Cribau (SH 732 641) – Uchaf reclassified
to 500m Sub-Uchaf
There has been a reclassification 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.
 |
| Cribau (centre foreground) (SH 732 641) |
The criteria for the list that this reclassification 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, with this hill being reclassified to the 500m Sub-Uchaf category, with
the criteria for this sub category being all Welsh hills at or above 500m in
height that have 14m or more and below 15m of drop. 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.
The name of the hill is Cribau, 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 A470 road and the Afon Conwy to its east, and has the village
of Llanrwst towards its east 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 does
not give it a summit or bwlch spot height, and even though contemporary maps
give it two continuous 10m contour rings implying its drop is greater than 10m
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 13th December 2005 by Myrddyn Phillips
resulting in a 51ft / 15.5m 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 three continuous contour rings which again implies that
its drop is greater than 10m.
As the drop value determined by the basic
levelling survey was marginal 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: 501.465m at SH 73254 64019
Summit: 501.887m
at SH 73264 64129
 |
| Gathering data at the first point surveyed for the summit position of Cribau |
 |
| Gathering data at the second point surveyed for the summit position of Cribau |
Therefore, the reclassification of Cribau to 500m
Sub-Uchaf status is due to a survey with the Trimble GeoXH 6000, resulting in a
501.9m summit height and a 487.3m bwlch height, with these values giving this
hill 14.6m of drop which is insufficient for it to be retained as an Uchaf.
The full details for the hill are:
Group: Carneddau
Name: Cribau
OS 1:50,000 map: 115
Summit Height: 501.9m
(converted to OSGM15)
Summit Grid Reference:
SH 73264 64129
Bwlch Height: 487.3m
(converted to OSGM15)
Bwlch Grid Reference:
SH 73056 63919
Drop: 14.6m
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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