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

Foel y Geifr (SH 716 050) – Dewey deletion

This is one in a series of Hill Reclassification posts that detail hills whose status has altered in the listing of the Deweys.  These posts tie in with a ChangeRegister giving detail to this list and its alterations since publication in the Mountain tables book. 

Foel y Geifr (SH 716 050)

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.

 

Postscript:  Michael Dewey died on the 5^th November 2022.  His wife; Gillian wished for this list to be carried on and made provision for it to be co-authored by Myrddyn Phillips.  Michael will always be the compiler and originator, it’s just that he’s now got a co-author to safeguard and carry this list on.

Mountain tables by Michael Dewey

The details for this deletion appear below:

The name the hill is listed by in the Deweys is Foel y Geifr, and it is adjoined to the Cadair Idris group of hills which are situated in the south-western part of North Wales, and it is positioned with the B4405 road to its north-west, the A493 road to its south and the A487 road to its east, and has the town of Machynlleth towards the south-east.

This hill was not included in the original 1995 Constable publication, but with a 515m summit spot height and bwlch contouring between 480m – 490m 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 Myrddyn Phillips who then conducted a basic levelling survey of this hill on the 26^th June 2000, resulting in over 30m of drop.  These details were forwarded to the list author; Michael Dewey and the hill was added to the list with the date of survey given in the Remarks column accompanying the list.

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR image of Foel y Geifr (SH 716 050)

Therefore, the deletion of this hill from the The 500-Metre Tops of England and Wales list was instigated on the 26^th May 2023 and is due to LIDAR analysis first reported by the DoBIH team based on detail produced by Joe Nuttall in his surface analysis programme, resulting in a 515.6m summit height and a 486.8m bwlch height, with these values giving this hill 28.8m of drop, which is insufficient for it to be classified as a Dewey. 

 

The full details for the hill are: 

Name:  Foel y Geifr 

OS 1:50,000 map:  124

OS 1:25,000 map:  23

Summit Height:  515.6m (LIDAR) 

Summit Grid Reference:  SH 71634 05092 (LIDAR) 

Bwlch Height:  486.8m (LIDAR) 

Bwlch Grid Reference:  SH 71726 05403 (LIDAR) 

Drop:  28.8m (LIDAR) 

 

Myrddyn Phillips (July 2023)