Mapping Mountains - Hill Reclassifications – Y Pedwarau

Craig y Ganllwyd (SH 707 258) - 400m Sub-Pedwar reclassified to Pedwar

There has been a reclassification of a 400m Sub-Pedwar to Pedwar status which has recently been confirmed by surveying with the Trimble GeoXH 6000.  The hill is Craig y Ganllwyd (SH 707 258) and it is situated in the hills of the Rhinogydd.  The hill has an interesting history for its summit height data, this is detailed below:

Ordnance Survey 1:2,500 map from 1888 – 1889:  1,411ft (430m)

Ordnance Survey 1:50,000 map:  c 430m uppermost ring contour

Ordnance Survey 1:25,000 map:  c 410m uppermost ring contour

Harvey Maps:  423m spot height

The bwlch contouring for the hill is between c 390m – c 400m with the Ordnance Survey enlarged mapping hosted on the Geograph website giving a spot height of 397m.

When compiling the Y Pedwarau the hill was listed as a 400m Sub-Pedwar with 26m of drop based on the 397m bwlch spot height and the 423m spot height that appears on the Harvey Map.

The survey with the Trimble GeoXH 6000 has now determined that this hill has over 30m of prominence and therefore should be included in the Y Pedwarau.

The hill will be added to the Y Pedwarau list in the 2^nd edition that will hopefully be published by Europeaklist.  The list of Pedwar hills is also available from the Haroldstreet website.

The full details for the hill are:

Cardinal Hill:  Y Llethr

Summit Height:  430.9m (converted to OSGM15)

Name:  Craig y Ganllwyd

OS 1:50,000 map:  124

Summit Grid Reference:  SH 707 258

Drop:  32.9m (Trimble summit and LIDAR bwlch)

Craig y Ganllwyd (SH 707 258) has now been confirmed as a Pedwar

For details on the survey that reclassified this hill to Pedwar status please click {here}

Myrddyn Phillips and Aled Williams (May 2014)