24.12.14 Mynydd Poeth
(SH 953 513) and Llechwedd (SH 969 506)
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Llechwedd (SH 969 506)
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With the potatoes set on a veerrrry low roast I
met Mark in Cerrigydrudion just before 10.00am for festive activity on some
Hiraethog Pedwar hills. Mark had
suggested visiting Mynydd Poeth, Llechwedd and Craig Hir (SH 960 544).
These hills are situated north of Cerrigydrudion
with Mynydd Poeth and Llechwedd to the south of Llyn Brenig with each
positioned either side of the B4501, whilst Craig Hir is further north and positioned
between Llyn Brenig and the Alwen Reservoir.
Each hill was of numerical interest as Mynydd
Poeth is listed as a Sub-Pedwar with c 29m of drop but a Tump with 30m of drop,
and with higher hills to its west and east and no spot height on either
connecting bwlch which are both between 380m – 390m, it meant that each bwlch
would need surveying. Llechwedd has a
summit spot height of 450m which is embedded in forestry and it also has a 449m
top outside of the conifer plantation, whist Craig Hir is immersed in mature
forestry and would test the capability of the Trimble to attain its 0.1m
logging accuracy and with a height of 453m based on a 1,485ft (452.6m) from an
old Ordnance Survey 1:10,560 map, it would be interesting to compare this
height with that of the Trimble’s if the mature conifers allowed data to be
logged.
We parked just off of the road at the start of a
forest track at SH 957 509, where one or two vehicles can be left. As Mark donned his wellies I nipped over the
adjacent fence and walked up the valley to valley direction from south to north
on the west side of the road. I’d
examined this bwlch in a Google car the previous evening and judged that the
direction of the bwlch went from one side of the road to the other and that the
critical bwlch lay behind a small mound which is given a separate 390m contour
ring on Ordnance Survey maps.
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One of two positions that data were gathered at the easterly bwlch from Mynydd Poeth
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When Mark joined me I had just completed the
first data set taken from the easterly bwlch from Mynydd Poeth, Mark
independently assessed the area of the bwlch and we decided that a second data
set was required and the Trimble was positioned slightly south from its first
placement. As it gathered data Mark
headed upto the summit, leaving me to scribble as much information relevant to
the Trimble’s chosen position, as it gathered the last of its 300 points I
happily took a few photos with the sun casting low light from the south.
As I packed the Trimble away I watched Mark
become a small figure cresting the upper slopes of Mynydd Poeth. Although the weather forecast for the day was
good and the sun was casting long shadows, the wind gave a chill to proceedings
and as I headed up the hill and joined Mark on the summit I put on a second
pair of gloves as it was decidedly wintery on the top.
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Mark heading toward the summit of Mynydd Poeth
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The summit position was checked against a ten
figure grid reference that Mark had input into his hand-held GPS, the Trimble
was positioned with its internal antenna aligned with the top of a small
embedded rock and once the 0.1m accuracy was attained I pressed ‘Log’ and
scampered away from the equipment.
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Gathering data at the summit of Mynydd Poeth
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Once five minutes of data were collected we
headed west down to the second option for the critical bwlch of Mynydd Poeth,
this proved to be in a vast blanket bog.
As we walked into this morass I adopted a spread legged stationary
surfing position with my body braced at the knee, as I flexed my knees the
whole bog wobbled like a ginormous water bed.
Quite a remarkable place and probably the largest blanket bog that I’d
had the pleasure to wobble on.
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Mark exploring the blanket bog
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Mark walked around in the middle of the bog
trying to assess the rough position of its critical bwlch, whilst I gained
height and dryness of foot to look down on it.
We both thought that a position close to a small patch of standing water
was where the critical bwlch lay. I
re-joined the bog as Mark retired to the relatively dry land beside an adjacent
fence and I stomped around a bit creating a small patch where the reed grass
was flattened, by doing so I hoped to give the Trimble a better chance of
picking up signals from orbiting satellites, as I stomped around and set the
Trimble up the distinct smell of methane oozed from the bog.
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Gathering data at the westerly bwlch from Mynydd Poeth
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Once the allocated five minutes of data
collector had ended I dived back into the bog to retrieve the Trimble and spent
a few seconds wandering around trying to find it, all I could see was reed
grass and puddles of water, eventually I stumbled across it, switched it off
and we headed back over Mynydd Poeth toward the car and our next hill;
Llechwedd.
As we crested the summit of Mynydd Poeth, the
view south-westward was dominated by Arennig Fawr which was a grey and sombre
shape without the snow of recent days, all gone as the mild westerly’s battled
with the cold of high winter air.
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Arennig Fawr; grey and somber
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We chose the forest track to make our way up
Llechwedd and opted for the open hillside for our descent. Again, Mark had made a reference to a ten
figure grid reference for where a forest ride left the track to head toward the
summit of Llechwedd, as we approached this position the southern skies had
turned grey and the first of the days showers fell with a mixture of light rain
and sleet being the norm.
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The forest track to the north of the summit of Llechwedd
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We followed the forest ride through copious
amounts of heather as it gained height toward the edge of the conifers, once
here we followed the edge of the forest hoping to find another ride that headed
north close to where the 450m spot height appears on the map. We couldn’t find it and concluded that the
ride must have been covered in new plantings after the last tree felling had
taken place. This meant a conifer bash!
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The forest ride leading to open hillside before the conifer bash to the summit
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With Mark leading the way with another ten
figure grid reference directing us through pine needles we miraculously popped out
into a small heather and brambled clearing, which has the remains of four metal
stations for the Fire Tower which is indicated on the map and which at one time
stood on the summit of the hill.
I positioned the Trimble on top of one of the
small remaining stantions, measured the offset from internal antenna to ground
level as 0.43m and hoped that it would obtain its 0.1m accuracy. Considering where it was positioned this
accuracy was obtained quickly and I pressed ‘Log’ and joined Mark for a cup of
mint and honey tea – yummy, yummy.
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Gathering data at the summit of Llechwedd
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The route out of the forest was direct toward
the nearest open hillside and proved fun with Mark leading the way on a compass
bearing and me following. I started
taking photos part of the way through the conifers and watched Mark being
engulfed by trees, seemingly disappearing and being swallowed whole.
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Pedwar bagging
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Once out from the conifers we headed west toward
where the 449m spot height appears on the map, thankfully this high point was
clear of conifers and as the sun sank lower in the western sky the Trimble
gathered another data set.
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Gathering data at the 449m map heighted top
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We then headed down to the car and drove a
couple of miles north and parked close to the Llyn Brenig visitor car park. By now daylight hours were receding and the
rich winter colours had been replaced by a dimmed light. We left the car, walked a short distance up
the road and headed on a footpath toward a forest track which bisected the
mature trees which make up the forestry around Craig Hir.
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Llyn Brenig
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Thankfully the gaps between the trees are large
and enables easy walking upto the high point of the hill, as this was neared
late afternoon light flickered through the canopy highlighting the mossed
remains of felled tree stumps.
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Approaching the summit of Craig Hir
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As the Trimble was placed on what we deemed to
be the high point we settled in for a long wait, I hoped it would attain its
required accuracy but its starting accuracy of 4.8m was not a good sign. I checked this height on numerous occasions
and its best was only 21cm. However,
this height had bounced back up on subsequent checks and after patiently waiting
for 15 minutes I closed it down, packed it away and down we went to Mark’s car
as another shower just skimmed us to the north.
Hoping that the roast potatoes had not turned to
charcoal I headed toward Christmas in Nantlle and stopped off to visit Dewi and
Linda in Porthmadog on the way. Good to
catch up with Dewi who I hadn’t seen for quite some time. Next stop Nantlle, I just hoped that Santa
had brought me a large bag of pick and mix!
Survey Result:
Mynydd Poeth
Bwlch Height: 387.6m (converted to OSGM15)
Bwlch Grid Reference: SH 95707 50953
Llechwedd
Summit Height: 450.2m (converted to OSGM15)
Summit Grid Reference: SH 96984 50697
Bwlch Height: 386.9m (converted to OSGM15)
Bwlch Grid Reference: SH 95069 51315
Drop: 63.4m
Dominance: 14.07%
For further details please
consult the Trimble survey spreadsheet click {here}
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