12.07.18 Twyn Llech (SO 255 353)
Having visited
Hatterrall Hill (SO 308 256) I drove north with Mark to the Gospel Pass and
parked just below its high point and we set off walking at around 4.50pm with
the plan to visit Twyn Llech, survey its northern and southern high points and
plot out where these lay in relation to the border between Wales and England.
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| Mark on the path leading to Hay Bluff |
Twyn Llech had already
been surveyed using the Trimble GeoXH 6000 in September 2017, resulting in the
northern high point being 0.9m higher than its southern counterpart, but this
southern point comprises undulating land and there was a distinct possibility
that slightly higher ground existed, therefore I wanted a minimum of another
two data sets as comparison.
Thankfully the muggy and
warm conditions of the early afternoon had been replaced with cooling air, with
the breeze from earlier having now disappeared and the late afternoon bringing stillness
to these hills.
We gained height on the
path toward the trig pillar atop Hay Bluff as a grey murk hung over the
southern part of mid Wales which looked decidedly uninviting, whereas blue
skies were to our south and the escarpment edge to our immediate north was the meeting
point between the two, we hoped the murk would not edge southward, thankfully
it did not and the 3½ hours we spent on the hill taking three data
sets and plotting out the route of the border was done in ideal conditions with
clear visibility and not a breath of breeze.
The path from Hay Bluff
heading south was completely dry and led to a small group of grazing horses
where one foal inquisitively approached Mark and stood attractively posing for
a photograph.
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| Horses between Hay Bluff and Twyn Llech |
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| Posing for a photo with the path leading back to Hay Bluff in the background |
Just to the south-west
of the main path as it starts its climb to the plateaux of Twyn Llech is the
rock outcrop of Llech y Lladron and it is this that gives its name to the hill,
I’d passed this way many times but had never ventured the few metres to investigate
the outcrop. This is the thief’s stone,
which no doubt relates to a tale long now forgotten and which gave a name to this
rock outcrop.
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| Mark standing atop Llech y Lladron |
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| Llech y Lladron |
Re-joining the main path
we steadily gained height toward the northern top of Twyn Llech, as height was
gained Mark followed his hand-held GPS which had an enlarged version of the
Ordnance Survey 1:50,000 map on its screen, this gave a detailed route of where
the border between England and Wales is situated according to this map compared
to the modern day path which over recent years has been flagged.
By following the flagged
path we were consistently on the Welsh side of the border according to the
detail on the 1:50,000 map, with the border firmly placed in the copious
amounts of heather just to our east.
Mark gave a running commentary as we approached the northern high point,
this helped in establishing where the 1:50,000 map places the border and it was
in the main always to the east of the flagged path.
Once near the northern
high point the grid reference from the previous Trimble survey zeroed us in to
the summit of the hill, we then spent a few minutes assessing the ground before
choosing a spot for the Trimble set-up position, the grid reference obtained from
post processing places this position in the exact same spot as the previous survey,
and as ten minutes of data were gathered we paced out the distance from the
Trimble set-up position on the summit of the hill to the flagged path and then
onward heading east to where the 1:50,000 map places the border between Wales
and England on the ground, this proved to be approximately 50 metres in
distance.
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| Gathering data at the northerly high point of Twyn Llech which is the summit of the hill |
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| The Trimble set-up position at the summit of Twyn Llech |
Once the Trimble was
closed down and packed away we walked the 350 metres further south toward the
southern high point, this is harder to establish when compared to its northerly
counterpart. I easily found where the
last Trimble set-up position was placed, but land further west in to the
undulating heather looked slightly higher and so we chose a position to gather
another ten minute data set, and as the Trimble quietly beeped away gathering
its 600 individual datum points Mark headed back to the northerly top to look
back at the Trimble position on the southerly top.
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| Gathering data at the first of the two southerly points surveyed |
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| Mark on the northern high point and summit of Twyn Llech |
I wanted to take another
data set from the undulating ground and having spent a number of minutes
kneeling and looking out toward where the Trimble was placed and how the ground
gradually decreased in height toward the ridge path and where it then gradually
increased in height, I eventually decided where the second placement for the
Trimble should be, once it was positioned on top of my rucksack to give it
elevation above its immediate surrounds I activated it to gather data.
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| Gathering data at the second of the two southerly points surveyed |
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| The Trimble set-up position at the second of the two southerly points surveyed |
Prior to this I paced 30
metres from the first southerly set-up position to the ridge path and a further
15 metres to where the 1:50,000 map indicates the border to be positioned on
the ground, this along with the same procedure being conducted on the northerly
high point confirmed that the Ordnance Survey position the border on their
contemporary 1:50,000 Landranger map to be east of the northerly and southerly high
points of this hill.
As the Trimble gathered
its second data set from the southerly point I walked up the flagged path to
meet Mark who was walking back from the northern high point, and we sat on a
peat hag as the ten minutes of data were gathered and stored.
Packing the Trimble away
we headed north back on the flagged path past the northern summit and down past
Llech y Lladron toward the trig pillar atop Hay Bluff, we stopped here for a
few minutes looking out at a grey scene only fragmented by a slither of oranged
colour as the sun forever sank in the western sky.
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| The distant Pen y Fan |
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| Looking out toward the last slithers of sunlight |
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| The western sky beyond Twmpa |
We arrived back at the
car at 8.20pm happy in the knowledge that the northerly and southerly high
points of Twyn Llech had been surveyed again and these data sets could now be
compared to those gathered in September 2017, and that the land border between
Wales and England had been plotted out according to detail on the contemporary Ordnance
Survey 1:50,000 Landranger map, and that this position had been measured
against that of the northerly and southerly high point of the hill. Time dictated that our planned evening meal
would have to wait for another day, but the chippie in Hay-on-Wye nourished our
hunger!
Survey Result:
Twyn Llech (significant name change)
Summit Height: 703.6m (converted to OSGM15, average of two
Trimble GeoXH 6000 surveys) (significant height revisions)
Summit Grid Reference: SO 25520 35383 (summit relocation confirmed)
Bwlch Height: 549.1m (converted to OSGM15, previously
Trimbled)
Bwlch Grid Reference: SO 23542 35192
Drop: 154.5m
Dominance: 21.96%
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