Mapping Mountains – Significant Height Revisions – 30-99m Twmpau

 

Coed y Fedw (SN 677 947) 

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

LIDAR image of Coed y Fedw (SN 677 947)

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

30-99m Twmpau – Welsh hills at or above 30m and below 100m in height that have 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

30-99m Twmpau by Myrddyn Phillips

The name the hill is listed by is Coed y Fedw, and it is adjoined to the Banc Llechwedd Mawr group of hills, which are situated in the northern part of South Wales (Region B, Sub-Region B1), and it is positioned with the A487 road to its south-east, and has the small community of Ffwrnais (Furnace) towards the east north-east.

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

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 22m of drop, based on an estimated c 46m summit height and an estimated c 24m bwlch height, with both heights based on interpolation of 10m 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 Coed y Fedw (SN 677 947)

The summit height produced by LIDAR analysis is 49.6m and is positioned at SN 67780 94773, 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 49.6m and this was derived from LIDAR analysis, this is 3.6m higher than the previously listed summit height of c 46m, which was based on interpolation of its uppermost 40m 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:  Banc Llechwedd Mawr 

Name:  Coed y Fedw 

OS 1:50,000 map:  135

Summit Height (New Height):  49.6m (LIDAR) 

Summit Grid Reference:  SN 67780 94773 (LIDAR)               

Bwlch Height:  22.1m (LIDAR) 

Bwlch Grid Reference:  SN 67635 94495 (LIDAR) 

Drop:  27.5m (LIDAR) 

               

Myrddyn Phillips (November 2024)

 

 

 

 

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Coed y Fedw (SN 677 947) – 30-99m Sub-Twmpau addition 

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

LIDAR image of Coed y Fedw (SN 677 947)

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

30-99m Twmpau – Welsh hills at or above 30m and below 100m in height that have 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

30-99m Twmpau by Myrddyn Phillips

The name the hill is listed by is Coed y Fedw, and it is adjoined to the Banc Llechwedd Mawr group of hills, which are situated in the northern part of South Wales (Region B, Sub-Region B1), and it is positioned with the A487 road to its south-east, and has the small community of Ffwrnais (Furnace) towards the east north-east.

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

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 22m of drop, based on an estimated c 46m summit height and an estimated c 24m bwlch height, with both heights based on interpolation of 10m 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.

Therefore, the confirmation of the addition of this hill to 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 49.6m summit height and a 22.1m bwlch height, with these values giving this hill 27.5m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Banc Llechwedd Mawr 

Name:  Coed y Fedw 

OS 1:50,000 map:  135

Summit Height:  49.6m (LIDAR) 

Summit Grid Reference:  SN 67780 94773 (LIDAR)               

Bwlch Height:  22.1m (LIDAR) 

Bwlch Grid Reference:  SN 67635 94495 (LIDAR) 

Drop:  27.5m (LIDAR) 

 

Myrddyn Phillips (November 2024)

  

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

Coed y Fedw (SJ 201 613)

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 detail on contemporary maps produced from Ordnance Survey data.

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 Mountainson the 13th May 2017.

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

The hill 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-west and minor roads to its south and east, and has the village of Gwernymynydd 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 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, and the lists updated, this hill was listed with an estimated c 24m of drop based on an estimated c 317m summit height and an estimated c 293m bwlch height, and it was subsequently listed under the point (Pt. c 317m) notation.

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 318m summit spot height.

Extract from the WalkLakes website

The details for this hill were also re-assessed against 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 resulted in its bwlch height being listed as c 294m based on interpolation of 5m contouring between 290m – 295m.

These re-assessments resulted in the 318m spot height on the WalkLakes website taken as that for the summit, and as this mapping indicates this position to be in woodland adjoined to the larger Coed y Fedw it is appropriate to use this name for listing purposes.

Therefore, the name this hill is now listed by in the Y Trichant – The 300m Hills of Wales is Coed y Fedw, and this was derived from the Ordnance Survey 1:25,000 Explorer map and the mapping on the WalkLakes website.

The full details for the hill are:

Group:  Moel y Gamelin

Name:  Coed y Fedw

Previously Listed Name:  Pt. c 317m

OS 1:50,000 map:  117

Summit Height:  318m (spot height)

                                                           

Summit Grid Reference:  SJ 20180 61372 (spot height)

Bwlch Height:  c 294m (interpolation)

Bwlch Grid Reference:  SJ 20367 61266 (interpolation)

Drop:  c 24m (spot height summit and interpolated bwlch)

Myrddyn Phillips (October 2020)

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

Coed y Fedw (SJ 201 613) – Sub-Trichant addition

There has been an addition to the list of Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on contemporary maps produced from Ordnance Survey data.

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

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

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

The name the hill is listed by is Coed y Fedw, 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-west and minor roads to its south and east, and has the village of Gwernymynydd towards the 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 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, and the lists updated, this hill was listed with an estimated c 24m of drop based on an estimated c 317m summit height and an estimated c 293m bwlch height based on interpolated detail from the Ordnance Survey 1:25,000 Explorer map.

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 318m summit spot height.

Extract from the WalkLakes website

The details for this hill were also re-assessed against 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 resulted in its bwlch height being listed as c 294m based on interpolation of 5m contouring between 290m – 295m.

Therefore, the addition of this hill to Sub-Trichant status is due to detail on contemporary maps produced from Ordnance Survey data, resulting in a 318m summit height and a c 294m bwlch height, with these values giving this hill c 24m of drop, which is sufficient for it to be classified as a Sub-Trichant.

The full details for the hill are:

Group:  Moel y Gamelin

Name:  Coed y Fedw

OS 1:50,000 map:  117

Summit Height:  318m (spot height)

Summit Grid Reference:  SJ 20180 61372 (spot height)

Bwlch Height:  c 294m (interpolation)

Bwlch Grid Reference:  SJ 20367 61266 (interpolation)

Drop:  c 24m (spot height summit and interpolated bwlch)

Myrddyn Phillips (October 2020)