20.10.16
Cribin Fawr (SH 794 152), Waun Oer (SH 785 147) only bwlch surveyed), Craig
Portas (SH 801 141), Mynydd Gartheiniog (SH 807 142), Mynydd yr Hewyrch (SH 816
150) and Maen Du (SH 822 151)
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| Cribin Fawr (SH 794 152) |
Bwlch Oerddrws is one of
the gateways between the east and its gentle sloping hills and the ruggedness
of the west at it plunges toward the coast, and at over 360m it is also a
convenient starting point to tackle the Aran ridge to its north or part of
Bryniau Dyfi to its south. It was the
latter Alan and I visited today, this was the second day out with the Leica and
Trimble and I was enthusiastic to see how my right knee dealt with the rigours
of two consecutive days in the hills after I twisted it a number of weeks ago.
By the time we parked
the Dyfi hills were clear of cloud and the forecast for the remainder of the
day was good with only an occasional shower predicted to meander across the
country.
I’d only ascended Cribin
Fawr once from this high starting point and then used a zig zagging path that
takes an almost direct route onto the hill’s northern ridge, today we decided
to explore the path that skirts the hill’s eastern ridge and continues westward
to gain the ridge north of the summit.
I set off first and
toiled in the overly warm conditions as little breeze was present, but progress
was made, as it always is, and as I plodded up the final slopes toward the
ridge, Alan appeared in front having taken a path directly up the eastern
ridge, and by the time I joined him on the summit of Cribin Fawr he had
assembled his Leica RX1250 and it was gathering data.
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| Alan beside the Leica RX1250 at the summit of Cribin Fawr |
When on a part of the
Berwyn yesterday we’d used a surveying method with the Leica gathering data for
approximately 20 minutes, followed by the Trimble set up over the same point
for five minutes, and whilst the latter gathered data Alan headed toward the
next survey point to set up his Leica and I would later join him to set up my
Trimble, this method worked extremely well and we used it again today.
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| Gathering data with the Trimble GeoXH 6000 at the summit of Cribin Fawr |
Once Leica and then
Trimble data were gathered I followed the wet path beside a fence past a number
of oozing black peat channels and continued south-eastward down to the first
bwlch of the day. We planned on
surveying three main bylchau with each having map contours between 550m – 560m,
and therefore their respective hills may swap dependent upon which is higher or
lower.
By the time I arrived
the Leica was gathering another 21 minute data set, this we listed as the
critical bwlch for Waun Oer; a 670m map heighted hill to the south-west of
Cribin Fawr. These meetings at each
summit and bwlch gave an opportunity to chat and relax as the equipment
gathered its data.
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| Relaxing at the bwlch of Waun Oer |
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| Gathering data with the Trimble GeoXH 6000 at the critical bwlch of Waun Oer |
Looming above us were
the steep slopes of Craig Portas which is a 605m map heighted Simm, Dewey and
Twmpau, and after Alan had packed the Leica away he headed up as I assembled
the Trimble, a few minutes later and with data stored I followed him up to the
hill’s featureless summit. During the
first few hours of the walk the sky remained a dulled light grey and the ever
present threat of rain pervaded as showers were breaking out further west and
north, and occasional spits of rain fell our way on the light breeze that ebbed
across the hills, but thankfully no persistent rain or heavy shower
materialised during the day on the hills we visited.
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| Craig Portas (SH 801 141) |
The summit of Craig
Portas is one that must be usually bi-passed unless visited by a bagger as the
main path skirts its upper northern cwm, leaving its summit lonely and tussock
ridden, today it was surveyed with both the Leica RX1250 and Trimble GeoXH
6000. After Alan headed off toward the
next bwlch, I remained at the summit and waited for the Trimble to gather its
customary five minutes of data and stood looking west toward the higher peaks
radiating out from Cadair Idris, whose profile always stands out from the Dyfi
ridge.
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| Alan beside the Leica RX1250 at the summit of Craig Portas |
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| Waun Oer (SH 785 147) from the summit of Craig Portas |
I soon joined Alan at
the next bwlch, this we listed as the critical one for Craig Portas, the bwlch
is a tight affair with a few rogue conifers to its immediate south, and a fence
and plunging drop to its immediate north, Alan had set his Leica on an extended
pole and after it had gathered 20 minutes of data I placed the Trimble on the
top of the Leica antenna and noted a 1.12m measurement offset between its
internal antenna and the critical point of the bwlch, and the two of us waited
for five minutes of data to be gathered.
As the equipment beeped away gathering its individual data points an
occasional flash of sunlight brightened the land giving colour to the otherwise
dulled surrounds.
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| Alan setting the Leica RX1250 up at the critical bwlch of Craig Portas, with Mynydd Gartheiniog in the background |
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| Alan beside the Leica RX1250 at the bwlch of Craig Portas |
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| The Trimble GeoXH 6000 gathering data perched on top of the Leica RX1250 at the bwlch of Craig Portas |
The next summit along
the ridge is another that must usually be bi-passed unless visited by a bagger
as its high point is positioned away from the path which continues toward the
high point of these hills; Mynydd yr Hewyrch.
We both visited its top, and as I set the Trimble up Alan continued
toward the next bwlch. This hill is a
part of Mynydd Gartheiniog and is listed as such in the 500m Twmpau, whilst
Michael uses the name of Craig Portas – East Top in his listing of Deweys. Its summit consists of soft tussocks with a
slight path of sorts leading toward its high point.
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| Ascending Mynydd Gartheiniog from Craig Portas |
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| Dramatic cloud out to the west |
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| Gathering data at the summit of Mynydd Gartheiniog |
As I joined Alan at the
next bwlch the western sky started showing signs of late afternoon light as
dramatic clouds built up out to the west, this late light remained with us for
the remainder of the walk giving beautiful conditions over Cadair Idris and
succulent autumnal colours on the high Aran.
As data were gathered at
the last of the three main bylchau Alan spotted two people near the summit of
Craig Portas, they continued toward Mynydd Gartheiniog and eventually
disappeared into the day. Beyond this
bwlch lay a fence line heading toward the summit of Mynydd yr Hewyrch; the high
point of Bryniau Dyfi, and as the Trimble gathered the last of its allotted 300
datum points I watched Alan make progress up the slope, beside the fence line
and disappearing beyond view.
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| The Trimble GeoXH 6000 gathering data at the critical bwlch of Mynydd Gartheiniog |
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| Looking toward Cadair Idris from the ascent of Mynydd yr Hewyrch |
The summit of Mynydd yr
Hewyrch consists of a large watery puddle with four grassed peat hags vying for
its high point; it is an unusually attractive place and is one that we spent a
great amount of time at, as three points were each surveyed with the Leica and
Trimble, with each having been Distoed by Alan.
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| The Leica RX1250 gathering data at one of the three points surveyed atop Mynydd yr Hewyrch |
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| Late afternoon light above Cadair Idris |
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| The Leica RX1250 gathering data at one of the three points surveyed atop Mynydd yr Hewyrch |
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| The Leica RX1250 gathering data at one of three points surveyed atop Mynydd yr Hewyrch |
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| The Trimble GeoXH 6000 gathering data at one of three points surveyed atop Mynydd yr Hewyrch |
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| The Leica RX1250 gathering data at one of three points surveyed atop Mynydd yr Hewyrch |
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| The Trimble GeoXH 6000 gathering data at one of three points surveyed atop Mynydd yr Hewyrch |
As the Leica was set up
at the third summit point I headed off toward Maen Du, the 674m map heighted
top further east which for many years was the recognised high point of the
hill. As I followed the narrow peaty
path colour cascaded down across the hills, it was radiant and piecing in its
intensity, giving brilliance to the autumnal colour. I stopped and soaked in the scene as grey
shadowed summits were edged against the glowing greens, oranges and autumnal yellows.
On my way toward Maen Du
I stopped and surveyed its connecting bwlch with Mynydd yr Hewyrch and then
continued to its summit, where Alan joined me a few minutes later. The summit of Maen Du was the eleventh survey
with the Trimble during the day and once data were gathered and the equipment
packed away we followed the path southward around the edge of Craig Maesglase
and its impressive plunging waterfall.
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| Long shadows and autumnal colours at the bwlch of Maen Du |
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| Aran Fawddwy |
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| Gathering data at the summit of Maen Du |
By now the colour was
intense as the last of the days light illuminated Aran Fawddwy, this late
intensity of colour only lasts for a few short minutes as the sun sinks ever
lower and once gone it was replaced by a subdued light that crept ever onward
toward darkness.
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| Our route down following the escarpment edge above Craig Maesglase |
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| Aran Fawddwy illuminated in late afternoon light |
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| Succulent autumnal colour illuminating Aran Fawddwy |
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| Maen Du with the high Aran in the background |
We arrived back at the
awaiting car at 6.55pm in dimmed light, having followed the path down onto a
lane with the ever present upper reaches of the cwm nestling the Nant Maesglase
at its heart, giving us a wonderful darkened and almost silhouetted view up to
the ridge line that we had just followed down.
Survey Result:
Cribin Fawr
Summit Height: 658.7m (converted to OSGM15, Trimble GeoXH 6000) 658.8m (Leica RX1250)
Summit Grid Reference: SH 79452 15285
Bwlch Height: 566m (spot height)
Bwlch Grid Reference: SH 78954 15066 (spot height)
Drop: 93m (Leica RX1250 summit and spot height bwlch)
Dominance: 14.09% (Leica RX1250 summit and spot height bwlch)
Waun Oer
Summit Height: 670m (triangulation pillar)
Summit Grid Reference: SH 78556 14786 (hand-held GPS via DoBIH)
Bwlch Height: 549.4m (converted to OSGM15, Trimble GeoXH 6000) 549.6m (Leica RX1250)
Bwlch Grid Reference: SH 80115 14398
Drop: 120m (triangulation pillar summit and Leica RX1250 bwlch)
Dominance: 17.97% (triangulation pillar summit and Leica RX1250 bwlch)
Craig Portas
Summit Height: 603.8m (converted to OSGM15, Trimble GeoXH 6000) 604.2m (Leica RX1250)
Summit Grid Reference: SH 80154 14120
Bwlch Height: 549.7m (converted to OSGM15, Trimble GeoXH 6000) 550.0m (Leica RX1250)
Bwlch Grid Reference: SH 80530 14218
Drop: 54.2m (Trimble GeoXH 6000) 54.2m (Leica RX1250)
Dominance: 8.97% (Leica RX1250 summit and bwlch)
Mynydd Gartheiniog
Summit Height: 586.3m (converted to OSGM15)
Summit Grid Reference: SH 80794 14282
Bwlch Height: 552.8m (converted to OSGM15, Trimble GeoXH 6000) 553.1m (Leica RX1250)
Bwlch Grid Reference: SH 80951 14527
Drop: 33.3m (Trimble GeoXH 6000 summit and Leica RX1250 bwlch) (Dewey and 500m Twmpau status
confirmed)
Dominance: 5.67% (Trimble GeoXH 6000 summit and Leica RX1250 bwlch)
Mynydd yr Hewyrch
Summit Grid Reference: SH 81697 15003
Bwlch Height: 360.5m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)
Bwlch Grid Reference: SH 80208 17001 (from previous Trimble GeoXH 6000 survey)
Drop: 318.0m (based on Trimble GeoXH 6000 bwlch and Leica RX1250 summit)
Dominance: 46.87% (based on Trimble GeoXH 6000 bwlch and Leica RX1250 summit) (Lesser Dominant status
confirmed)
Maen Du
Summit Height: 675.0m (converted to OSGM15)
Summit Grid Reference: SH 82237 15172
Bwlch Height: 667.8m (converted to OSGM15)
Bwlch Grid Reference: SH 81910 15043
Drop: 7.2m
Dominance: 1.07%
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