Myrddyn Phillips - Mapping Mountains: Mapping Mountains – Hill Reclassifications

Tuesday 16 January 2018

Mapping Mountains – Hill Reclassifications – Y Pedwarau

Twyn y Waun (artificial summit at SO 082 070 and natural summit at SO 084 073) – Pedwar reclassified to Dual Summit Pedwar

There has been a reclassification to the listing of Y Pedwarau due to a survey with the Trimble GeoXH 6000 that was instigated by an on-site visit by Rob Woodall and an article written by Aled Williams in 2015 and entitled ‘Artificial Pedwar Hills.’ The Y Pedwarau is the title for the list of 400m hills of Wales and takes in all Welsh hills at and above 400m and below 500m in height that have a minimum 30m of drop, the list is a joint compilation between Myrddyn Phillips and Aled Williams and it commenced publication on Mapping Mountains on the 30.01.17.

Accompanying the main Y Pedwarau list are five categories of sub hills, however this hill has not been reclassified from one of these categories to another, as a new classification of Dual Summit has been created to accommodate the details relating to this hill.

Dual Summit hills:

A hill classified as a Dual Summit is defined as one which has an extant natural summit coupled with that of a higher artificial summit, with the latter that can be described as stable in character. In the main, these recent man-made constructions are the result of quarrying activities producing spoil tips. These recent man-made constructions are treated differently to ancient man-made constructions such as hill forts and tumuli, as if the latter are deemed stable and of an earthen character their age dictates that they can be viewed as being permanent in nature and are now effectively a part of the hill. For those bagging Dual Summit hills, a visit to either the natural high point or the elevated man-made high point is sufficient to claim an ascent of the hill.

The name of the hill is Twyn y Waun and prior to the Trimble GeoXH 6000 survey this hill was listed with an estimated c 451m summit height based on a 450m uppermost contour on the Ordnance Survey 1:50,000 map and the Interactive Coverage Map hosted on the Geograph website and a drop of c 63m which has now been re-evaluated.

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.

Twyn y Waun is situated in the Y Cymoedd – dwyreiniol range of hills and is listed as a Cardinal Hill, and is placed in the Region of South Wales (Region C, Sub-Region C2). The hill is positioned between the towns of Merthyr Tudful (Merthyr Tydfil) to its west and Rhymni (Rhymney) to its east and has the A 465 Heads of the Valleys Road to its north-west.

Twyn y Waun is now listed as a Dual Summit hill and its natural summit is a part of designated open access land and can be approached from the convenience of a minor road to its east, whilst as its man-made summit is a part of a working mine permission to visit should be sought, however the artificial summit is on the border of designated open access land shown on the Ordnance Survey 1:25,000 Explorer map, and for those wishing to visit an ascent of this artificial summit from the natural summit is an easy extension of the short walk from the minor road to the east.

The full details for the hill are:

Cardinal Hill: Twyn y Waun

Summit Height: 476.0m (artificial Dual Summit) 450.6m (converted to OSGM15, Trimble GeoXH 6000, natural Dual Summit)

Name: Twyn y Waun

OS 1:50,000 map: 160

Summit Grid Reference: SO 08209 07041 (artificial Dual Summit) SO 08442 07378 (LIDAR, natural Dual Summit)

Drop: 96.0m (Trimble GeoXH 6000 summit and LIDAR bwlch, artificial Dual Summit) 70.7m (Trimble GeoXH 6000 summit and LIDAR bwlch, natural Dual Summit)

For the additions, deletions and reclassifications to the Y Pedwarau reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers: