Mapping Mountains – Hill Reclassifications – The 500-Metre Tops of England and Wales – Deweys

Cefn Coch (SH 923 266) – Dewey addition

This is one in a series of retrospective Hill Reclassification posts that detail hills whose status has altered in the listing of the Deweys and where I have had direct association with the status change.  These posts will tie in with a forthcoming Change Register giving detail to this list and its alterations since publication in the Mountain tables book.

Cefn Coch (SH 923 266)

The 500-Metre Tops of England and Wales are affectionately known after their hill list compiler; Michael Dewey.  This list mixes metric and imperial height in its criteria to bookend up to the 2000ft height band and takes in all hills in England, Isle of Man and Wales that are 500m and above and below 2000ft (609.6m) in height that have 30m minimum drop.

This list formed one of a number of lists that appeared in the Mountain tables book published by Constable in 1995 and at the time of publication comprised 373 hills with 164 in England, 5 in the Isle of Man and 204 in Wales.  The Deweys have undergone extensive revision since first publication with the initial stages forming the basis of this revision given below:

1995    Mountain tables published by Constable with 373 hills listed as Deweys.

April 2000    Strider (LDWA quarterly booklet) publishes contact details for David Purchase and Myrddyn Phillips who have found and list 24 and 14 possible new 500m tops respectively.

It was expanded versions of the above two lists that formed the basis of the next publication:

25^th May 2000    List of Possible 500 Metre Tops by Michael Dewey listing 44 hills.

David Purchase expands his Additional Dewey 500m Hills and Myrddyn Phillips produces lists of English 500m hills to measure and Welsh 500m hills to measure.

These lists formed the basis of the next publication:

29^th June 2000    Possible/Probable 500’s by Michael Dewey listing 77 hills.  Michael adopts following protocol; if one person proposes that a top should qualify as a 500 by personal survey, and is then confirmed by a second person, it should then be promoted to the main list.

April 2002    The 500+ Tops of England and Wales – The ‘New Deweys’ published in the Strider booklet and listing 66 new qualifying hills.

25^th May 2006    Rob Woodall republishes Michael’s main and possible/probable lists on the RHB Yahoo group file database.  

 

Mountain tables by Michael Dewey

The details for this addition appear below:

The name the hill is listed by in the Deweys is Cefn Coch, and it is adjoined to the Aran group of hills which are situated in the southern part of north Wales, and it is positioned with the A494 road to its north and west, the A458 road to its south and the B4393 road to its south-east, and has the town of Y Bala towards the north.

This hill was not included in the original 1995 Constable publication, but with a 594m summit spot height and bwlch contouring between 560m – 570m that appear on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, the interpolated drop value was estimated sufficient for this hill to be a potential new Dewey.

Extract from the Ordnance Survey 1:25,000 Explorer map

The above detail was noted by David Purchase and Myrddyn Phillips, and the latter was joined by Rob Woodall to then conduct a basic levelling survey of this hill on the 28^th October 2001, resulting in 103ft / 31.4m of drop.  These details were forwarded to the list author; Michael Dewey and the hill was added to the list on the 2^nd November 2001.

Rob Woodall during the basic levelling survey of Cefn Coch

Since the inclusion of this hill in the Dewey list the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and gave a 565m spot height on the area of this hill’s bwlch, and when coupled with the 594m summit spot height these values gave this hill 29m of drop.

The Trimble GeoXH 6000 gathering data at the summit of Cefn Coch

The Leica RX1250 gathering data at the bwlch of Cefn Coch

As this hill qualified for the Dewey list through a basic levelling survey and as the online Vector Map Local only gave the hill 29m of drop, it was prioritised for a GNSS survey, and this took place on the 19^th October 2016.  The summit and bwlch of this hill were surveyed by Alan Dawson and Myrddyn Phillips using a Leica RX1250 and Trimble GeoXH 6000 respectively, resulting in a 592.9m summit height and a 561.7m bwlch height, with these values giving this hill 31.25m of drop, and therefore confirming its Dewey status.

The full details for the hill are:

Name:  Cefn Coch

OS 1:50,000 map:  125

OS 1:25,000 map:  23

Summit Height:  592.9m (Leica RX1250)

Summit Grid Reference:  SH 92310 26675 (Leica RX1250)

Bwlch Height:  561.7m (Leica RX1250)

Bwlch Grid Reference:  SH 92501 26927 (Leica RX1250)

Drop:  31.25m (Leica RX1250)

Myrddyn Phillips (August 2020)