Tuesday, 18 August 2015

Mapping Mountains – Significant Height Revisions – Y Pedwarau

Craig y Derlwyn (SH 702 259) 

There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to the listing of the Y Pedwarau, with these details being retrospective as the survey that resulted in this height revision was conducted on 3rd May 2014.

The criteria for the listing that this height revision affects are:

Y Pedwarau - Welsh hills at or above 400m and below 500m in height that have 30m minimum drop.

400m Sub- PedwarauWelsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.

The name of the hill is Craig y Derlwyn and it is situated in the hills of the Rhinogydd, which are positioned in the west of North Wales between Abermaw (Barmouth) which is to the hill's south and Trawsfynydd which is to the hill's north.

The hill can be accessed from the small community of Ganllwyd to its south-east, however even though forest paths and tracks head toward the hill much of the land outside of these is rough and wild.  Don’t let this put you off though, as when this hill is combined with its neighbours of Craig Aberserw and Craig y Ganllwyd they make one of the better outings in the eastern part of the Rhinogydd.

The summit height of this hill has been increased from its current Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map height, as prior to the survey with the Trimble GeoXH 6000 the hill was listed with a summit height of c 428m based on it having a relatively large uppermost contour ring of 420m on both of these Ordnance Survey maps.  Its new summit height is 430.8m (converted to OSGM15) which is 2.8m higher than its previously estimated height and 10.8m higher than its uppermost ring contour on current Ordnance Survey maps.

The full details for the hill are:

Cardinal Hill:  Y Llethr

Summit Height (New Height):  430.8m (converted to OSGM15)

Name:  Craig y Derlwyn

OS 1:50,000 map:  124

Summit Grid Reference:  SH 70245 25934
Drop:  25.3m (converted to OSGM15)

Gathering data at the summit of Craig y Derlwyn

Myrddyn Phillips and Aled Williams (August 2015)

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