Monday, 22 May 2017

Mapping Mountains – Hill Reclassifications – Y Pedwarau



Pen y Crocbren (SN 854 934) – 400m Sub-Pedwar deletion

There has been a deletion from 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 deletion 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 c 21m of drop based on the 469m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and an estimated bwlch height of c 448m based on interpolation of bwlch contouring between 440m – 450m.

The hill is situated in the Pumlumon group of hills with its Cardinal Hill being Foel Fadian (SN 828 953) and is placed in the Region of Mid and West Wales (Region B, Sub-Region B2), and is positioned with the small community of Dylife to the north-east.

If wanting to visit the hill it can be easily accessed as the public footpath that traverses it from a west to east direction is a part of Glyndŵr’s Way.  Access to this long distance footpath can be found from north of the hill where public footpaths join it towards the hill’s west and east which can make for a small circular walk.

The name of the hill is Pen y Crocbren 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 Crocbren

Summit Height:  467.7m

Summit Grid Reference:  SN 85485 93464

Bwlch Height:  448.7m

Bwlch Grid Reference:  SN 85232 93470

Drop:  19.0m


Therefore, the 467.7m LIDAR data produced for the summit position at SN 85485 93464 and the 448.7m LIDAR data produced for the bwlch position at SN 85232 93470 gives this hill 19.0m of drop which is insufficient for it to retain its status as a 400m Sub-Pedwar.


The full details for the hill are:

Cardinal Hill:  Foel Fadian

Summit Height:  467.7m (LIDAR data)

Name:  Pen y Crocbren

OS 1:50,000 map:  135, 136

Summit Grid Reference:  SN 85485 93464

Drop:  19.0m (LIDAR data)


The overall total for Y Pedwarau remains at 443 hills with eight additions, and twelve 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 21 hills being added and 17 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 (May 2017)


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