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

Moel yr Wden (SH 780 356) – 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.

Moel yr Wden (SH 779 353)

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 Moel yr Wden, and it is adjoined to the Arenig group of hills which are situated in the central part of north Wales, and it is positioned with the A4212 road to its north-west, the A470 road to its south-west and the A494 road to its south-east, and has the village of Trawsfynydd towards the west.

The Name: Moel yr Wden is a transposed name as local enquiry confirms that it is applicable to a 520m upper contour map heighted hill positioned to the west of this, the qualifying Dewey, with the name placement on the Ordnance Survey 1:50,000 Landranger map being appropriate.

This hill was not included in the original 1995 Constable publication, as with a 560m uppermost contour and bwlch contouring between 530m – 540m that appear on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and with the opposing 540m contours relatively close together, this implied this hill was unlikely to have sufficient drop to qualify for this list. 

Extract from the Ordnance Survey 1:50,000 Landranger map

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

Although the above was noted by Myrddyn Phillips, a basic levelling survey of this hill was conducted on the 21^st July 2000, with a surprising result of 112ft / 34.1m of drop.  As this result was at odds with Ordnance Survey contouring, Michael Dewey was informed, but it was decided not to promote this hill to Dewey status and wait for the result of a second survey of this hill.

The second basic levelling survey of this hill was conducted on the 27^th October 2001 by Myrddyn Phillips and Rob Woodall, resulting in the same drop value as the first; 112ft / 34.1m.  These details were forwarded to the list author; Michael Dewey and the hill was added to the list on the 2^nd November 2001.

Graham Jackson and Janet Jackson during the line survey of Moel yr Wden

As this hill qualified for the Dewey list through a basic levelling survey and as this was at odds with Ordnance Survey map contouring, it was prioritised for a line survey, and this took place on the 31^st March 2008.  The line survey consisted of two teams; Graham Jackson and Janet Jackson who concentrated on the drop value of Moel yr Wden, and John Barnard and Myrddyn Phillips who line surveyed from the 619m map heighted summit of Gallt y Daren (SH 778 344) to the bwlch position of Moel yr Wden, this resulted in 34.1m of drop with the summit of Moel yr Wden being 572.9m in height dependent upon the accuracy of the 619m spot height atop Gallt yr Daren.  This survey confirmed this hill’s Dewey status.

The Leica 530 set-up position at the summit of Moel yr Wden

The Leica 530 set-up position at the bwlch of Moel yr Wden

As the resulting height of Moel yr Wden was still at odds with its 560m uppermost Ordnance Survey contour the hill was prioritised for a GNSS survey.  This was conducted by John Barnard, Graham Jackson and Myrddyn Phillips on the 25^th November 2008, resulting in a 572.3m summit height and a 538.2m bwlch height, with these values giving this hill 34.0m of drop, confirming that the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map are missing an uppermost 570m ring contour.

The full details for the hill are:

Name:  Moel yr Wden

OS 1:50,000 map:  124

OS 1:25,000 map:  18, 23

Summit Height:  572.3m (Leica 530)

Summit Grid Reference:  SH 78012 35618 (Leica 530)

Bwlch Height:  538.2m (line survey relative to summit height)

Bwlch Grid Reference:  SH 77981 35395 (Leica 530)

Drop:  34.1m (line survey)

Myrddyn Phillips (August 2020)