Sunday, 23 April 2017

Mapping Mountains – Hill Reclassifications – Y Pedwarau


Pen y Bryn Du (SJ 166 347) - 400m Sub-Pedwar deletion

There has been a deletion to the listing of Y Pedwarau due to analysis of LIDAR data by Aled Williams.  Y Pedwarau is the title for the list of 400m hills of Wales and takes in all Welsh hills at or 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, 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 455m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and the 435m bwlch spot height that appears on the Ordnance Survey 1:25,000 Explorer map.

The hill is situated in the Y Berwyn group of hills with its Cardinal Hill being Moel Fferna (SJ 116 397) and is placed in the Region of North Wales (Region A, Sub-Region A4), and is positioned with the small communities of Llanarmon Dyffryn Ceiriog to its south south-west and Pandy to its east north-east.

If wanting to visit the hill permission to do so should be sought as it is not on open access land.  It is positioned between two stream valleys to its west and east, both have rights of access on tracks that head to the north of the summit and would give access to the hill and its summit.

The name of the hill is Pen y Bryn Du 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:


Pen y Bryn Du

Summit Height:  455.3m

Summit Grid Reference:  SJ 16699 34722

Bwlch Height:  435.9m

Bwlch Grid Reference:  SJ 16535 35083

Drop:  19.4m


Therefore, the 455.3m LIDAR data produced for the summit position at SJ 16699 34722 and the 435.9m LIDAR data produced for the bwlch position at SJ 16535 35083 gives this hill 19.4m of drop which is insufficient for its retention as a 400m Sub-Pedwar.


The full details for the hill are:

Cardinal Hill:  Moel Fferna

Summit Height:  455.3m (LIDAR data)

Name:  Pen y Bryn Du

OS 1:50,000 map:  125

Summit Grid Reference:  SJ 16699 34722

Drop:  19.4m (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 216 with 18 hills being added and 15 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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