Pt. 504.7m (SH 744 624) – Uchaf deletion
There has been a deletion to a hill that is listed in the Yr Uchafion, with the summit height,
bwlch height and their locations, the drop and status of the hill confirmed by
a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams
which took place on the 17th February 2019.
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| Pt. 504.7m (SH 744 624) |
The criteria for the list that this deletion applies to are:
Yr Uchafion – This is the draft title for the Welsh 500m P15s list that takes in all
hills in Wales at or above 500m in height with 15m minimum drop. Accompanying the main list are three sub
lists, these are; 500m Sub-Uchaf, 490m Sub-Uchaf and the Double Sub category. The
list is co-authored by Myrddyn Phillips and Aled Williams with the introduction to the list being published on Mapping Mountains in November 2015.
As the authors do not know an appropriate name for
the hill either from historic research or from local enquiry it is being listed
by the point (Pt. 504.7m) notation, 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 is positioned with the A5 road to its south and the A470
road and the Afon Conwy to its east, and has the village of Betws-y-coed
towards its south-east.
This hill was not included when the original list
of Welsh 500m P15s was compiled as the Ordnance Survey 1:25,000 Explorer map
gives it one continuous contour ring and without any spot height at either its
summit or bwlch its drop value was hard to determine through interpolation
alone.
 |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
This hill was first surveyed using a basic
levelling staff on the 18th May 2004 by Myrddyn Phillips resulting
in a 49½ft / 15.1m
drop value, which was sufficient for it to be classified as an Uchaf.
The details for this hill were reassessed when the
Ordnance Survey Vector Map Local hosted on the Geograph website became
available online, and which is entitled the Interactive Coverage Map. This mapping compliments its 1:25,000 map
counterpart and does not give a spot height at either this hill’s summit or
bwlch.
The details for this hill were next re-assessed
when the OS Maps website became available online. This is the replacement for OS Get-a-map and
has contours at 5m intervals. This map
shows the hill as having two continuous contour rings which implies that its
drop may not be sufficient for the minimum of 15m required to be classified as
an Uchaf.
As the drop value determined by the basic
levelling survey was marginal compared to the 15m drop criterion this hill was
prioritised for a survey with the Trimble GeoXH 6000. The hill has two potential high points and
each was surveyed as well as its critical bwlch, resulting in the following:
1st potential summit: 504.523m at SH 74415 62527
Summit:
501.691m at SH 74482 62452
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| The Trimble GeoXH 6000 gathering data at the summit of Pt. 504.7m (SH 744 624) |
Therefore, the deletion of Pt. 501.7m from Uchaf
status is due to a survey with the Trimble GeoXH 6000, resulting in a 501.7m
summit height and a 491.4m bwlch height, with these values giving this hill 13.3m
of drop which is insufficient for it to be retained as an Uchaf.
The full details for the hill are:
Group: Carneddau
Name: Pt. 504.7m
OS 1:50,000 map: 115
Summit Height: 504.7m
(converted to OSGM15)
Summit Grid Reference:
SH 74482 62452
Bwlch Height: 491.4m
(converted to OSGM15)
Bwlch Grid Reference:
SH 74150 62406
Drop: 13.3m
For the additions, deletions and reclassifications to Yr Uchafion / The Welsh 500m P15s
reported on Mapping Mountains please consult the following Change Registers:
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