Friday, 17 January 2025

Mapping Mountains – Hill Reclassifications – 100m Twmpau


Close (SJ 094 090) – 100m Twmpau reclassified to 100m Sub-Twmpau

There has been a reclassification to the list of 100m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Close (SJ 094 090)

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

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

100m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Close, and this was derived from the Tithe map, and it is adjoined to the Esgeiriau Gwynion group of hills, which are situated in the southern part of North Wales (Region A, Sub-Region A3), and it is positioned with minor roads to its north, west and north-east, and the A495 road to its south-east, and has the town of Llanfair Caereinion towards the south south-east.

When the original 100m 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.

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-assessed and it was listed with an estimated c 36m of drop, based on the 199m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 163m bwlch height, based on interpolation of 5m contouring between 160m – 165m. 

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 reclassification of this hill to 100m Sub-Twmpau status is due to LIDAR analysis, resulting in a 197.4m summit height and a 168.6m bwlch height, with these values giving this hill 28.8m of drop, which is insufficient for it to be classified as a 100m Twmpau. 

 

The full details for the hill are: 

Group:  Esgeiriau Gwynion 

Name:  Close 

OS 1:50,000 map:  125

Summit Height:  197.4m (LIDAR) 

Summit Grid Reference:  SJ 09460 09012 (LIDAR) 

Bwlch Height:  168.6m (LIDAR) 

Bwlch Grid Reference:  SJ 08798 09899 & SJ 08797 09900 (LIDAR) 

Drop:  28.8m (LIDAR) 

 

Myrddyn Phillips (January 2025)

 

 

 

 

 

  

Thursday, 16 January 2025

Mapping Mountains – Significant Name Changes – Y Trichant – The 300m Hills of Wales

 

Crugyn (SN 993 755) 

There has been a Significant Name Change 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 Crugyn (SN 993 755)

The criteria for the list that this name change 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, and the Introduction to the Mapping Mountains publication of the list appearing on the 1st January 2022. 

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

The hill is adjoined to the Hirddywel group of hills, which are situated in the northern part of South Wales (Region B, Sub-Region B2), and it is positioned with minor roads to its north and south, and the B4518 road to its west, and has the town of Llanidloes towards the north north-west.

The hill appeared in the original 300m height band of Welsh P30 hills published on Geoff Crowder’s v-g.me website, under the transposed name of The Garth, with an accompanying note stating; Name from buildings to the West.


The Garth350cSN994756136/147214Name from buildings to the West


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

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

Since the original publication of the Welsh P30 lists on Geoff Crowder’s v-g.me website there have been a number of 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 were 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, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites, and it is the series of Ordnance Survey Six-Inch maps that form the basis of the change in the listed name of this hill.

The Ordnance Survey series of Six-Inch maps formed the base map Ordnance Survey used for many decades leading to the production of the 1:10,000 Series of maps, both have now been superseded by the digitised Master Map.  The series of Six-Inch maps are excellent for name placement and especially so compared to the contemporary Ordnance Survey 1:25,000 Explorer map, and it is the series of Six-Inch maps that uses the name of Crugyn for the summit of this hill.

Extract from the Ordnance Survey series of Six-Inch maps

Therefore, the name this hill is now listed by in the Y Trichant – The 300m Hills of Wales is Crugyn and this was derived from the Ordnance Survey series of Six-Inch maps. 

 

The full details for the hill are: 

Group:  Hirddywel 

Name:  Crugyn 

Previously Listed Name:  The Garth 

OS 1:50,000 map:  136, 147

Summit Height:  351.5m (LIDAR)                                                           

Summit Grid Reference:  SN 99332 75553 (LIDAR) 

Bwlch Height:  328.0m (LIDAR) 

Bwlch Grid Reference:  SN 99476 75955 (LIDAR) 

Drop:  23.4m (LIDAR) 

 

Myrddyn Phillips (January 2025)

 

Wednesday, 15 January 2025

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

 

Pt. 430.6m (NY 314 101) – 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 Pt. 430.6m (NY 314 101)

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

The FoursThe 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 hill is listed by the point (Pt. 430.6m) notation, and it is adjoined to the High Raise group of hills, which are situated in the English Lake District, and it is positioned with the B5343 road to its south and the A591 road to its east, and has the village of Grasmere towards the south-east.

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 10th 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 not listed, with subsequent interpolation giving it an estimated c 13m of drop, based on an estimated c 431m summit height and an estimated c 418m col height, with both heights 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.

Therefore, the addition of this hill to Sub-Four status is due to LIDAR analysis, resulting in a 430.6m summit height and a 415.1m col height, with these values giving this hill 15.5m of drop, which is sufficient for it to be classified as a Sub-Four.

 

The full details for the hill are:

Group:  High Raise

Name:  Pt. 430.6m

OS 1:50,000 map:  90

Summit Height:  430.6m (LIDAR)

Summit Grid Reference:  NY 31454 10181 (LIDAR)

Col Height:  415.1m (LIDAR)

Col Grid Reference:  NY 31376 10238 (LIDAR)

Drop:  15.5m (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 1st edition of this list by Europeaklist please consult the following Change Registers:

 

The Fours

 

Sub-Fours

 

Myrddyn Phillips and Aled Williams (January 2025)

  

Tuesday, 14 January 2025

Mapping Mountains – Summit Relocations – 200m Twmpau


Erw Hir (SJ 102 076) 

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

LIDAR image of Erw Hir (SJ 102 076)

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

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

200m Twmpau by Myrddyn Phillips

The name the hill is now listed by is Erw Hir, and this was derived from the Tithe map, and it is adjoined to the Esgeiriau Gwynion group of hills, which are situated in the southern part of North Wales (Region A, Sub-Region A3), and it is positioned with a minor road to its north and east, the A495 road to its north-west and the A458 road to its south, and has the town of Llanfair Caereinion towards the south.

When the original 200m 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 233m summit height, based on the spot height that appears on the contemporary Ordnance Survey 1:25,000 Explorer map.

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 72m of drop, based on the 233m summit spot height positioned at SJ 10300 07633 and an estimated c 161m bwlch height, based on interpolation of 5m contouring between 160m - 165m.  The drop value of this hill has subsequently reduced due to a bwlch swap with Cae TÅ· Cefn Ysgubor (SJ 111 080). 

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

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

LIDAR analysis gives the highest ground on this hill as 231.4m positioned at SJ 10294 07618.  However, this is a part of a raised field boundary and protocols dictate that as this is deemed a relatively recent man-made construct such ground is discounted from the height of a hill. 

LIDAR summit image of Erw Hir (SJ 102 076)

The height produced by LIDAR analysis to the natural summit of this hill is 231.3m and this is positioned at SJ 10280 07620, and this comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

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

Therefore, the summit height produced by LIDAR analysis is 231.3m and this is positioned at SJ 10280 07620, this position is relatively close to where the spot height appears on the Ordnance Survey 1:25,000 Explorer map, and is approximately 14 metres westward from the high point of the raised field boundary. 

 

The full details for the hill are: 

Group:  Esgeiriau Gwynion 

Name:  Erw Hir 

OS 1:50,000 map:  125

Summit Height:  231.3m (LIDAR) 

Summit Grid Reference (New Position):  SJ 10280 07620 (LIDAR) 

Bwlch Height:  197.0m (LIDAR) 

Bwlch Grid Reference:  SJ 10681 08135 (LIDAR) 

Drop:  34.3m (LIDAR) 

 

Myrddyn Phillips (January 2025)

 

 

 

  

Monday, 13 January 2025

Mapping Mountains – Significant Height Revisions – The Welsh P15s

 

Pt. 83.1m (SN 539 026) 

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 Pt. 83.1m (SN 539 026) 

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 10th May 2019. 

The Welsh P15s by Myrddyn Phillips

The hill is being listed by the point (Pt. 83.1m) notation, and it is adjoined to the Mynydd Sylen group of hills, which are situated in the southern part of South Wales (Region B, Sub-Region B5), and it is positioned with the A476 road to its north-west and minor roads to its immediate south and east, and has the town of Llanelli towards the south-west.

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 86m summit height derived from interpolation of the uppermost 85m ring contour that appears on the Ordnance Survey 1:25,000 Explorer map, and the 72m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

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

LIDAR summit image of Pt. 83.1m (SN 539 026)

The summit height produced by LIDAR analysis is 83.1m 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 83.1m and this was derived from LIDAR analysis.  This is 2.9m lower than the estimated c 86m summit height previously lsited and which was derived from interpolation of the uppermost 85m ring contour that appears on the Ordnance Survey 1:25,000 Explorer map. 

 ills of Wales, and are reproduced below@

The full details for the hill are: 

Group:  Mynydd Sylen 

Name:  Pt. 83.1m 

OS 1:50,000 map:  159

Summit Height (New Height):  83.1m (LIDAR)                                                           

Summit Grid Reference:  SN 53910 02627 (LIDAR)                                                  

Bwlch Height:  70.6m (LIDAR) 

Bwlch Grid Reference:  SN 54258 03092 (LIDAR) 

Drop:  12.6m (LIDAR) 

 

Myrddyn Phillips (January 2025)