Saturday, 15 April 2017

Mapping Mountains – Hill Reclassifications – Yr Uchafion

Pt. 524.0m (SN 881 163) - 500m Sub-Uchaf addition

There has been an addition to the listing of Yr Uchafion instigated from analysis of LIDAR data by Aled Williams.  Yr Uchafion is the draft title for a list of the Welsh 500m P15s that takes in all hills in Wales at or above 500m that have a minimum drop of 15m, the list is a joint compilation with Aled Williams, with the details relating to this list being published on the Mapping Mountains site in November 2015.

The listing of Yr Uchafion includes three sub lists; the 500m Sub-Uchaf, 490m Sub-Uchaf and the Double Sub-Uchaf category.  This hill has been included as a 500m Sub-Uchaf, with the criteria for this classification being all Welsh hills at or above 500m in height that have 14m or more and below 15m of drop.

This hill is given a 524m summit spot height on the Ordnance Survey 1:25,000 Explorer map and has bwlch contouring between 510m – 520m, implying that it has insufficient drop to be considered for the 500m Sub-Uchaf category.

The hill is adjoined to the Fforest Fawr group of hills with its Cardinal Hill being Fan Gyhirych (SN 880 191) and is placed in the Region of South Wales (Region C, Sub-Region C2), and is situated with the small community of Glyntawe to its west.

The hill can be accessed via public footpaths from Penwyllt towards its west, or from towards its south-east from the end of a minor road that heads north following the course of the Nedd Fechan.

As the authors do not know either a local or historical name that is appropriate for the hill the point (Pt. 524m) notation is being used, and its inclusion as a 500m Sub-Uchaf is due to analysis of LIDAR data by Aled Williams.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

Aled’s analysis of LIDAR data gives the hill the following details:

Pt. 524m

Summit Height:  524.0m (converted to OSGM15)

Summit Grid Reference:  SN 88113 16370

Bwlch Height:  509.4m (converted to OSGM15)

Bwlch Grid Reference:  SN 87908 16298

Drop:  14.6m

Therefore, the 524.0m (converted to OSGM15) LIDAR data produced for the summit position at SN 88113 16370 and the 509.4m (converted to OSGM15) LIDAR data produced for the bwlch position at SN 87908 16298 gives this hill 14.6m of drop, which is sufficient for its inclusion as a 500m Sub-Uchaf

The full details for the hill are:

Cardinal Hill:  Fan Gyhirych

Summit Height:  524.0m (converted to OSGM15) (LIDAR data)

Name:  Pt. 524.0m

OS 1:50,000 map:  160

Summit Grid Reference:  SN 88113 16370 
Drop:  14.6m (converted to OSGM15) (LIDAR data)

The overall total for Yr Uchafion / The Welsh 500m P15s remains at 631 hills with the total for the 500m Sub-Uchaf category now being 26.

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

Myrddyn Phillips and Aled Williams (April 2017)

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