Sunday, 6 August 2017

Change Register - Y Trechol - The Dominant Hills of Wales - Lesser Dominant Hills



Change Register

Y Trechol – The Dominant Hills of Wales

The Lesser Dominant Hills of Wales


Y Trechol  – The Dominant Hills of Wales are the Welsh P30 hills whose prominence equal or exceed half that of their absolute height, with the minimum qualifying mark given as a percentage (50%).  The list was conceptualized after adding drop values to the hand written Master Lists that took in the P30 hills of Wales that were published on Geoff Crowder’s v-g.me website, this was during 2006 and 2007 and the compilation of what was to become Y Trechol – The Dominant Hills of Wales followed soon afterward.

The original title for the list was the UPP’s, an abbreviation for the Ultra Prominent Peaks of Wales; this title was later changed to The Dominant Hills of Wales.  The change of name was instigated after a discussion with Mark Trengove who informed me that the same concept of Dominance had been used by Eberhard Jurgalski in written format in 2001 and in published format in 2004.  I also realised that the original title could be confused with the listing of 5,000ft prominence world peaks that are known as the Ultras, their title having been shortened from the Ultra Prominent Peaks, as it was sensible not to use a working title that was similar to another that used different criteria I opted for the title of Y Trechol - The Dominant Hills of Wales, with the term of Dominance used to describe it, and the words Y Trechol being the Welsh for The Dominants.  Accompanying the main list is a sub list entitled The Lesser Dominant Hills of Wales, these are the additional P30 Welsh hills whose prominence is 33% or more and below 50% of their absolute height, it is these hills that this Change Register concentrates on.

Although Y Trechol – The Dominant Hills of Wales was originally compiled in 2006 – 2007 after drop values were added to the Welsh P30 lists, the listing did not commence publication until 3rd December 2015, with ‘commence’ being the operative word as this is ongoing with bi-weekly, monthly, bi-monthly or quarterly instalments of hill groups being published on Mapping Mountains.

Although the criteria has remained the same in the Dominant and Lesser Dominant list, the listing has benefited greatly since its first compilation with the advent of independent surveyors using GPS / GNSS receivers,  the analysis of LIDAR data and the availability of an expanded range of online Ordnance Survey maps all adding greater accuracy to the numerical data.  However, it is not just numerical data that has seen this list develop since its first inception, as local enquiry and historical research are enhancing the place-name data used for the listed hill names.

It seems fitting that the list of Y Trechol – The Dominant Hills of Wales – The Lesser Dominant Hills of Wales should now benefit from a detailed Change Register, and although the changes to this list have been catalogued on the Mapping Mountains site it will be useful to list all status changes to the list since first compilation and present them in a Change Register.

The Change Register to Y Trechol – The Dominant Hills of Wales – The Lesser Dominant Hills of Wales appears below with the reclassifications to the Lesser Dominant list being detailed chronologically in receding order. 



Change Register

Y Trechol – The Dominant Hills of Wales

The Lesser Dominant Hills of Wales 






Carn Ysgubor    102.4m at SM 69953 24603 

Carn Ysgubor (SM 699 246) now reclassified back to a Lesser Dominat

This hill was originally listed as a Lesser Dominant and subsequently reclassified to a Dominant hill based on the result of a survey conducted with the Trimble GeoXH 6000 (see below), the adoption of OSGM15 has resulted in accurately known heights in Wales increasing by approximately 2-4cm and this has resulted in Carn Ysgubor being reclassified back to Lesser Dominant status.  The announcement of this hill’s reclassification back to a Lesser Dominant was made on the Mapping Mountains site on 05.07.17, the hill was previously listed with 50.00% Dominance based on the 102.4m summit and 51.2m bwlch heights produced by a survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips on the 15.05.16, these values when converted to OSGM15 are 102.395m summit and 51.208m bwlch heights, with these values giving 51.187m drop and 49.99% Dominance.  Lesser Dominant total increases by one and confirmed as 285.





Pt. 119m    119m at SH 72136 00406 

The details relating to this hill were re-evaluated and completed on the 06.06.16 resulting in it being reclassified from a Lesser Dominant hill to a Dominant hill, with this being announced on Mapping Mountains on the 03.12.16 when the Tarennydd group of hills were published, with a retrospective Hill Reclassifications post appearing on Mapping Mountains on 28.05.17.  The hill was previously listed with 48.25% Dominance based on an estimated c 114m summit height and a 59m bwlch height which appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps, and its reclassification is due to the 119m summit spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website which is sufficient for this hill to qualify as a Dominant hill.  Lesser Dominant total decreases by one and confirmed as 284.





Coed y Garth    87m at SH 66100 16583 

The re-evaluation relating to the details of this hill were completed on the 02.06.16 and its inclusion as a Lesser Dominant hill was announced on Mapping Mountains on the 03.11.16 when the Cadair Idris group of hills were published, with a retrospective Hill Reclassifications post appearing on Mapping Mountains on 27.05.17, the hill was previously considered not to have the minimum 30m of drop required for consideration to this list as Ordnance Survey maps of the day did not have spot heights for either the summit or bwlch, however with an 87m summit spot height on the Harvey 1:25,000 Superwalker map and a 56m bwlch spot height on the Ordnance Survey enlarged mapping hosted on the Geograph website this hill is now listed with 31m of drop and 35.63% Dominance which is sufficient for it to be included as a Lesser Dominant hill.  Lesser Dominant total increases by one and confirmed as 285.





Foel Fawr    72.0m at SM 70542 22567 

Foel Fawr (SM 705 225) classified as a Lesser Dominant due to a survey with the Trimble GeoXH 6000

The addition of this hill to Lesser Dominant status was announced on Mapping Mountains on the 09.06.16, with the survey that resulted in this hill’s addition being conducted on the 15.05.16, and the Hill Reclassifications post being published on Mapping Mountains on the 12.06.16, the hill was not previously listed in Y Trechol – The Dominant Hills of Wales as it was listed with an estimated drop of c 29m based on the 72m summit spot height and an estimated bwlch height of c 43m based on interpolation of contouring between 40m – 45m, with this drop value insufficient for consideration to the Dominant and Lesser Dominant list.  The hill has subsequently been surveyed using a Trimble GeoXH 6000 by Myrddyn Phillips on the 15.05.16, resulting in a 72.0m (converted to OSGM15) summit height and a 41.9m (converted to OSGM15) bwlch height, with these values giving this hill 30.1m of drop and 41.78% Dominance.  Lesser Dominant total increases by one and confirmed as 284.





Carn Ysgubor    102.4m at SM 69953 24603 

Carn Ysgubor (SM 699 246) is situated on the northern part of Ynys Dewi

The announcement of this hill’s reclassification from a Lesser Dominant to a Dominant hill was made on the Mapping Mountains site on 09.06.16 with the Hill Reclassifications post being published on the 10.06.16, the hill was previously listed with 49.50% Dominance based on the 101m summit spot height 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, with these values giving this hill c 50m of drop.  This hill was subsequently surveyed with the Trimble GeoXH 6000 by Myrddyn Phillips on 15.05.16, resulting in the summit height being 102.4m and the bwlch height being 51.2m, giving a drop value of 51.2m and a Dominance value of 50.00%.  The survey data for this hill has subsequently been converted to OSGM15 resulting in the hill being reclassified back to Lesser Dominant status (see above).  Lesser Dominant total decreases by one and confirmed as 283.





Moel y Gadair    66.7m at SH 52165 39135 

The Trimble GeoXH 6000 gathering data at the summit of Moel y Gadair (SH 521 391)

The deletion of this hill from a Lesser Dominant was announced on Mapping Mountains on the 06.03.16 with the Hill Reclassifications post published on the 08.03.16, the hill was originally listed with 46.27% Dominance based on the 67m summit spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and an estimated bwlch height of c 36m based on bwlch contouring between 30m – 40m, with these values giving the hill c 31m of drop.  This hill was subsequently surveyed with the Trimble GeoXH 6000 by Myrddyn Phillips on 15.06.15, resulting in a 66.7m (converted to OSGM15) summit height and incorrect placement of the Trimble at the area of the bwlch due to interpolation of bwlch contours, therefore the bwlch of this hill was re-surveyed with the Trimble GeoXH 6000 on the 23.02.16 resulting in a 38.1m (converted to OSGM15) bwlch height which when combined with the 66.7m summit height gives this hill only 28.5m of drop, which is insufficient for its continued classification as a Lesser Dominant hill.  Lesser Dominant total decreases by one and confirmed as 284.





Moelfre    74.1m at SH 55830 37553 

Moelfre (SH 558 375) reclassified from a Dominant to a Lesser Dominant

The reclassification of this hill to a Lesser Dominant was announced on Mapping Mountains on the 03.03.16 with the Hill Reclassifications post published on the 04.03.16, the hill was previously listed with 50.00% Dominance based on the 74m summit spot height on the Ordnance Survey enlarged mapping hosted on the Geograph website and an estimated bwlch height of c 37m based on bwlch contouring between 35m – 40m.  This hill was subsequently surveyed with the Trimble GeoXH 6000 by Myrddyn Phillips on 23.02.16, resulting in 74.1m (converted to OSGM15) summit and 37.8m (converted to OSGM15) bwlch heights, with these values giving a drop of 36.3m and a Dominance of only 49.00%.  Lesser Dominant total increases by one and confirmed as 285.





Moel y Penmaen    153m at SH 33810 38687  

This hill’s classification as a Lesser Dominant was announced on the 11.02.16 when the Pen Llŷn group of hills was published on the Mapping Mountains site, with a retrospective Hill Reclassifications post appearing on the 22.03.17, the hill is listed in this sub category as it has a 153m summit spot height on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 92m which is based on the 10m contour intervals on the 1:50,000 Landranger and the 1:25,000 Explorer map as well as the 5m contour intervals on the Ordnance Survey enlarged mapping hosted on the Geograph website, with these values giving this hill c 61m of drop and 39.87% Dominance.  Lesser Dominant total increases by one and confirmed as 284.





Pt. c 71m    c 71m at SH 31034 29730  

The inclusion of this hill as a Lesser Dominant was announced on the 11.02.16 when the Pen Llŷn group of hills was published on the Mapping Mountains site, with a retrospective Hill Reclassifications post appearing on Mapping Mountains on 21.03.17, the hill was previously listed with c 25m of drop based on 10m contour intervals at the bwlch on Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps which is insufficient for consideration as either a Dominant or Lesser Dominant hill.  As the more detailed Ordnance Survey mapping hosted on the Geograph website has 5m contour intervals and a 41m bwlch spot height for this hill, it gives a drop of c 30m based on an estimated c 71m summit height and a Dominance of 42.25% which is sufficient for inclusion in the Lesser Dominant list.  Lesser Dominant total increases by one and confirmed as 283.





Pt. 66m    66m at SH 29957 27041 

This hill’s reclassification from a Lesser Dominant hill was announced on the 11.02.16 when the Pen Llŷn group of hills was published on Mapping Mountains, with a retrospective Hill Reclassifications post appearing on Mapping Mountains on 19.03.17, the hill was previously listed with 48.44% Dominance based on a 64m map heighted summit at SH 295 266.  In recent times the Ordnance Survey larger scaled mapping has become available on the Geograph website and this more detailed map shows a 66m summit spot height at SH 299 270 and a connecting 32m bwlch spot height, with the subsequent drop of 34m sufficient for this hill to qualify as a Dominant hill with 51.52% Dominance.  Lesser Dominant total decreases by one and confirmed as 282. 




3rd December 2015 – Mapping Mountains starts publication of Y Trechol The Dominant Hills of Wales. 

Lesser Dominant total confirmed as 283.





Bryn Mawr    178.1m at SJ 25117 19054 

The wooded summit of Bryn Mawr (SJ 251 190)

The reclassification of this hill from a Lesser Dominant to a Dominant hill was due to a survey conducted by Myrddyn Phillips with the Trimble GeoXH 6000 on the 08.08.15, with its details appearing in the Carnedd Wen group of hills when published on Mapping Mountains on the 03.06.17, with a retrospective Hill Reclassifications post appearing on Mapping Mountains on 16.07.17, the hill was previously listed with 49.13% Dominance based on an estimated c 173m summit height and an estimated c 88m bwlch height, with the latter height later confirmed via an 88m spot height appearing on the Ordnance Survey enlarged mapping hosted on the Geograph website.  The subsequent survey with the Trimble produced a 178.1m (converted to OSGM15) summit height, giving this hill 90m of drop and 50.53% Dominance.  Lesser Dominant total decreases by one and confirmed as 283.





Mynydd Coch    468.3m at SH 80458 09952 

Mynydd Coch (SH 804 099) just fails to meet the criteria for Lesser Dominant status

The deletion of this hill from Lessser Dominant status was announced on Mapping Mountains on the 17.05.15, with a retrospective Hill Reclassifications post appearing on Mapping Mountains on 08.10.16, the hill was previously listed with 33.48% Dominance based on its 469m summit spot height and its 312m bwlch spot height, with these values giving this hill 157m of drop.  This hill was subsequently surveyed with the Trimble GeoXH 6000 by Myrddyn Phillips and Graham Jackson on the 13.05.15, resulting in a 468.3m (converted to OSGM15) summit height, giving the hill 156m of drop and 33.31% Dominance which is insufficient for its retention in the Lesser Dominant list.  Lesser Dominant total decreases by one and confirmed as 284.





Carreglefain    260.7m at SH 32421 41054 

The impressive summit cliff of Carreglefain (SH 324 410)

The announcement of this hill’s reclassification from a Lesser Dominant to a Dominant hill was made on the Mapping Mountains site on 01.12.14 with the Hill Reclassifications post being published on the 20.03.17, the hill was previously listed with 48.66% Dominance based on the 261m summit spot height on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 134m based on bwlch contouring between 130m – 140m.  This hill was subsequently surveyed with the Trimble GeoXH 6000 by Myrddyn Phillips on 24.11.14, resulting in the summit height being 260.7m (converted to OSGM15) and the bwlch height being 130.1m (converted to OSGM15), giving a drop value of 130.6m and a Dominance value of 50.08%.  Lesser Dominant total decreases by one and confirmed as 285.





Pt. 68.2m    68.2m at SH 38337 94993 

Pt. 68.2m (SH 383 949) is now reclassified to a Lesser Dominant

This hill’s reclassification from a Dominant to a Lesser Dominant was announced on the Mapping Mountains site on 13.09.14 with the Hill Reclassifications post appearing on the 07.12.15, the hill was previously listed with a summit height of 67m based on the spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website and an estimated bwlch height of c 33m, with these values giving this hill c 34m of drop and 50.75% Dominance.  This hill was subsequently surveyed with the Trimble GeoXH 6000 by Myrddyn Phillips and Alex Cameron on 07.09.14, resulting in the summit height being 68.2m (converted to OSGM15) and the bwlch height being 34.2m (converted to OSGM15), giving a drop value of 34.0m and a Dominance of only 49.85%, which is insufficient for it to retain its Dominant status.  Lesser Dominant total increases by one and confirmed as 286.





Pt. 258m    258m at SH 64705 06587 

The details relating to this hill were re-evaluated and completed on the 16.04.14 resulting in it being classified as a Lesser Dominant hill, with this being announced on Mapping Mountains on the 03.12.16 when the Tarennydd group of hills were published, with a retrospective Hill Reclassifications post appearing on Mapping Mountains on the 29.05.17.  The hill was previously listed with c 81m of drop which when coupled with its 258m summit spot height only gave the hill 31.40% Dominance, and its inclusion as a Lesser Dominant hill is due to the 171m bwlch spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website which is sufficient for this hill to qualify with 33.72% Dominance.  Lesser Dominant total increases by one and confirmed as 285.





Pt. 259m    259m at SJ 18114 43816 

The details relating to this hill were re-evaluated and completed on the 29.03.14 resulting in it being added to the list of Lesser Dominant hills, with this being announced on Mapping Mountains when the Y Berwyn group of hills were published on the 03.03.17, with a retrospective Hill Reclassifications post appearing on Mapping Mountains on 04.06.17.  The hill was previously listed with 33.20% Dominance based on the 259m summit spot height on the Ordnance Survey 1;25,000 Explorer map and an estimated bwlch height of c 173m, and its addition is due to a re-interpolation of the hill’s bwlch height resulting in 87m of drop and 33.59% Dominance, which is sufficient for it to be classified as a Lesser Dominant hill.  Lesser Dominant total increases by one and confirmed as 284.






Coed y Gaer    359.9m at SO 00488 84392


Gathering data at the summit of Coed y Gaer with the Trimble GeoXH 6000

The addition of this hill to Lesser Dominant status was confirmed by a survey with the Trimble GeoXH 6000 that took place on the 09.02.14, with the relevant post announcing the survey details being published on Mapping Mountains on the 11.02.14, with a retrospective Hill Reclassifications post appearing on Mapping Mountains on the 23.08.17.  The hill was previously listed with an estimated c 119m of drop based on its 362m summit spot height and an estimated bwlch height of c 243m, with the drop and Dominance value subsequently amended when a 241m bwlch spot height appeared on the Ordnance Survey enlarged mapping hosted on the Geograph website, with the confirmation of this hill’s addition as a Lesser Dominant by a survey with the Trimble GeoXH 6000 resulting in a 359.9m summit height and a 238.3m bwlch height, with these values giving this hill 121.7m of drop and 33.80% of Dominance.  Lesser Dominant total increases by one and confirmed as 283.





31st November 2012 – Compilation of hand written list completed of Y Trechol The Dominant Hills of Wales.

Lesser Dominant total confirmed as 282.





11th April 2011 – Started compilation of hand written list of Y Trechol The Dominant Hills of Wales.

Lesser Dominant total confirmed as 282.





23rd April 2009 – Criteria established and first hill purposely bagged that met the criteria of Y Trechol The Dominant Hills of Wales.

Lesser Dominant total confirmed as 282.








Myrddyn Phillips (August 2017)





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