Mapping Mountains – Hill Reclassifications – Humps

Moel Farlwyd (SH 707 486) – Subhump reclassified to Hump

This is the thirty seventh 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 and / or surveys that I have instigated, or it is the recommendation that their status is altered.

At the summit of Moel Farlwyd (SH 707 486)

Many preceding posts detailing these hill reclassifications are retrospective as they were initiated from studying the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map, or from surveying with the Trimble GeoXH 6000, or from LIDAR analysis, and for this reclassification that affected the Humps the email I posted on the RHB Yahoo Group forum in relation to this hill was dated 01.02.20.

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 the reclassification appear below:

There has been a reclassification to the listing of the Humps (HUndred Metre Prominences) partly instigated by study of contemporary Ordnance Survey maps conducted by Myrddyn Phillips.

The name the hill is listed by is Moel Farlwyd and it is adjoined to the Moelwynion group of hills, and it is positioned with the A470 road to its west, and has the town of Blaenau Ffestiniog towards the south.

Prior to this reclassification this hill was listed as a Subhump with 98m of drop based on the 577m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and a bwlch height of 479m based on interpolation of 10m contours between 470m – 480m.

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

The details for this hill were re-assessed using a combination of various scaled Ordnance Survey maps, including the mapping on the OS Maps website.  This is the replacement for OS Get-a-map and has contours at 5m intervals which are proving 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 re-assessment resulted in a recommendation of this hill being reclassified to a Hump with an estimated c 100m – c 101m of drop.

Extract from the OS Maps website

This hill was subsequently surveyed on the 06.02.20 by John Barnard and Graham Jackson using a Leica GS15, resulting in a 575.7m summit height and a 474.3m bwlch height, with these values giving this hill 101.4m of drop.

The listing of the Humps was updated accordingly with the reclassification of this hill from Subhump to Hump and augmented on the 07.02.20.

The full details for the hill are:

Name:  Moel Farlwyd

OS 1:50,000 map:  115

OS 1:25,000 map:  18

Summit Height:  575.7m (converted to OSGM15, Leica GS15)

Summit Grid Reference:  SH 70738 48643 (Leica GS15)

Bwlch Height:  474.3m (converted to OSGM15, Leica GS15)

Bwlch Grid Reference:  SH 71144 48719 (Leica GS15)

Drop:  101.4m (Leica GS15)

Myrddyn Phillips (June 2020)