07.07.26 Yr Wyddfa
(SH 609 543, only bwlch surveyed)
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| The Trimble GeoXH 6000 and Leica Gs15 gathering data at the summit of Yr Wyddfa |
In September 2014 along
with Graham Jackson and John Barnard I surveyed the summit of Yr Wyddfa. In attendance was Mark Greaves representing
Ordnance Survey. It was Mark who later
processed the gathered data. Our
endeavours were filmed by Stephen Edwards of Cread Cyf and Aled Llŷr,
with the film appearing on ITV Wales.
The summit architecture of Yr Wyddfa has changed
over many years, with all manner of structures being built. These have consisted of huts where horses were
stabled and the Victorian tourists who ascended on them could rest, take in the
view, if indeed one existed and recover from their exploits before the journey
back down the mountain.
Over time huts evolved in to a hotel and
latterly a summit café. However, these
constructions did not limit themselves to the ground surrounding the summit,
they also took in the summit itself, with massive cairns of stone, a flag pole
and latterly a summit plinth with a weather station and identification plague
on top of what is fashioned to resemble a triangulation pillar. This stands atop the aforementioned plinth which
has been constructed over the natural summit tor. Thankfully we have a bench mark height to the
bedrock which can supposedly still be accessed from a small window on the side
of the weather station. It was the
wisdom of Ordnance Survey who installed the bench mark and documented its
height, as all we could do when resurveying the summit of Yr Wyddfa was take a
measurement to the concrete plinth, which is an obvious man-made addition to
the height of the mountain.
As with many listings, the qualification whether
a hill should be included is dependent upon its drop. This is the height difference between its
summit and bwlch that connects to the next higher summit along its watershed. The approximate position of the Yr Wyddfa
bwlch had been known for many years and to my knowledge was first documented by
Alan Dawson. This connecting bwlch is
positioned beside the Forth and Clyde canal in Scotland.
The Ordnance Survey give a 46m spot height on
the 1:25,000 Explorer map at NS 76804 78578, which could be where the critical
point of this bwlch is positioned.
However, map study shows two burns descending southward from the
hillside above the small community of Kelvinhead. As these two burns near the canal one heads
westward and the other eastward, suggesting that the bwlch is positioned on
ground between the two. This is the best
available evidence we have at the moment for the position of this bwlch, until
LIDAR becomes available for this part of the country.
This was a survey I had wanted to do for many
years, but opportunity was limited as I now rarely venture north in to
Scotland. However, with an offer to stay
accompanied by John Kirk, in Mark Trengove and his wife’s newly built second
home in Laird in Wester Ross, this gave us the prospect to survey this bwlch on
our way north.
Arriving at Mark’s at midday we quickly packed
my gear in his car and he then proceeded to drive to John’s in Burnley where we
over-nighted before John took over the driving duties heading north. As the hours of travel slowly ticked by the
weather became more inclement with fine drizzled spots of rain hitting the
windscreen. By the time we left the M80
and drove in to Kelvinhead the sky was coloured light grey and light rain interspersed
with more drizzle met us as I quickly got my walking boots on for the walk down
to the canal.
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| Heading down the path toward the bwlch |
John seemed to know this area well and we
followed him toward the gate giving access to the narrow path leading down
beside what turned out to be one of the burns, which only showed its watery
trickle as we approached the canal. This
burn was on our right as we descended, whilst the burn on our left was no more
than a slight indentation consisting of lots of greenery, which as least
intimated that water was in fact present.
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| Nearing the bwlch |
A gate gave further access to the canal towpath,
and it was close to this gate where the majority of our efforts were
concentrated, as all ground on the path descended to this point and beyond the
gate all ground went uphill for a short distance to the canal towpath. On our way through the gate we had a quick
discussion where we considered the critical point to be positioned. We then visited the canal which was unexpectedly wide at this point. The surprise
at its width was based on the experience of my local Montgomeryshire canal
where two narrow boats crossing would be the limit; this canal was like a river. However, John later explained that this part
consisted of a water basin where boats could pass without difficulty.
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| Arriving on the canal towpath |
We stood beside the water for a number of
minutes with John pointing out the ditch on the far side of the canal. If whilst on the valley to valley traverse
the height of a cutting was taken as the critical point of the bwlch, the ditch
formed a major difficulty in our endeavours as from this vantage point it
looked lower on the hill to hill traverse, but again John explained that
breaking the ditch is a bank that goes in the hill to hill direction, thus
increasing the high point of the valley to valley traverse if following the
ditch. Therefore, it seemed we were safe
in taking the ground close to the gate as the critical point for the bwlch of
Yr Wyddfa.
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| The western view of the canal |
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| Looking south on the hill to hill traverse with the ditch evident adjacent to the opposing bank |
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| The eastern view of the canal |
Once a few photos of the canal were taken we
backtracked to the gate and had a good inspection of the path and its downward
passage toward this point. We initially
considered gathering data from the ground immediately through and at the base
of the gate, but soon the Trimble was moved to the path leading toward the
gate. Ground hereabouts within a ten
metre distance looked consistently flattish and with little margin of
uncertainly for such a survey the Trimble was quickly positioned on my
rucksack, which in instances like this forms a convenient makeshift
tripod. Once the 0.1m accuracy level was
attained before data should be logged, I pressed ‘Log’ and headed back through
the gate to stand away from the equipment as it gathered its customary five
minutes of data.
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| The Trimble GeoXH 6000 gathering data at the bwlch of Yr Wyddfa |
After data were gathered and stored I closed the
equipment down and took a series of photos from various directions of the
Trimble in situ. It was then packed away
and we headed up the path toward the dry confines of John’s car. On the way we met David Henderson on his quad
bike with three attendant sheep dogs scampering after him. I flagged him down for a chat.
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| The northern view from the bwlch |
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| The eastern view from the bwlch |
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| The southern view from the bwlch |
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| The western view from the bwlch |
We spent a number of minutes with David; he told
us he’s known as Dov by all his friends.
I happily explained the significant of the land he farms and
specifically the point on the path no more than five minutes down from where we
were now standing. He didn’t look amazed,
which was a disappointment and seemed to take in the critical nature of this
point in his stride. Aw well!
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| The view further east |
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| David Henderson with Bessie, Roy and Peggy |
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| Leaving the bwlch |
After leaving David we continued on the slight
uphill leading back to the houses in Kelvinhead. By now the intermittent rain and drizzle had
in the main relented, just long enough for me to get my walking boots off and
after a quick repositioning of my gear around the back seat of John’s car, we
were away on our trip heading farther north in to the beautiful wilds of
northern Scotland.
Survey Result:
Yr Wyddfa
Summit Height: 1084.8m (converted to OSGM15) (Ordnance
Survey historical data to bedrock at summit)
Summit Grid Reference: SH 60985 54374 (Old triangulation pillar and
Ordnance Survey historical data to bedrock at summit)
Bwlch Height: 47.6m (converted to OSGM15, Trimble GeoXH
6000)
Bwlch Grid Reference: NS 75797 78295 (Trimble GeoXH 6000)
Drop: 1037.2m (Ordnance Survey historical data to
bedrock at summit and Trimble GeoXH 6000 bwlch)
Dominance: 95.61% (Ordnance Survey historical data to
bedrock at summit and Trimble GeoXH 6000 bwlch)
My thanks to Alan Dawson with
help processing these data
For details on the 1st
summit survey of this hill
For details on the 2nd
summit survey of this hill
For further details please consult the Trimble Survey Spreadsheet
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