Mapping Mountains – Summit Relocations – 200m Twmpau

 

Pen y Bryn (SO 075 896) 

There has been a Summit Relocation to a hill that is listed in the 200m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Pen y Bryn (SO 075 896)

The criteria for the list that this summit relocation applies to are:

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

200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Pen y Bryn and this was derived from the Tithe map, and it is adjoined to the Hirddywel group of hills, which are situated in the northern part of South Wales (Region B, Sub-Region B2), and it is positioned with minor roads to its west, south and east, and the A489 road to its north-east, and has the town of Y Drenewydd (Newtown) towards the east north-east.

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

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with 27m of drop, based on the 239m summit spot height positioned at SO 07518 89633 that appears on the Ordnance Survey 1:25,000 Explorer map and the 212m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.

LIDAR analysis gives the highest ground on this hill as 239.0m positioned at SO 07514 89646.  However, this is a part of a raised field boundary and protocols dictate that as this is deemed a relatively recent man-made construct such ground is discounted from the height of a hill. 

LIDAR summit image of Pen y Bryn (SO 075 896)

The height produced by LIDAR analysis to the highest remaining natural ground on this hill is 238.6m and this is positioned at SO 07529 89658, and this comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies when the high point of the hill is found to be positioned; in a different field, to a different feature such as in a conifer plantation,  within a different map contour either on Ordnance Survey maps or interactive mapping, to a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is considered a relatively recent man-made construct, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist.

Therefore, the summit height produced by LIDAR analysis is 238.6m and this is positioned at SO 07529 89658, this position is approximately 25 metres north-eastward from where the 239m spot height appears on the Ordnance Survey 1:25,000 Explorer map and is approximately 15 metres north-eastward from the high point of the raised field boundary. 

 

The full details for the hill are: 

Group:  Hirddywel 

Name:  Pen y Bryn 

OS 1:50,000 map:  136

Summit Height:  238.6m (LIDAR) 

Summit Grid Reference (New Position):  SO 07529 89658 (LIDAR) 

Bwlch Height:  210.5m (LIDAR) 

Bwlch Grid Reference:  SO 07074 89710 (LIDAR) 

Drop:  28.1m (LIDAR) 

 

Myrddyn Phillips (March 2025)

 

 

Mapping Mountains – Significant Height Revisions – The Welsh P15s

 

Cae Cwar y Tŷ (SN 907 499) 

There has been a Significant Height Revision to a hill that is listed in The Welsh P15s, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Cae Cwar y Tŷ (SN 907 499)

The criteria for the list that this height revision applies to are:

The Welsh P15s – Welsh hills with 15m minimum drop, irrespective of their height, with an accompanying sub list entitled the Welsh Sub-P15s, with the criteria for this sub category being all Welsh hills with 14m or more and below 15m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list appearing on Mapping Mountains on the 10^th May 2019. 

The Welsh P15s by Myrddyn Phillips

The name the hill is now listed by is Cae Cwar y Tŷ, and this was derived from the Tithe map, and it is adjoined to the Drygarn Fawr group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned with the A483 road to its north and a minor road to its south-west and east, and has the town of Llanwrtyd towards the south-west.

When the listing that became known as The Welsh P15s was being compiled, this hill was included in the accompanying sub list with 14m of drop, based on the 257m summit spot height and the 243m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR summit image of Cae Cwar y Tŷ (SN 907 499)

The summit height produced by LIDAR analysis is 259.0m and when compared to the originally listed summit height this comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revisions applies to any listed hill whose interpolated height and Ordnance Survey, Harvey or other interactive map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000 or analysis of data produced via LIDAR.  Also included are hills whose summit map data is missing an uppermost ring contour when compared with the data produced by the Trimble or by LIDAR analysis.

Therefore, the new listed summit height of this hill is 259.0m and this was derived from LIDAR analysis.  This is 2.0m higher than the originally listed summit height of 257m that appeared as a spot height on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map.

 

ills of Wales, and are reproduced below@

The full details for the hill are: 

Group:  Drygarn Fawr 

Name:  Cae Cwar y Tŷ 

OS 1:50,000 map:  147

Summit Height (New Height):  259.0m (LIDAR)                                                           

Summit Grid Reference:  SN 90705 49957 (LIDAR)                                                  

Bwlch Height:  243.4m (LIDAR) 

Bwlch Grid Reference:  SN 90715 49674 & SN 90716 49675 (LIDAR) 

Drop:  15.6m (LIDAR) 

 

Myrddyn Phillips (March 2025)

 

Mapping Mountains – Significant Name Changes – 100m Twmpau

Cae Cefn (SO 315 009) 

There has been a Significant Name Change 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 derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Cae Cefn (SO 315 009)

The criteria for the list that this name change applies to are:

100m Twmpau - Welsh hills at or above 100m and below 200m in height that have 30m minimum drop, with an accompanying sub list entitled the 100m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 100m and below 200m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

100m Twmpau by Myrddyn Phillips

The hill 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 minor roads to its west, south and east, and the A4042 road farther to its west, and has the town of Pont-y-pŵl (Pontypool) towards the 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 under the point (Pt. 156m) notation with 19m of drop, based on the 156m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger map and the 137m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

As the summit of this hill comprises bounded land the details for it were examined on the Tithe map.  The term Tithe map is generally given to a map of a Welsh or English parish or township and which was prepared after the 1836 Tithe Commutation Act.  This act allowed tithes to be paid in cash rather than goods.  The Tithe maps gave names of owners and occupiers of land in each parish and importantly for place-name research they also included the name of enclosed land.  This enclosed land is usually based on a field system, however not every field is given a name, but many are and especially so in Wales. 

Extract from the Tithe map

The enclosed land where the summit of this hill is situated is given the number 62 on the Tithe map, this can be cross referenced against the apportionments; it is these apportionments that give the name of the owner or occupier of the land as well as the name of the land.  The land where the summit of this hill is situated is named as Cae Cefn in the apportionments, with the details on the Tithe map appearing in the parish named as Usk and in the county named as Monmouth. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the 100m Twmpau is Cae Cefn, and this was derived from the Tithe map. 

 

The full details for the hill are:

Group:  Cefn yr Ystrad

Name:  Cae Cefn

Previously Listed Name:  Pt. 156m   

OS 1:50,000 map:  171

Summit Height:  159.4m (LIDAR) 

Summit Grid Reference:  SO 31564 00957 & SO 31565 00959 (LIDAR) 

Bwlch Height:  135.7m (LIDAR) 

Bwlch Grid Reference:  SO 31507 01161 (LIDAR) 

Drop:  23.7m (LIDAR) 

 

Myrddyn Phillips (March 2025)

  

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Rhos Uchaf (SH 593 699) – 30-99m Sub-Twmpau addition 

There has been an addition to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Rhos Uchaf (SH 593 699)

The criteria for the list that this addition 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.  The list is authored by Myrddyn Phillips, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

30-99m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Rhos Uchaf, and this was derived from the Tithe map, and it is adjoined to the Glyder Fawr 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 A5 road to its immediate west and the A55 road to its south-east, and has the city of Bangor towards the north-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 not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category.

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 16m of drop, based on an estimated c 93m summit height and an estimated c 77m bwlch height, with both heights based on interpolation of 5m contouring. 

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

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.

Therefore, the addition of this hill to 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 92.5m summit height and a 71.8m bwlch height, with these values giving this hill 20.7m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Glyder Fawr

Name:  Rhos Uchaf 

OS 1:50,000 map:  114, 115

Summit Height:  92.5m (LIDAR) 

Summit Grid Reference:  SH 59332 69923 (LIDAR)               

Bwlch Height:  71.8m (LIDAR) 

Bwlch Grid Reference:  SH 59236 69468 (LIDAR) 

Drop:  20.7m (LIDAR) 

 

Myrddyn Phillips (March 2025) 

Mapping Mountains – Hill Reclassifications – Y Trichant – The 300m Hills of Wales

 

New Field (SJ 257 040) – Sub-Trichant addition

There has been confirmation of an addition to the list of Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of New Field (SJ 257 040)

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

Y Trichant – The 300m Hills of Wales – Welsh hills at or above 300m and below 400m in height that have 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant, with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips with the Introduction to the list and the renaming of it appearing on Mapping Mountains on the 13^th May 2017, and the Introduction to the Mapping Mountains publication of the list appearing on the 1^st January 2022. 

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The name the hill is now listed by is New Field, and this was derived from the Tithe map, and it is adjoined to the Stiperstones group of hills, which are situated in the north-eastern part of South Wales (Region B, Sub-Region B2), and it is positioned with a minor road to its west and east, with the B4388 road farther to its west, and has the town of Y Trallwng (Welshpool) towards the north-west.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included in the accompanying Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category.

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 23m of drop, based on an estimated c 367m summit height and an estimated c 344m bwlch height, with both heights based on interpolation of 5m contouring that appears on the Ordnance Survey 1:25,000 Explorer map. 

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

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.

Therefore, the confirmation of the addition of this hill to Sub-Trichant status is due to LIDAR analysis, resulting in a 366.8m summit height and a 342.5m bwlch height, with these values giving this hill 24.3m of drop, which is sufficient for it to be classified as a Sub-Trichant. 

 

The full details for the hill are: 

Group:  Stiperstones 

Name:  New Field 

OS 1:50,000 map:  126

Summit Height:  366.8m (LIDAR)                                                           

Summit Grid Reference:  SJ 25743 04016 (LIDAR) 

Bwlch Height:  342.5m (LIDAR) 

Bwlch Grid Reference:  SJ 26066 04674 (LIDAR) 

Drop:  24.3m (LIDAR) 

 

Myrddyn Phillips (March 2025)