Friday, 5 February 2016

Mapping Mountains – Summit Relocations – 200m Twmpau

Bwlch Clump (SJ 170 108)  

There has been a detwinning of summits that is being detailed as a Summit Relocation initiated by a survey with the Trimble GeoXH 6000 in the list of 200m Twmpau (thirty welsh metre prominences and upward) hills, with the following details being retrospective as the survey that resulted in this summit relocation was conducted on the 20th January 2016.

The hill was originally included in the main 200m P30 list that appeared on Geoff Crowder’s website as a single summit 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), with its 262m summit listed at SJ 173 109 which is where this spot height appears on the Ordnance Survey 1:25,000 Explorer map.  The hill later gained a twin summit when the Ordnance Survey enlarged mapping hosted on the Geograph website became available, and which included a 262m spot height for the adjacent hill at SJ 170 108, which 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.

The hill is situated in the eastern part of the Carnedd Wen range of hills, and between the small communities of Meifod and Maesmawr, with access to the hill relatively easy as there are public footpaths to the west and east, although its summit does not appear on open access land, 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 summit 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 (converted to OSGM15)

The Trimble GeoXH 6000 gathering data at the confirmed higher summit of Bwlch Clump, with the old twin topped summit of Pt. 262.8m 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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