Tuesday, 18 April 2017

Mapping Mountains – Hill Reclassifications – Y Pedwarau


Pt. 458.5m (SN 982 116) - 400m Sub-Pedwar deletion

There has been an alteration to the listing of Y Pedwarau due to analysis of LIDAR data by Aled Williams.  Y Pedwarau is the title for the co-authored listing of the 400m hills of Wales, with the criteria for this list being all Welsh hills at or above 400m and below 500m in height with a minimum 30m of drop.

Accompanying the main Y Pedwarau list are five categories of sub hills, with this alteration affecting the 400m Sub-Pedwar category.  The criteria for 400m Sub-Pedwar qualification is all Welsh hills at or above 400m and below 500m in height with 20m or more and below 30m of drop.

Prior to analysis of LIDAR data the hill was listed with 20m of drop based on the 458m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 438m bwlch spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website.

The hill is situated in the Fforest Fawr group of hills with its Cardinal Hill being Fan Fawr (SN 969 193) and is placed in the Region of South Wales (Region C, Sub-Region C2).  The hill is positioned above the small communities of Penderyn to its south-west and Llwyn Onn to its east. 

The hill is situated on open access land and can be easily accessed from either its north north-west from the A 4059 road and also taking in the 485m map heighted Pedwar of Cadair Fawr (SN 977 123), or it can be accessed from its south-east from the convenience of a narrow minor road that reaches over 400m in height.

As the authors do not know an individual name for the hill either from local and / or historical research we are following the point (Pt. 458.5m) notation and its deletion from 400m Sub-Pedwar status is due to the 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. 458.5m

Summit Height:  458.5m

Summit Grid Reference:  SN 98267 11645

Bwlch Height:  438.9m

Bwlch Grid Reference:  SN 98245 11829

Drop:  19.6m


Therefore, the 458.5m LIDAR data produced for the summit position at SN 98267 11645 and the 438.9m LIDAR data produced for the bwlch position at SN 98245 11829 gives this hill 19.6m of drop which is insufficient for its retention as a 400m Sub-Pedwar.


The full details for the hill are:

Cardinal Hill:  Fan Fawr

Summit Height:  458.5m (LIDAR data)

Name:  Pt. 458.5m

OS 1:50,000 map:  160

Summit Grid Reference:  SN 98267 11645

Drop:  19.6m (LIDAR data)


The overall total for Y Pedwarau remains at 445 hills with eight additions, and ten reclassifications to 400m Sub-Pedwar status since publication of the list by Europeaklist in May 2013.

The overall total for the 400m Sub-Pedwarau is now 217 with 18 hills being added and 14 hills being taken out of this category since publication of the list by Europeaklist in May 2013.

The list of Pedwar hills is available from the Haroldstreet website (January 2014) with all subsequent changes detailed on the Mapping Mountains site, with the list also having commenced publication on Mapping Mountains on the 30.01.17.

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











Myrddyn Phillips and Aled Williams (April 2017)


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