Monday, 24 August 2015

Mapping Mountains – Summit Relocations – The Fours

The Wrekin (SJ 628 081)  

There has been a Summit Relocations to the listing of The Fours initiated by a survey with the Trimble GeoXH 6000, with the survey that resulted in the following details taking place on 3rd August 2015.  The Fours are the English 400m hills that have a minimum drop of 30m.

The survey was conducted in the Shropshire hills to the south-west of Wellington which forms a part of Telford, and was conducted during a walk in the company of Charlie Leventon, who had suggested visiting the hill.

The name of the hill is The Wrekin and it is one of the most popular hills in Shropshire with many thousands of visitors each year ascending its well-maintained north-easterly path.  However, the great majority of these people only visit the triangulation pillar which stands near to a panoramic viewfinder.  The trig pillar is given the height of 407m on current Ordnance Survey maps and its flush bracket given the height of 407.106m in the OS Trig Database.  But the hill also has a northerly summit which is of similar height to the ground beside the trig pillar; this was commented on by Charlie in a Summitsup post on his blog dated 16th October 2014.  When data were processed Charlie sent me details to an Ordanance Survey block that is positioned on the northern summit and just below the highest point where the Trimble collected data from, the height given it on the Trigpointing UK site is 406.798m. 

The hill is listed in The Fours with its summit position previously given as SJ 628 080 which is the position of the 407m trig point on current Ordnance Survey maps.  The northerly summit and the highest ground beside the trig pillar were surveyed with the Trimble GeoXH 6000 and the results appear below:

Northerly summit:  406.9m (406.883m to three decimal places and converted to OSGM15) at SJ 62832 08197.

Ground beside trig:  406.7m (406.746m to three decimal places and converted to OSGM15) at SJ 62807 08094

The position of the relocated summit is at SJ 62832 08197 and is the top of featureless ground that mainly consists of earth with grass beside it, this position is not given a spot height on current Ordnance Survey maps but the survey result with the Trimble GeoXh 6000 gave it as 0.14m higher when compared to the highest ground beside the triangulation pillar.

The full details for the hill are:

Cardinal Hill:  The Wrekin

Summit Height:  406.9m (converted to OSGM15)

Name:  The Wrekin

OS 1:50,000 map:  127

Summit Grid Reference (New Position):  SJ 62832 08197
Drop:  310m

The Trimble GeoXH 6000 gathering data at the new summit position of The Wrekin, with the old position of the summit beside the triangulation pillar in the background of this photo

For details on the survey that relocated the summit of this hill please click {here}

Myrddyn Phillips and Aled Williams (August 2015)

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