Mapping Mountains – Significant Height Revisions – Y Trichant - The 300m Hills of Wales

Y Trichant – Significant Height Revisions

Y Trichant are the Welsh hills at or above 300m and below 40om in height that have a minimum drop of 30m, with these hills forming the 300m height band within the listing of the Twmpau (thirty welsh metre prominences and upward).  Accompanying the main P30 list is a sub list entitled the 300m Sub-Trichant with the qualification to 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, with the Introduction to the re-naming of this list and its publication history appearing on Mapping Mountains on 13.05.17.

The list is authored by Myrddyn Phillips and the posts that have appeared on Mapping Mountains detailing the significant height revisions to the main P30 list and the sub list appear below presented chronologically in receding order.

Mapping Mountains - Significant Height Revisions - Y Trichant

Ffridd Felen (SH 855 388) - 35th significant height revision

Hill Reclassifications post for Ffridd Felen

 

There has been a Significant Height Revision to a hill that is listed in the 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 initially conducted by Aled Williams and subsequently by Myrddyn Phillips. 

LIDAR image of Ffridd Felen (SH 855 388)

The criteria for the list that this height revision 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. 

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

The name the hill is listed by is Ffridd Felen, and it is adjoined to the Arenig group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A3), and it is positioned with a minor road to its north-east and the A4212 road to its north-west, and has the town of Y Bala towards the east south-east. 

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 an estimated c 21m of drop, based on the 392m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 371m bwlch height, with the latter based on interpolation of 10m contouring between 370m – 380m 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. 

LIDAR analysis gives the summit height of this hill as 395.0m 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 summit 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 395.0m and this was derived from LIDAR analysis, this is 3.0m higher than the previously listed summit height of 392m which appears as a spot height on the contemporary Ordnance Survey 1:25,000 Explorer map. 

 

The full details for the hill are: 

Group:  Arenig 

Name:  Ffridd Felen 

OS 1:50,000 map:  124, 125

Summit Height (New Height):  395.0m (LIDAR)                                                           

Summit Grid Reference:  SH 85563 38821 (LIDAR) 

Bwlch Height:  372.0m (LIDAR) 

Bwlch Grid Reference:  SH 85597 38395 (LIDAR) 

Drop:  23.0m (LIDAR) 

 

Myrddyn Phillips (December 2021)

Mapping Mountains - Significant Height Revisions - Y Trichant

Pt. 360.1m (SN 604 447) - 34th significant height revision

Hill Reclassifications post for Pt. 360.1m

Significant Name Changes post for Pt. 360.1m

 

There has been a Significant Height Revision to a hill that is listed in the 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 detail on contemporary maps produced from Ordnance Survey data and LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Pt. 360.1m (SN 604 447)

The criteria for the list this height revision affects 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. 

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

The hill is now listed by the Point (Pt. 360.1m) notation, as an appropriate name for it either from historic research or local enquiry has not been found, and it is adjoined to the Elenydd group of hills, which are situated in the central part of the Mid and West Wales Region (Region B, Sub-Region B2), and it is positioned with a minor road to its north-east and the A482 road to its south-west, and has the town of Llanbedr Pont Steffan (Lampeter) towards the north-west. 

When the original 300m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was included in the Hills to be surveyed sub list with a summit height of 357m, based on the spot height 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. 

LIDAR analysis gives the summit height of this hill as 360.1m 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 summit 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. 

LIDAR summit image of Pt. 360.1m (SN 604 447)

Therefore, the new listed summit height for this hill is 360.1m and this was derived from LIDAR analysis, this is 3.1m higher than the previously listed summit height of 357m which appears as a spot height on the contemporary Ordnance Survey 1:25,000 Explorer map. 

 

The full details for the hill are: 

Group:  Elenydd 

Name:  Pt. 360.1m 

OS 1:50,000 map:  146

Summit Height (New Height):  360.1m (LIDAR)                                                           

Summit Grid Reference:  SN 60451 44797 (LIDAR) 

Bwlch Height:  c 324m (interpolation) 

Bwlch Grid Reference:  SN 61574 45299 (interpolation) 

Drop:  c 36m (LIDAR summit and interpolated bwlch) 

 

Myrddyn Phillips (October 2021)

 

 

 

Mapping Mountains - Significant Height Revisions - Y Trichant

Top Field (SO 110 879) - 33rd significant height revision

Significant Name Changes post for Top Field

 

There has been a Significant Height Revision to a hill that is listed in the 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 and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

Top Field (SO 110 879)

The criteria for the list this height revision affects 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. 

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

The name the hill is listed by is Top Field and this was derived from the Tithe map, and it is adjoined to the Cilfaesty group of hills, which are situated in Mid and West 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 south-west, and has the town of Y Drenewydd (Newtown) towards the north. 

When the original 300m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was included in the Hills to be surveyed sub list with a summit height of 371m, based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map, with an accompanying note stating; 374m on 1986 1:50,000 map.  On the contemporary Ordnance Survey 1:50,000 Landranger map, the summit spot height is now given as 371m. 

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 image of Top Field (SO 110 879)

LIDAR analysis gives the summit height of this hill as 373.6m, and as the summit has now been surveyed with the Trimble GeoXH 6000 it is this result that is being prioritised for listing purposes 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 summit 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. 

The Trimble GeoXH 6000 gathering data at the summit of Top Field

Therefore, the new listed summit height for this hill is 373.8m and this was derived from a Trimble GeoXH 6000 survey, this is 2.8m higher than the previously listed summit height of 371m which appears as a spot height on the contemporary Ordnance Survey 1:25,000 Explorer map and now also appears on the 1:50,000 Landranger map. 

 

The full details for the hill are: 

Group:  Cilfaesty 

Name:  Top Field 

OS 1:50,000 map:  136

Summit Height (New Height):  373.8m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 11015 87958 (Trimble GeoXH 6000) 

Bwlch Height:  346.1m (LIDAR) 

Bwlch Grid Reference:  SO 11279 88639 (LIDAR) 

Drop:  27.7m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

 

Myrddyn Phillips (October 2021)

Mapping Mountains - Significant Height Revisions - Y Trichant

Bryn (SJ 013 427) - 32nd significant height revision

Significant Name Changes post for Bryn

 

There has been a Significant Height Revision to a hill that is listed in the 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 Bryn (SJ 013 427)

The criteria for the list that this height revision 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. 

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

The name the hill is listed by is Bryn and this was derived from the Tithe map, and it is adjoined to the Arenig group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A3), and it is positioned with minor roads to its north, west and south, the A5 road farther to its north and the A494 road farther to its south-east, and has the small town of Corwen towards the east. 

When the original 300m 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 309m summit height based on the spot height 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. 

LIDAR analysis gives the summit height of this hill as 311.75m 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 summit 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, this hill’s new listed summit height is 311.8m and this was derived from LIDAR analysis, this is 2.8m higher than the previously listed summit height of 309m which appears as a spot height on the contemporary Ordnance Survey 1:25,000 Explorer map. 

 

The full details for the hill are: 

Group:  Arenig 

Name:  Bryn 

OS 1:50,000 map:  125

Summit Height (New Height):  311.75m (LIDAR)                                                           

Summit Grid Reference:  SJ 01302 42727 (LIDAR) 

Bwlch Height:  265.6m (LIDAR) 

Bwlch Grid Reference:  SJ 00726 42379 (LIDAR) 

Drop:  46.2m (LIDAR) 

 

Myrddyn Phillips (September 2021)

 

Mapping Mountains - Significant Height Revisions - Y Trichant

Mynydd Tŷ’r Sais (SH 855 004) - 31st significant height revision

Survey post for Mynydd Tŷ'r Sais

Hill Reclassifications post for Mynydd Tŷ'r Sais

Summit Relocations post for Mynydd Tŷ'r Sais

 

There has been a Significant Height Revision to a hill that is listed in the Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by a Trimble GeoXH 6000 survey, prompted by an enquiry from Ronnie Bowron based on detail in the summit analysis programme produced by Joe Nuttall. 

Mynydd Tŷ'r Sais (SH 855 004)

The criteria for the list this height revision affects 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. 

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

The name the hill is listed by is Mynydd Tŷ’r Sais and it is adjoined to the Pumlumon group of hills, which are situated in the north-western part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with the A470 road to its north, minor roads to its west and south, and the B4518 road to its east, and has the village of Llanbrynmair towards the north-east. 

When the original 300m height band of Welsh P30 hills was 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 26m of drop, based on the 359m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and the 1:25,000 Explorer map and the 333m 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

Since the original publication of the P30 lists of Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the mapping on the OS Maps website and the WalkLakes website. 

One of the resources now available online is the mapping on the OS Maps website.  This is the replacement for OS Get-a-map and until recent times had contours at 5m intervals which were proving consistently more accurate compared to the 5m contours that sometimes appear on the Ordnance Survey 1:25,000 Explorer map and used to appear on the online Vector Map Local.  This mapping shows an uppermost 360m ring contour and bwlch contouring much nearer the 330m height when compared to the contouring on the Ordnance Survey 1:25,000 Explorer map. 

Another resource now available online is the mapping on the WalkLakes website which hosts an interactive map originated from the Ordnance Survey Open Data programme.  This map has many spot heights not on other publicly available Ordnance Survey maps and for this hill a 362m spot height is given on the area of its summit and again the bwlch contouring is much nearer the 330m height when compared to the contouring on the Ordnance Survey 1:25,000 Explorer map. 

Extract from the WalkLakes website

These details resulted in this hill being prioritised for a Trimble GeoXH 6000 survey.  This took place on the 30.03.21 resulting in a 362.2m summit height, 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 summit 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. 

The Trimble GeoXH 6000 gathering data at the summit of Mynydd Tŷ'r Sais

Therefore, this hill’s new listed summit height is 362.2m and this was derived from a Trimble GeoXH 6000 survey, this is 3.2m higher than the previously listed summit height of 359m which appears as a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map. 

 

The full details for the hill are: 

Group:  Pumlumon 

Name:  Mynydd Tŷ’r Sais 

OS 1:50,000 map:  135, 136

Summit Height (New Height):  362.2m (converted to OSGM15)                                                           

Summit Grid Reference:  SH 85514 00483 

Bwlch Height:  329.9m (converted to OSGM15) 

Bwlch Grid Reference:  SH 86220 00690 

Drop:  32.2m 

 

Myrddyn Phillips (July 2021)

 

Mapping Mountains - Significant Height Revisions - Y Trichant

Ffridd (SH 953 451) - 30th significant height revision

Significant Name Changes post for Ffridd

 

There has been a Significant Height Revision to a hill that is listed in the 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 Ffridd (SH 953 451)

The criteria for the list this height revision affects 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. 

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

The name the hill is listed by is Ffridd and this was derived from the Tithe map, and it is adjoined to the Arenig group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A3), and it is positioned with the A5 road to its north-east, the B4501 road to its west and a minor road to its south, and has the village of Llangwm towards the east south-east. 

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

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the Hills to be surveyed sub list with a summit height of 361m, based on the spot height that appears on the Ordnance Survey 1:50,000 Landranger map, with the Ordnance Survey 1:25,000 Explorer map just having an uppermost 360m ring contour without any spot height. 

Extract from the Ordnance Survey 1:50,000 Landranger 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 summit height of this hill as 363.6m 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 summit 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, this hill’s new listed summit height is 363.6m and this was derived from LIDAR analysis, this is 2.6m higher than the previously listed summit height of 361m which appears as a spot height on the contemporary Ordnance Survey 1:50,000 Landranger map. 

 

The full details for the hill are: 

Group:  Arenig 

Name:  Ffridd 

OS 1:50,000 map:  116

Summit Height New Height):  363.6m (LIDAR)                                                           

Summit Grid Reference:  SH 95302 45157 (LIDAR) 

Bwlch Height:  338.5m (LIDAR) 

Bwlch Grid Reference:  SH 94841 45316 (LIDAR) 

Drop:  25.1m (LIDAR) 

 

Myrddyn Phillips (June 2021)

 

 

Mapping Mountains - Significant Height Revisions - Y Trichant

Banc (SN 721 762) - 29th significant height revision

Survey Post for Banc

Hill Reclassifications post for Banc

Significant Name Changes post for Banc

 

There has been a Significant Height Revision to a hill that is listed in the 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 and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

Banc (SN 721 762)

The criteria for the list this height revision affects 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. 

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

The name the hill is listed by is Banc and this was derived from the Tithe map, and it is adjoined to the Elenydd group of hills which are situated in the central part of the Mid and West Wales Region (Region B, Sub-Region B2), and it is encircled by minor roads with farther afield the A4120 road to its north and the B4343 road to its east, and has the village of Pontarfynach (Devil’s Bridge) towards the east north-east. 

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 350m summit spot height and the 328m 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.  The 350m summit spot height is now shown on the interactive mapping available on the Magic Maps website with the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps only showing an uppermost 340m ring contour. 

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 Banc

LIDAR analysis gives the summit height of this hill as 350.75m, and as the summit has now been surveyed with the Trimble GeoXH 6000 it is this result that is being prioritised for listing purposes 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 summit 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. 

The Trimble GeoXH 6000 gathering data at the summit of Banc

Therefore, this hill’s new listed summit height is 350.9m and this was derived from a Trimble GeoXH 6000 survey, this is 10.9m higher than the uppermost 340m ring contour that appears on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps. 

 

The full details for the hill are: 

Group:  Elenydd 

Name:  Banc 

OS 1:50,000 map:  135, 147

Summit Height (New Height):  350.9 (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference:  SN 72127 76209 (Trimble GeoXH 6000) 

Bwlch Height:  329.1m (LIDAR) 

Bwlch Grid Reference:  SN 72361 75991 (LIDAR) 

Drop:  21.7m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

 

Myrddyn Phillips (May 2021)

Mapping Mountains - Significant Height Revisions - Y Trichant

Pt. 375m (SJ 256 529) - 28th significant height revision

 

There has been a Significant Height Revision to a hill that is listed in the 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 detail on contemporary maps produced from Ordnance Survey data. 

The criteria for the list this height revision affects 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. 

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

The hill is being listed by the point (Pt. 375m) notation as an appropriate name for it either through local enquiry and / or historic research has not been found by the author, and it is adjoined to the Moel y Gamelin group of hills, which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the A525 road to its north-west and the B5430 road to its south, and has the village of Bwlchgwyn towards the north-east. 

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website the summit height of this hill was listed as 378m with an accompanying note stating; Height from 1986 1:50,000 map.  The 378m spot height is the rounded metric equivalent of the 1240ft imperial height that appeared on the summit area of this hill on the Ordnance Survey series of Six-Inch maps. 

After the P30 lists were standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was later listed with an estimated c 372m summit height based on interpolation of its uppermost 370m ring contour that appears on the Ordnance Survey 1:25,000 Explorer map.  This height was amended as the land taking in the position of the 1240ft / 378m spot height now comprises a part of the Bwlchgwyn Quarry and therefore there is a likelihood this no longer exists. 

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

Since publication of these P30 lists on Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the mapping on the WalkLakes website, and it is this mapping that gives this hill a 375m summit spot height. 

Extract from the WalkLakes website

The summit spot height of 375m on the WalkLakes website is not a dramatic height revision when compared to some revised heights, but it does come 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 summit 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, this hill’s new listed summit height is 375m and this was derived from data on the WalkLakes website, this is 3m lower than the originally listed height of 378m and 3m higher than the interpolated c 372m summit height that was previously given for this hill. 

 

The full details for the hill are:

Group:  Moel y Gamelin

Name:  Pt. 375m

OS 1:50,000 map:  117

Summit Height (New Height):  375m (spot height)

Summit Grid Reference:  SJ 25652 52980 (hand-held GPS via DoBIH)

Bwlch Height: 338m (spot height)

Bwlch Grid Reference:  SJ 25275 52868 (spot height)

Drop:  37m (spot height summit and bwlch)

 

Myrddyn Phillips (April 2021)

 

Mapping Mountains - Significant Height Revisions - Y Trichant

Glog (SJ 114 037) - 27th significant height revision

Survey post for Glog

Significant Name Changes post for Glog

 

There has been a Significant Height Revision to a hill that is listed in the 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 detail on contemporary maps produced from Ordnance Survey data and a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

Glog (SJ 114 037)

The criteria for the list this height revision affects 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. 

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

The name the hill is listed by is Glog and this was derived from local enquiry, and it is adjoined to the Carnedd Wen group of hills which are situated in the south-eastern part of North Wales (Region A, Sub-Region A4), and it has the B4385 road to its north, the B4389 road to its west, the B4390 road to its south and the B4385 road to its east, and has the small town of Llanfair Caereinion towards the north north-west. 

When the original 300m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was included in the main P30 list with a summit height of c 320m, based on the uppermost contour that appears on the Ordnance Survey 1:25,000 Explorer map. 

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

The summit of this hill has now been surveyed with the Trimble GeoXH 6000 resulting in 315.4m at SJ 11434 03700, this is not a dramatic decrease in height compared to some revised heights, but it does come 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 summit 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. 

The Trimble GeoXH 6000 gathering data at the summit of Glog

Therefore, this hill’s new listed summit height is 315.4m and this was derived from a Trimble GeoXH 6000 survey, this is positioned at SJ 11434 03700 and is 4.6m lower than its previously listed height of c 320m which was based on the uppermost 320m ring contour that appears on the Ordnance Survey 1:25,000 Explorer map. 

 

The full details for the hill are:

Group:  Carnedd Wen 

Name:  Glog 

OS 1:50,000 map:  136

Summit Height (New Height):  315.4m (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference:  SJ 11434 03700 (Trimble GeoXH 6000) 

Bwlch Height:  c 253m (interpolation) 

Bwlch Grid Reference:  SJ 11080 03903 (interpolation) 

Drop:  c 62m (Trimble GeoXH 6000 summit and interpolated bwlch)

 

Myrddyn Phillips (March 2021)

 

 

Mapping Mountains - Significant Height Revisions - Y Trichant

Y Dduallt (ST 041 961) - 26th significant height revision

Hill Reclassifications post for Y Dduallt

Summit Relocations post for Y Dduallt

 

There has been a Significant Height Revision to a hill that is listed in the Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived by Joe Nuttall who produced a summit analysis programme using LIDAR, and then by LIDAR analysis initially conducted by Jim Bloomer and subsequently by Myrddyn Phillips. 

LIDAR image of Y Dduallt (ST 041 961)

The criteria for the list this height revision affects 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. 

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

The name the hill is listed by is Y Dduallt, 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 is encircled by minor roads with the A4233 road further to its west and the A4059 road and the A470 road further to its east, and has the town of Pontypridd towards the south-east. 

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

After the P30 lists were standardised, and interpolated heights and drop values also included, this hill was listed with 21m of drop based on the 354m summit spot height positioned at ST 04088 96112 and the 333m bwlch spot height that appear on the Ordnance Survey 1:25,000 Explorer map.  With its adjacent hill positioned at ST 036 958 listed with an estimated c 360m summit height based on the uppermost ring 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

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 363.0m and this is positioned at ST 04179 96153, this is a relatively dramatic increase in height compared to some revised heights, and it 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 summit 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, this hill’s new listed summit height is 363.0m and this was derived from LIDAR analysis, this is positioned at ST 04179 96153 and is 9.0m higher than its previously listed height of 354m which appears as a spot height on the Ordnance Survey 1:25,000 Explorer map. 

 

The full details for the hill are:

Group:  Cymoedd Morgannwg 

Name:  Y Dduallt 

OS 1:50,000 map:  170

Summit Height (New Height):  363.0m (LIDAR)                                                           

Summit Grid Reference:  ST 04179 96153 (LIDAR) 

Bwlch Height:  312.2m (LIDAR) 

Bwlch Grid Reference:  ST 03283 95733 (LIDAR) 

Drop:  50.8m (LIDAR)

 

Myrddyn Phillips (February 2021) 

Mapping Mountains - Significant Height Revisions - Y Trichant

Blaen Pathiog (SN 927 820) - 25th significant height revision

Hill Reclassifications post for Blaen Pathiog

Summit Relocations post for Blaen Pathiog

 

There has been a Significant Height Revision to a hill that is listed in the 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 and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

LIDAR image of Blaen Pathiog (SN 927 820)

The criteria for the list this height revision affects 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. 

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

The name the hill is listed by is Blaen Pathiog and it is adjoined to the Pumlumon group of hills, which are situated in the north-western part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with the A470 road to its south-east, and has the town of Llanidloes towards the north-east. 

When the original 300m height band of Welsh P30 hills was 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 considered not to meet the criteria then used for the main P30 category, and listed with a 377m summit height, based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map. 

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

After the P30 lists were standardised, and interpolated heights and drop values also included, this hill was listed with an estimated c 33m of drop based on the 379m summit spot height that appeared on the Ordnance Survey Vector Map Local that was hosted on the Geograph website and an estimated c 346m bwlch height, based on interpolation of 10m contouring between 340m – 350m.  The 379m summit spot height has latterly also appeared on the online mapping 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. 

LIDAR summit image of Blaen Pathiog

LIDAR analysis gives the summit height of this hill as 376.1m, and as the summit has now been surveyed with the Trimble GeoXH 6000 it is this result that is being prioritised for listing purposes 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 summit 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. 

The Trimble GeoXH 6000 gathering data at the summit of Blaen Pathiog

Therefore, this hill’s new listed summit height is 376.3m and this was derived from a Trimble GeoXH 6000 survey, this is positioned at SN 92775 82001 and is 2.7m lower than its previously listed height of 379m which 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 and which now appears on the online mapping available on the Magic Maps website. 

 

The full details for the hill are:

Group:  Pumlumon

Name:  Blaen Pathiog

OS 1:50,000 map:  136

Summit Height (New Height):  376.3m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 92775 82001 (Trimble GeoXH 6000)

Bwlch Height: 343.3m (LIDAR)

Bwlch Grid Reference:  SN 92760 81765 (LIDAR)

Drop:  33.1m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Myrddyn Phillips (December 2020)

Mapping Mountains - Significant Height Revisions - Y Trichant

Pt. 372m (SJ 215 551) - 24th significant height revision

There has been a Significant Height Revision to a hill that is listed in the 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 detail on contemporary maps produced from Ordnance Survey data.

The criteria for the list this height revision affects 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 13th May 2017.

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

The hill is being listed by the point (Pt. 372m) notation as an appropriate name for it either through local enquiry and / or historic research has not been found by the author, and it is adjoined to the Moel y Gamelin group of hills, which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with a minor road to its immediate south and the B5430 road to its north, and has the village of Llanarmon-yn-Iâl towards the west north-west.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website the summit height of this hill was listed as c 375m, based on what was thought to be the uppermost contour that appeared on contemporary Ordnance Survey 1:25,000 Explorer maps.

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

Since publication of these P30 lists on Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map.  This mapping had many more spot heights not on other publicly available Ordnance Survey maps, and for this hill it showed a 372m spot height on the area of its summit.

The summit spot height of 372m on the Ordnance Survey Vector Map Local is not a dramatic height revision when compared to some revised heights, but it does come 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 summit 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, this hill’s new listed summit height is 372m and this was derived from data on the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map, this is 3m lower than the interpolated c 375m summit height that was previously given for this hill.

The full details for the hill are:

Group:  Moel y Gamelin

Name:  Pt. 372m

OS 1:50,000 map:  117

Summit Height (New Height):  372m (spot height)

Summit Grid Reference:  SJ 21512 55133 (spot height)

Bwlch Height:  346m (spot height)

Bwlch Grid Reference:  SJ 21519 55047 (spot height)

Drop:  26m (spot height summit and bwlch)

Myrddyn Phillips (December 2020)

Mapping Mountains - Significant Height Revisions - Y Trichant

Mynydd Fynnon Wen (SN 724 797) - 23rd significant height revision

There has been a Significant Height Revision to a hill that is listed in the 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 Mynydd Fynnon Wen (SN 724 797)

The criteria for the list this height revision affects 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 13th May 2017.

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

The name the hill is listed by is Mynydd Fynnon Wen and it is adjoined to the Pumlumon group of hills, which are situated in the north-western part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with the A44 road to its north and the A4120 road to its south and east, and has the village of Ponterwyd towards the east north-east.

When the original 300m 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 378m summit height, based on the spot height 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.

LIDAR summit image of Mynydd Fynnon Wen

The summit height produced by LIDAR analysis is 375.8m and this is positioned at SN 72420 79716, this is not a dramatic decrease in height compared to some revised heights, but it does come 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 summit 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, this hill’s new listed summit height is 375.8m and this was derived from LIDAR analysis, this is positioned at SN 72420 79716 and is 2.2m lower than its originally listed height of 378m which appears as a spot height on the Ordnance Survey 1:25,000 Explorer map.

The full details for the hill are:

Group:  Pumlumon

Name:  Mynydd Fynnon Wen

OS 1:50,000 map:  135, 147

Summit Height (New Height):  375.8m (LIDAR)

Summit Grid Reference:  SN 72420 79716 (LIDAR)

Bwlch Height: 344.9m (LIDAR)

Bwlch Grid Reference:  SN 72479 79425 (LIDAR)

Drop:  30.9m (LIDAR)

Myrddyn Phillips (November 2020)

Mapping Mountains - Significant Height Revisions - Y Trichant

Mynydd Derw Llwydion (SN 904 900) - 22nd significant height revision

1st Survey post for Mynydd Derw Llwydion

2nd Survey post for Mynydd Derw Llwydion

Hill Reclassifications post for Mynydd Derw Llwydion

Summit Relocations post for Mynydd Derw Llwydion

There has been a Significant Height Revision to a hill that is listed in the Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips.

Mynydd Derw Llwydion (SN 904 900)

The criteria for the list this height revision affects 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 13th May 2017.

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

The name the hill is listed by is Mynydd Derw Llwydion and it is adjoined to the Pumlumon group of hills, which are situated in the north-western part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with minor roads to its north and west, and the B4518 road to its south, and has the town of Llanidloes towards the south-east.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the accompanying Hills to be surveyed sub list, and listed with a 387m summit height, based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map and which is positioned at SN 90722 90066.

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

The summit and bwlch of this hill were surveyed using the Trimble GeoXH 6000 on the 18^th April 2014, resulting in a 388.1m summit height taken to the position of the 387m spot height and a 358.1m bwlch height, with the hill being reclassified to Trichant status due to this survey.

Gathering data during the first Trimble GeoXH 6000 summit survey

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 Mynydd Derw Llwydion

LIDAR analysis gave the position of the summit to the west of where the 387m spot height appears on the map, which is also where the first Trimble GeoXH 6000 survey was conducted, therefore the summit position given by LIDAR was visited on the 11^th July 2020 and a data set taken from its high point.

Gathering data during the second Trimble GeoXH 6000 summit survey

The summit height produced by the second Trimble GeoXH 6000 survey is 389.3m and this is positioned at SN 90460 90041, this is not a dramatic increase in height compared to some height revisions, but it does come 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 summit 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, this hill’s new listed summit height is 389.3m and this was derived from a Trimble GeoXH 6000 survey, this is positioned at SN 90460 90041 and is 2.3m higher than its originally listed height of 387m which appears as a spot height on the Ordnance Survey 1:25,000 Explorer map.

The full details for the hill are:

Group:  Pumlumon

Name:  Mynydd Derw Llwydion

OS 1:50,000 map:  136

Summit Height (New Height):  389.3m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 90460 90041 (Trimble GeoXH 6000)

Bwlch Height: 358.1m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SN 90391 90264 (Trimble GeoXH 6000)

Drop:  31.3m (Trimble GeoXH 6000)

For details on the first Trimble GeoXH 6000 survey of this hill

For details on the second Trimble GeoXH 6000 survey of this hill

Myrddyn Phillips (October 2020)

Mapping Mountains - Significant Height Revisions - Y Trichant

Moel Truan (SJ 113 468) - 21st significant height revision

There has been a Significant Height Revision to a hill that is listed in the 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 detail on contemporary maps produced from Ordnance Survey data.

The criteria for the list this height revision affects 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 13th May 2017.

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

The name the hill is listed by is Moel Truan and it is adjoined to the Moel y Gamelin group of hills, which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the B5429 road to its north, the A494 road to its west and the A5104 road to its south, and has the town of Corwen towards the south-west.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website the summit height of this hill was listed as c 340m which was the uppermost contour that appeared on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.

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

After the P30 lists were 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 342m summit height based on interpolation of its uppermost 340m ring contour.

Since publication of these P30 lists on Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the mapping on the WalkLakes website, and it is this mapping that gives this hill a 344m summit spot height.

Extract from the WalkLakes website

The summit spot height of 344m on the WalkLakes website is not a dramatic height revision when compared to some revised heights, but it does come 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 summit 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, this hill’s new listed summit height is 344m and this was derived from data on the WalkLakes website, this is 2m higher than the interpolated c 342m summit height that was previously given for this hill.

The full details for the hill are:

Group:  Moel y Gamelin

Name:  Moel Truan

OS 1:50,000 map:  116

Summit Height (New Height):  344m (spot height)

Summit Grid Reference:  SJ 11316 46806 (spot height)

Bwlch Height: 296m (spot height)

Bwlch Grid Reference:  SJ 12338 47708 (spot height)

Drop:  48m (spot height summit and bwlch)

Myrddyn Phillips (October 2020)

Mapping Mountains - Significant Height Revisions - Y Trichant

Pt. 396.4m (SH 955 525) - 20th significant height revision

There has been a Significant Height Revision to a hill that is listed in the Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips.

Lidar image of Pt. 396.4m (SH 955 525)

The criteria for the list this height revision affects 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 13th May 2017.

The hill is being listed by the point (Pt. 396.4m) notation as an appropriate name for it either through local enquiry and / or historic research has not been found by the author, and it is adjoined to the Mynydd Hiraethog group of hills which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the Alwen Reservoir to its immediate north-west, the A543 road to its west, the A5 road to its south and the B4501 road to its east, and has the village of Pentrefoelas towards the west.

When the original 300m 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, and it was listed with the summit height of c 390m.

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 c 25m of drop, based on an estimated c 393m summit height and an estimated c 368m bwlch height, with both values based on interpolation of 10m 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.

The summit height produced by LIDAR analysis is 396.4m and is positioned at SH 95514 52528, this is not a dramatic height revision compared to some revised heights, but it does come 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 summit 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, this hill’s new listed summit height is 396.4m and this was derived from LIDAR analysis, this is 3.4m higher compared to its previously listed summit height of c 393m that was derived from interpolation of 10m contouring that appears on the Ordnance Survey 1:25,000 Explorer map.

The full details for the hill are:

Group:  Mynydd Hiraethog

Name:  Pt. 396.4m

OS 1:50,000 map:  116

Summit Height (New Height):  396.4m (LIDAR)

Summit Grid Reference:  SH 95514 52528 (LIDAR)

Bwlch Height: 367.5m (LIDAR)

Bwlch Grid Reference:  SH 95277 52580 (LIDAR)

Drop:  28.9m (LIDAR)

Myrddyn Phillips (August 2020)






Mapping Mountains - Significant Height Revisions - Y Trichant

Cefn Ucaf (SJ 012 461) - 19th significant height revision

Hill Reclassifications post for Cefn Uchaf

Significant Name Changes post for Cefn Uchaf

Summit Relocations post for Cefn Uchaf

There has been a Significant Height Revision to a hill that is listed in the Y Trichant – The 300m Hills of Wales, 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 Cefn Uchaf (SJ 012 461)

The criteria for the list this height revision affects 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 13th May 2017.

The name the hill is listed by is Cefn Uchaf and this was derived from the Tithe map, and it is adjoined to the Mynydd Hiraethog group of hills which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the B5105 road to its north, the A5 road to its south and the A494 road to its east, and has the town of Corwen towards the east south-east.

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 that accompanied the main P30 list, as it was considered not to meet the criteria then used for this sub category. 

When the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with 2om of drop, based on the 337m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 317m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which is 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 Cefn Uchaf

The summit height produced by LIDAR analysis is 340.0m and is positioned at SJ 01294 46112, this is not a dramatic height revision compared to some revised heights, but it does come 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 summit 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, this hill’s new listed summit height is 340.0m and this was derived from LIDAR analysis, this is 3.0m higher compared to its previously listed summit height of 337m that was derived from the spot height that appears on the Ordnance Survey 1:25,000 Explorer map.

The full details for the hill are:

Group:  Mynydd Hiraethog

Name:  Cefn Uchaf

OS 1:50,000 map:  116

Summit Height (New Height):  340.0m (LIDAR)

Summit Grid Reference:  SJ 01294 46112 (LIDAR)

Bwlch Height: 319.1m (LIDAR)

Bwlch Grid Reference:  SJ 00949 46115 (LIDAR)

Drop:  20.9m (LIDAR)

Myrddyn Phillips (August 2020)

Mapping Mountains - Significant Height Revisions - Y Trichant

Bryn Gwyn (SJ 213 617) - 18th significant height revision

Survey post for Bryn Gwyn

There has been a Significant Height Revision to a hill that is listed in the Y Trichant – The 300m Hills of Wales, with the summit height and its position confirmed by a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and which took place on the 18^th December 2019.

Gathering data at the the summit of Bryn Gwyn (SJ 213 617)

The criteria for the list this height revision affects 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.

The name the hill is listed by is Bryn Gwyn and it is adjoined to the Moel y Gamelin group of hills, which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the A494 road to its north and minor roads to its west, south and east, and has the village of Gwernymynydd towards the north.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website the summit height of this hill was listed as c 335m which was based on a non-interpolated height of its uppermost contour that appears on Ordnance Survey 1:25,000 Explorer maps.

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

After the P30 lists were standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated 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 gave a 339m summit height for this hill.  The 339m summit spot height also appears on Ordnance Survey data available on the Magic Maps website.

Extract from the Magic Maps website

The summit height produced by the Trimble GeoXH 6000 is 338.6m and is positioned at SJ 21352 61727, this is not a dramatic height revision when compared to some revised heights, but it does come 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 summit 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, this hill’s new listed summit height is 338.6m and this was derived from a Trimble GeoXH 6000 survey, this is 3.6m higher than the non-interpolated c 335m summit height that was previously given for this hill.

The full details for the hill are:

Group:  Moel y Gamelin

Name:  Bryn Gwyn

OS 1:50,000 map:  117

Summit Height (New Height):  338.6m (converted to OSGM15)

Summit Grid Reference:  SJ 21352 61727

Bwlch Height: c 302m (interpolation)

Bwlch Grid Reference:  SJ 21258 61471 (interpolation)

Drop:  c 37m (Trimble GeoXH 6000 summit and interpolated bwlch)

Myrddyn Phillips (April 2020)

Mapping Mountains - Significant Height Revisions - Y Trichant

Cefn Sarnau (SO 014 341) - 17th significant height revision

There has been a Significant Height Revision to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales and Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips.

LIDAR image of Cefn Sarnau (SO 014 341)

The criteria for the two listings this height revision affects are:

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being listed in the 390m Sub-Pedwar category.  The criteria for 390m Sub-Pedwar status being all Welsh hills at or above 390m and below 400m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

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 13th May 2017.

The name the hill is listed by is Cefn Sarnau and it is adjoined to the Mynydd Epynt group of hills, which are situated in the south-eastern part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with the Afon Honddu and the B4520 road to its east, and has the small community of Capel Isaf (Lower Chapel) towards the north-east.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website the summit height of this hill was listed as c 390m which was based on the uppermost contour that appears on Ordnance Survey 1:25,000 Explorer maps.

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

When the P30 lists were 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 395m summit height, and these details were used when the hill was listed in the 1^st edition of the Y Pedwarau published by Europeaklist in May 2013.

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 Cefn Sarnau

The summit height produced by LIDAR analysis is 397.6m and is positioned at SO 01415 34161, this is not a dramatic height revision when compared to some revised heights, but it does come 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 summit 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, this hill’s new listed summit height is 397.6m and this was derived from LIDAR analysis, this is 2.6m higher than the estimated c 395m summit height that was previously given for this hill.

The full details for the hill are:

Group:  Mynydd Epynt

Name:  Cefn Sarnau

OS 1:50,000 map:  160

Summit Height (New Height):  397.6m (LIDAR)

Summit Grid Reference:  SO 01415 34161 (LIDAR)

Bwlch Height: 355.65m (LIDAR)

Bwlch Grid Reference:  SO 01482 34779 (LIDAR)

Drop:  42.0m (LIDAR)

Myrddyn Phillips (March 2020)






Mapping Mountains - Significant Height Revisions - Y Trichant

Foel Lus (SH 732 761) - 16th significant height revision

There has been a Significant Height Revision to a hill that is listed in the Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

Foel Lus (SH 732 761)

The criteria for the listing that this significant height revision 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 13th May 2017.

The name the hill is listed by is Foel Lus 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 positioned with the A55 road to its north-west, and has the town of Penmaen-mawr towards the west and the town of Conwy towards the east north-east.  

This hill was included in the original 300m height band of Welsh P30 hills published on Geoff Crowder’s v-g.me website.  After the accompanying 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 60m of drop based on the 362m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated bwlch height of c 302m based on contouring between 300m – 310m.

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 Foel Lus

The summit height produced by LIDAR analysis in comparison to the previously listed summit height 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 summit 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, this hill’s new listed summit height is 360.0m and this was produced by LIDAR analysis.  This is not a dramatic revision in height compared to some revised heights and is 2.0m lower than the previous listed height of 362m which was derived from the summit spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.

The full details for the hill are:

Group:  Carneddau

Name:  Foel Lus

OS 1:50,000 map:  115

Summit Height (New Height):  360.0m (LIDAR)

Summit Grid Reference:  SH 73238 76184 (LIDAR)

Bwlch Height:  299.9m (LIDAR)

Bwlch Grid Reference:  SH 73386 75791 (LIDAR)

Drop:  60.1m (LIDAR)

Myrddyn Phillips (December 2019)

Mapping Mountains - Significant Height Revisions - Y Trichant

Dinas (SH 699 738) - 15th significant height revision

Hill Reclassifications post for Dinas

There has been a Significant Height Revision to a hill that is now listed in the Y Trichant – The 300m Hills of Wales, 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 summit image of Dinas (SH 699 738)

The criteria for the listing that this significant height revision 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.

The name the hill is listed by is Dinas 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 positioned with the A55 road to its north-west, and has the town of Penmaen-mawr towards the north-east and the town of Llanfairfechan 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 Hills to be surveyed sub list that accompanied the main P30 list, as it did not 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, but as the contemporary Ordnance Survey 1:25,000 Explorer map did not have a summit spot height and only an uppermost 320m continuous contour and bwlch contouring between 300m – 310m, an accurate interpolated drop value was hard to determine.

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

The details for this hill were re-examined 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 has many spot heights not available on any other publicly available Ordnance Survey map.

The details for this hill were also re-assessed when the OS Maps website became available online.  This is the replacement for OS Get-a-map and has contours at 5m intervals which are proving consistently more accurate compared to the 5m contours that sometimes appear on Ordnance Survey 1:25,000 Explorer maps and the online Vector Map Local.  These re-assessments resulted in the hill being listed with an estimated c 24m of drop, based on an estimated summit height of c 328m and an estimated bwlch height of c 304m.

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.

The summit height produced by LIDAR analysis in comparison to the previously listed estimated summit height 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, this hill’s new listed summit height is 325.9m and this was produced by LIDAR analysis.  This is not a dramatic revision in height compared to some revised heights and is 2.1m lower than the previous estimated height of c 328m which was based on interpolation of the uppermost 320m ring contour on contemporary Ordnance Survey maps.

The full details for the hill are:

Group:  Carneddau

Name:  Dinas

OS 1:50,000 map:  115

Summit Height (New Height):  325.9m (LIDAR)

Summit Grid Reference:  SH 69978 73828 (LIDAR)

Bwlch Height:  301.5m (LIDAR)

Bwlch Grid Reference:  SH 70198 73941 (LIDAR)

Drop:  24.4m (LIDAR)

Myrddyn Phillips (November 2019)

Mapping Mountains - Significant Height Revisions - Y Trichant

Pen Rhiw Warren (ST 214 904) - 14th significant height revision

Hill Reclassifications post for Pen Rhiw Warren

There has been a Significant Height Revision to a hill that is now listed in the Y Trichant, 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 Pen Rhiw Warren (ST 214 904)

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

Y Trichant – Welsh hills at or above 300m and below 400m in height with 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.

The name of the hill is Pen Rhiw Warren and its present state is the result of mine spoil, and it is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and is positioned with the A468 road and the Afon Rhymni (Rhymney River) to its south, the B4251 and A467 roads and the Afon Sirhywi (Sirhowy River) towards the north, and has the town of Caerffili (Caerphilly) towards the west south-west.

This hill was not included in the main P30 list or the accompanying Hills to be surveyed sub list when the original Welsh 300m P30 hills 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 a bwlch height between 310m – 320m and a broken uppermost contour ring of 320m, therefore it did not meet the criteria used within this list.

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

The details for this hill were 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, and rail and road cuttings it shows present day continuous contours, as opposed to the broken contours on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.  The mapping on OS Maps shows this hill as having eight continuous 5m contour rings, implying that the hill has at least 35m of drop.

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.

The summit height produced by LIDAR analysis and its position in relation to the contours shown on the contemporary Ordnance Survey 1:25,000 Explorer map 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.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these revisions.

Therefore this hill’s new summit height is 350.5m and this was produced by LIDAR analysis, this is a dramatic increase in height and is 30.5m higher compared to the uppermost 320m contour ring on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, but is in accordance with the 5m contouring on the OS Maps website.

The inclusion of this hill to Trichant status and its dramatic increase in height is due to terra-forming by man’s intrusion and is the result of raised mine spoil.  As the hill in its present form is considered solid and stable its inclusion as a Trichant and its increase in known height is accepted as a present-day representation of the land.

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Pen Rhiw Warren

OS 1:50,000 map:  171

Summit Height (New height):  350.5m (LIDAR)

Summit Grid Reference:  ST 21463 90441 (LIDAR)

Bwlch Height:  313.9m (LIDAR)

Bwlch Grid Reference:  ST 21869 90427 (LIDAR)

Drop:  36.6m (LIDAR)

Myrddyn Phillips (August 2019)

Mapping Mountains - Significant Height Revisions - Y Trichant

Mynydd y Grug (ST 177 906) - 13th significant height revision

Summit Relocations post for Mynydd y Grug

There has been a Significant Height Revision to a hill that is listed in the Y Trichant, 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 Grug (ST 177 906)

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

Y Trichant – Welsh hills at or above 300m and below 400m in height with 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.

The name of the hill is Mynydd y Grug and it is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and it is positioned with the A469 road to its west, the B4251 and the Afon Sirhywi (Sirhowy River) to its north-east and the A468 road to its south, and has the town of Caerffili (Caerphilly) towards the south-west.

When the original Welsh 300m P30 list was published on Geoff Crowder’s v-g.me website this hill was listed with a 348m summit height, based on the spot height positioned at ST 17688 90958 that appears on the Ordnance Survey 1:25,000 Explorer map, with an accompanying note stating; Workings probably obliterated 350c top at ST176908 on 1986 1:50000 map.  As heights on 1:25,000 scale mapping were prioritised in this list over those on 1:50,000 scale mapping this hill’s summit was listed to where the 348m spot height appears on the 1:25,000 Explorer map.

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

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

The details for this hill were re-assessed when the Ordnance Survey Vector Map became available online and this shows a 375m summit spot height with contemporary Ordnance Survey 1:25,000 Explorer maps showing an uppermost 370m ring contour and a raised summit area which is the bi-product of mine waste spoil.

Extract from the contemporary 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 Mynydd y Grug

The summit height produced by LIDAR analysis and its position in relation to the 348m spot height 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.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these revisions.

The summit height produced by LIDAR analysis is 374.2m and is positioned at ST 17753 90669, this is a dramatic increase in height over the 348m spot height that appeared on contemporary Ordnance Survey 1:25,000 Explorer maps of the day when the Welsh 300m P30s were first listed, and is 24.2m higher than the uppermost 350m ring contour on contemporary Ordnance Survey 1:50,000 Landranger maps.  However, the 374.2m height produced by LIDAR is in accordance with the uppermost 370m ring contour on contemporary Ordnance Survey 1:25,000 Explorer maps and detail on the OS Maps website.

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Mynydd y Grug

OS 1:50,000 map:  171

Summit Height (New height):  374.2m (LIDAR)

Summit Grid Reference:  ST 17753 90669 (LIDAR)

Bwlch Height:  169.85m (LIDAR)

Bwlch Grid Reference:  ST 16783 95144 (LIDAR)

Drop:  204.3m (LIDAR)

Myrddyn Phillips (July 2019)

Mapping Mountains - Significant Height Revisions - Y Trichant

Mynydd y Lan (ST 209 923) - 12th significant height revision

Summit Relocations post for Mynydd y Lan

There has been a Significant Height Revision to a hill that is listed in the Y Trichant and the Y Trechol – The Dominant Hills of Wales, 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 Lan (ST 209 923)

The criteria for the two listings that this significant height revision applies to are:

Y Trichant – Welsh hills at or above 300m and below 400m in height with 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.

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.

The name of the hill is Mynydd y Lan and it is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and it is encircled by roads with the B4251 to its south and west, the A472 to its north and the A467 and B4591 and the Afon Ebwy (Ebbw River) to its east, and has the town of Trecelyn (Newbridge) towards the north and the village of Pontycymer (Crosskeys) towards the east.

When the original Welsh 300m P30 list was published on Geoff Crowder’s v-g.me website this hill was listed with a 381m summit height, based on the spot height positioned at ST 20794 92508 that appears on the Ordnance Survey 1:25,000 Explorer map, with an accompanying note stating that the Ordnance Survey 1:50,000 Landranger map has a 385m spot height positioned at ST 20898 92357.  As heights on 1:25,000 scale mapping were prioritised in this list over those on 1:50,000 scale mapping this hill’s summit was listed to where the 381m spot height appears on the 1:25,000 Explorer map.

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

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

When the Welsh Dominant list was originally compiled this hill was listed with 56.43% dominance based on its 381m summit spot height and its 166m bwlch spot height, with the latter appearing on the Ordnance Survey 1:25,000 Explorer map, with these values giving this hill 215m of drop.

However, it was not until LIDAR became available that the details for this hill were next 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 Mynydd y Lan

LIDAR bwlch image of Mynydd y Lan

The summit height produced by LIDAR analysis and its position in relation to the 385m spot height 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.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these revisions.

The summit height produced by LIDAR analysis is 381.3m and is positioned at ST 20903 92337, this is 3.7m lower than the 385m spot height that appears on the Ordnance Survey 1:50,000 Landranger map at approximately the same position.

The full details for the hill are:

Group:  Cymoedd Gwent

Name:  Mynydd y Lan

OS 1:50,000 map:  171

Summit Height (New height):  381.3m (LIDAR)

Summit Grid Reference:  ST 20903 92337 (LIDAR)

Bwlch Height:  159.5m (LIDAR)

Bwlch Grid Reference:  ST 19806 96725 (LIDAR)

Drop:  221.8m (LIDAR)

Dominance:  58.17% (LIDAR)

Myrddyn Phillips (July 2019)

Mapping Mountains - Significant Height Revisions - Y Trichant

Pen y Bigil (SH 576 621) - 11th significant height revision

Survey post for Pen y Bigil

Hill Reclassifications post for Pen y Bigil

There has been a Significant Height Revision to a hill that is listed in the Y Trichant, and which was initiated by LIDAR analysis and a subsequent survey with the Trimble GeoXH 6000 both of which were conducted by Myrddyn Phillips, with the latter taking place on the 06.10.18.

Pen y Bigil (SH 576 621)

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

Y Trichant – Welsh hills at or above 300m and below 400m in height with 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.

The name of the hill is Pen y Bigil and it 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 it has the A4244 road to its north-west and the A4086 road and Llyn Padarn to its south, and has the villages of Deiniolen towards the north and Llanberis towards the south.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the Hills to be surveyed sub list as it was thought not to 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 33m of drop, based on an estimated c 326m summit height and an estimated c 293m bwlch height, with each based on interpolation of 5m contouring on the contemporary 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 1:25,000 historical map and the series of Six-Inch maps became available online, the former has a 1081ft height and the latter has a 1080ft height given to this hill’s summit, these heights equate to 329m in metric, and when coupled with the c 293m estimated bwlch height gives this hill c 36m of drop.

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

Extract from the Ordnance Survey series of Six-Inch maps

However, it was not until LIDAR became available that the details for this hill were next re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales, and soon after analysing this hill with LIDAR it was surveyed with the Trimble GeoXH 6000. 

LIDAR image of Pen y Bigil

The 331.0m summit height produced by the Trimble GeoXH 6000 is not a dramatic increase from the 329m spot height, but does come 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.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these revisions.

Therefore, this hill’s new summit height as surveyed with the Trimble GeoXH 6000 is 331.0m which is 2m higher than its updated height of 329m that appears as an imperial height on the Ordnance Survey 1:25,000 historical map and the series of Six-Inch maps, and 5m higher than its previously estimated height of c 326m.

The Trimble GeoXH 6000 gathering data at the summit of Pen y Bigil

The full details for the hill are:

Group:  Glyderau

Name:  Pen y Bigil

OS 1:50,000 map:  114, 115

Summit Height (new height):  331.0m (converted to OSGM15)

Summit Grid Reference:  SH 57600 62119

Bwlch Height:  292.6m (LIDAR)

Bwlch Grid Reference:  SH 58014 62043 (LIDAR) 

Drop:  38.4m (Trimble summit and LIDAR bwlch)

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (March 2019)

Mapping Mountains - Significant Height Revisions - Y Trichant

Cefn Llanbister (SO 116 733) - 10th significant height revision

Survey post for Cefn Llanbister

Summit Relocation post for Cefn Llanbister

There has been a Significant Height Revision to a hill that is listed in the Y Trichant, and which was initiated by LIDAR analysis and followed by a survey with the Trimble GeoXH 6000 both of which were conducted by Myrddyn Phillips, with the latter taking place on the 03.07.18 in warm and clear conditions.

LIDAR image of Cefn Llanbister

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

Y Trichant – Welsh hills at or above 300m and below 400m in height with 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 its renaming appearing on Mapping Mountains on the 13^th May 2017.

The name of the hill is Cefn Llanbister and it is placed in the Beacon Hill group of hills, which are situated in the north-eastern part of Mid and West Wales (Region B, Sub-Region B1), and it is positioned with the Afon Ieithon (River Ithon) and the A 483 road to its west and the B 4356 road to its north, and has the small community of Llanbister at its base to the west of the summit.

As the summit of the hill is a part of open access land it can be approached from most directions with public footpaths accessing this land from the west and east, with the most convenient access to the hill via a track that leaves the B 4356 road just to the north of the summit.

When the original Welsh 300m P30 list was published on Geoff Crowder’s v-g.me website this hill was listed with a 373m summit height based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map, with an accompanying note stating 376m at SO GR117732 on 1986 1:50000 map.

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

Prior to LIDAR analysis and the subsequent survey with the Trimble GeoXH 6000 the listed height of this hill had been updated to 376m based on the spot height on the Ordnance Survey 1:50,000 Landranger map.

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

The 377.5m (converted to OSGM15) summit height produced by the Trimble GeoXH 6000 is not a dramatic increase from the 376m spot height, but does come 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.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these revisions.

Therefore, this hill’s new summit height as surveyed with the Trimble GeoXH 6000 is 377.5m (converted to OSGM15) which is 1.5m higher than its updated height of 376m and 4.5m higher than its original listed height of 373m which appears on the Ordnance Survey 1:25,000 Explorer map.

The Trimble GeoXH 6000 gathering data at the summit of Cefn Llanbister which resulted in this hill's significant height revision

The full details for the hill are:

Group:  Beacon Hill

Name:  Cefn Llanbister

OS 1:50,000 map:  136, 148

Summit Height (New height):  377.5m (converted OSGM15)

Summit Grid Reference:  SO 11690 73303

Bwlch Height:  335.3m (converted to OSGM15)

Bwlch Grid Reference:  SO 12399 74601

  

Drop:  42.2m (converted to OSGM15)

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (November 2018)

Mapping Mountains - Significant Height Revisions - Y Trichant

Upper Park (SJ 189 052) - 9th significant height revision

Survey post for Upper Park

Summit Relocation post for Upper Park

There has been a Significant Height Revision to a hill that is listed in the Y Trichant and Y Trechol – The Dominant Hills of Wales, and which was initiated by a survey with the Trimble GeoXH 6000, with the survey that confirmed this height revision being conducted on the 7^th January 2018.

The criteria for the two listings that this height revision affects are:

Y Trichant - Welsh hills at and above 300m and below 400m in height that have 30m minimum drop. 

Y Trechol - The Dominant Hills of Wales - These are the Welsh P30 hills whose prominence  equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those addition Welsh P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The name of the hill is Upper Park and it is situated in the Carnedd Wen range of hills which are in the south-eastern part of North Wales (Region A, Sub-Region A4), and it is positioned between the A 458 road to its north and the A 483 road to its south-east, and has the town of Y Trallwng (Welshpool) to its north-east.

As the summit of the hill is not on designated open access land and is part of a private estate permission to visit should be sought, for those wishing to do so there are a number of options for an ascent, all of which use tracks through forested plantations.

Prior to the survey with the Trimble GeoXH 6000 the height of the hill was originally listed as 352m, with this taken from the spot height that appears on the Ordnance Survey 1:25,000 Explorer map, latterly the hill has been listed with an estimated c 353m summit height.

The 354.0m (converted to OSGM15) summit height produced by the Trimble GeoXH 6000 is not a dramatic increase from the 352m spot height, but does come 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 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, and also hill’s that do not possess a summit spot height and whose estimated summit height has a 2m or more discrepancy when compared to data produced either by the Trimble or by LIDAR.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these revisions.

Therefore, this hill’s new summit height is 354.0m (converted to OSGM15) which is 2.0m higher than the 352m spot height that appears on the Ordnance Survey 1:25,000 Explorer map.

The full details for the hill are:

Group:  Carnedd Wen

Summit Height (New Height):  354.0m (converted to OSGM15)

Name:  Upper Park

OS 1:50,000 map:  125

Summit Grid Reference:  SJ 18980 05270 

        

Drop:  177.0m (converted to OSGM15)

Dominance:  49.998%

The Trimble GeoXH 6000 gathering data at the summit of Upper Park (SJ 189 052) which resulted in this hill's significant height revision

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (February 2018)

Mapping Mountains - Significant Height Revisions - Y Trichant

Mynydd yr Heol (SO 107 601) - 8th significant height revision

Survey post for Mynydd yr Heol

Hill Reclassifications post for Mynydd yr Heol

There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to a hill that is listed in the Y Trichant, with the survey that resulted in this height revision conducted on the 3^rd October 2017.

The criteria for the listing this height revision affects are:

Y Trichant – Welsh hills at and above 300m and below 400m in height that have 30m minimum drop.  The list is authored by Myrddyn Phillips and the Introduction to the list and its re-naming was published on Mapping Mountains on the 13^th May 2017.

The name of the hill is Mynydd yr Heol and it is situated in the Fforest Glud range of hills which are in the eastern part of Mid and West Wales (Region B, Sub-Region B1), and the hill is positioned between the town of Llandrindod (Llandrindod Wells) to its west and the small community of Hundred House to its south.

The grazed summit of Mynydd yr Heol (SO 107 601)

As the summit of the hill is not on designated open access land permission to visit should be sought, for those wishing to do so the nearest public footpath is south of the summit and it passes over the bwlch of the hill in a west – east direction.  However, the easiest and most convenient ascent is from the east following a green track up the hill from the convenience of a minor lane.

Prior to the survey with the Trimble GeoXH 6000 the height of the hill was listed as 382m, with this taken from the summit spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.

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

The 386.8m (converted to OSGM15) summit height produced by the Trimble GeoXH 6000 is a dramatic increase from the previously listed summit height of 382m, and therefore it comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revision applies to any listed hill whose Ordnance Survey summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000, or a previous estimated summit height based on contour interpolation.  Also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these revisions.

The summit of this hill is easily identified and consists of closely cropped grass at the top of a field used for grazing.  Just below the summit to the south-west is a small, but steep section of exposed rock, similar to an old quarry, otherwise the summit area is not remarkable, except of course for its dramatic increase in known height.

Therefore, this hill’s new summit height is 386.8m (converted to OSGM15) which is 4.8m higher than its previously listed height of 382m which is shown on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.

The full details for the hill are:

Cardinal Hill:  Gilwern Hill

Summit Height (New Height):  386.8m (converted to OSGM15)

Name:  Mynydd yr Heol

OS 1:50,000 map:  148

Summit Grid Reference:  SO 10793 60177  

       

Drop:  31.2m (converted to OSGM15)

Gathering data with the Trimble GeoXH 6000 from the summit of Mynydd yr Heol which resulted in this hill's significant height revision

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (December 2017)

Mapping Mountains - Significant Height Revisions - Y Trichant

Teisen Priodas (SN 820 108) - 7th significant height revision

Survey post for Teisen Priodas

Hill Reclassifications post for Teisen Priodas

Significant Name Changes post for Teisen Priodas

There has been a Significant Height Revision to a hill that is now listed in the Y Trichant due to analysis of LIDAR data by Kevin McGovern and also independently by Aled Williams and George Gradwell, which was subsequently confirmed by a survey with the Trimble GeoXH 6000 that was conducted on the 13th June 2017. 

Y Trichant is the title for the hills in the 300m height band of the Twmpau (thirty welsh metre prominences and upward) and takes in all Welsh hills at or above 300m and below 400m in height that have a minimum 30m of drop, with the introduction to the re-naming of this list appearing on Mapping Mountains on the 13^th May 2017.

The ridge that this hill is a part of is named Mynydd y Drum and it consists of three listed hills, one being a sub hill which is deemed natural, and two being P30s that are the consequence of mine workings, with one of these P30s having been fully landscaped.  It is this fully landscaped P30 whose details are given in this article.  

When visiting this hill I made place-name enquiries with two of the remaining six mine workers and was told that the name the hill is known by is Teisen Priodas, which translated into English means the wedding cake, an apt name as the hill has three tiers and is relatively flat on top.

Teisen Priodas is adjoined to the Fforest Fawr group, with its Cardinal Hill being Fan Gyhirych (SN 880 191) and is placed in the Region of South Wales (Region C, Sub-Region C2), with the hill positioned between the small communities of Abercraf (Abercrave) to the north and Y Coelbren towards the east.

As the hill is a part of the Nant Helen Opencast Mine permission to visit should be sought, however Ordnance Survey maps still show public footpaths crossing the opencast workings with the nearest one placed just to the west of the summit and crossing land associated with the mine from a south to a north direction, this public footpath is probably on a part of land that has been landscaped.

Teisen Priodas consists of waste spoil that is now landscaped, and as it is customary for Ordnance Survey maps to show mine workings without any form of contour line the hill had not been classified prior to the analysis of LIDAR data, although the area of this hill’s bwlch does possess contours.  The mine is situated on the north-eastern part of the Mynydd y Drum ridge, with the south-western part of this broad ridge still intact having not been mined and possessing a 200m Sub-Twmpau that is listed by the name of Mynydd y Drum.

The highest ring contour shown on Ordnance Survey 1:25,000 Explorer maps for the whole  broad ridge of Mynydd y Drum is 290m which appears on the south-western part of this ridge where the 296.2m summit of the Sub-Twmpau is situated at SN 80718 09753, and also at the eastern periphery of the mine at SN 833 112.  

The survey with the Trimble GeoXH 6000 produced a summit height for Teisen Priodas of 337.9m (converted to OSGM15) which comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revision applies to any listed hill whose Ordnance Survey summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000, or a previous estimated summit height based on interpolation of contours.  Also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 map is being prioritised in favour of the 1:50,000 map for detailing these revisions.

The summit area of this hill is now landscaped and relatively flat and expansive, with the high point toward the eastern part of the summit plateau which consists of long grasses.

Therefore this hill’s new summit height is 337.9m (converted to OSGM15), as no summit contours exist for this hill above the 290m given to the far eastern part of the mine workings on the Ordnance Survey 1:25,000 Explorer map, this is a dramatic 47.9m increase in height compared to its uppermost ring contour. 

The full details for the hill are:

Cardinal Hill:  Fan Gyhirych 

Summit Height (New Height):  337.9m (converted to OSGM15)

Name:  Teisen Priodas

OS 1:50,000 map:  160

Summit Grid Reference:  SN 82013 10833

         

Drop:  93.3m (converted to OSGM15)

The Trimble GeoXH 6000 gathering data at the summit of Teisen Priodas (SN 820 108) which confirmed this hill's significant height revision

For details on the Hill Reclassification post instigated from analysis of LIDAR data

For details on the survey that confirmed this hill's significant height revision

Myrddyn Phillips (August 2017)

Mapping Mountains - Significant Height Revisions - Y Trichant

Moel Llaethbwlch (SJ 113 167) - 6th significant height revision

Survey post for Moel Llaethbwlch


There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to a hill that is listed in the Y Trichant, with the survey that resulted in this height revision conducted on the 6th April 2017.

The criteria for the listing that this height revision affects are:

Y Trichant - Welsh hills at and above 300m and below 400m in height that have 30m minimum drop.  The list is authored by Myrddyn Phillips and the Introduction to the list and its re-naming was published on Mapping Mountains on the 13th May 2017.

The name of the hill is Moel Llaethbwlch and it is situated in the Y Berwyn range of hills which are in the south-east part of North Wales, and the hill is positioned between the town of Llanfyllyn to the north-east and the village of Meifod to the south-east.

As the summit of the hill is not a part of designated open access land permission to visit should be sought, with the nearest public footpaths contouring round the hill’s northern lower slopes and also its lower southern slopes.

Prior to the survey with the Trimble GeoXH 6000 the height of the hill was estimated as c 370m based on the small uppermost 370m ring contour on Ordnance Survey 1:25,000 Explorer maps, and to my knowledge no spot height has ever appeared on an Ordnance Survey map for this hill.

The 372.1m (converted to OSGM15) height produced by the Trimble GeoXH 6000 is not a dramatic increase from the previously estimated summit height of c 370m, but it does come within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revision applies to any listed hill whose Ordnance Survey summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000, or a previous estimated summit height based on contour interpolation.  Also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 map is being prioritised in favour of the 1:50,000 map for detailing these revisions.

The summit of this hill is easily identified and consists of closely cropped grass at the top of a field used for grazing.  Although the immediate summit area is relatively flat it is encircled by what looks like the remains of a small hill fort, although I have found no evidence to support this.

Therefore this hill’s new summit height is 372.1m (converted to OSGM15) which is 2.1m higher than its previously estimated height of c 370m and also 2.1m higher than its 370m uppermost ring contour on Ordnance Survey maps.

The full details for the hill are:

Cardinal Hill:  Moel y Fronllwyd

Summit Height (New Height):  372.1m (converted to OSGM15)

Name:  Moel Llaethbwlch

OS 1:50,000 map:  125

Summit Grid Reference:  SJ 11335 16724

          

Drop:  43.3m (converted to OSGM15)

The Trimble GeoXH 6000 gathering data at the summit of Moel Llaethbwlch (SJ 113 167)  which resulted in this hill's significant height revision

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (May 2017)

Mapping Mountains - Significant Height Revisions - Y Trichant

Penmaen Mawr (SH 704 752) - 5th significant height revision

Survey post for Penmaen Mawr

1st Hill Reclassifications post for Penmaen Mawr

2nd Hill Reclassifications post for Penmaen Mawr


There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 that was conducted on the 14^th July 2016 to a hill that is listed in the Y Trichant, with the hill subsequently analysed with LIDAR data by Aled Williams and it is the latter result that is being detailed in this Significant Height Revisions post.

The criteria for the listing that this height revision affects are:

Y Trichant - Welsh hills at and above 300m and below 400m in height that have 30m minimum drop.  Sub-Trichant - Welsh hills at and above 300m and below 400m in height that have 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips and the Introduction to the list and its re-naming has been published on Mapping Mountains.

The hill is named Penmaen Mawr  and it is situated in the Carneddau range of hills, and is positioned above and to the immediate south of the busy A 55 as it heads westward between the towns of Penmaenmawr and Llanfairfechan, which are situated to the hill’s east and west respectively.

The summit is a part of the hill named Penmaen Mawr and the extended hill has been quarried with its old 1,550ft (472m) map heighted summit now a distant memory as the whole inner section of the summit has been blown apart leaving two remaining tops with this post concentrating on the lower easterly summit.

The lower easterly summit is impressive as it forms a sheer rock face from its south and has steep slopes descending northward to the A 55 below.  Each summit is listed by the same name of Penmaen Mawr as they are both a part of the hill that is known by this name.

The summit area for the whole of Penmaen Mawr now appears on Ordnance Survey maps as a blank area with ‘Quarries’ written over it, and therefore is devoid of any uppermost continuous contour rings, which is the norm for the representation of quarried areas on Ordnance Survey maps, with the highest contour line being 350m for the area where the lower easterly peak is situated.

Therefore this hill’s new summit height is 385.8m (LIDAR data) which is 35.8m higher than its uppermost contour line on Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps, and its 31.3m drop value is sufficient for it to be classified as a Trichant.

The full details for the hill are:

Cardinal Hill:  Tal y Fan

Summit Height:  385.8m (LIDAR data)

Name:  Penmaen Mawr

OS 1:50,000 map:  115

Summit Grid Reference:  SH 70441 75241

Drop:  31.3m (LIDAR data)

Aled with Penmaen Mawr (SH 704 752) in the background

Myrddyn Phillips (July 2016)

Mapping Mountains - Significant Height Revisions - Y Trichant

Penmaen Mawr (SH 698 755) - 4th significant height revision

Survey post for Penmaen Mawr


There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to a hill that is listed in the Y Pedwarau and the Y Trichant, with the survey that resulted in this height revision being conducted on the 14^th July 2016.

The criteria for the listings that this height revision affects are:

Y Pedwarau - Welsh hills at and above 400m and below 500m in height that have 30m minimum drop.  300m Double Sub- Pedwarau - Welsh hills at and above 390m and below 400m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams.

Y Trichant - Welsh hills at and above 300m and below 400m in height that have 30m minimum drop.  Sub-Trichant - Welsh hills at and above 300m and below 400m in height that have 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips and the Introduction to the list and its re-naming has been published on Mapping Mountains.

The hill is named Penmaen Mawr  and it is situated in the Carneddau range of hills, and is positioned above and to the immediate south of the busy A 55 as it heads westward between the towns of Penmaenmawr and Llanfairfechan, which are situated to the hill’s east and west respectively.

The summit area of Penmaen Mawr has been quarried, and prior to the first quarry opening in 1830 and the subsequent resulting expansion of operations the hill was substantially higher, with a 1,550ft (472m) map height given it on the Ordnance Survey Popular and New Popular One-Inch maps, with this height also appearing on the Ordnance Survey Six-Inch map published in 1888.

The quarrying of this hill has created two summits with a gaping hole between, the westerly summit is higher than the easterly, although the latter is more impressive due to a shear rock face leading toward its high point.  Each summit is listed by the same name of Penmaen Mawr as they are both a part of the hill that is known by this name, and their height data is given below:

Penmaen Mawr:  390.4m (converted to OSGM15, Trimble GeoXH 6000) at SH 69865 75523

Penmaen Mawr:  385.8m (LIDAR data) at SH 70292 75649

Over recent years the summit area of this hill has appeared without any uppermost contour lines as is the norm for quarried ground that is represented on Ordnance Survey maps, with the highest contour being 370m which appears on the upper western part of this hill.

Therefore this hill’s new summit height is 390.4m (converted to OSGM15) which is 20.4m higher than its uppermost contour on Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.

The full details for the hill are:

Cardinal Hill:  Tal y Fan

Summit Height:  390.4m (converted to OSGM15)

Name:  Penmaen Mawr

OS 1:50,000 map:  115

Summit Grid Reference:  SH 69865 75523

Drop:  26.9m (converted to OSGM15)

The Trimble GeoXH 6000 gathering data 0.39m above the summit of Penmaen Mawr (SH 698 755) which resulted in this hill's significant height revision

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (July 2016)

Mapping Mountains - Significant Height Revisions - Y Trichant

Cefn Llwydallt (SO 074 409) - 3rd significant height revision

Survey post for Cefn Llwydallt


There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to a hill that is listed in the Y Trichant, with the following details being retrospective as the survey that resulted in this height revision was conducted on the 29^th September 2015.  The Y Trichant comprises all Welsh hills at and above 300m and below 400m in height that have 30m minimum drop, with the Introduction to this list and its re-naming being published on Mapping Mountains.

The name of the hill is Cefn Llwydallt and it is situated in the south-eastern lands of Mynydd Epynt, and is positioned above the small communities of Erwyd (Erwood) to the north-east, Capel Uchaf (Upper Chapel) to the west and Llaneglwys to the south-west.

Access to the hill is relatively easy as the summit is situated on open access land and there is a minor road to the north-west next to where the bwlch of the hill is positioned.  Alternate routes to the summit can use public footpaths from the north-east, east and south that head toward the open access land, with the summit of the hill positioned amongst small gorse bushes.

The hill was surveyed in the afternoon toward the end of a ridge walk that took in a number of hills from Cefn Clawdd (SO 043 403) heading eastward, and prior to the survey with the Trimble GeoXH 6000 the hill was listed as being 378m high based on the old 1,240ft (378.0m) imperial height given the hill on the Ordnance Survey Six-Inch map.

The survey result for the summit produced by the Trimble GeoXH 6000 is 380.7m (converted to OSGM15).  This is not a dramatic height revision when compared to its old listed height, but it does come within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revision applies to any listed hill whose Ordnance Survey summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000, also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 map is being prioritised for detailing these revisions.

Therefore this hill’s new summit height is 380.7m (converted to OSGM15) which is 2.7m higher than the previously listed height of 378m which was based on the old imperial 1,240ft height taken from the Ordnance Survey Six-Inch map.

The full details for the hill are:

Cardinal Hill:  Clepyn Melyn

Summit Height (New Height):  380.7m (converted to OSGM15)

Name:  Cefn Llwydallt

OS 1:50,000 map:  147, 160

Summit Grid Reference:  SO 07422 40950 

Drop:  41.0m (converted to OSGM15)

Gathering data from the summit of Cefn Llwydallt which resulted in this hill's significant height revision

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (October 2015)

Mapping Mountains - Significant Height Revisions - Y Trichant

Coed y Gaer (SO 004 843) - 2nd significant height revision

Survey post for Coed y Gaer

Subsequent LIDAR analysis negates the need for this Significant Height Revision post.  However, it is being kept with the results from LIDAR analysis prioritised in preference to those from the Trimle GeoXH 6000 survey. 

There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to the listing of Y Trichant - The 300m Hills of Wales and Y Trechol - The Dominant Hills of Wales, with the following details being retrospective as the survey that resulted in this height revision was conducted on 9^th February 2014.  The hill is listed as a Lesser Dominant as well as a Trichant, with the latter being the 300m height band of Twmpau (thirty welsh metre prominences and upward) hills.

The criteria for the two listings that this height revision affects are:

Y Trichant - The 300m Hills of Wales - these are the Welsh hills at or above 300m and below 400m in height that have a minimum drop of 30m. 

Y Trechol - The Dominant Hills of Wales - these are the Welsh P30 hills whose prominence  equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those addition Welsh P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The name the hill is listed y is Coed y Gaer and it is situated in the Hirddywel range of hills to the east of Llanidloes, and the survey was conducted in the company of Mark Trengove on a particularly wet and cold day.  The hill can be accessed from a minor lane to the south of its summit; and it overlooks the A470 and the Afon Hafren (River Severn) which are to its north-west.

The height given the hill on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map is 362m, with the height resulting from the survey with the Trimble being 359.9m (converted to OSGM15).  This is not a dramatic height revision but it does come within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revision applies to any listed hill whose Ordnance Survey summit spot height has a 2m or more discrepancy when compared to the surveyed height produced by the Trimble GeoXH 6000, also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 map is being prioritised for detailing these revisions.

LIDAR image of Coed y Gaer (SO 004 843)

The full details for the hill are:

Cardinal Hill:  Pegwn Mawr

Summit Height (New Height):  361.0m (LIDAR)

Name:  Coed y Gaer

OS 1:50,000 map:  136

Summit Grid Reference:  SO 00491 84393 (LIDAR)

  

Drop:  121.5m (LIDAR)

Dominance:  33.65% (LIDAR)

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (August 2015)

Mapping Mountains - Significant Height Revisions - Y Trichant

Old Radnor Hill (SO 251 587) - 1st significant height revision

Survey post for Old Radnor Hill


There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to the listing of the Y Trichant, with the following details being retrospective as the survey that resulted in this height revision was conducted on 11^th January 2014.

The name of the hill is Old Radnor Hill and it is situated in the southern part of the Fforest Glud range of hills, which is known in English as the Radnor Forest, this range of hills is in the heartland of mid Wales and the survey was conducted on a fine and bright winter’s day.

The hill is listed in the Y Trichant, these are the hills in the 300m height band of the Twmpau  (thirty welsh metre prominences and upward) and it is situated south-east of Maesyfed (New Radnor), with the nearest major road being the A44 which skirts the hill on its northern and eastern side.  The A44 road to the east of this hill comprises a road cutting which would significantly increase this hill’s drop value if the natural bwlch is considered to no longer exist and if the nearest point to it is not taken as that for the drop value of the hill.

The summit height of Old Radnor Hill has been dramatically decreased over time due to it being quarried.  However, prior to the survey with the Trimble GeoXH 6000 its listed height was an estimated c 317m based on the uppermost contour on the Ordnance Survey enlarged mapping hosted on the Geograph website showing part of a 315m contour ring.

This hill's new summit height is 312.6m, which is 4.6m lower than its previously estimated listed height and 2.4m lower than the 315m uppermost ring contour on the Ordnance Survey enlarged mapping on the Geograph website.

The full details for the hill are:

Cardinal Hill:  Gwaun Ceste

Summit Height (New Height):  312.6m (converted to OSGM15)

Name:  Old Radnor Hill

OS 1:50,000 map:  148

Summit Grid Reference:  SO 25135 58770

  

Drop:  89.9m (Trimble summit and LIDAR bwlch)

The quarried remains of Old Radnor Hill

For details on the survey that significantly revised the summit height of this hill

Myrddyn Phillips (August 2015)