Friday, 5 February 2016

Mapping Mountains – Summit Relocations – 200m Twmpau

Bwlch Clump (SJ 170 108)  

This is the twenty third post under the heading of Summit Relocations, with the following details being retrospective as the Trimble survey that resulted in this summit relocation was conducted on the 20th January 2016.

The twenty third summit relocation initiated from a survey with the Trimble GeoXH 6000 was conducted in the eastern part of the Carnedd Wen range of hills, between the small communities of Meifod and Maesmawr.

The hill was originally included in the main 200m P30 list that appeared on Geoff Crowder’s website as a single summit under the current 1:25,000 Explorer map height of 262m (SJ 173 109), and listed under the partly invented name of Pen y Bryn Wood (Bryn Wood being the name of the wood to the north-east of the originally listed hill’s summit).  The hill gained a twin summit when the Ordnance Survey enlarged map on the Geograph website included a 262m spot height for the adjacent hill at SJ 170 108, this was named as Bwlch Clump on this map.  Therefore the main purpose of this survey was to ascertain which of the two summits is higher and separate their twin top status.

Access to the hill is easy as there are public footpaths to its west and east, although its summit does not appear on open access ground, therefore permission to visit the high point should be sought.

The names of the two map heighted twin tops are Pt. 262.8m and Bwlch Clump, with the former point (Pt.) notation being used as a name for the hill does not exist on current maps, with the latter name appearing on the Ordnance Survey enlarged Geograph map.

Prior to the survey with the Trimble GeoXH 6000 this hill was listed as a twin top with each 262m map heighted top appearing at SJ 173 109 and SJ 170 108 respectively.

The survey results for this once twin topped P30 are:

Pt . 262.8m

262.8m (converted to OSGM15) summit at SJ 17354 10914

243.5m (converted to OSGM15) bwlch at SJ 17190 10797

19.4m drop

Bwlch Clump

263.9m (converted to OSGM15) summit at SJ 17063 10813

234.9m (converted to OSGM15) bwlch at SJ 17089 10581

29.1m drop

Therefore the survey with the Trimble GeoXH 6000 confirms that Bwlch Clump is 1.1m higher than Pt. 262.8m, and therefore Bwlch Clump is now listed as the prioritised, higher summit.

The full details for the hill are:

Cardinal Hill:  Carnedd Wen

Summit Height:  263.9m (converted to OSGM15)

Name:  Bwlch Clump

OS 1:50,000 map:  125

Summit Grid Reference (confirmed higher summit):  SJ 17063 10813

Drop:  29.1m

The Trimble GeoXH 6000 gathering data at the confirmed higher summit of Bwlch Clump, with the old twin topped summit of Pt. 263m in the background of this photograph

For details on the survey that confirmed the higher of the two map heighted twin tops of this hill please click {here}

Myrddyn Phillips (January 2016)

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