Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

 

Box Cemetery (SN 520 009) – 30-99m Sub-Twmpau addition 

There has been 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 Box Cemetery (SN 520 009)

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, 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 now listed by is Box Cemetery and this was derived from online sources, 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 a minor road to its north-east, the A476 road to its north-west, a minor road and the A484 road to its south-west and the A4138 road to its east, and has the town of Llanelli surrounding it.

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 19m of drop, based on the 48m summit spot height that apperas on the Ordnance Survey 1:25,000 Explorer map and the 29m 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 addition of this hill to 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 48.5m summit height and a 27.1m bwlch height, with these values giving this hill 21.4m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Mynydd Sylen 

Name:  Box Cemetery 

OS 1:50,000 map:  159

Summit Height:  48.5m (LIDAR) 

Summit Grid Reference:  SN 52024 00937 & SN 52025 00938 & SN 52028 00939 & SN 52030 00937 (LIDAR)     

Bwlch Height:  27.1m (LIDAR) 

Bwlch Grid Reference:  SN 52103 01769 (LIDAR) 

Drop:  21.4m (LIDAR) 

 

Myrddyn Phillips (September 2024)

 

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

 

Mynydd Morfil (SN 040 313) – Sub-Trichant addition

There has been confirmation of 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 LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Mynydd Morfil (SN 040 313)

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 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 Mynydd Morfil, and it is adjoined to the Mynydd Preseli group of hills, which are situated in the south-western part of South Wales (Region B, Sub-Region B1), and it is positioned with the B4313 road to its north and a minor road to its south-west, and has the town of Abergwaun (Fishguard) 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, 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 23m of drop, based on an estimated c 301m summit height and an estimated c 278m bwlch height, with both heights based on interpolation of 5m 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 confirmation of the addition of this hill to Sub-Trichant status is due to LIDAR analysis, resulting in a 300.4m summit height and a 278.1m bwlch height, with these values giving this hill 22.2m of drop, which is sufficient for it to be classified as a Sub-Trichant. 

 

The full details for the hill are: 

Group:  Mynydd Preseli 

Name:  Mynydd M0rfil 

OS 1:50,000 map:  145

Summit Height:  300.4m (LIDAR)                                                           

Summit Grid Reference:  SN 04057 31302 (LIDAR) 

Bwlch Height:  278.1m (LIDAR) 

Bwlch Grid Reference:  SN 04718 31316 & SN 04723 31318 (LIDAR) 

Drop:  22.1m (LIDAR) 

 

Myrddyn Phillips (September 2024)

 

 

 

 

 

Terms applied to Hill Status alteration

 

Terms applied to Hill Status alteration

Introduction: 

For many years I considered there were only three terms applicable to status change within an objective hill list.  With a fourth term a subsidiary of one of the three.  These are detailed below: 

Addition:  When a hill not in the list is added to it. 

Reclassification:  When a hill that is already in the list changes status.  As in, from the main list to the accompanying sub list or vice versa. 

Deletion:  When a hill in the list is deleted from it. 

Reinstatement:  When a hill previously in a list that was deleted from it, is reinstated to it.  Although this term is a subsidiary of an Addition, it can also be considered a separate term. 

However, not all status alteration is covered by the four terms outlined above. 

 

Explanation: 

When compiling The Welsh P15s I considered taking the accompanying sub list down to P10.  However, such a task would add a number of years to what was already a huge undertaking that eventually took eight years to complete.  Because of this I decided to opt for a P14 sub list.  This would at least capture many hills that stood a chance of P15 qualification after more detailed scrutiny such as using a GNSS receiver or LIDAR analysis. 

When updating the numerical details in the The Fours – The 400m Hills of England list for December 2013 Europeaklist publication, I decided to use the same listing method as The Welsh P15s and list the English 400m hills down to P14.  This was a fail safe to hopefully capture all the P20 subs that then accompanied the main list.  This has served us well as we recently revised the Sub-Fours to also include P15s. 

When updating the English 400m list for July 2024 publication on Mapping Mountains, all of these hills including those listed as P14s were analysed via LIDAR.  By doing so a number of hills that were listed with 15m or more and below 20m of drop and therefore would meet the newly revised P15 Sub-Four status were found to have less than the minimum 15m of drop required.  In affect, once the Sub-Four category was revised and prior to LIDAR analysis these hills were Sub-Fours in all but publication and then found not to meet the criteria for this sub category.  I did consider they could be deemed as deletions, but as they were never officially listed as Sub-Fours, they did not meet this description.  Therefore, these hills were not additions, reclassifications nor deletions. 

But if not deletions, what were they? 

A little thought came up with the term of exclusions. 

This term fitted perfectly with what had happened to these hills, as when originally listed they met the criteria which would be later used for Sub-Four status.  However, when updating using a more accurate listing method; in this case LIDAR analysis, they were found not to meet the minimum drop criterion.  Therefore, they were once considered part of the revised list but never officially published as such and having been LIDARed now excluded. 

The important factor at play in this scenario is that these hills were never officially listed as Sub-Fours, so they cannot be considered deletions, as this phrase implies that they were once officially part of the published list. 

The above scenario details the fifth tenet of terms applicable to hill status alteration; Exclusion. 

However, there is a sixth term; Rejection. 

The term Rejection applies to hills listed by previous hill list compilers which have been rejected by the respective current author, with each using the same criteria for qualification.  The important factor in this scenario is that these hills were never listed by the current author, who upon analysis of a previous list rejected them based on using the same qualififying criteria. 

Therefore, the six terms applicable to status alteration are: 

 

The Six Terms: 

Addition:  When a hill not in the list is added to it. 

Reclassification:  When a hill that is already in the list changes status.  As in, from the main list to the accompanying sub list or vice versa. 

Deletion:  When a hill in the list is deleted from it. 

Reinstatement:  When a hill previously in a list that was deleted from it, is reinstated to it.  Although this term is a subsidiary of an Addition, it can also be considered a separate term. 

Exclusion:  Specific to hills originated by the list author that met criteria for a revised list but never officially published that are now excluded. 

Rejection:  Specific to hills not originated by the list author and included in previous listings and rejected by current authors and which are based on the same criteria.  Also included are previously unlisted hills proposed as possible inclusions, which are later rejected and their details then documented.

 

Myrddyn Phillips (September 2024) 

 

My thanks for comments and input on the Tump forum from:

Jez Turner and Henry Marston; the former’s comments made me consider that the term Exclusion did not take in all similar examples; and this resulted in the term; Rejection.

Alan Dawson and Rob Woodall; the former’s comments resulted in the inclusion of the term; Reinstatement as one of the four originating terms, and the latter’s comments resulted in the term Rejection also taking in previously unlisted hills.

Mapping Mountains – Summit Relocations – 900m Twmpau

 

900m Twmpau – Summit Relocations

The 900m Twmpau (thirty welsh metre prominences and upward) are the Welsh hills at or above 900m and below 1000m in height that have a minimum drop of 30m.  Accompanying the main P30 list is a theoretical sub list entitled the 900m Sub-Twmpau with the qualification to this sub category being all Welsh hills at or above 900m and below 1000m in height with 20m or more and below 30m of drop.

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

Mapping Mountains - Summit Relocations - 900m Twmpau

Foel Fras (SH 696 681) - 1st summit relocation

Significant Height Revisions post for Foel Fras

There has been a Summit Relocation to a hill that is listed in the Y Pellennig – The Remotest Hills of Wales, Welsh Highlands – Uchafion Cymru and 900m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Leica RX1250 survey conducted by Alan Dawson. 

Foel Fras (SH 696 681) from the summit of Trwsgl (SH 663 679)

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

Y Pellennig –The Remotest Hills of Wales - Welsh hills whose summit is at least 2.5km from the nearest paved public road and the hill has a minimum 15m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available as a downloadable e-booklet or print-booklet version on Mapping Mountains Publications with the up-to-date master list available on Mapping Mountains to download in Google Doc format. 

Y Pellennig - The Remotest Hills of Wales by Myrddyn Phillips and Aled Williams

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

900m Twmpau - Welsh hills at or above 900m and below 1000m in height with 30m minimum drop, with an accompanying sub list entitled the 900m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 900m and below 1000m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips and is available to download in Google Doc format from Mapping Mountains.

900m Twmpau by Myrddyn Phillips

The name the hill is listed by is Foel Fras and it is adjoined to the Carnedd Llywelyn 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, the A5 road to its south-west and the B5106 and A470 roads to its east, and has the town of Bethesda towards the west south-west. 

When the original list that later became known as the Welsh Highlands – Uchafion Cymru was first compiled, this hill was listed with 58m of drop, based on the 942m summit spot height adjoined to a triangulation pillar positioned at SH 69652 68173 that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and the 884m bwlch spot height that appears on the Ordnance Survey 1:25,000 Explorer map.

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

However, the summit area of this hill is rocky and includes a number of substantial upright rock spikes.  One of the earliest Abney Level surveys to ascertain the high point of this hill was conducted in 2011 by Graham Jackson.  This survey concluded that a rock spike approximately 55 metres south-wesward of the trig pillar is the highest point of this hill. 

This rock spike was subsequently surveyed by Alan Dawson using the Leica RX1250, resulting in a 944.1m summit height positioned at SH 69611 68118, 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, 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.

The Leica RX1250 gathering data at the summit of Foel Fras (SH 696 681).  Photo: Alan Dawson  

Therefore, the new listed summit height of this hill is 944.1m and this is positioned at SH 69611 68118 and this was derived from a Leica RX1250 survey, this position is approximately 55 metres south-westward from where the triangulation pillar is positioned and importantly it is positioned to a different feature.

 

The full details for the hill are:

Group:  Carnedd Llywelyn

Name:  Foel Fras

OS 1:50,000 map:  115

Summit Height:  944.1m (converted to OSGM15, Leica RX1250) 

Summit Grid Reference (New Position):  SH 69611 68118 (Leica RX1250) 

Bwlch Height:  881.3m (converted to OSGM15, Leica RX1250) 

Bwlch Grid Reference:  SH 68799 66515 (Leica RX1250) 

Drop:  62.8m (Leica RX1250) 

Remoteness:  3.975km

 

Myrddyn Phillips (August 2024)

Mapping Mountains – Significant Height Revisions – 500m Twmpau and Welsh Highlands – Uchafion Cymru

 

Foel Ganol (SH 687 715) 

There has been a Significant Height Revision to a hill that is listed in the 500m Twmpau and the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Aled Williams. 

LIDAR image of Foel Ganol (SH 687 715)

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

500m Twmpau – Welsh hills at or above 500m and below 600m in height that have 30m minimum drop, with an accompanying sub category entitled the 500m Sub-Twmpau consisting of all Welsh hills at or above 500m and below 600m in height that have 20m or more and below 30m of drop.  With the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips and is published on Mapping Mountains in Google Doc format.

500m Twmpau by Myrddyn Phillips

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 name the hill is listed by is Foel Ganol and it is adjoined to the Carnedd Llywelyn 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 a minor road to its west, and has the town of Llanfairfechan towards the north.

When the list of Welsh 500m P15s that later became known as the Welsh Highlands – Uchafion Cymru was first compiled, this hill was listed with 40m of drop, based on the 536m summit spot height and the 496m bwlch spot height 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 summit image of Foel Ganol (SH 687 715)

LIDAR analysis gives the summit of this hill as 533.1m positioned at SH 68797 71588, and when compared to its originally listed summit height of 536m 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 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 533.1m and this was derived from LIDAR analysis, this is 2.9m lower than the originally listed summit height of 536m, which was based on the spot height 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:  Carnedd Llywelyn

Name:  Foel Ganol

OS 1:50,000 map:  115

Summit Height (New Height):  533.1m (LIDAR)

Summit Grid Reference:  SH 68797 71588 (LIDAR)  

Bwlch Height:  495.0m (LIDAR)

Bwlch Grid Reference:  SH 69012 71563 (LIDAR)

Drop:  38.2m (LIDAR)

 

Myrddyn Phillips and Aled Williams (September 2024)