Werfa (SS 912 947) – Subhump deletion
This is the thirty eighth 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.
Werfa (SS 912 947) |
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 |
There has been a deletion to the listing of the Humps (HUndred
Metre Prominences) instigated by LIDAR analysis initially conducted by
Aled Williams and then independently by Joe Nuttall who produced a summit
analysis programme based on heights and drops of hills produced by LIDAR, and
as there was a discrepancy in bwlch position for these two studies LIDAR analysis
was then conducted by Myrddyn Phillips.
LIDAR bwlch image of Werfa |
The bwlch of Werfa |
Prior to this deletion this hill was listed as a Subhump with
90m of drop based on the 568m summit spot height adjoined to a triangulation
pillar and which appears on the Ordnance Survey 1:50,000 Landranger and
1:25,000 Explorer maps and a bwlch height of c 478m based on interpolation of
10m contouring between 470m – 480m.
Extract from the Ordnance Survey 1:25,000 Explorer map |
This summit of this hill was subsequently surveyed on the 17.04.21
by Myrddyn Phillips and Aled Williams using a Trimble GeoXH 6000, resulting in
a 567.5m summit height and when coupled with the 479.9m bwlch height ascertained
from LIDAR analysis, these values give this hill 87.5m of drop.
The Trimble GeoXH 6000 gathering data at the summit of Werfa |
The full details for the hill are:
Name: Werfa [Mynydd
Llangeinwyr] (as listed in the Humps)
OS 1:50,000 map: 170
OS 1:25,000 map: 166
Summit Height: 568m (as
listed in the Humps, with the Trimble GeoXH 6000 survey giving 567.5m)
Summit Grid Reference:
SS 91278 94773 (as listed in the Humps, with the Trimble GeoXH 6000
survey giving SS 91274 94767)
Bwlch Height: 480.0m (as
listed in the Humps with independent LIDAR analysis giving 479.9m)
Bwlch Grid Reference:
SS 9118 9707 (as listed in the Humps with independent LIDAR analysis
giving SS 91189 97075)
Drop: 88m (as listed
in the Humps with the Trimble GeoXH 6000 summit survey and independent LIDAR
bwlch analysis giving 87.5m)
Myrddyn Phillips (July 2021)
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