Mapping Mountains – Hill Reclassifications – Humps

 

Cefn Dreiniog (SJ 145 147) – proposed Subhump deletion

This is the thirty ninth in a series of Hill Reclassification posts that detail hills whose status has either been altered in the listing of the Humps (HUndred Metre Prominences) through map study, surveys or LIDAR analysis that I have been involved in, or it is the recommendation that their status is altered.

Cefn Dreiniog (SJ 145 147)

Many preceding posts detailing these hill reclassifications are retrospective as they were initiated from studying the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map, or from surveying with the Trimble GeoXH 6000, or from LIDAR analysis, and for this proposed deletion that affects the Humps the email I posted on the pedantic@groups.io forum in relation to this hill was dated 24.03.21.

The listing of Humps was published in book format by Lulu in 2009 and entitled More Relative Hills of Britain, its author; Mark Jackson gives credit to a number of people who contributed toward the formation of this list, these include; Eric Yeaman, Alan Dawson, Clem Clements, Rob Woodall, Bernie Hughes, Pete Ridges and others.  When the list was published in book format there were 2987 Humps listed with their criteria being any British hill that has 100m or more of drop, irrespective of their height.  Accompanying the main list is a sub category entitled Subhumps, with the criteria being any British hill that has 90m or more and below 100m of drop.

More Relative Hills of Britain by Mark Jackson

The details for this proposed deletion appear below:

There has been a proposed deletion to the listing of the Humps (HUndred Metre Prominences) instigated by a combination of detail on maps produced from Ordnance Survey data and a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips.

The name the hill is listed by is Cefn Dreiniog and it is adjoined to the Y Berwyn group of hills, and it is encircled by minor roads with the A495 road farther to its south-east, and has the village of Meifod towards the south south-east.

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

This hill is currently listed as a Subhump with 90m of drop based on the 318m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and the 228m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map.

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

This hill was subsequently surveyed on the 16.03.21 by Myrddyn Phillips using a Trimble GeoXH 6000, resulting in a 317.1m summit height and when coupled with the 228m bwlch height, these values give this hill 89m of drop, which is insufficient for Sumhump status.

 

The full details for the hill are:

Name:  Cefn Dreiniog

OS 1:50,000 map:  125

OS 1:25,000 map:  239

Summit Height:  318m (as listed in the Humps, with the Trimble GeoXH 6000 survey giving 317.1)

Summit Grid Reference:  SJ 14508 14704 (as listed in the Humps, with the Trimble GeoXH 6000 survey giving SJ 14506 14701)

Bwlch Height:  228m

Bwlch Grid Reference:  SJ 140 148

Drop:  90m (as listed in the Humps with the Trimble GeoXH 6000 summit survey and bwlch spot height giving 89m)

 

Myrddyn Phillips (July 2021)