Monday, 19 June 2017

Mapping Mountains – Hill Reclassifications – Y Pedwarau


Pt. 459.9m (SN 768 794) – 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 hill being deleted from the 400m Sub-Pedwar categoryThe 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 20m of drop based on the 459m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 439m based on interpolation of bwlch contouring between 430m – 440m.

The hill is situated in the Elenydd range with its Cardinal Hill being Draws Drum (SN 790 811) and is placed in the Region of Mid and West Wales (Region B, Sub-Region B2), and is positioned with the small community of Pontarfynach (Devil’s Bridge) to the south-west and Ponterwyd to the north-west.

The hill is a part of designated open access land and can be accessed directly from the A 4120 and B 4343 roads which are to the west of the summit, public footpaths also give access to the open access land and originate towards the north-west and the west respectively, otherwise if wanting to visit the hill a longer route can be devised that takes in a number of adjacent hills.

The hill is being listed under the point (Pt. 459.9m) notation as an appropriate name for it either from local or historical research is not known by the authors, 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. 459.9m

Summit Height:  459.9m (converted to OSGM15)

Summit Grid Reference:  SN 76846 79457

Bwlch Height:  439.9m (converted to OSGM15)

Bwlch Grid Reference:  SN 77051 79549

Drop:  19.98m


Therefore, the 459.9m LIDAR data produced for the summit position at SN 76846 79457 and the 439.9m LIDAR data produced for the bwlch position at SN 77051 79549 gives this hill 19.98m of drop which is insufficient for its continued inclusion as a 400m Sub-Pedwar.


The full details for the hill are:

Cardinal Hill:  Draws Drum

Summit Height:  459.9m (converted to OSGM15, LIDAR data)

Name:  Pt. 459.9m

OS 1:50,000 map:  135, 147

Summit Grid Reference:  SN 76846 79457

Drop:  19.98m (converted to OSGM15, LIDAR data)


The total for Y Pedwarau remains at 442 hills with nine additions, and fourteen 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 219 with 25 hills being added and 19 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 (June 2017)


No comments: