Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Redding (ST 087 776) – 30-99m Sub-Twmpau reclassified to 30-99m Twmpau

There has been confirmation of a reclassification to the list of 30-99m Twmpau, 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 Redding

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

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 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.

The name of the bounded land where the summit of this hill is situated is Redding, and this was derived from the Tithe map and it is this name that the hill is now being listed by.  The hill 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 has the M4 towards its north-west and the A4232 road to its east, and has the city of Caerdydd (Cardiff) towards its east.

This hill was included in the accompanying Hills to be surveyed sub list when the original Welsh 30-99m P30 hills were published on Geoff Crowder’s v-g.me website, as it did not meet the criteria then used for the main P30 list.  The sub list has now been standardised and interpolated drop values and interpolated summit heights have also been included in the main P30 and sub list.

When interpolated heights were used in this list this hill was listed with an estimated c 30m of drop, based on the 81m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 51m based on interpolation of bwlch contouring between 50m – 55m.

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

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website became available online; this mapping is entitled the Interactive Coverage Map, and its larger scale enabled a better assessment of bwlch contouring, this resulted in the same estimated c 51m bwlch height giving this hill the same estimated drop value of c 30m.

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 confirmation of this hill’s reclassification to 30-99m Twmpau status is due to LIDAR analysis, resulting in an 80.3m summit height and a 49.05m bwlch height, with these values giving this hill 31.3m of drop.

The full details for the hill are:

Group:  Cymoedd Morgannwg

Name:  Redding

OS 1:50,000 map:  170

Summit Height:  80.3m (LIDAR, natural summit)

Summit Grid Reference:  ST 08782 77683 (LIDAR, natural summit)

Bwlch Height:  49.05m (LIDAR)

Bwlch Grid Reference:  ST 08551 79827 (LIDAR)

Drop:  31.3m (LIDAR)

Myrddyn Phillips (June 2019)

Mapping Mountains – Hill Reclassifications – Hewitts

Fan y Big (SO 036 206) – Hewitt reclassified to SubHewitt

This is one in a series of retrospective Hill Reclassification posts that detail hills whose status has altered in the listing of the Welsh Hewitts (an acronym for Hill in England, Wales or Ireland over Two Thousand feet high).  These reclassification posts will give details of hills where I have direct association with their change of status, and they will tie in with a forthcoming Change Register giving detail to this list and its alterations since first publication.

The listing of Welsh Hewitts was published in booklet format by TACit Tables in February 1997 and entitled The Hewitts and Marilyns of Wales.  This list evolved out of The Absolute Summits of England and Wales which were known as the Sweats (an acronym for Summits in Wales and England Above Two-thousand FEET) and which was published by Cicerone Press in 1992 in the book entitled The Relative Hills of Britain.  The list compiler for the Hewitts and the preceding Sweats is Alan Dawson.

When the Welsh Hewitts list was published in booklet format there were 137 qualifying hills listed with their criteria being any Welsh hill at or above 2000ft (609.6m) in height with 30m minimum drop, accompanying the main list are two sub category’s entitled SubHewitts, with the two sets of criteria being any Welsh hill at or above 600m and below 2000ft (609.6m) in height that have a minimum drop of 30m and any Welsh hill at or above 2000ft (609.6m) in height with 20m or more and below 30m of drop.

The Hewitts and Marilyns of Wales by Alan Dawson

The details for the hill reclassification appear below:

The name of the hill is Fan y Big, and it is adjoined to the Bannau Brycheiniog group of hills, and it is positioned between the towns of Aberhonddu (Brecon) to its north and Merthyr Tudful to its south.

Fan y Big (SO 036 206)

Prior to this hill’s reclassification to SubHewitt status it was listed as a Hewitt with 30m of drop based on the 719m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and the 689m bwlch spot height that appears on the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map.

As the listed drop value of 30m is the minimum required for Hewitt status it was prioritised for a GNSS survey.  Prior to this survey taking place Aled Williams analysed this hill with LIDAR data resulting in a 716.3m summit height and a 688.1m bwlch height, with these values giving this hill 28.2m of drop.

LIDAR summit image of Fan y Big

Subsequently the GNSS survey took place on the 30^th June 2018 with a repeat summit survey taking place on the 21^st August 2018.  The hill was surveyed by Myrddyn Phillips using a Trimble GeoXH 6000 to determine the summit and bwlch height and also its drop value, resulting in the following:

1^st summit survey 30.06.18:  716.800m

2^nd summit survey 30.06.18:  716.676m

3^rd summit survey 21.08.18:  716.754m

Bwlch survey 30.06.18:  688.2m

 

The average of the three summit surveys comes to 716.7m and with a surveyed bwlch height of 688.2m, these values give this hill 28.5m of drop, with all these details being forwarded to the list author.

The Trimble GeoXH 6000 gathering data at the summit of Fan y Big

The reclassification of this hill from Hewitt to SubHewitt status was accepted by the list author and its new classification augmented in to the listing of the Hewitts in July 2018.

The full details for the hill are:

Name:  Fan y Big

OS 1:50,000 map:  160

OS 1:25,000 map:  12

Summit Height:  716.7m (converted to OSGM15, average of three summit surveys)

Summit Grid Reference:  SO 03654 20669 (as listed in the Hewitts)

Bwlch Height:  688.2m (converted to OSGM15)

Bwlch Grid Reference:  SO 037 198 (as listed in the Hewitts)

Drop:  28.5m

Myrddyn Phillips (June 2019)

Mapping Mountains – Significant Name Changes – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Shelone Wood (SS 736 944)

There has been a Significant Name Change to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, the bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Shelone Wood

The criteria for the two listings that this name change applies to are:

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 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.

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, with the Introduction to the Mapping Mountains publication of this list appearing on the 3^rd December 2015.

The hill 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 has the A474 road to its east, the M4 and the Afon Nedd (River Neath) to its west, and the M4 and the A48 roads to its south, and has the town of Castell-nedd (Neath) towards its north.  

The hill originally appeared in the 30-99m P30 list on Geoff Crowder’s v-g.me website under a partly transposed and invented name of Briton Ferry Hill, with an accompanying note stating; Name from surrounding district. 

Briton Ferry Hill

54m

SS736945

170

165

Name from surrounding district

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.  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 what I presumed to be a district and add the word Hill to it.  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 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 historical 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 Vector Map Local hosted on the Geograph website, and which is entitled the Interactive Coverage Map.  Both of these maps name the wood which the summit is situated beside as Shelone Wood and this is appropriate to use in listing terms for the name of the hill.

Extract from the Ordnance Survey series of Six-Inch maps

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website

Therefore the name this hill is now listed by in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales is Shelone Wood, and this was derived from the series of Ordnance Survey Six-Inch maps and the Ordnance Survey Vector Map Local hosted on the Geograph website, and which is entitled the Interactive Coverage Map. 

The full details for the hill are:

Group:  Cymoedd Morgannwg

Name:  Shelone Wood

Previously Listed Name:  Briton Ferry Hill 

OS 1:50,000 map:  170

Summit Height:  55.9m (LIDAR)

Summit Grid Reference:  SS 73625 94495 (LIDAR)

Bwlch Height:  8.7m (LIDAR)

Bwlch Grid Reference:  SS 74250 94893 (LIDAR)

 

Drop:  47.2m

Dominance:  84.37%

Myrddyn Phillips (June 2019)

Mapping Mountains – Significant Height Revisions – 30-99m Twmpau and Y Pellennig – The Remotest Hills of Wales

Pt. 22.2m (SM 701 226)

There has been a Significant Height Revision to a hill that is now listed in the 30-99m Twmpau and Y Pellennig – The Remotest 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 Aled Williams.

Pt. 22.2m (SM 701 226)

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

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, this height band of hills has two accompanying sub lists, the first of which is 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, and the second sub category which this hill is a part of is entitled the Double Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 20m and below 30m 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.  This list is authored by Myrddyn Phillips.

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 a joint compilation between 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 the Mapping Mountains site in Google Doc format.

As the authors do not know an appropriate name for this hill either from historic research or local enquiry it is being listed by the point (Pt. 22.2m) notation, and it is adjoined to the Carn Llidi group of hills which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), and it is positioned in a small sheltered bay on the southern side of Ynys Dewi.

This hill did not appear in the accompanying Hills to be surveyed sub list when the original Welsh 30-99m P30 hills were published on Geoff Crowder’s v-g.me website, as it did not meet the criteria then used for this sub category, however this sub list has now been standardised, with interpolated drop values and interpolated summit heights also included.

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

Even when this sub list was standardised contemporary Ordnance Survey 1:25,000 Explorer maps do not give the hill any contour ring.  The lack of contour rings is also applicable to the Ordnance Survey Vector Map Local hosted on the Geograph website which is entitled the Interactive Coverage Map.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website

The details for this hill were re-assessed when the OS Maps website became available online.  This is the replacement for OS Get-a-map and has 5m contour intervals, and this mapping gives this hill an uppermost 15m ring contour.

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 is 22.2m, this height comes within the parameters of the Significant Height Revisions used within this page heading, and 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.

LIDAR image of Pt. 22.2m, 1m contour (black), 10m contour (red) and sea level (yellow)

Close up LIDAR image of Pt. 22.2m, 1m contour (black), 10m contour (red) and sea level (yellow)

Therefore, this hill’s new listed summit height is 22.2m and this was derived from LIDAR analysis conducted by Aled Williams, this is 22.2m higher than information on the Ordnance Survey 1:25,000 Explorer map and 7.2m higher than the uppermost 15m contour ring on the OS Maps website.

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Carn Llidi 

Name:  Pt. 22.2m

OS 1:50,000 map:  157

Summit Height (New height):  22.2m (LIDAR)

Summit Grid Reference:  SM 70180 22696 (LIDAR)

Bwlch Height:  N/A, sea level

Bwlch Grid Reference:  N/A, sea level

 

Drop:  22.2m (LIDAR)

Remoteness:  3.400km

Myrddyn Phillips and Aled Williams (June 2019)

© Crown: CHERISH PROJECT 2019. Produced with EU funds through the Ireland Wales Co-operation Programme 2014-2020. All material made freely available through the Open Government Licence.

Mapping Mountains – Hill Reclassifications – Yr Uchafion

Pt. 504.7m (SH 744 624) – Uchaf deletion

There has been a deletion to a hill that is listed in the Yr Uchafion, 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 and Aled Williams which took place on the 17^th February 2019.

Pt. 504.7m (SH 744 624)

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

Yr Uchafion – This is the draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height with 15m minimum drop.  Accompanying the main list are three sub lists, these are; 500m Sub-Uchaf, 490m Sub-Uchaf and the Double Sub category. The list is co-authored by Myrddyn Phillips and Aled Williams with the introduction to the list being published on Mapping Mountains in November 2015.

As the authors do not know an appropriate name for the hill either from historic research or from local enquiry it is being listed by the point (Pt. 504.7m) notation, 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 is positioned with the A5 road to its south and the A470 road and the Afon Conwy to its east, and has the village of Betws-y-coed towards its south-east.

This hill was not included when the original list of Welsh 500m P15s was compiled as the Ordnance Survey 1:25,000 Explorer map gives it one continuous contour ring and without any spot height at either its summit or bwlch its drop value was hard to determine through interpolation alone.

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

This hill was first surveyed using a basic levelling staff on the 18^th May 2004 by Myrddyn Phillips resulting in a 49½ft / 15.1m drop value, which was sufficient for it to be classified as an Uchaf.

The details for this hill were reassessed when the Ordnance Survey Vector Map Local hosted on the Geograph website became available online, and which is entitled the Interactive Coverage Map.  This mapping compliments its 1:25,000 map counterpart and does not give a spot height at either this hill’s summit or bwlch.

The details for this hill were next 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.  This map shows the hill as having two continuous contour rings which implies that its drop may not be sufficient for the minimum of 15m required to be classified as an Uchaf.

As the drop value determined by the basic levelling survey was marginal compared to the 15m drop criterion this hill was prioritised for a survey with the Trimble GeoXH 6000.  The hill has two potential high points and each was surveyed as well as its critical bwlch, resulting in the following:

1^st potential summit:  504.523m at SH 74415 62527

Summit:  501.691m at SH 74482 62452

The Trimble GeoXH 6000 gathering data at the summit of Pt. 504.7m (SH 744 624)

Therefore, the deletion of Pt. 501.7m from Uchaf status is due to a survey with the Trimble GeoXH 6000, resulting in a 501.7m summit height and a 491.4m bwlch height, with these values giving this hill 13.3m of drop which is insufficient for it to be retained as an Uchaf.

The full details for the hill are:

Group:  Carneddau

Name:  Pt. 504.7m

OS 1:50,000 map:  115

Summit Height:  504.7m (converted to OSGM15)

Summit Grid Reference:  SH 74482 62452

Bwlch Height:  491.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 74150 62406 

  

Drop:  13.3m 

For the additions, deletions and reclassifications to Yr Uchafion / The Welsh 500m P15s reported on Mapping Mountains please consult the following Change Registers:

The Welsh 500m P15s (Yr Uchafion)

The Welsh 500m P15s (Yr Uchafion) – 500m Subs

The Welsh 500m P15s (Yr Uchafion) – 490m Subs

The Welsh 500m P15s (Yr Uchafion) – Double Subs

For details on the survey of Pt. 504.7m

Myrddyn Phillips and Aled Williams (June 2019)