Saturday 14 January 2017

Change Register - The Welsh Highlands - Uchafion Cymru - 490m Subs


Change Register

The Welsh Highlands - Uchafion Cymru
490m Subs

All hills in Wales at or above 500m in height with a minimum prominence of 15m; from the 500.5m summit of Moel Bowydd to the 1084.8m summit of Yr Wyddfa




On the 7th January 2023 it was announced that the 490m subs have been dispensed with, therefore the Change Registers for these are now redundant.  However, they will remain on Mapping Mountains as a historical documentation of this list, although their totals will no longer be used.




The Welsh Highlands - Uchafion Cymru is a hill list co-authored by Myrddyn Phillips and Aled Williams, and was first announced on the Mapping Mountains site on 4th November 2015 where a complete breakdown of hill totals was listed by Group.  The list then comprised of 630 hills within the main list that met the qualifying criteria with over 100 of these hills making their first known appearance in any form of hill list; emphasising the fact that this listing is the most comprehensive of its kind for this height band of hill in Wales.

The listing originated in 2004 at which time it included a sub category for those hills that met the qualifying height but only had 14m or more and below 15m of drop, these are now known as the Welsh Highland Subs and as of the 7th January 2023 been revised with their criteria being all Welsh hills at and above 500m in height with 10m or more and below 15m of drop.  This listing now includes two other sub categories; the 490m Subs and the Double Subs and this Change Register details those hills that are, or have been listed within the 490m Subs category.

The 490m Subs are those hills that fail to meet the Welsh Highlands - Uchafion Cymru qualification by 10m or less of height, these are the hills that are 490m or more and below 500m in height that have a minimum 15m of drop.

Since ‘The Welsh Highlands - Uchafion Cymru listing originated it has developed ever since with it now being co-authored with Aled Williams, having the two other sub categories within it, and having over 330 marginal hills surveyed using a basic levelling technique.  It is now also benefiting from the accurate surveys conducted with GPS / GNSS receiver, an expanded range of Ordnance Survey maps available online and most recently, by analysis of LIDAR data.

However, it is not just numerical data that has seen this list develop since its first inception, it is also place-name data, and it was because of this and their mutual interest in hill lists that the authors first corresponded.

In recent years, acronyms or short monikers referring to specific hill lists have become increasingly popular in hill-walking circles, and during the compilation of this list which used to be referred to as the ‘The Welsh 500m P15s’ the authors have used the Welsh word ‘Uchaf (Higher)’ to refer to these hills, with the plural being ‘Uchafion’, since these summits take in the higher tier of the Welsh uplands.  For the time being this moniker will be used on the Mapping Mountains site to refer to this class of hill.

It seems fitting that the list of ‘The Welsh Highlands - Uchafion Cymru – 490m Subs should now benefit from a detailed Change Register, and although the hill list in its entirety is not yet published it is prudent for this Change Register to initially detail the changes to this sub category since the November 2015 introduction published on the Mapping Mountains site.

The Change Register to ‘The Welsh Highlands - Uchafion Cymru – 490m Subs appears below with the reclassifications to the 490m Subs list being detailed chronologically in receding order.




Change Register

The Welsh Highlands - Uchafion Cymru – 490m Subs






On the 7th January 2023 it was announced that the 490m subs have been dispensed with, therefore the Change Registers for these are now redundant.  However, they will remain on Mapping Mountains as a historical documentation of this list, although their totals will no longer be used.




Cwar Blaen Dyffryn    496.0m at SO 09829 14840 

LIDAR image of Cwar Blaen Dyffryn (SO 098 148)

This hill’s addition to 490m Sub-Uchaf status was announced on Mapping Mountains via a Hill Reclassifications post that was published on the 21.11.20.  Its inclusion is due to LIDAR analysis conducted by Aled Williams, resulting in a 496.0m summit height and a 477.6m bwlch height, with these values giving this hill 18.4m of drop.  490m Sub-Uchaf total increases by one and confirmed as 65.   





Twynau Gwynion    496.8m at SO 06765 10701

LIDAR image of Twynau Gwynion (SO 067 107)

This hill’s reclassification back to 490m Sub-Uchaf status was announced on Mapping Mountains on 02.02.20, with the hill initially listed as a 490m Sub-Uchaf and consequently reclassified to 490m Double Sub status based on DTM LIDAR analysis.  Its reinstatement as a 490m Sub-Uchaf is due to DSM LIDAR analysis conducted by Aled Williams, resulting in a 496.8m summit height and a 481.4m bwlch height, with these values giving this hill 15.5m of drop.  490m Sub-Uchaf total increases by one and confirmed as 64.   





Cefn Wylfre    490.1m at SO 14585 51034

The addition of this hill to 490m Sub-Uchaf status was announced on the Mapping Mountains site on the 08.10.17, the hill was previously not classified as with an estimated drop of c 15m based on the 489m summit spot height that appears on the Ordnance Survey 1:25,000 map and an estimated bwlch height of c 474m based on bwlch contouring between 470m – 480m its summit did not reach the minimum qualifying height of 490m for this sub category.  The hill’s addition to a 490m Sub-Uchaf is due to analysis of LIDAR data by Aled Williams, with the resulting 49o.1m summit height and 474.9m bwlch height giving this hill 15.2m of drop, which when coupled with the hill’s summit height is sufficient for it to qualify as a 490m Sub-Uchaf.  490m Sub-Uchaf total increases by one and confirmed as 63.  





Pt. 499.1m    499.1m at SN 86343 76073

This hill’s reclassification from an Uchaf was announced on the Mapping Mountains site on the 13.03.17, with the hill previously listed with an estimated c 500m summit height based on the flatness of the summit area in relation to the small uppermost 500m ring contour on Ordnance Survey maps.  The hill’s reclassification to a 490m Sub-Uchaf is due to analysis of LIDAR data by Aled Williams, with the resulting 499.1m summit height being too low for the hill to qualify as an Uchaf490m Sub-Uchaf total increases by one and confirmed as 62.

  



Twynau Gwynion    496.2m at SO 06765 10699

THIS HILL HAS SUBSEQUENTLY BEEN REINSTATED TO 490m SUB-UCHAF STATUS

This hill’s reclassification was announced on the Mapping Mountains site on 10.01.17, with the hill previously listed as a 490m Sub-Uchaf with 16m of drop based on the 498m summit spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps, and a 482m bwlch spot height on the Ordnance Survey enlarged mapping hosted on the Geograph website.  This hill was reclassified from a 490m Sub-Uchaf to a Double Sub-Uchaf from LIDAR data analysed by Aled Williams, resulting in the hill having a 496.2m summit and 481.3m bwlch height, with these values giving this hill 14.9m of drop which is insufficient for this hill to retain its 490m Sub-Uchaf status.  490m Sub-Uchaf total decreases by one and confirmed as 61.   
   



4th November 2015 – Mapping Mountains first publishes details to ‘The Welsh Highlands - Uchafion Cymru – 490m Subs

490m Subs total confirmed as 62.




Myrddyn Phillips and Aled Williams (January 2017)

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