Tuesday, 14 July 2015

Mapping Mountains – Summit Relocations – Y Pedwarau

Pt. 483.6m (SH 735 428)

There is a Summit Relocation to the Y Pedwarau list of Welsh 400m hills that has been confirmed by a survey with the Trimble GeoXH 6000.  The Y Pedwarau takes in all 400m summits in Wales that have a minimum 30m of drop.

This summit relocation was initiated from a visual inspection conducted by Aled Williams on 4th July 2015 in the hills between the Moelwynion and the Migneint, and which was later confirmed by the survey with the Trimble GeoXH 6000 on the 14th March 2016.

The hill is listed as a Pedwar with its summit position previously given as SH 735 429, this grid reference is the position of the 486m spot height that appears on the Harvey 1:40,000 British Mountain Map.

The summit area of this hill has four small 480m contour rings on the current Ordnance Survey 1:25,000 Explorer map.  None of these contour rings has a spot height given to them on Ordnance Survey maps with the one positioned furthest north also being the largest, the position of this contour ring is where the 486m spot height appears on Harvey Maps.

The position of the ten figure grid reference determined by the Trimble GeoXH 6000 for the four 480m contour rings that appear on the current Ordnance Survey 1:25,000 map and their respective heights appear below:

Contour 1:  SH 73542 42903    482.686m (converted to OSGM15)

Contour 2:  SH 73563 42818    482.965m (converted to OSGM15)

Contour 3:  SH 73541 42812    483.574m (converted to OSGM15)

Contour 4:  SH 73475 42798    480.924m (converted to OSGM15)

Contour 1 is the largest and is where the 486m Harvey Maps spot height appears, Contour 4 is the smallest and Contours 2 and 3 are placed near to one another.  It is Contour 3 at SH 73537 42813 that is noticeably higher from every position, and this was confirmed by the Trimble survey.

The hill is unnamed on current Ordnance Survey maps and therefore the point (Pt. 483.6m) notation has been adopted.  Since publication of the 1st edition of Y Pedwarau by Europeaklist our place-name research has continued and Aled has confirmed this hill’s name from a local source, and this name will be used in future publications of Y Pedwarau.

The full details for the hill are:

Cardinal Hill:  Graig Goch

Summit Height:  483.6m (converted to OSGM15)

Name:  Pt. 483.6m

OS 1:50,000 map:  124

Summit Grid Reference (New Position):  SH 73541 42812 
Drop:  34.4m (converted to OSGM15)

The new summit position of Pt. 483.6m is highlighted in yellow, with the old position of the summit highlighted in red on this photograph.  Photo: Aled Williams

Aled Williams and Myrddyn Phillips (July 2015 and March 2016)

No comments: