18.09.19
Pen yr Orsedd (SH 892 555, only bwlch surveyed)
Pen yr Orsedd is a fine
unassuming hill with its high point consisting of a few rogue embedded rocks
amongst its grassland moored summit. The
last time I visited was in June 2014 with Mark Trengove and Aled Williams. As the Trimble gathered its customary summit
data we lazed in the sun with Llyn Alwen forming a majestic backdrop.
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| Gathering data at the summit of Pen yr Orsedd (SH 892 555) |
Since the summit survey the
5m contouring on the OS Maps website has become available and this is proving an
excellent resource when checking on height values and their placement, and in
the main, is proving more accurate compared to the standard contouring on
Ordnance Survey 1:25,000 Explorer maps.
The summit height
produced by the Trimble GeoXH 6000 for Pen yr Orsedd is 442.211m and with an
estimated bwlch height of c 409m based on contouring between 400m – 410m it
meant that this hill was relatively safe as a Pedwar with an estimated c 33m of
drop. However, the 5m bwlch contours on
the OS Maps website is between 410m – 415m with interpolation giving an
estimated bwlch height of c 412m, with this value giving the hill an estimated
c 30m of drop, which is the minimum drop value for Pedwar status. Therefore the bwlch needed to be surveyed and
given an accurate height.
The bwlch of Pen yr
Orsedd is positioned close to the A543 road as it makes its way north-eastward
from the outskirts of Pentrefoelas toward Dinbych (Denbigh). Google maps indicated I could park at the
entrance to a small disused quarry a couple of hundred metres from where a gate
gives access down to the area of the bwlch.
Having parked I walked the short distance to the gate where there is now
a long flat gravelled area beside the road with sufficient space for a number
of cars to be parked.
The bwlch looked
relatively inviting with beige tinged moor grass predominating, interspersed
with occasional rogue tussocks. Leading
from the gate was a sheep path and a line of vehicle tracks on the moored
grass.
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| The bwlch of Pen yr Orsedd |
I was soon at the area
of the bwlch and the sheep path crossed directly over it, although contour
interpolation placed its critical point slightly to the north. Having deposited my rucksack on where I
judged the bwlch to be positioned, I walked a short distance up the opposing
hillside to look down on it from a different viewpoint. I then contoured to the south and decided
that my rucksack was placed at its critical point.
Sauntering back to the
bwlch I aligned the placement of the Trimble atop my rucksack with the critical
point of the bwlch and set it to gather data.
During data gathering I again ventured up the opposing hillside and
decided that I should take a second data set from just south of the equipment’s
current position.
 |
| Gathering data at the bwlch of Pen yr Orsedd |
Whilst the Trimble
quietly beeped away gathering its individual datum points I took a series of
photos with a succulent yellowed moor as foreground and the great mass of sun
drenched Yr Wyddfa floating above all surrounds as backdrop.
 |
| Yr Wyddfa floating above the moor |
Once the allotted data
were gathered and stored I headed a short distance southward and positioned the
Trimble again atop my rucksack to give it elevation above its immediate
surrounds. This time it was placed
directly on top of one of many impressive rounded green grassed tussocks beside
the start of a bogged water course that indicated this placement to be lower
than the first, which agreed with my visual inspection.
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| The set-up position for the second data set at the area of the bwlch of Pen yr Orsedd |
Bwlch surveying was
proving very enjoyable. It is much
easier than summit surveying and especially so if positioned beside a
road. This bwlch proved another
wonderful place with just the occasional sheep as company, the bwlch just sat
there, seldom visited and giving tranquillity to an otherwise busied scene with
the main road being so close.
Once the allotted data
were gathered from the impressive greened grassed tussock I packed the Trimble
away and walked the short distance back to my car, checked the map and headed
further north-east to the next bwlch, which connects to the Pedwar of Bryn
Trillyn.
Survey Result:
Pen yr Orsedd
Summit Height: 442.2m (converted to OSGM15, from previous
Trimble GeoXH 6000 survey)
Summit Grid Reference: SH 89294 55542 (from previous Trimble GeoXH 6000 survey)
Bwlch Height: 409.2m (converted to OSGM15)
Bwlch Grid Reference: SH 90076 55064
Drop: 33.0m
Dominance: 7.47%
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