Mapping Mountains – Summit Relocations – Y Trichant – The 300m Hills of Wales

 

Gorn Hill (SN 968 844) 

There has been a Summit Relocation 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 Gorn Hill (SN 968 844)

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

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

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

The name the hill is listed by is Gorn Hill, and it is adjoined to the Hirddywel group of hills, which are situated in the northern part of South Wales (Region B, Sub-Region B2), and it is positioned with the A470 road to its north and a minor road to its south, and has the town of Llanidloes 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 main P30 list with a 326m summit height, based on the spot height positioned at SN 96892 84574 that appears on the contemporary 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 Gorn Hill (SN 968 844)

LIDAR analysis gives the highest ground on this hill as 326.4m positioned at SN 96895 84496, and this in relation to the previously listed summit position which LIDAR analysis gives as 326.1m in height and positioned at SN 96896 84576 and SN 96896 84575 and SN 96898 84575 comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

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

Extract from the DataMapWales interactive mapping

Therefore, the summit height produced by LIDAR analysis is 326.4m and this is positioned at SN 96895 84496, this position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and is approximately 78 metres southward from where the previously listed summit and the spot height is positioned and importantly the new summit position is placed in a different contour on the DataMapWales interactive mapping. 

 

The full details for the hill are:

Group:  Hirddywel 

Name:  Gorn Hill 

OS 1:50,000 map:  136

Summit Height:  326.4m (LIDAR)                                                           

Summit Grid Reference (New Position):  SN 96895 84496 (LIDAR) 

Bwlch Height:  278.1m (LIDAR) 

Bwlch Grid Reference:  SN 97747 83851 & SN 97747 83848 (LIDAR) 

Drop:  48.3m (LIDAR) 

 

Myrddyn Phillips (November 2024)

 

Mapping Mountains – Significant Height Revisions – Welsh Highlands – Uchafion Cymru

Pt. 914.9m (SH 659 585) 

There has been a Significant Height Revision to a hill that is listed in the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Trimble GeoXH 6000 survey conducted by Aled Williams. 

Pt. 914.9m (SH 659 585).  Photo: Aled Williams

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

Welsh Highlands – Uchafion Cymru – Welsh hills at or above 500m in height with 15m minimum drop, with an accompanying sub list entitled the Welsh Highland Subs, the criteria for which is all Welsh hills at or above 500m in height with 10m or more and below 15m of drop.  This list is authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and the latest update relating to the list published on Mapping Mountains in January 2023.

Welsh Highlands - Uchafion Cymru by Aled Williams and Myrddyn Phillips

The hill is being listed by the point (Pt. 914.9m) notation, and it is adjoined to the Glyder Fawr group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with the A5 road to its north and the A4086 road to its south, and has the village of Capel Curig towards the east.

When the initial P10 sub list was completed in June 2020 this hill was listed with 9.4m of drop, based on a 31ft basic levelling survey conducted by Myrddyn Phillips on the 02.05.99.  However, with no significant independent contour of note on the contemporary Ordnance Survey 1:25,000 Explorer map it was difficult to give this hill an accurate summit height. 

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

The hill was subsequently analysed via LIDAR by Aled Williams, resulting in a 913.9m summit height and a 905.1m bwlch height, with these values giving this hill 8.8m of drop, which was insufficient for it to be classified as a Welsh Highland Sub.  However, with the drop value relatively close to the qualifying criterion of 10m this hill was prioritised for a survey with the Trimble GeoXH 6000. 

The Trimble GeoXH 6000 gathering data at the summit of Pt. 914.9m (SH 659 585).  Photo: Aled Williams

The Trimble GeoXH 6000 survey gives the summit of this hill as 914.9m positioned at SH 65981 58563, and this comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

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

Therefore, the new listed summit height of this hill is 914.9m and this was derived from a Trimble GeoXH 6000 survey, this is 14.9m higher than the uppermost 900m contour that appears on the contemporary Ordnance Survey 1:25,000 Explorer map.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Glyder Fawr

Name:  Pt. 914.9m           

OS 1:50,000 map:  115

Summit Height (New Height):  914.9m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 65981 58563 (Trimble GeoXH 6000)

Bwlch Height:  904.4m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SH 65982 58556 (Trimble GeoXH 6000)   

Drop:  10.5m (Trimble GeoXH 6000) 

 

Aled Williams and Myrddyn Phillips (November 2024)

 

  

Mapping Mountains – Hill Reclassifications – The Fours – The 400m Hills of England

 

Stile Crag (NY 761 986) – Sub-Four addition

There has been an addition to the listing of the The Fours – The 400m Hills of England, with the summit height, col height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Stile Crag (NY 761 986)

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

The Fours – The 400m Hills of England - English hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main list is a sub list entitled the Sub-Fours, the criteria for which are all English hills at or above 400m and below 500m in height that have 15m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available to download in Google Doc format from the Mapping Mountains site.

The Fours - The 400m Hills of England by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Stile Crag, and it is adjoined to the Peel Fell group of hills, which are situated in the north-east of the country close to the border with Scotland, and it is positioned with the A68 road to its north-east, and has the village of Byrness towards the north.

When the Introduction to the first group of hills for the updated and revised listing of the The Fours – The 400m Hills of England was published by Mapping Mountains on the 10^th September 2022, it was announced that the accompanying sub lists were being revised with the two 390m categories dispensed with and the criteria and name of the 400m Sub-Fours revised.  The one accompanying sub list is now named the Sub-Fours with its criteria being all English hills 400m and above and below 500m in height that have 15m and more and below 30m of drop.

Prior to this revision this hill was listed with 14m of drop, based on the 430m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and the 416m col spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

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

Therefore, the confirmation of the addition of this hill to Sub-Four status is due to LIDAR analysis, resulting in a 428.7m summit height and a 413.5m col height, with these values giving this hill 15.2m of drop, which is sufficient for it to be classified as a Sub-Four.

 

The full details for the hill are:

Group:  Peel Fell

Name:  Stile Crag

OS 1:50,000 map:  80

Summit Height:  428.7m (LIDAR)

Summit Grid Reference:  NY 76126 98692 (LIDAR)

Col Height:  413.5m (LIDAR)

Col Grid Reference:  NY 75900 97897 (LIDAR)

Drop:  15.2m (LIDAR)

 

For the additions, deletions and reclassifications to The Fours – The 400m Hills of England reported on Mapping Mountains since the December 2013 publication of the 1^st edition of this list by Europeaklist please consult the following Change Registers:

 

The Fours

 

Sub-Fours

 

Myrddyn Phillips and Aled Williams (November 2024)

Mapping Mountains – Hill Reclassifications – 200m Twmpau

Cae Cownog (SJ 111 135 & SJ 112 135) – 200m Sub-Twmpau addition 

There has been confirmation of an addition to the list of 200m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Cae Cownog (SJ 111 135 & SJ 112 135)

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

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

200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Cae Cownog and this was derived from the Tithe map, and it is adjoined to the Foel Cedig group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A3), and it is positioned encircled by minor roads, with the B4393 road farther to its north, the B4382 road farther to its south-west and the A495 road farther to its south-east, and has the village of Meifod towards the east.

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

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with 21m of drop, based on the 212m summit spot height that appears on the contemporary Ordnance Survey 1:25,000 Explorer map and the 191m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

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

Therefore, the confirmation of the addition of this hill to 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 212.5m summit height and a 191.0m bwlch height, with these values giving this hill 21.6m of drop, which is sufficient for it to be classified as a 200m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Foel Cedig 

Name:  Cae Cownog 

OS 1:50,000 map:  125

Summit Height:  212.5m (LIDAR) 

Summit Grid Reference:  SJ 11199 13511 & SJ 11200 13515 (LIDAR) 

Bwlch Height:  191.0m (LIDAR) 

Bwlch Grid Reference:  SJ 11120 13695 (LIDAR) 

Drop:  21.6m (LIDAR) 

 

Myrddyn Phillips (November 2024)

 

 

 

  

Mapping Mountains – Significant Height Revisions – The Welsh P15s

Y Faerdre (SH 784 795) 

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

LIDAR image of Y Faerdre (SH 784 795)

The criteria for the list that this hill used to be included in are:

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

The Welsh P15s by Myrddyn Phillips

The name the hill is now listed by is Y Faerdre and this was derived from the Tithe map, and it is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned with the A546 road to its west and the B5115 road and the A470 road to its east, and has the town of Llandudno towards the south-east.

When the listing that became known as The Welsh P15s was being compiled, this hill was included in the P14 sub list with an estimated c 14m of drop, based on an estimated c 97m summit height and an estimated c 83m bwlch height, with both heights based on interpolation of 5m contouring. 

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

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

LIDAR summit image of Y Faerdre (SH 784 795)

The summit height produced by LIDAR analysis is 93.2m and when compared to the originally listed summit height this comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

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

Therefore, the new listed summit height of this hill is 93.2m and this was derived from LIDAR analysis.  This is 3.8m lower than the estimated c 97m summit height previously lsited and which was derived from interpolation of the uppermost 95m contour ring that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

 ills of Wales, and are reproduced below@

The full details for the hill are: 

Group:  Mynydd Hiraethog 

Name:  Y Faerdre 

OS 1:50,000 map:  115

Summit Height (New Height):  93.2m (LIDAR)                                                           

Summit Grid Reference:  SH 78472 79515 (LIDAR)                                                  

Bwlch Height:  81.1m (LIDAR) 

Bwlch Grid Reference:  SH 78520 79419 (LIDAR) 

Drop:  12.2m (LIDAR) 

 

Myrddyn Phillips (November 2024)