Saturday, 11 July 2015

Mapping Mountains – Summit Relocations – Y Pedwarau

Lan Fawr (SN 939 578) 

There has been a Summit Relocation to the listing of the Y Pedwarau initiated from a survey with the Trimble GeoXH 6000.  Y Pedwarau takes in all 400m Welsh hills that have a minimum drop of 30m, and the following details are retrospective as the survey that resulted in this summit relocation was conducted on 21st May 2015.

Accompanying the main P30 Y Pedwarau list are a number of sub category of hills, with this hill being listed as a 400m Sub-Pedwarau, these are the Welsh 400m hills that have 20m or more and below 30m of drop.

The hill is positioned in the wilds of the Elenydd and the survey was conducted on a fine and bright day during a circuit of five hills.  The hill is situated between the small communities of Pontnewydd-ar-Wy (Newbridge-on-Wye) to its east and Beulah to its south.

The name of the hill is Lan Fawr, and its summit position used to be listed at SN 940 577 as this is where the 461m spot height appears on current Ordnance Survey maps, this point is situated on moorland that is prone to be water logged.

The position of the relocated summit is at SN 93963 57819 and is the top of a large erratic boulder, this position is not given a spot height on current Ordnance Survey maps but the survey result produced by the Trimble GeoXH 6000 gave it as 0.25m higher when compared to the high point of its adjacent moorland top.

The full details for the hill are:

Cardinal Hill:  Gorllwyn

Summit Height:  460.8m (converted to OSGM15)

Name:  Lan Fawr

OS 1:50,000 map:  147

Summit Grid Reference (New Position):  SN 93963 57819  

Drop:  22.0m (converted to OSGM15)

The Trimble GeoXH 6000 gathering data at the new summit position of Lan Fawr, with the old position of the summit in the background of the photo

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

Myrddyn Phillips and Aled Williams (May 2015)

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