Saturday, 30 May 2020

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

Carn Hyddgen (SN 792 908) – 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.

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:

25th 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:

29th 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.

25th 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 Carn Hyddgen, and it is adjoined to the Pumlumon group of hills which are situated in the western part of Mid Wales, and it is positioned with the A487 road to the west, the A44 road to the south and the B4518 road to the east, and has the town of Machynlleth towards the north-north-west.

This hill was not included in the original 1995 Constable publication, but with a 566m summit spot height and bwlch contouring between 510m – 520m that appear on the Ordnance Survey 1:25,000 Explorer map, this hill was an automatic entry to the listing of Deweys.  However, its proximity to the hill named Foel Uchaf (SN 802 912) on contemporary Ordnance Survey maps, which is given a 565m summit spot height may have implicated it being missed from the original listing, and when Carn Hyddgen was included this may have led to the subsequent deletion of Foel Uchaf; the lower map heighted hill, which was later reinstated.

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

The above detail was noted by David Purchase and Myrddyn Phillips who worked independently but also exchanged all data.  These details were forwarded to the list author; Michael Dewey and the hill was added to the list on the 11th May 2000.

Extract from the Magic Maps website

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 gives a 514m spot height on the area of this hill’s bwlch, and when coupled with the 566m summit spot height these values give this hill 52m of drop.  The 514m spot height is also shown on Ordnance Survey data that appears on the Magic Maps website.

The full details for the hill are:

Name:  Carn Hyddgen

OS 1:50,000 map:  135

OS 1:25,000 map:  215

Summit Height:  566m (spot height)

Summit Grid Reference:  SN 79233 90831 (hand-held GPS via DoBIH)

Bwlch Height:  514m (spot height)

Bwlch Grid Reference:  SN 80386 92697 (spot height)

Drop:  52m (spot height summit and bwlch)

Myrddyn Phillips (May 2020)

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