Mapping Mountains – Significant Name Changes – The Welsh P15s

 

Graig Pen y Bont (SN 349 055) 

There has been a Significant Name Change 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 Graig Pen y Bont (SO 349 055)

The criteria for the list that this name change 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 hill is adjoined to the Ysgyryd Fawr group of hills, which are situated in the south-eastern part of South Wales (Region B, Sub-Region B4), and it is positioned with minor roads to its north and east, and the B4598 road to its west, and has the town of Brynbuga (Usk) towards the south-east.

When the listing that became known as The Welsh P15s was being compiled, this hill was not included as with an uppermost 60m contour and bwlch contouring between 50m – 60m 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, with subsequent interpolation giving it an estimated c 68m summit height and being listed under the point (Pt. c 68m) notation. 

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 134 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 Graig Pen y Bont in the apportionments, with the details on the Tithe map appearing in the parish named as Cemais Comawndwr and in the county named as Monmouth. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the The Welsh P15s is Graig Pen y Bont, and this was derived from the Tithe map. 

 

The full details for the hill are: 

Group:  Ysgyryd Fawr 

Name:  Graig Pen y Bont

Previously Listed Name:  Pt. c 68m 

OS 1:50,000 map:  161

Summit Height:  70.3m (LIDAR)                                                           

Summit Grid Reference:  SO 34901 05538 (LIDAR)                                                  

Bwlch Height:  55.9m (LIDAR) 

Bwlch Grid Reference:  SO 34994 05530 (LIDAR) 

Drop:  14.4m (LIDAR) 

 

Myrddyn Phillips (May 2025)

 

 

Mapping Mountains – Significant Height Revisions – The Welsh P15s

Graig Pen y Bont (SO 349 055) 

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 Graig Pen y Bont (SO 349 055)

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 Graig Pen y Bont, and this was derived from the Tithe map, and it is adjoined to the Ysgyryd Fawr group of hills, which are situated in the south-eastern part of South Wales (Region B, Sub-Region B4), and it is positioned with minor roads to its north and east, and the B4598 road to its west, and has the town of Brynbuga (Usk) towards the south-east.

When the listing that became known as The Welsh P15s was being compiled, this hill was not included as with an uppermost 60m contour and bwlch contouring between 50m – 60m 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, with subsequent interpolation giving it an estimated c 68m summit height. 

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 Graig Pen y Bont (SO 349 055)

The summit height produced by LIDAR analysis is 70.3m and when compared to detail on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, 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 70.3m and this was derived from LIDAR analysis.  This is 10.3m higher than the uppermost 60m contour that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and 2.3m higher than the subsequent interpolated height of c 68m. 

 ills of Wales, and are reproduced below@

The full details for the hill are: 

Group:  Ysgyryd Fawr 

Name:  Graig Pen y Bont 

OS 1:50,000 map:  161

Summit Height (New Height):  70.3m (LIDAR)                                                           

Summit Grid Reference:  SO 34901 05538 (LIDAR)                                                  

Bwlch Height:  55.9m (LIDAR) 

Bwlch Grid Reference:  SO 34994 05530 (LIDAR) 

Drop:  14.4m (LIDAR) 

 

Myrddyn Phillips (May 2025) 

Mapping Mountains – Hill Reclassifications – The Welsh P15s

 

Graig Pen y Bont (SO 349 055) – Welsh Sub-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 Graig Pen y Bont (SO 349 055)

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 now listed by is Graig Pen y Bont, and this was derived from the Tithe map, and it is adjoined to the Ysgyryd Fawr group of hills, which are situated in the south-eastern part of South Wales (Region B, Sub-Region B4), and it is positioned with minor roads to its north and east, and the B4598 road to its west, and has the town of Brynbuga (Usk) towards the south-east.

When the listing that became known as The Welsh P15s was being compiled, this hill was not included as with an uppermost 60m contour and bwlch contouring between 50m – 60m 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 Sub-P15 status is due to LIDAR analysis, resulting in a 70.3m summit height and a 55.9m bwlch height, with these values giving this hill 14.4m 0f drop, which is sufficient for it to be classified as a Welsh Sub-P15. 

 

The full details for the hill are: 

Group:  Ysgyryd Fawr 

Name:  Graig Pen y Bont 

OS 1:50,000 map:  161

Summit Height:  70.3m (LIDAR)                                                           

Summit Grid Reference:  SO 34901 05538 (LIDAR)                                                  

Bwlch Height:  55.9m (LIDAR) 

Bwlch Grid Reference:  SO 34994 05530 (LIDAR) 

Drop:  14.4m (LIDAR) 

 

Myrddyn Phillips (May 2025)