149m

Bwlch Grid Reference:  ST 11456 82400 (I)

Drop:  c 31m

Myrddyn Phillips (June 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Coed Cae Bach (SS 855 841) – 100m Twmpau addition (24th reclassification)

Significant Name Changes post for Coed Cae Bach

Significant Height Revisions post for Coed Cae Bach

There has been an addition of a hill to the 100m 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 Coed Cae Bach

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the enclosed land that once comprised ground where the summit of this hill is situated is Coed Cae Bach, and this was derived from the Tithe map and it is this name that the hill is now listed by.  The hill is adjoined to the Cymoedd Morgannwg group of hills, which are situated in the central part of South Wales (Region C, Sub-Region C2), and it forms a part of landscaped ground that once made up the Margam opencast mine, and is encircled by minor roads to its north, west and east and has the B4281 road and the small communities of Cefn Cribwr and Kenfig Hill towards its south.

This hill did not appear in the original 100m height band of Welsh P30 hills when they were published on Geoff Crowder’s v-g.me website as contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps of the day showed the opencast mine without any ring contours of note.

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

This area was re-examined when the OS Maps website became available online.  This is the replacement for OS Get-a-map and has contours at 5m intervals and for the majority of land comprising old mine workings it shows present day contours, as opposed to the blank space showed on the counterparts of the 1:50,000 Landranger and 1:25,000 Explorer maps.

Extract from OS Maps

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. 

The addition of Coed Cae Bach to 100m Twmpau status is due to analysis of data on the OS Maps website coupled with LIDAR analysis and inspection of imagery on Google Maps and Google Earth with the conclusion that this hill is solid and stable.  LIDAR analysis has resulted in a 102.3m summit height and a 72.0m bwlch height, with these values giving this hill 30.4m of drop, which is sufficient for this hill to be classified as a 100m Twmpau.

Extract from Google Maps

  

The full details for the hill are:

Group:  Cymoedd Morgannwg

Name:  Coed Cae Bach

OS 1:50,000 map:  170

Summit Height:  102.3m (LIDAR)

Summit Grid Reference:  SS 85525 84189 (LIDAR)

Bwlch Height:  72.0m (LIDAR)

Bwlch Grid Reference:  SS 85129 84233 (LIDAR)

Drop:  30.4m (LIDAR)

Myrddyn Phillips (May 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pedwar Erw (SS 864 837) – 100m Twmpau addition (23rd reclassification)

Significant Name Changes post for Pedwar Erw

Significant Height Revisions post for Pedwar Erw

There has been an addition of a hill to the 100m 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 Pedwar Erw

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the enclosed land that once comprised ground where the summit of this hill is situated is Pedwar Erw, and this was derived from the Tithe map and it is this name that the hill is now listed by.  The hill is adjoined to the Cymoedd Morgannwg group of hills, which are situated in the central part of South Wales (Region C, Sub-Region C2), and it forms a part of landscaped ground that once made up the Margam opencast mine, and is encircled by minor roads to its north, west and east and has the B4281 road and the small communities of Cefn Cribwr and Kenfig Hill towards its south.

This hill did not appear in the original 100m height band of Welsh P30 hills when they were published on Geoff Crowder’s v-g.me website as contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps of the day showed the opencast mine without any ring contours of note.

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

This area was re-examined when the OS Maps website became available online.  This is the replacement for OS Get-a-map and has contours at 5m intervals and for the majority of land comprising old mine workings it shows present day contours, as opposed to the blank space showed on the counterparts of the 1:50,000 Landranger and 1:25,000 Explorer maps.

Extract from OS Maps

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. 

The addition of Pedwar Erw to 100m Twmpau status is due to analysis of data on the OS Maps website coupled with LIDAR analysis and inspection of imagery on Google Maps and Google Earth with the conclusion that this hill is solid and stable.  LIDAR analysis has resulted in a 131.0m summit height and a 98.4m bwlch height, with these values giving this hill 32.5m of drop, which is sufficient for this hill to be classified as a 100m Twmpau.

Extract from Google Maps

The full details for the hill are:

Group:  Cymoedd Morgannwg

Name:  Pedwar Erw

OS 1:50,000 map:  170

Summit Height:  131.0m (LIDAR)

Summit Grid Reference:  SS 86413 83767 (LIDAR)

Bwlch Height:  98.4m (LIDAR)

Bwlch Grid Reference:  SS 86635 84031 (LIDAR)

Drop:  32.5m (LIDAR)

Myrddyn Phillips (May 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Barclodiau (SH 466 848) – 100m Sub-Twmpau reclassified to 100m Twmpau (22nd reclassification)

Survey post for Barclodiau

There has been confirmation of a reclassification to a hill that is listed in the 100m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis and a subsequent summit survey with the Trimble GeoXH 6000, with both conducted by Myrddyn Phillips and the latter taking place on the 28^th October 2018.

Barclodiau (SH 466 848)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the hill is Barclodiau, and it is adjoined to the Ynys Môn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it has the A5025 road to its north-east and the B5111 road to its west, and is positioned between the small communities of Llannerch-y-medd towards its west and Moelfre towards its east north-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 that accompanied the main P30 list, as it did not meet the criteria then used in this list. 

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 168m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 138m based on interpolation of 5m contouring.

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

The drop value for this hill was re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website became available online; this mapping is entitled the Interactive Coverage Map.  Although this mapping has the same 5m contour intervals as the 1:25,000 Explorer map its scale is greatly enlarged giving the opportunity for better interpolation.  This re-assessment resulted in the estimated c 30m drop value for this hill remaining the same.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph 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.  

The confirmation of the reclassification of Barclodiau to 100m Twmpau status is due to LIDAR analysis, with a subsequent summit survey with the Trimble GeoXH 6000 resulting in a 168.6m Trimble summit height and a 137.1m LIDAR bwlch height, with these values giving this hill 31.5m of drop which is sufficient for it to be classified as a 100m Twmpau.

The Trimble GeoXH 6000 gathering data at the summit of Barclodiau

The full details for the hill are:

Group:  Ynys Môn

Name:  Barclodiau

OS 1:50,000 map:  114, 115

Summit Height:  168.6m (converted to OSGM15)

Summit Grid Reference:  SH 46674 84803

Bwlch Height:  137.1m (LIDAR)

Bwlch Grid Reference:  SH 46583 85001 (LIDAR)

Drop:  31.5m (Trimble summit and LIDAR bwlch)

For details on the summit survey of this hill

Myrddyn Phillips (May 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Mynydd y Castell (SS 806 864) – 100m Sub-Twmpau reclassified to 100m Twmpau (21st reclassification)

There has been confirmation of a reclassification to a hill that is listed in the 100m 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 Mynydd y Castell

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the hill is Mynydd y Castell, and it is adjoined to the Cymoedd Morgannwg group of hills, which are situated in the central part of South Wales (Region C, Sub-Region C2), and it has the A48 road and the M4 motorway to its south-west and the town of Aberafan towards its north-west and the village of Y Pîl (Pyle) towards its south 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 included in the Hills to be surveyed sub list that accompanied the main P30 list, as it was thought at that stage not to meet the criteria used in this list. 

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 38m of drop, based on an estimated summit height of c 121m and an estimated bwlch height of c 83m, with both heights based on interpolation of 10m contouring on the Ordnance Survey 1:25,000 Explorer map.

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

The drop value for this hill was re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website became available online; this mapping is entitled the Interactive Coverage Map.  Although this mapping still has no summit spot height it does have an 83m bwlch spot height and the advantage of 5m contouring which enabled a better interpolation of the drop value, and the hill was subsequently listed with c 37m of drop.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph 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. 

The confirmation of the reclassification of Mynydd y Castell to 100m Twmpau status is due to LIDAR analysis, resulting in a 120.1m summit height and an 83.8m bwlch height, with these values giving this hill 36.2m of drop which is sufficient for it to be classified as a 100m Twmpau.

The full details for the hill are:

Group:  Cymoedd Morgannwg

Name:  Mynydd y Castell

OS 1:50,000 map:  170

Summit Height:  120.1m (LIDAR, natural ground)

Summit Grid Reference:  SS 80681 86460 (LIDAR, natural ground)

Bwlch Height:  83.8m (LIDAR)

Bwlch Grid Reference:  SS 80753 86593 (LIDAR)

Drop:  36.2m (LIDAR)

Myrddyn Phillips (May 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Bryn Mawr (SH 765 766) – 100m Sub-Twmpau reclassified to 100m Twmpau (20th reclassification)

Survey post for Bryn Mawr

There has been confirmation of a reclassification to a hill that is listed in the 100m Twmpau, with the summit height and its location, the drop and status of the hill confirmed by LIDAR analysis, and a subsequent summit survey with the Trimble GeoXH 6000, both conducted by Myrddyn Phillips with the latter taking place on the 15^th October 2018.

Bryn Mawr (SH 765 766)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the hill is Bryn Mawr, and it is adjoined to the Carneddau group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is encircled by minor roads with the B5106 and the Afon Conwy (River Conwy) to its east, and has the town of Conwy towards its north-east.

When the original 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 that accompanied the 100m height band of P30 hills, as it did not at that stage meet the criteria used in this list. 

When the sub list was standardised, and interpolated heights and drop values also included this hill was listed with an estimated c 28m of drop, based on an estimated summit height of c 143m and an estimated bwlch height of c 115m, with both based on interpolation of 10m contouring on the Ordnance Survey 1:25,000 Explorer map.

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

The drop value for this hill was re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website became available online; this mapping is entitled the Interactive Coverage Map.  Although this mapping still has no spot heights for either summit or bwlch it does have 5m contouring which enabled a better interpolation of height, and with an estimated c 143m summit and c 113m bwlch it gave this hill an estimated c 30m of drop.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph 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. 

LIDAR image of Bryn Mawr (SH 765 766)

The confirmation of the reclassification of Bryn Mawr to 100m Twmpau status is due to LIDAR analysis and a subsequent summit survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips, resulting in a 114.0m summit height and a 110.7m bwlch height, with these values giving this hill 33.3m of drop which is sufficient for it to be classified as a 100m Twmpau.

The full details for the hill are:

Group:  Carneddau

Name:  Bryn Mawr

OS 1:50,000 map:  115

Summit Height:  144.0m (converted to OSGM15)

Summit Grid Reference:  SH 76562 76669

Bwlch Height:  110.7m (LIDAR)

Bwlch Grid Reference:  SH 76263 76359 (LIDAR)

Drop:  33.3m (Trimble summit and LIDAR bwlch)

For details on the summit survey of this hill

Myrddyn Phillips (April 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Clytiau Poethion (SH 763 717) – 100m Twmpau addition (19th reclassification)

Survey post for Clytiau Poethion

Significant Name Changes post for Clytiau Poethion


There has been an addition of a hill that is now listed in the 100m Twmpau, with the summit height and its location, the drop and status of the hill confirmed by LIDAR analysis, and a subsequent summit survey with the Trimble GeoXH 6000, both conducted by Myrddyn Phillips with the latter taking place on the 10^th October 2018.

LIDAR image of Clytiau Poethion and Maes Glas Mawr

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the bounded land where the summit of this hill is situated is Clytiau Poethion, and this was derived from the Tithe map and it is the name that this hill is now listed by, and it is adjoined to the Carneddau group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and the hill is encircled by minor roads with the B5106 and the Afon Conwy (River Conwy) to its east, and has the town of Conwy to its north.

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website the adjacent northerly hill known as Maes Glas Mawr (SH 76876 72414) was included in the main P30 list as its summit was thought to be higher than that of Clytiau Poethion (SH 76337 71799).

However, it was not until LIDAR became available that the details for each 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.  

Importantly LIDAR analysis gave Clytiau Poethion as higher than Maes Glas Mawr and this has subsequently been confirmed by a Trimble GeoXH 6000 survey, therefore the bylchau for each hill is swapped as are their classifications, resulting in a Trimble GeoXH 6000 summit height for Clytiau Poethion of 109.1m positioned at SH 76337 71799, and a bwlch height of 68.7m produced by LIDAR analysis and positioned at SH 77496 72493, with these values giving this hill 40.35m of drop, which is sufficient for this hill to be included in the 100m Twmpau.

Gathering data at the summit of Maes Glas Mawr

Gathering data at the summit of Clytiau Poethion

The full details for the hill are:

Group:  Carneddau

Name:  Clytiau Poethion

OS 1:50,000 map:  115

Summit Height:  109.1m (converted to OSGM15)

Summit Grid Reference:  SH 76337 71799

Bwlch Height:  68.7m (LIDAR)

Bwlch Grid Reference:  SH 77496 72493 (LIDAR)

Drop:  40.35m (LIDAR)

For details on the summit survey of this hill

Myrddyn Phillips (March 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Goetre Coed (ST 091 965) – 100m Twmpau addition (18th reclassification)

There has been an addition of a hill to the listing of 100m Twmpau, with the summit height and its location, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Goetre Coed (ST 091 965)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the bounded land where the summit of this hill is situated is Goetre Coed, and this was derived from the Tithe map and it is the name that this hill is now listed by.  The hill is adjoined to the Fforest Fawr group of hills, which are situated in the northern part of South Wales (Region C, Sub-Region C2), and it is almost encircled by the Afon Taf (River Taff) with only its south-western side free from the river, and is positioned with the A470 road to its south-west and the A4054 road to its north-east, and has the small town of Treharris to its north-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 either the main P30 list or the accompanying Hills to be surveyed sub list as it was thought not to have sufficient drop to be a listed as a P30 and it was also thought not to meet the criteria then used for the sub-list.

When this list was standardised and interpolated heights and drop values also included, the details for the hill were re-assessed, but as the bwlch of the hill has a rail and road cutting the contours are not continuous on the Ordnance Survey 1:25,000 Explorer map, therefore its drop value was difficult to estimate and it remained unlisted.

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

The details for this hill were next re-assessed when the 5m contouring on OSMaps became available online, and as this mapping had continuous contours on the area of this hill’s bwlch an estimated c 40m drop value could be given to the hill, based on its 166m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 128m based on interpolation of 5m contouring between 125m – 130m.

Extract from OSMaps

However, it was not until LIDAR became available and analysed 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 Goetre Coed

The summit height produced by LIDAR analysis is 165.9m and is positioned at ST 09189 96517, and the bwlch height is 125.8m and is positioned at ST 09052 96269, with these values giving this hill 40.2m of drop which is sufficient for its inclusion to 100m Twmpau status.

The full details for the hill are:

Group:  Fforest Fawr

Name:  Goetre Coed

OS 1:50,000 map:  171

Summit Height:  165.9m (LIDAR)

Summit Grid Reference:  ST 09189 96517 (LIDAR)

Bwlch Height:  125.8m (LIDAR)

Bwlch Grid Reference:  ST 09052 96269 (LIDAR)

Drop:  40.2m (LIDAR)

Myrddyn Phillips (March 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Maes Glas Mawr (SH 768 724) – 100m Twmpau reclassified to 100m Sub-Twmpau (17th reclassification)

Survey post for Maes Glas Mawr

Significant Name Changes post for Maes Glas Mawr

There has been a reclassification to a hill that is listed in the 100m Twmpau, with the summit height, its location, the drop and status of the hill confirmed by LIDAR analysis, and a subsequent summit survey with the Trimble GeoXH 6000, both conducted by Myrddyn Phillips with the latter taking place on the 10^th October 2018.

Maes Glas Mawr (SH 768 724)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

The name of the bounded land where the summit of this hill is situated is Maes Glas Mawr, and this was derived from local enquiry and it is the name that this hill is now listed by, and it is adjoined to the Carneddau group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is encircled by minor roads with the B5106 road and the Afon Conwy (River Conwy) to its east, and has the town of Conwy towards its north.

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 main P30 list as its summit was thought to be higher than its adjacent and southerly hill known as Clytiau Poethion which is positioned at SH 76337 71799, both hills have now been surveyed with Clytiau Poethion confirmed as the higher resulting in the reclassification of Maes Glas Mawr.

When this list was standardised and interpolated heights and drop values also included Maes Glas Mawr was listed with an estimated c 39m of drop based on the 107m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger map and an estimated bwlch height of c 68m based on interpolation of 10m bwlch contouring between 60m – 70m.

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

These values were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and entitled the Interactive Coverage Map became available online, and the listed drop value remained the same.

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 image of Maes Glas Mawr

Importantly LIDAR analysis gave Clytiau Poethion (SH 76337 71799) as higher than Maes Glas Mawr and this has subsequently been confirmed by a Trimble GeoXH 6000 survey, therefore the bylchau for each hill is swapped as are their classifications, resulting in a Trimble GeoXH 6000 summit height for Maes Glas Mawr of 108.5m positioned at SH 76876 72414, and a bwlch height of 87.05m produced by LIDAR analysis and positioned at SH 76604 71933, with these values giving this hill 21.4m of drop, which is sufficient for this hill to be reclassified to 100m Sub-Twmpau status.

The full details for the hill are:

Group:  Carneddau

Name:  Maes Glas Mawr

OS 1:50,000 map:  115

Summit Height:  108.5m (converted to OSGM15)

Summit Grid Reference:  SH 76876 72414

Bwlch Height:  87.05m (LIDAR)

Bwlch Grid Reference:  SH 76604 71933 (LIDAR)

Drop:  21.4m (LIDAR)

For details on the summit survey of this hill

Myrddyn Phillips (March 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pt. 156.9m (SN 679 244) – 100m Sub-Twmpau reclassified to 100m Twmpau (16th reclassification)

There has been confirmation of a reclassification to a hill that is listed in the 100m Twmpau, with the summit height and its location, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Pt. 156.9m (SN 679 244)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

As an appropriate name for the hill is not known either from historic research or from local enquiry it is being listed by the point (Pt. 156.9m) notation, and it is adjoined to the Y Mynydd Du group of hills, which are situated in the north-western part of South Wales (Region C, Sub-Region C1), and it is encircled by minor roads and is positioned with the A40 road and the Afon Tywi (River Towy) to its north-west, and has the village of Llangadog towards the north-east and the town of Llandeilo towards the west 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 included in the Hills to be surveyed sub list as it did not meet the criteria then used for the main P30 list; however this sub list has now been standardised and interpolated heights and drop values also included in the main P30 and the accompanying sub list.

When this list was standardised and interpolated heights also included this hill was listed with an estimated c 30m of drop, based on the 157m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 127m bwlch height based on interpolation of 10m contouring.

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

These values were re-assessed when the Ordnance Survey Interactive Coverage Map hosted on the Geograph website became available online, and the listed drop value remained the same.

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. 

The summit height produced by LIDAR analysis is 156.85m and is positioned at SN 67900 24456, and the bwlch height is 125.1m and is positioned at SN 67831 24303, with these values giving this hill 31.7m of drop, which is sufficient for this hill to be classified as a 100m Twmpau.

The full details for the hill are:

Group:  Y Mynydd Du

Name:  Pt. 156.9m

OS 1:50,000 map:  159

Summit Height:  156.85m (LIDAR)

Summit Grid Reference:  SN 67900 24456 (LIDAR)

Bwlch Height:  125.1m (LIDAR)

Bwlch Grid Reference:  SN 67831 24303 (LIDAR)

Drop:  31.7m (LIDAR)

Myrddyn Phillips (March 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Bryniau (SH 579 711) – 100m Sub-Twmpau reclassified to 100m Twmpau (15th reclassification)

Survey post for Bryniau

Significant Name Changes post for Bryniau

Summit Relocations post for Bryniau

There has been confirmation of a Hill Reclassification to a hill that is listed in the 100m Twmpau, with the summit height and its location, drop and status of the hill initially confirmed by LIDAR analysis and subsequently by a summit survey with the Trimble GeoXH 6000 which were conducted by Myrddyn Phillips, with the latter taking place on the 1^st October 2018.

LIDAR image of Bryniau

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

When the original 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 that accompanied the 100m height band of P30 hills as it did not at that stage meet the criteria used in this list.  When the sub list was standardised, and interpolated heights and drop values also included this hill was listed with an estimated c 30m of drop, based on the 117m spot height adjoined to a triangulation pillar positioned at SH 57894 71129 and an estimated bwlch height of c 87m based on interpolation of bwlch contouring on Ordnance Survey 1:25,000 Explorer maps. 

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

The drop value was re-assessed when the Ordnance Survey Interactive Coverage Map became available online via the Geograph website, this mapping has a 118m spot height positioned to the north-east of the trig pillar at SH 579 711, which resulted in the summit relocation of this hill from ground beside its triangulation pillar, and the drop value was again estimated to be c 30m, with a revised estimated bwlch height of c 88m.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website

However, it was not until LIDAR became available that these two positions could be compared and confirmation that the land where the 118m spot height appears is higher than the land beside the 117m map heighted trig pillar and that the hill had sufficient drop to be classified as a P30.

LIDAR image of Bryniau

The land where the summit of this hill is situated is a part of Bryniau and this was derived from local enquiry and substantiated from the Tithe map, and it is the name that this hill is now listed by.  The hill is adjoined to the Glyderau group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and is positioned with the A4087 road to its west and minor roads to its south and east, and has the small city of Bangor towards its north.

If wanting to visit the hill permission to do so should be sought as the summit area is not a part of designated open access land, for those wishing to do so the easiest approach is via a track leading to the old farmhouse of Bryniau.

The confirmation of the reclassification of Bryniau to 100m Twmpau status is due to LIDAR analysis and a summit survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips, resulting in a 117.6m summit height and an 87.4m bwlch height, with these values giving this hill 30.1m of drop which is sufficient for it to be classified as a 100m Twmpau.

The Trimble GeoXH 6000 gathering data at the summit of Bryniau

The full details for the hill are:

Group:  Glyderau

Name:  Bryniau

OS 1:50,000 map:  114, 115

Summit Height:  117.6m (converted to OSGM15)

Summit Grid Reference:  SH 57971 71196

Bwlch Height:  87.4m (LIDAR)

Bwlch Grid Reference:  SH 57748 70845 (LIDAR) 

Drop:  30.1m (Trimble summit and LIDAR bwlch)

For details on the summit survey of Bryniau

Myrddyn Phillips (February 2019)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Warren Wood (SN 600 190) – 100m Twmpau reclassified to 100m Sub-Twmpau (14th reclassification)

Significant Name Changes post for Warren Wood

There has been a reclassification to the 100m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

When the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the main P30 list.  When the accompanying sub list was standardised, and interpolated heights also included this hill was listed with an estimated c 31m of drop, based on an estimated c 190m summit height and an estimated bwlch height of c 159m based on interpolation of 10m bwlch contouring between 150m – 160m on the Ordnance Survey 1:25,000 Explorer map.  The drop value was re-assessed when the Ordnance Survey Interactive Coverage Map became available online via the Grograph website, this mapping has contour intervals at 5m for this hill, and the drop value was again estimated to be c 31m.

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

The name of the hill is Warren Wood and it is adjoined to the Mynydd Sylen group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and it is positioned with the B 4300 road to the north, the A 476 road to the east, and has the town of Llandeilo towards the north-east.

If wanting to visit the summit of the hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so the easiest access is from a minor road to the west and south.

The reclassification of Warren Wood to 100m Sub- Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips.  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 Warren Wood

LIDAR bwlch image of Warren Wood

The 1m DTM LIDAR analysis gives the hill the following details:

Name:  Warren Wood

Summit Height:  189.4m

Summit Grid Reference:  SN 60037 19085

Bwlch Height:  160.4m

Bwlch Grid Reference:  SN 59229 18910

Drop:  28.95m

Therefore, the 189.4m LIDAR analysis for the summit position at SN 60037 19085 and the 160.4m LIDAR analysis for the bwlch position at SN 59229 18910 gives this hill 28.95m of drop, which is insufficient for continued 100m Twmpau status.

The full details for the hill are:

Group:  Mynydd Sylen

Name:  Warren Wood

OS 1:50,000 map:  159

Summit Height:  189.4m (LIDAR)

Summit Grid Reference:  SN 60037 19085 (LIDAR)

Bwlch Height:  160.4m (LIDAR)

Bwlch Grid Reference:  SN 59229 18910 (LIDAR)

Drop:  28.95m (LIDAR)

Myrddyn Phillips (October 2018)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Caer Lleiniau Uchaf (SN 521 198) – 100m Sub-Twmpau reclassified to 100m Twmpau (13th reclassification)

Significant Name Changes post for Caer Lleiniau Uchaf

There has been a reclassification to the 100m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

When the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill appeared in the accompanying Hills to be surveyed sub list as it did not meet the criteria then used for the main P30 list; however this sub list has now been standardised and interpolated heights also included in the main P30 and the accompanying sub list.

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

When this list was standardised and interpolated heights also included this hill was listed with an estimated c 28m of drop, based on an estimated c 111m summit height and an estimated bwlch height of c 83m based on interpolation of 10m bwlch contouring between 80m – 90m on the Ordnance Survey 1:25,000 Explorer map.  The drop value was re-assessed when the Ordnance Survey Interactive Coverage Map became available online via the Grograph website, this mapping has contour intervals at 5m for this hill, and the drop value was again estimated to be c 28m.

The name of the bounded land where the summit of this hill is situated is Caer Lleiniau Uchaf, and this was derived from the Tithe map.  The hill is adjoined to the Mynydd Sylen group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and it is positioned with the B 4300 and A 40 roads, and the Afon Tywi (River Towy) to its north, and has the small community of Llanarthne towards the east north-east.

If wanting to visit the summit of the hill permission to do so should be sought as it is not a part of designated open access land, however public footpaths cross the upper part of the hill and these approach from the north, south and east.

The reclassification of Caer Lleiniau Uchaf to 100m Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR image of Caer Lleiniau Uchaf

Extract from the Ordnance Surveys series of Six-Inch maps with the 372ft (113.4m) height similar in value to the LIDAR height, and with the farm named as Glan-bedw as opposed to contemporary maps where it is named Greenhill Farm

The 1m DTM LIDAR analysis gives the hill the following details:

Name:  Caer Lleiniau Uchaf

Summit Height:  113.2m

Summit Grid Reference:  SN 52155 19862

Bwlch Height:  82.0m

Bwlch Grid Reference:  SN 51657 19346

Drop:  31.2m

Therefore, the 113.2m LIDAR analysis for the summit position at SN 52155 19862 and the 82.0m LIDAR analysis for the bwlch position at SN 51657 19346 gives this hill 31.2m of drop, which is sufficient for 100m Twmpau status.

The full details for the hill are:

Group:  Mynydd Sylen

Name:  Caer Lleiniau Uchaf

OS 1:50,000 map:  159

Summit Height:  113.2m (LIDAR)

Summit Grid Reference:  SN 52155 19862 (LIDAR)

Bwlch Height:  82.0m (LIDAR)

Bwlch Grid Reference:  SN 51657 19346 (LIDAR)

Drop:  31.2m (LIDAR)

Myrddyn Phillips (October 2018)






Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pt. 184.3m (SN 202 110) – 100m Twmpau reclassified to 100m Sub-Twmpau (12th reclassification)

There has been a reclassification to the 100m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

Prior to LIDAR analysis this hill was listed with an estimated c 30m of drop based on the 184m summit height given to a triangulation pillar on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated bwlch height of c 154m based on interpolation of 5m bwlch contouring between 150m – 155m on the Ordnance Survey 1:25,000 Explorer map.

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

As I do not know an appropriate name for this hill it is being listed by the point (Pt. 184.3m) notation, with its previously listed name of Castle Ely Hill being an invention and now considered inappropriate and the Tithe map only giving a generic name of Field.  The hill is adjoined to the Brandy Hill group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), and is positioned with the coast to its south and the B 4314 road to its north-east, and has the small community of Rhos-goch (Red Roses) towards its north.

If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so the nearest public right of way is on a lane / track to the east of the summit.

The reclassification of this hill to 100m Sub-Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR image of Pt. 184.3m (SN 20227 11011)

The 1m and 2m DTM LIDAR analysis gives the hill the following details:

Name:  Pt. 184.3m

Summit Height:  184.3m

Summit Grid Reference:  SN 20227 11011

Bwlch Height:  154.7m

Bwlch Grid Reference:  SN 20492 11533

Drop:  29.5m

Therefore, the 184.3m 2m DTM LIDAR analysis for the summit position at SN 20227 11011 and the 154.7m 1m DTM LIDAR analysis for the bwlch position at SN 20492 11533 gives this hill 29.5m of drop, which is not sufficient for its continued 100m Twmpau status.

The full details for the hill are:

Group:  Brandy Hill

Name:  Pt. 184.3m

OS 1:50,000 map:  158

Summit Height:  184.3m (2m DTM LIDAR)

Summit Grid Reference:  SN 20227 11011 (2m DTM LIDAR)

Bwlch Height:  154.7m (1m DTM LIDAR)

Bwlch Grid Reference:  SN 20492 11533 (1m DTM LIDAR)

Drop:  29.5m (LIDAR)

Myrddyn Phillips (September 2018)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

White Park (SN 158 091) – 100m Sub-Twmpau reclassified to 100m Twmpau (11th reclassification)

Significant Name Changes post for White Park

There has been confirmation of a reclassification to the 100m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 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.

When the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill appeared in the accompanying Hills to be surveyed sub list as it did not meet the criteria then used for the main P30 list; however this sub list has now been standardised and interpolated heights also included in the main P30 and the accompanying sub list.

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

When this list was standardised and interpolated heights also included this hill was listed with an estimated c 29m of drop, based on the 137m height given to a triangulation pillar on the summit area and an estimated bwlch height of c 108m based on interpolation of 5m bwlch contouring between 105m – 110m on the Ordnance Survey 1:25,000 Explorer map.  The drop value was re-assessed prior to LIDAR analysis and a tentative estimate of c 30m then given.

The name of the bounded land where the summit of this hill is situated is White Park, and this was derived from the Tithe map.  The hill is adjoined to the Brandy Hill group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), and is positioned between the coast to its south and the A 47 road to its north, and has the small community of Ludchurch to its north-west.

If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land and has no rights of way on it, although a permissive path does cross the hill to the south of its summit.

The confirmation of the addition of White Park to 100m Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR image of the bwlch of White Park

LIDAR image of the summit of White Park

The 2m DTM LIDAR analysis gives the hill the following details:

Name:  White Park

Summit Height:  138.1m

Summit Grid Reference:  SN 15867 09111

Bwlch Height:  107.1m

Bwlch Grid Reference:  SN 15723 09669

Drop:  31.0m

Therefore, the 138.1m LIDAR analysis for the summit position at SN 15867 09111 and the 107.1m LIDAR analysis for the bwlch position at SN 15723 09669 gives this hill 31.0m of drop, which confirms its addition to 100m Twmpau status.

LIDAR image of White Park

The full details for the hill are:

Group:  Brandy Hill

Name:  White Park

OS 1:50,000 map:  158

Summit Height:  138.1m (LIDAR)

Summit Grid Reference:  SN 15867 09111 (LIDAR)

Bwlch Height:  107.1m (LIDAR)

Bwlch Grid Reference:  SN 15723 09669 (LIDAR)

Drop:  31.0m (LIDAR)

Myrddyn Phillips (September 2018)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Tal y Garreg (SH 574 035) – 100m Sub-Twmpau addition (10th reclassification)

There has been confirmation of an addition to the 100m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:

100m Twmpau - Welsh hills at and above 100m and below 200m in height with 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 and above 100m and below 200m in height with 20m and more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.

This hill did not appear in the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website as it did not meet the criteria for this sub category; however this sub list has now been standardised and interpolated heights also included.

When this sub list was standardised and interpolated heights also included this hill was listed with an estimated c 21m of drop, based on the 178m height given to a triangulation pillar at the summit and an estimated bwlch height of c 157m based on bwlch contouring between 150m – 160m.

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

The name of the hill is Tal y Garreg and it is adjoined to the Cadair Idris group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), and the hill is positioned between the coast to its west and the Afon Dysynni to its south and has the small community of Tywyn towards the south- south-east.

If wanting to visit the hill an ascent can start from either the south or north of its summit following public footpaths and bridleways, with one of the former passing over its high point.

The confirmation of the addition of Tal y Garreg to 100m Sub-Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

The 1m DTM LIDAR analysis gives the hill the following details:

Tal y Garreg

Summit Height:  177.3m

Summit Grid Reference:  SH 57402 03580 and SH 57401 03579

Bwlch Height:  156.8m

Bwlch Grid Reference:  SH 57558 03762

Drop:  20.6m

LIDAR image of Tal y Garreg

Therefore, the 177.3m LIDAR analysis for the summit position at SH 57402 03580 and SH 57401 03579 and the 156.8m LIDAR analysis for the bwlch position at SH 57558 03762 gives this hill 20.6m of drop, which confirms its addition to 100 Sub-Twmpau status.

The full details for the hill are:

Group:  Cadair Idris

Name:  Tal y Garreg

OS 1:50,000 map:  124

Summit Height:  177.3m (LIDAR)

Summit Grid Reference:  SH 57402 03580 and SH 57401 03579 (LIDAR)

Bwlch Height:  156.8m (LIDAR)

Bwlch Grid Reference:  SH 57558 03762 (LIDAR)

Drop:  20.6m

Myrddyn Phillips (May 2018)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Cae Nesaf Glanrafon (SH 317 387) – 100m Sub-Twmpau addition (9th reclassification)

Significant Name Changes post for Cae Nesaf Glanrafon

There has been an addition to the 100m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:

100m Twmpau - Welsh hills at and above 100m and below 200m in height with 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 and above 100m and below 200m in height with 20m and more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.

Prior to LIDAR analysis this hill was listed with an estimated c 18m of drop based on the 107m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 89m based on bwlch contouring at 5m intervals and between 85m – 90m on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.

Extract from the Ordnance Survey Interactive Coverage map hosted on the Geograph website

The bounded land where the summit of this hill is situated is named Cae Nesaf Glanrafon on the Tithe map and it is adjoined to the Pen Llŷn group of hills, which is situated in the north-west part of North Wales (Region A, Sub-Region A1), and is positioned to the immediate south of the B 4354 road and north-east of the A 497 road and has the small community of Nefyn to its north-west.

If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land and has no rights of way on it.

The addition of Cae Nesaf Glanrafon to 100m Sub-Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

The LIDAR analysis gives the hill the following details:

Cae Nesaf Glanrafon

Summit Height:  107.4m

Summit Grid Reference:  SH 31707 38723

Bwlch Height:  86.7m

Bwlch Grid Reference:  SH 31781 38801

Drop:  20.7m

LIDAR image of Cae Nesaf Glanrafon

Therefore, the 107.400m LIDAR analysis for the summit position at SH 31707 38723 and the 86.662m LIDAR analysis for the bwlch position at SH 31781 38801 gives this hill 20.738m of drop, which is sufficient for 100 Sub-Twmpau status.

The full details for the hill are:

Group:  Pen Llŷn

Name:  Cae Nesaf Glanrafon

Summit Height:  107.4m (LIDAR)

Summit Grid Reference:  SH 31707 38723 (LIDAR)

OS 1:50,000 map:  123

Drop:  20.7m (LIDAR)

Myrddyn Phillips (April 2018)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Mynydd Carreg (SH 163 291) – 100m Twmpau reclassified to 30-99m Twmpau (8th reclassification)

Survey post for Mynydd Carreg

There has been a reclassification of a 100m Twmpau to a 30-99m Twmpau (thirty welsh metre prominences and upward) initiated by a survey with the Trimble GeoXH 6000.  The details relating to this hill’s reclassification are retrospective as the survey with the Trimble took place on the 28^th December 2014.

The criteria for 100m Twmpau status is all Welsh hills at or above 100m and below 200m in height with 30m minimum drop, whilst the criteria for 30-99m Twmpau status is all Welsh hills at or above 30m and below 100m in height with 30m minimum drop.

When drop values were added to the original Welsh P30 lists that were published on Geoff Crowder’s v-g.me website, this hill was listed with an estimated c 95m summit height based on an uppermost 90m contour ring, and a bwlch height of c 54m, based on interpolation of bwlch contouring between 50m – 60m, with these values giving this hill c 41m of drop.  When the Ordnance Survey enlarged mapping hosted on the Geograph website became available online the whole of Wales was checked for new spot heights and as this hill was given a 100m summit spot height it was reclassified to the 100m P30 list, which was later renamed the 100m Twmpau.

Therefore, prior to the survey with the Trimble GeoXH 6000 this hill was listed with an estimated c 46m of drop based on its 100m summit spot height and an estimated c 53m bwlch height, based on interpolation of bwlch contouring between 50m – 55m.

The name of the hill is Mynydd Carreg and it is situated in the Pen Llŷn range of hills with its Cardinal Hill being Mynydd y Rhiw (SH 228 293) and is placed in the North Wales Region (Region A, Sub-Region A1), and is positioned with the small community of Aberdaron to the south south-east of the hill.

As the summit of the hill is not a part of designated open access land permission to visit its high point should be sought.  However, as the summit is a local viewpoint with a car park at the foot of the hill it is likely that an ascent will have no objection.

The full details for the hill are:

Cardinal Hill:  Mynydd y Rhiw

Summit Height:  99.2m (converted to OSGM15)

Name:  Mynydd Carreg

OS 1:50,000 map:  123

Summit Grid Reference:  SH 16371 29168

Drop:  c 46m

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

For details on the survey that reclassified this hill from a 100m Twmpau to a 30-99m Twmpau

Myrddyn Phillips (September 2017)






Mapping Mountains - Hill Reclassifications - 100m Twmpau

Bryn y Llan or Highermost Gredington (SJ 453 383) - 100m Sub-Twmpau addition (7th reclassification)

There has been an addition to the listing of the 100m Twmpau (thirty welsh metre prominences and upward) due to analysis of the Ordnance Survey enlarged mapping on the Geograph website by Myrddyn Phillips and which has now been refined and confirmed by analysis of LIDAR data by Aled Williams.  With the criteria for the 100m Twmpau being all Welsh hills 100m or more and below 200m in height with 30m minimum drop.

Accompanying the Twmpau list is a sub list entitled the Sub-Twmpau.  With the criteria for 100m Sub-Twmpau qualification being all Welsh hills at or above 100m and below 200m in height with 20m or more and below 30m of drop, with this addition affecting this sub category of hill.

Prior to analysis of the Ordnance Survey enlarged mapping on the Geograph website and the subsequent analysis of LIDAR data the hill was not classified.  Analysis of the Ordnance Survey enlarged map gave the hill an estimated drop of c 23m based on the 114m summit spot height and an estimated bwlch height of c 91m, with these values being sufficient for the hill to be classified as a 100m Sub-Twmpau.

The hill is a part of the Maelor Saesneg group of hills, this part of Wales is the land to the east of the Afon Dyfrdwy (River Dee) and originated as a cantref of the Kingdom of Powys, with its Cardinal Hill being Pt. 157m (SJ 549 440) and is placed in the Region of North Wales (Region A, Sub-Region A4), and is situated with the small community of Hanmer to the north and Cumber’s Bank to the north north-west.

According to the map the summit of the hill is situated in mixed woodland and as it is not a part of open access land permission to visit the high point should be sought.  There is access toward the summit on public footpaths from the north originating from Hanmer that follows the eastern shore of Hanmer Mere, and from the south-west following the boundary of the woodland in its upper section.

The name of the hill is Bryn y Llan or Highermost Gredington and this was derived from the Tithe map by Aled Williams, and its addition to 100m Sub-Twmpau status is due to analysis of the Ordnance Survey enlarged mapping on the Geograph website by Myrddyn Phillips and confirmation of its status via LIDAR data analysed by Aled Williams.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

Aled’s analysis of LIDAR data gives the hill the following details:

Bryn y Llan or Highermost Gredington

Summit Height:  115.1m

Summit Grid Reference:  SJ 45301 38375

Bwlch Height:  91.0m

Bwlch Grid Reference:  SJ 51088 36435

Drop:  24.1m

Therefore, the 115.1m LIDAR data produced for the summit position at SJ 45301 38375 and the 91.0m LIDAR data produced for the bwlch position at SJ 51088 36435 gives this hill 24.1m of drop, which is sufficient for its inclusion as a 100m Sub-Twmpau, therefore this hill is included in this sub category and the total in the Twmpau will be updated accordingly.

The full details for the hill are:

Cardinal Hill:  Pt. 157m (SJ 549 440)

Summit Height:  115.1m (LIDAR data)

Name:  Bryn y Llan or Highermost Gredington

OS 1:50,000 map:  126

Summit Grid Reference:  SJ 45301 38375 

  

Drop:  24.1m (LIDAR data)

My thanks to Aled Williams for sending the details of this hill to me.

Myrddyn Phillips (April 2017)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pandy Bank (SJ 336 538) - 100m Twmpau addition (6th reclassification)

Survey post for Pandy Bank

Significant Name Changes post for Pandy Bank


There has been an addition to the 100m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000.   The hill is situated on the northern outskirts of Wrecsam (Wrexham) overlooking the community of Pandy, in the easterly part of the Bryniau Clwyd range of hills.

The Trimble GeoXH 6000 survey that resulted in this hill’s inclusion as a 100m Twmpau was conducted in the afternoon on the 5^th April 2016 in good, dry and sometimes bright conditions.  With the bwlch height subsequently ascertained from LIDAR analysis initially conducted by Chris Crocker and latterly by Myrddyn Phillips.  

The hill can be accessed from its north from the end of the Pont y Capel Lane where there is sufficient space for three or four cars to be parked.  A broad path leaves the end of the paved road beside a low metal barrier barring entrance to four wheel drive vehicles; a sign proclaims that the land beyond this point is private, so those wishing to visit should technically seek permission to do so.  The broad path leads through woodland toward a high metal fence that borders the adjacent Shrewsbury – Chester railway line where the bwlch of the hill is situated.  The broad path follows this boundary and the summit can be accessed up its steep northern face or from its south, all approaches are steep and much of the hill’s upper slopes have silver birch covering them.

The hill is named Pandy Bank and its summit is positioned at SJ 336 538.  This is a locally known name for the hill and was found when I made enquiries during my ascent.  The only name that appears on current Ordnance Survey maps relating to this hill is ‘Spoil Heap (disused)’.  As the Ordnance Survey detail implies, this hill is the relic of mining waste which was deposited from the old Gresford Colliery.  This site now forms a part of the Gresford Industrial Park.

Contemporary Ordnance Survey 1:50,000 and 1:25,000 mapping does not give this hill any ring contours; however the Ordnance Survey enlarged mapping hosted on the Geograph website does, and uses contour intervals of 5m, with an uppermost contour ring of 105m and bwlch contouring between 70m – 75m.  These contours give the hill a minimum of 30m of drop and contour interpolation prior to the summit survey with the Trimble GeoXH 6000 and subsequent LIDAR analysis suggested that the hill had 34m – 35m of drop.  

The survey with the Trimble GeoXH 6000 resulted in a 105.4m (converted to OSGM15) summit height and the subsequent LIDAR analysis resulted in a bwlch height of 70.2m, with these values giving this hill 35.1m of drop.

The full details for the hill are:

Group:  Bryniau Clwyd

Name:  Pandy Bank

OS 1:50,000 map:  117

Previously Listed Name:  Not previously classified 

Summit Height:  105.4m (converted to OSGM15)

Summit Grid Reference:  SJ 33630 53882

Bwlch Height:  70.3m (LIDAR)

Bwlch Grid Reference:  SJ 33704 53783 (LIDAR)

Drop:  35.1m (Trimble summit and LIDAR bwlch)

Pandy Bank (SJ 336 538) the new 100m Twmpau

For details on the summit survey of Pandy Bank

Myrddyn Phillips (April 2016)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pentre Clawdd Gorse (SJ 311 442) - 100m Twmpau addition (5th reclassification)

Summit survey post and bwlch survey post for Pentre Clawdd Gorse

Summit Relocations post for Pentre Clawdd Gorse
  

There has been an addition of a hill to the list of 100m Twmpau (thirty welsh metre prominences and upward) instigated by a summit survey with the Trimble GeoXH 6000 and subsequent LIDAR bwlch analysis.   The hill is situated to the east of the A483 road and to the north-east of Rhiwabon (Ruabon) in the eastern part of the Moel y Gamelin range of hills.

LIDAR image of Pentre Clawdd Gorse (SJ 311 442)

The Trimble GeoXH 6000 survey that initiated this hill’s addition to the 100m Twmpau list was conducted in the afternoon of the 23^th February 2016 on a beautiful winter’s day in good, dry and sunny conditions.

The name the hill is listed by is Pentre Clawdd Gorse and access to it is relatively easy as its summit is positioned on Wat’s Dyke, this ancient earthwork stretches from the Dee estuary in the north to Shropshire in the south, and public footpaths follow its course over this hill.

Pentre Clawdd Gorse is adjoined to the summit of Wynnstay Park (SJ 31001 42958) which is approximately one kilometre due south from it, with the latter having a 141m spot height given it on Ordnance Survey 1:25,000 Explorer maps.  The summit of Wynnstay Park was surveyed on the 20^th October 2015 with the Trimble GeoXH 6000 and subsequently analysed via LIDAR, resulting in a 141.2m summit height.

The survey with the Trimble GeoXH 6000 resulted in a summit height of 142.0m, giving Pentre Clawdd Gorse as 0.8m higher than Wynnstay Park.  The area of the bwlch was analysed via LIDAR resulting in a 109.8m height, with these values giving this hill 32.2m of drop, which is sufficient for this hill to be classified as a 100m Twmpau. 


The full details for the hill are:

Group:  Moel y Gamelin

Name:  Pentre Clawdd Gorse

OS 1:50,000 map:  117

Summit Height:  142.0m (converted to OSGM15)

Summit Grid Reference:  SJ 31131 44252 

  

Bwlch Height:  109.8m (LIDAR)

Bwlch Grid Reference:  SJ 30789 44141 (LIDAR)

Drop:  32.2m (Trimble summit and LIDAR bwlch)

The summit of Pentre Clawdd Gorse (SJ 311 442) the new addition to the 100m Twmpau list

For details on the survey that resulted in this hill being added to the 100m Twmpau list please click {here} for summit and {here} for the bwlch survey.

Myrddyn Phillips (February 2016)







Mapping Mountains - Hill Reclassifications - 100m Twmpau

The Pimple (SJ 299 472) - 100m Sub-Twmpau addition (4th reclassification)

Survey post for The Pimple

Significant Height Revisions post for The Pimple

Significant Name Changes post for The Pimple

Summit Relocations post for The Pimple


There has been an addition to the Sub category within the 100m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000.   The hill is situated next to the small community of Pentre Bychan which is adjacent to Rhosllanerchrugog, in the easterly part of the Bryniau Clwyd.

These details are retrospective as the Trimble GeoXH 6000 survey that resulted in this hill’s inclusion as a 100m Sub- Twmpau was conducted on the 20^th October 2015 on a beautiful autumnal day in good, dry and sunny conditions.

The hill can be accessed from its west where a public footpath traverses the course of the valley where its bwlch is positioned.  However, permission should be sought for those wishing to visit as the summit is not on open access land.  When I visited I asked permission to do so and was kindly directed to the best ascent route.

The hill is named The Pimple and its summit is positioned at SJ 299 472.  This is a locally known name for the hill and was found when I made enquiries during a number of data sets taken at the area of the bwlch.  The hill remains unnamed on current Ordnance Survey maps and its locally known name relates directly to the past industrial heritage of the hill, as its summit is made of mining waste that is now stabilised and grassed over.  The uppermost part of the summit is relatively small in area and squat, and looks like a pimple as it sits upon another elevated part of the hill.

Current mapping does not give this hill any summit ring contours, although the adjacent field does have a 154m map spot height on it, both of these points were surveyed with the summit known as The Pimple being 0.4m higher according to the Trimble data.

The survey with the Trimble GeoXH 6000 resulted in a 153.5m (converted to OSGM15) summit height and a 128.3m (converted to OSGM15) bwlch height, giving this hill 25.2m of drop and confirming its entry in to the 100m Sub-Twmpau ranks.

The full details for the hill are:

Cardinal Hill:  Moel y Gamelin

Summit Height:  153.5m (converted to OSGM15)

Name:  The Pimple

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 29984 47262

Drop:  25.2m (converted to OSGM15)

Gathering data at the summit of The Pimple, which resulted in this hill's confirmation as a 100m Sub-Twmpau

For details on the survey that resulted in this hill being included as a 100m Sub-Twmpau please click {here}

Myrddyn Phillips (October 2015)







Mapping Mountains - Hill Reclassifications - 100m Twmpau

Bersham Bank (SJ 311 481) - 100m Twmpau addition (3rd reclassification)

Survey post for Bersham Bank

Significant Height Revisions post for Bersham Bank

Significant Name Changes post for Bersham Bank
  

There has been an addition to the 100m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000.   The hill is situated on the southern outskirts of Rhostyllen, which is a south-western suburb of Wrecsam (Wrexham), in the easterly part of the Bryniau Clwyd.

These details are retrospective as the Trimble GeoXH 6000 survey that resulted in this hill’s inclusion as a 100m Twmpau was conducted on the 13^th October 2015 in good, dry and sometimes bright conditions, in the afternoon of an early autumnal day.

The hill can be accessed from its east from a road adjacent to an industrial estate.  Beside the road is a perimeter fence seemingly barring entrance to a path on the lower slopes of the hill, however, one section of the six foot high fence has been toppled over giving access to the public, including local people, who I was told occasionally walk up the hill.

The hill is named Bersham Bank and its summit is positioned at SJ 311 481.  This is the preferred locally known name for the hill and was found when I made enquiries after my ascent.  The only name that appears on current Ordnance Survey maps relating to this hill is ‘Colliery (disused)’.  As the Ordnance Survey detail implies, this hill is the relic of coal waste which was deposited from the workings of the Bersham Colliery which closed its operations in December 1986.

Current mapping does not give this hill any ring contours, although other hills created from coal waste that are relatively near to Bersham Bank at SJ 311 469 and SJ 300 473 do possess separate ring contours.  Although current maps do not give this hill any summit contours, the ones at its bwlch are between 100m – 105m, with the height of the bwlch estimated as being c 103m.

The survey with the Trimble GeoXH 6000 resulted in a 153.6m (converted to OSGM15) summit height and with the bwlch estimated to be c 103m high; these values give the hill c 51m of drop.

The full details for the hill are:

Cardinal Hill:  Moel y Gamelin

Summit Height:  153.6m (converted to OSGM15)

Name:  Bersham Bank

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 31159 48116

Drop:  c 51m

Bersham Bank (SJ 311 481) is now confirmed as a 100m Twmpau

For details on the survey that resulted in this hill being added to the list of 100m Twmpau hills please click {here}

Myrddyn Phillips (October 2015)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Castell Dinbych (SJ 051 657) - 100m Sub-Twmpau reclassified to 100m Twmpau (2nd reclassification)

Survey post for Castell Dinbych

There has been a reclassification to the Twmpau list with a 100m Sub-Twmpau being reclassified to a 100 Twmpau due to a survey with the Trimble GeoXH 6000.  The hill is situated in the centre of Dinbych (Denbigh) in north-east Wales, and its name is Castell Dinbych (Denbigh Castle in English).  

The present construct is the remains of one of Edward 1’s fortifications after he visited his neighbours and asked them not to be so rebellious.  It is situated in an impressive position overlooking the town to the west and the Vale of Clwyd to the east.  In its time the castle must have been an imposing construction, one no doubt meant to subjugate.  

The critical bwlch of the hill may be placed in someone’s living room beside a road named Bryn Stanley; I asked permission to place the Trimble on a fence post adjacent to a front garden as satellite reception may have been awkward inside the bungalow.

The full details for the hill are:

Cardinal Hill:  Mwdwl Eithin

Summit Height:  143.2m (converted to OSGM15)

Name:  Castell Dinbych

OS 1:50,000 map:  116

Summit Grid Reference:  SJ 051 657

Drop:  33.0m (converted to OSGM15)

Castell Dinbych (SJ 051 657) is now reclassified to a 100m Twmpau

For details on the survey that confirmed this hill's 100m Twmpau status please click {here}

Myrddyn Phillips (August 2014)

Mapping Mountains - Hill Reclassifications - 100m Twmpau

Bryn y Beili (SJ 235 643) - 100m Twmpau addition (1st reclassification)

Survey post for Bryn y Beili

Significant Height Revisions post for Bryn y Beili

There has been a new addition to the Welsh 100m P30 list due to a recent survey with the Trimble GeoXH 6000.  The hill is situated in the centre of Yr Wyddgrug (Mold) in north-east Wales.  The name of the hill is Bryn y Beili (Bailey Hill in English), and it is almost hidden from view when approaching from the High Street as it rises behind the former Pendref Chapel and is surrounded by a high wall, trees and shrubs.  

Bryn y Beili has the remains of a Norman castle on its summit which may have been built on a much earlier burial mound.  This hill lends its name to the current usage of Yr Wyddgrug and Mold as the name of the town; yr, gŵydd, crug (high hill, the prominent mound) in Cymraeg, and mont, hault in Norman French.  

The hill was proposed by Mark Trengove as a potential new P30 and involved an exciting survey as the Trimble GeoXH 6000 was run over by a car whilst surveying in the area of the bwlch.  Our second survey attained a good data set from the tree covered summit and was backed up with a basic levelling survey from the position of a spot height just below the summit.

The full details for the hill are:

Cardinal Hill:  Moel y Gamelin

Summit Height:  143.0m (converted to OSGM15)

Name:  Bryn y Beili

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 235 643

Drop:  31.5m (converted to OSGM15)

Bryn y Beili (SJ 235 643), the new 100m Twmpau

For details on the survey that promoted this hill to 100m Twmpau status please click {here}

Myrddyn Phillips (May 2014)