Sunday, 27 March 2016

Mapping Mountains – Significant Height Revisions – Y Pedwarau


Craig y Garreg Lwyd (SH 730 427)  

This is the twenty eighth post under the heading of Significant Height Revisions, and the Trimble survey that resulted in this height revision was conducted on the 14th March 2016 in good, bright conditions, albeit with a chilling easterly breeze blowing.

The twenty eighth major height revision initiated from a survey with the Trimble GeoXH 6000 was conducted in the compact group of hills between the Moelwynion to the west and the wilds of Y Migneint to the east, and which is situated in north-west Wales.

The hill is positioned above and to the north-west of Llyn Morwynion and can easily be accessed from a number of tracks that lead in from its south, south-west and south-east, with each track starting from the B 4391 road as it makes its way eastward from Llan Ffestiniog toward its connection with the A 4212.  The hill is positioned to the south-east of Blaenau Ffestioniog and to the east of Llan Ffestiniog.

The hill is named Craig y Garreg Lwyd and appears on the Ordnance Survey enlarged map on the Geograph website with a 478m spot height at its summit.  As the 473.4m (converted to OSGM15) Trimble result was significantly lower than this spot height I checked all available Six-Inch maps on the National Library of Scotland website, the Historical Ordnance Survey maps available on the Sabre Maps website and the Ordnance Survey Vector mapping and could find no evidence of a previous imperial height or another current metric height for this hill.  Therefore, it seems that the 478m spot height is the only height adjoined to the summit of this hill on publicly available maps.

Therefore this hill’s new summit height is 473.4m (converted to OSGM15) which is 4.6m lower than its previously listed height of 478m which appears on the Ordnance Survey enlarged mapping on the Geograph website.


The full details for the hill are:

Cardinal Hill:  Graig Goch

Summit Height:  473.4m (converted to OSGM15)

Name:  Craig y Garreg Lwyd

OS 1:50,000 map:  124

Summit Grid Reference:  SH 73044 42742

Drop:  29.9m


Gathering data 0.82m above the summit of Craig y Garreg Lwyd (SH 730 427) which resulted in this hill's significant height revision

For details on the survey that significantly revised the summit height of this hill please click {here}

Myrddyn Phillips and Aled Williams (March 2016)





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