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

Y Drum (SJ 082 378) – 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 Change Register giving detail to this list and its alterations since publication in the Mountain tables book. 

Y Drum (SJ 082 378)

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 Y Drum, and it is adjoined to the Y Berwyn group of hills, which are situated in the south-eastern part of north Wales, and it is positioned with the A5 road to its north and the B4401 road to its west, and has the village of Cynwyd towards the north-west. 

This hill was not included in the original 1995 Constable publication, as with a 579m summit spot height and a 551m bwlch spot height that appear on the Ordnance Survey 1:25,000 Explorer map it was accepted that the hill had under 30m of drop. 

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

Since the 1995 publication of this list by Constable there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the mapping on the OS Maps website.  This is the replacement for OS Get-a-map and it used to have contours at 5m intervals which proved consistently more accurate compared to the 5m contours that sometimes appear on Ordnance Survey 1:25,000 Explorer maps and used to appear on the online Vector Map Local.  This mapping had bwlch contouring between 545m – 550m, with interpolation giving an estimated bwlch height of c 549m and therefore an estimated c 30m of drop. 

With this newly acquired information the hill was prioritised for a GNSS survey and this took place on the 26^th November 2020.  The summit and bwlch of this hill were surveyed by Myrddyn Phillips with Aled Williams and Mark Trengove assisting, using a Trimble GeoXH 6000 resulting in a 579.1m summit height and a 549.0m bwlch height, with these values giving this hill 30.1m of drop. 

The Trimble GeoXH 6000 gathering data at the bwlch of Y Drum

The Trimble GeoXH 6000 gathering data at the summit of Y Drum

These details were forwarded to the list author; Michael Dewey and the hill was subsequently added to his list on 28^th November 2020. 

 

The full details for the hill are: 

Name:  Y Drum 

OS 1:50,000 map:  125

OS 1:25,000 map:  255

Summit Height:  579.1m (converted to OSGM15)

Summit Grid Reference:  SJ 08247 37893

Bwlch Height:  549.0m (converted to OSGM15)

Bwlch Grid Reference:  SJ 08003 38256

Drop:  30.1m

 

Myrddyn Phillips (June 2021)