Mapping Mountains – Significant Height Revisions – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

 

Cefn y Coed (SH 667 172) 

There has been a Significant Height Revision to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Cefn y Coed (SH 667 172)

The criteria for the two listings that this height revision 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. 

30-99m Twmpau by Myrddyn Phillips

Y Trechol – The Dominant Hills of Wales – Welsh P30 hills whose prominence equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those additional Welsh P30 hills whose prominence is between one third and half that of their absolute height.  The list is authored by Myrddyn Phillips with the Introduction to the start of the Mapping Mountains publication of this list appearing on the 3^rd December 2015, and the list is now available in its entirety on Mapping Mountains in Google Doc format. 

Y Trechol - The Dominant Hills of Wales by Myrddyn Phillips

The name the hill is now listed by is Cefn y Coed and this was derived from the Tithe map, 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 it is positioned with the A493 road to its south-east, and has the town of Dolgellau towards the east.

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 with a non-interpolated summit height of c 90m positioned at SH 666 172, with an accompanying note stating; Two points of same height, a reference to the two uppermost 90m ring contours that appear on the contemporary Ordnance Survey 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-evaluated and it was listed with an estimated c 64m of drop, based on an estimated c 91m summit height positioned at SH 66668 17206 and an estimated c 27m bwlch height, based on interpolation of 10m contouring between 20m – 30m, with these values giving this hill 70.33% dominance.

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 89.0m and is positioned at SH 66751 17241, and 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 or Harvey 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 to the data produced by the Trimble or by LIDAR analysis.

Therefore, the new listed summit height of this hill is 89.0m and this was derived from LIDAR analysis, this is 2.0m lower than the previously listed summit height of c 90m, which was based on interpolation of the uppermost 90m ring contour that appears on the contemporary Ordnance Survey 1:25,000 Explorer map.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Cadair Idris 

Name:  Cefn y Coed 

OS 1:50,000 map:  124

Summit Height (New Height):  89.0m (LIDAR) 

Summit Grid Reference:  SH 66751 17241 (LIDAR)               

Bwlch Height:  26.7m (LIDAR) 

Bwlch Grid Reference:  SH 67045 17182 (LIDAR) 

Drop:  62.3m (LIDAR) 

Dominance:  69.98% (LIDAR) 

 

Myrddyn Phillips (May 2024)

 

 

  

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

 

Cae Pen y Cefn (SH 532 377) – 30-99m Sub-Twmpau addition 

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

LIDAR image of Cae Pen y Cefn (SH 532 377)

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, 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 Cae Pen y Cefn and this was derived from the Tithe map, and it is adjoined to the Moel Hebog group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with a minor road to its north and south, and the A497 road farther to its north, and has the town of Porthmadog towards the east north-east.

When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category.

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 20m of drop, based on the 58m summit spot height that appears on the contemporary Ordnance Survey 1:25000 Explorer map, and an estimated c 38m bwlch height, based on interpolation of 5m contouring between 35m – 40m. 

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 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 57.8m summit height and a 37.3m bwlch height, with these values giving this hill 20.5m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Moel Hebog 

Name:  Cae Pen y Cefn 

OS 1:50,000 map:  124

Summit Height:  57.8m (LIDAR) 

Summit Grid Reference:  SH 53267 37729 (LIDAR)               

Bwlch Height:  37.3m (LIDAR) 

Bwlch Grid Reference:  SH 53729 38357 (LIDAR) 

Drop:  20.5m (LIDAR) 

 

Myrddyn Phillips (May 2024)

 

 

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

 

Lletwith (SN 865 405) – 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 Lletwith (SN 865 405)

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 Lletwith and this was derived from the Tithe map, and it is adjoined to the Mynydd Epynt group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned with minor roads to its north, west and east, and the A483 road farther to its north-west, and has the town of Llanymddfri (Llandovery) towards the south-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 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 22m of drop, based on the 335m summit spot height that appears on the contemporary Ordnance Survey 1:25,000 Explorer map and the 313m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

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

Therefore, the addition of this hill to Sub-Trichant status is due to LIDAR analysis, resulting in a 335.3m summit height and a 310.7m bwlch height, with these values giving this hill 24.6m of drop, which is sufficient for it to be classified as a Sub-Trichant. 

 

The full details for the hill are: 

Group:  Mynydd Epynt 

Name:  Lletwith 

OS 1:50,000 map:  147, 160

Summit Height:  335.3m (LIDAR)                                                           

Summit Grid Reference:  SN 86562 40517 & SN 86560 40522 & SN 86564 40525 (LIDAR) 

Bwlch Height:  310.7m (LIDAR) 

Bwlch Grid Reference:  SN 86110 40186 (LIDAR) 

Drop:  24.6m (LIDAR) 

 

Myrddyn Phillips (May 2024)

 

 

 

 

 

 

Mapping Mountains – Significant Name Changes – 200m Twmpau

 

Home Warren (SO 115 289) 

There has been a Significant Name Change 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 Home Warren (SO 115 289)

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

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

200m Twmpau by Myrddyn Phillips

The hill is adjoined to the Mynydd Epynt group of hills, which are situated in the central part of South Wales (Region B, Sub-Region B1), and it is positioned encircled by minor roads, with the A470 road farther to its north-west, the A40 road farther to its south-west and the B4560 road farther to its east, and has the town of Aberhonddu (Brecon) towards the west.

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill appeared under the transposed name of Pentwyn, with an accompanying note stating; Name from buildings to the North-West.

Pentwyn

229m

SO116289

161

13

Name from buildings to the North-West.

During my early hill listing I thought it appropriate to either invent a name for a hill, or use a name that appeared near to the summit of the hill on Ordnance Survey maps of the day.  My preference was to use farm names and put Pen, Bryn or Moel in front of them or as in this instance transpose the name of farm and use it for that of the hill.  This is not a practice that I now advocate as with time and inclination place-name data can be improved either by asking local people or by examining historic documents, through this form of research an appropriate name for the hill can usually be found. 

Extract from the Ordnance Survey 1:25,000 Explorer 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 58 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 Home Warren in the apportionments, with the details on the Tithe map appearing in the parish of Llanfihangel-Tal-y-llyn and in the county named as Breconshire. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the 200m Twmpau is Home Warren, and this was derived from the Tithe map. 

 

The full details for the hill are:

Group:  Mynydd Epynt

Name:  Home Warren

Previously Listed Name:  Pentwyn   

OS 1:50,000 map:  161

Summit Height:  229.3m (LIDAR) 

Summit Grid Reference:  SO 11574 28969 & SO 11573 28967 (LIDAR) 

Bwlch Height:  195.7m (LIDAR) 

Bwlch Grid Reference:  SO 10983 29324 (LIDAR) 

Drop:  33.6m (LIDAR) 

 

Myrddyn Phillips (May 2024)

 

 

 

Mapping Mountains – Hill Reclassifications – The Welsh P15s

 

Cae Cenfas Ucha (SN 751 118) – Welsh P15 addition 

There has been an addition to the list of 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 Cenfas Ucha (SN 751 118)

The criteria for the list that this addition 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 listed by is Cae Cenfas Ucha and this was derived from the Tithe map, and it is adjoined to the Mynydd Du group of hills, which are situated in the southern part of South Wales (Region B, Sub-Region B5), and it is positioned with a minor road to its west and south, and the A4068 road to its east, and has the community of Y Gurnos towards the south-east. 

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

When the listing that became known as The Welsh P15s was being compiled, this hill was not included as with an uppermost 170m contour and bwlch contouring between 160m – 170m that appear on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, it was judged not to meet the criterion for the main P15 or the accompanying P14 sub list. 

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 Welsh P15 status is due to LIDAR analysis, resulting in a 182.8m summit height and a 164.5m bwlch height, with these values giving this hill 18.3m of drop, which is sufficient for it to be included in the main list of The Welsh P15s. 

 

The full details for the hill are: 

Group:  Mynydd Du 

Name:  Cae Cenfas Ucha 

OS 1:50,000 map:  160

Summit Height:  182.8m (LIDAR)                                                           

Summit Grid Reference:  SN 75108 11870 (LIDAR) 

Bwlch Height:  164.5m (LIDAR) 

Bwlch Grid Reference:  SN 75202 12488 (LIDAR) 

Drop:  18.3m (LIDAR) 

 

Myrddyn Phillips (May 2024)