Friday, 30 December 2016

Mapping Mountains – Hill Reclassifications – Y Pedwarau

Lan (SO 052 391) - 400m Sub-Pedwar reclassified to Pedwar

There has been a reclassification to the listing of the Y Pedwarau with a 400m Sub-Pedwar being promoted to the ranks of Pedwar by analysis of LIDAR data by Aled Williams.  Y Pedwarau are all hills in Wales at or above 400m and below 500m in height that have a minimum drop of 30m.

The hill is situated in the group of hills known as Mynydd Epynt with its Cardinal Hill being Clepyn Melyn (SN 961 464) and is placed in the Region of Mid and West Wales (B-2).  The hill is positioned between the small communities of Lower Chapel to the south south-west and Erwyd (Erwood) to the north-east, and the summit area of the hill is covered in the Brycheiniog Forest conifer plantation with the nearest forest track to the summit being to the north, this track ascends the hill from the small community of Llaneglwys to the east south-east and contours around the hill’s eastern slopes before heading northward of its summit.

The name of the hill is Lan and this was found on the Tithe map from research conducted by Aled Williams, the hill was previously listed as a 400m Sub-Pedwar with c 29m of drop based on an estimated summit height of c 407m and an estimated bwlch height taken from contour interpolation of c 378m.

As Aled was analysing other hills in the vicinity against LIDAR data, he did likewise with Lan.  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:


Summit Height:  413.6m

Summit Grid Reference:  SO 05243 39144

Bwlch Height:  377.0m

Bwlch Grid Reference:  SO 04871 39392

Drop:  36.6m

Therefore, the 413.6m LIDAR data produced for the summit position at SO 05243 39144 and the 377.0m LIDAR data produced for the bwlch position at SO 04871 39392 is sufficient for this hill to be reclassified to a Pedwar with 36.6m of drop, and therefore Lan is included in the listing of the Y Pedwarau and the list will be updated accordingly.

The full details for the hill are:

Cardinal Hill:  Clepyn Melyn

Summit Height:  413.6m (LIDAR data)

Name:  Lan

OS 1:50,000 map:  160

Summit Grid Reference:  SO 05243 39144

Drop:  36.6m (LIDAR data)

This now brings the overall total for the Y Pedwarau to 446 hills with seven additions, and eight reclassifications to 400m Sub-Pedwar status since publication of the list by Europeaklist in May 2013.  The hill will be taken out of the 400m Sub-Pedwar list and added to the main list in forthcoming publications.  The list of Pedwar hills is available from the Haroldstreet website (January 2014) with all subsequent changes available via the Mapping Mountains site.

The list of additions and reclassifications from the Pedwar list since the 1st edition of the Y Pedwarau was published by Europeaklist are as follows:


Lan (LIDAR data) (SO 052 391) 400m Sub-Pedwar reclassified to Pedwar with 36.6m drop


Myrddyn Phillips and Aled Williams (December 2016)

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