Cefn Cyfarwydd (SH 752 630) – 500m Double Sub-Pedwar
reclassified to 500m Sub-Pedwar
There has been a reclassification of a hill that
is listed in the Y Pedwarau, with the summit height, bwlch height
and their locations, the drop and status of the hill confirmed by a survey with
the Trimble GeoXH 6000 conducted by Myrddyn Phillips and Aled Williams which
took place on the 17th February 2019.
 |
| Cefn Cyfarwydd (SH 752 630) |
The criteria for the list that this
reclassification applies to are:
Y Pedwarau – Welsh hills at or above 400m
and below 500m in height with 30m minimum drop, accompanying the main Y Pedwarau list are five categories of
sub hills, with this hill being reclassified from a 500m Double Sub-Pedwar to a 500m
Sub-Pedwar. The criteria for 500m Double Sub-Pedwar status being all
Welsh hills at or above 500m and at or below 510m in height that have 20m or
more and below 30m of drop, with the criteria for 500m Sub-Pedwar status being all Welsh hills at or above 500m and at
or below 510m in height with 30m minimum drop.
The list is a joint compilation between Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.
The name of the hill is Cefn Cyfarwydd, and it is
adjoined to the Carneddau group of hills, which are situated in the north-western part of North Wales (Region A,
Sub-Region A1), and it is positioned with the A5
road to its south and the B5106 and the A470 roads and the Afon Conwy to its
east, and has the villages of Trefriw and Llanrwst towards the east.
Prior to the survey with the Trimble GeoXH 6000
this hill was listed with 26m of drop based on the 503m summit and 477m bwlch
spot heights that appear on the Ordnance Survey 1:25,000 Explorer map.
 |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
The details for this hill were re-assessed when
the Ordnance Survey Vector Map Local hosted on the Geograph website became
available online; this mapping is entitled the Interactive Coverage Map. As this mapping is larger in format it
enables a better judgement of interpolated heights and it occasionally has
contours at 5m intervals compared to the 10m contour intervals normally shown
on the 1:25,000 Explorer map. However,
this mapping has the same spot heights and 10m contouring as the 1:25,000
Explorer map and therefore the drop value for this hill remained listed as 26m.
The area taking in this hill was re-examined when
the OS Maps website became available online.
This is the replacement for OS Get-a-map and has contours at 5m
intervals. This mapping shows the 477m
bwlch spot height to be positioned on a separate 475m contour ring implying
that the height of this hill’s bwlch is substantially lower than 477m, with
interpolation based on this contouring giving the hill c 30m of drop. But it was not until the survey with the
Trimble GeoXH 6000 that the increased drop value was confirmed.
 |
| Extract from the OS Maps website |
The reclassification of Cefn Cyfarwydd from 500m Double Sub-Pedwar status is due to
a survey with the Trimble GeoXH 6000, resulting in a 501.7m summit height and a
471.0m bwlch height, with these values giving this hill 30.7m of drop which is
sufficient for it to be classified as a 500m
Sub-Pedwar.
 |
| The Trimble GeoXH 6000 gathering data at the summit of Cefn Cyfarwydd |
The full details for the hill are:
Group: Carneddau
Name: Cefn Cyfarwydd
OS 1:50,000 map: 115
Summit Height: 501.7m
(converted to OSGM15)
Summit Grid Reference:
SH
75201 63067
Bwlch Height:
471.0m (converted to OSGM15)
Bwlch Grid Reference:
SH 74708 62751
Drop: 30.7m
For the additions, reclassifications and deletions to Y Pedwarau reported on Mapping Mountains
since the May 2013 publication of the list by Europeaklist please consult the available
and following Change Registers:
Myrddyn Phillips and Aled Williams (July 2019)
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