27.05.21 Knowle Hill (SO 213 617), Bache Hill (SO 213
636), Great Creigiau (SO 198 636), Black Mixen (SO 196 643) and Great Rhos (SO
182 638)
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| Black Mixen (SO 196 643) |
I hadn’t been on the
higher Fforest Glud hills since 2005.
Prior to my last visit the circuit taking in Bache Hill, Black Mixen and
Great Rhos was one I used to do on a regular basis. Sixteen years is a long time to have neglected
these hills. Since my last visit my
surveying activities have become more refined.
Where I then used a basic levelling staff to measure the drop value for
potential P15 and P30 hills, I now have a Trimble which is capable of producing
highly accurate height data.
When purchasing the
Trimble there were a number of summits and also bylchau of note that I wanted
to survey. Many of these have now taken
place; including Foel Cedig and Cyrniau Nod, the bwlch for Great Rhos and Pegwn
Mawr, Foel Penolau in the Rhinogydd and the high point of the main easternmost
ridge of Mynyddoedd Duon, there are others still awaiting to be surveyed. One of these is Bache Hill; a heather bound
summit adjacent to land reclaimed for grazing and a large conifer plantation.
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| Bache Hill (SO 213 636) |
Bache Hill is given a
610m summit spot height on contemporary Ordnance Survey maps. This height is adjoined to a triangulation
pillar which has a 610.209m flush bracket height. The flush bracket is positioned approximately
0.35m above the base of the trig pillar.
Therefore, the ground at the base of the trig pillar is approximately 609.859m. This height is only 0.26m above the benchmark
height of 2,000ft (609.6m). However, the
trig pillar is positioned on top of an ancient tumulus, which I had surveyed
with my old basic levelling staff as being approximately 9ft (2.7m) in height.
Tumuli are man-made and were
built in the Bronze Age and therefore are approximately 5,000 years old,
because of this many hill list authors consider them as being a part of the
hill and therefore accept their height as that for the summit, even if a lower,
natural summit still exists. However,
there are some people who do not accept this, and would give the height and
position to the remaining natural summit, even if the tumulus is higher. Today one of the main surveying objectives
was the summit of Bache Hill.
Since the late 1990s
when I first started surveying hills I have looked at summits and bylchau with
a surveyor’s eye. Whereas prior to this
a summit was to be bagged and the view admired, now I spend time assessing the
lay of land. Although I hadn’t been to
the summit of Bache Hill for sixteen years I was aware that there seemed to be
higher natural ground westward from where the trig pillar and tumulus is
positioned, and as the approximate height of the tumulus is 9ft (2.7m) and with
the flush bracket height giving the ground at the base of the trig pillar as
approximately 609. 859m, these values give the natural ground at the base of
the tumulus as approximately 607.159m in height. This is below 2,000ft. Was the natural summit of this hill to the
west of the tumulus and if so was it sufficiently higher than the base of the
tumulus to break through the 2,000ft (609.6m) barrier. My thoughts prior to today’s survey were that
the natural summit was intact and to the west of the tumulus and that it is
below 2,000ft (609.6m) in height.
Having met Aled in Caersŵs
we were parked and walking from above Maesyfed (New Radnor) by just past
9.00am, following the bridleway heading north and then eastward above Mutton
Dingle. It was already warm, but with
blue skies above and a forecast for dry conditions and little breeze it was
ideal for the task at hand.
We left the bridleway to
visit the summit of Knowle Hill, which stands aloof of the conifer plantation
to its north. I’d often used this ascent
route whilst combining the three highest Radnorshire hills, but until today had
never visited the high point of this hill.
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| LIDAR image of Knowle Hill (SO 213 617) |
Prior to this visit I
had LIDARed this hill and found a remaining natural bwlch to the west of the
raised track that continues to the forestry track which if so desired
eventually leads to Whimble and Bache Hill.
Having arrived at the top of the closely cropped grazing field that
constitutes the summit of Knowle Hill we assessed the lay of land and soon the
Trimble was set up gathering its first data set of the day.
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| Gathering data at the summit of Knowle Hill |
Leaving the summit of
Knowle Hill we headed down to the raised track crossing the area of the bwlch
and continued up the near forestry track, turning right on a gravelled narrower
track which led up toward another forestry track and open hillside beyond. Even at this early stage of the walk I felt
the heat debilitating. I had planned to
join Aled and visit Whimble; a fine hill that I had visited on four previous
occasions, the last of which it had been Trimbled. The phrase of the Trimble on Whimble still
makes me smile. But realising there were
many surveys ahead and that Aled is much quicker around the hills than me, I
left him to make his way up Whimble as I steadily plodded up a green track
toward the summit of Bache Hill.
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| Aled just setting off for the summit of Whimble |
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| Aled can just be seen on the path heading up Whimble |
I knew before arriving
at the summit what I wanted to do and that was to take the first data set from
the highest ground at the base of the tumulus and another three at the base and
approximately 45° from each other.
One data set from the high point of the tumulus and at least one from
the area where I suspected the natural summit to be placed westward of the
tumulus.
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| 1st survey at the western base of the tumulus with the natural summit of Bache Hill in the centre background |
Arriving at the summit I
set to work. The tumulus is impressive
and dominates the summit area of the hill and is one of the finest of its kind
in this part of Wales. I soon had the
Trimble set up at what I judged to be the highest ground at the immediate base
of the tumulus. I then repeated this
process and took three other readings at the base, each approximately 90°
from one another. This would give a good
spread of the height of the base of the tumulus. Using one’s eye to ascertain height gain is
not ideal, however having judged the lay of land for many hundreds of hills one
becomes attuned to such things, and to my eye the tumulus is positioned on what
could be deemed as the easternmost edge of this hill’s summit plateau. Land hereabouts descended east, whilst to the
west land seemed to be higher. This is
where I had previously thought the natural summit of the hill to be positioned. Aled also thought this when he arrived at the
summit after his ascent of Whimble and a scramble up Whinyard Rocks.
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| 2nd survey at the northern base of the tumulus |
As Aled approached the
summit of Bache Hill the Trimble was in the process of collecting data from the
high point of the tumulus. Once data
were gathered and stored we looked west and under Aled’s direction I marched
off in to the heather to a point north-westward of the tumulus. This point was on a slight rise, but there
was still higher ground to the west.
Having set the Trimble up and gathered the allotted data I headed to the
area where we both thought the natural summit of the hill to be positioned.
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| 5th survey at the high point of the tumulus |
This whole area is
broad, however once at the place where we each thought the highest natural
ground of the hill to be situated, I looked back toward the tumulus and trig
pillar and followed the lay of land as it gently descended northward and
southward, with the position we were now at being the crest of the land heading
directly toward the tumulus. A further
two data sets were taken from this area, giving in all eight data sets from the
summit area of Bache Hill.
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| 8th survey in the vicinity of the natural summit of Bache Hill |
Leaving the summit of
Bache Hill we headed down to its connecting bwlch with Black Mixen. This is placed near a fence and beside a
series of small reed infested pools. As
I assessed the lay of land Aled gained height on the green track that would
lead us up to our next two hills. From
this vantage point he directed me to where the bwlch lay.
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| Gathering data at the bwlch of Bache Hill |
Our next objective was
Great Creigiau; a hill whose delights I had previously visited, once to purposely
bag its summit, and the other when I wandered its heathery realm chasing Broken
Spectres and a cloud inversion. Today this
hill was on Aled’s surveying agenda. The
underfoot conditions proved torturous with heather, bog, tussocks and
holes. Walking toward its high point was
like swaying on a ship’s deck during a storm.
But when a hill is on a surveying agenda it has to be surveyed, and both
its summit and bwlch were duly Trimbled.
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| Gathering data at the summit of Great Creigiau |
Now back on the green
track we followed this around the top of Cwm Siân to the trig pillar
perched on the tumulus atop Black Mixen.
It was here that Aled shot off again, as he wanted to visit Fron Wen
which is immersed in the northerly conifer plantation and would entail lost
height which would then have to be reclaimed.
We made plans to meet beside the trig pillar on Great Rhos in 60 – 90
minutes time.
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| Great Rhos from above Cwm Siân |
This left me at the
summit of Black Mixen to gather the next data set of the day. As the Trimble quietly beeped away gathering
its all-important data I sat on the side of the summit tumulus and waved across
to three contractors who were on the large mast close to the summit. Music and singing accompanied there work,
which added a surreal element to the day’s proceedings.
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| Gathering data at the summit of Black Mixen |
The next point to survey
was the connecting bwlch between Black Mixen and Great Rhos. A path through the heather leads from the
tumulus atop Black Mixen all the way to this bwlch. As the previous two weeks had been unusually
wet for this time of year the path was muddied but the underfoot conditions
were never difficult.
The continuation of this
path crosses the bwlch at an ancient Cross Dyke. The path was at least 1m above ground at its
base, with it acting as a raised walkway that was under filled. Wanting to get to the summit of Great Rhos
before Aled, as we had made provisional plans to either meet there or down at
the bwlch connecting with Fron Hill, I didn’t want him getting to the summit
before me and thinking that I had already left.
So one data set from this bwlch would, for now, have to suffice.
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| Gathering data at the bwlch of Black Mixen |
It was good to be back
on these hills after such a long gap between my visits. Stretches of land between frequently visited
hills can bring back so many memories and this next section in particular
brought back memories of struggling in the snow when the outer crust just held
my weight but only until I transferred it to my other leg and in I then sank, a
frustrating process that continued all the way from this bwlch around the
corner of the near forestry plantation.
This forest has now been felled and as I made progress toward the corner
and then up following the fence line toward where a path emerges out of the
forest, I watched a number of birds of prey circling the upper reaches of
Harley Dingle.
A muddied path now led
all the way to the high point of Great Rhos, I stopped on occasion and looked
back to see if Aled was heading my way.
No sign yet, so I slowly continued toward the trig pillar atop the
summit.
Having assessed the lay
of land beside the trig pillar I placed the Trimble atop my rucksack, measured
the offset between its internal antenna and the ground at its base and set it
to gather data. I then sat in the
heather about 20 metres away and left it quietly beeping away gathering data. During this Aled appeared heading my way on
the muddied path. It was good to see him
again; he’d done well considering the lost height when visiting Fron Wen.
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| Gathering data at the summit of Great Rhos |
Once the allotted data
were gathered and stored we followed paths and tracks down from Great Rhos
toward the connecting bwlch with Fron Hill, only stopping for a welcome rest
overlooking Davy Morgan’s Dingle.
At the bwlch Aled headed
up to visit Fron Hill whilst I slowly made my way down the continuation of the
green track heading in to the lower reaches of Harley Dingle. I stopped frequently to take photographs as
shadows played across the hills. From
this direction Whimble always looks good; although lower in height its profile
dominates the surrounding landscape.
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| The profile of Whimble always looks impressive |
I waited for Aled beside
the foot bridge that crosses the stream in the lower part of Harley Dingle and
lay in the sun relaxing and resting. In
all 16 data sets were taken during the day with many results being of interest,
especially so for Bache Hill. Aled soon
joined me after his visit to Fron Hill; he’d covered much more height and
distance than me during the day.
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| At the start of the green track leading back to the awaiting car |
Our route back now headed
slightly uphill joining a delightful green track that contoured its way around
the southerly flank of Whimble before we used fields and gates to head back
toward the awaiting car. It had been a
long day, but also a very enjoyable one on the hill.
Survey Result:
Knowle Hill
Summit Height: 387.9m (converted to OSGM15, Trimble GeoXH
6000)
Summit Grid Reference: SO 21397 61735 (Trimble GeoXH 6000)
Bwlch Height: 357.7m (LIDAR)
Bwlch Grid Reference: SO 21337 61955 (LIDAR)
Drop: 30.2m (Trimble GeoXH 6000 summit and LIDAR
bwlch) (Sub-Trichant reclassified to Trichant)
Dominance: 7.80% (Trimble GeoXH 6000 summit and LIDAR
bwlch)
Bache Hill
Summit Height: 610.1m (converted to OSGM15)
Summit Grid Reference: SO 21386 63643
Bwlch Height: 569.2m (converted to OSGM15)
Bwlch Grid Reference: SO 20436 63761
Drop: 40.9m
Dominance: 6.70%
Great Creigiau
Summit Height: 643.4m (converted to OSGM15) (significant height revision)
Summit Grid Reference: SO 19810 63643
Bwlch Height: 633.3m (converted to OSGM15)
Bwlch Grid Reference: SO 19959 63879
Drop: 10.1m
Dominance: 1.57%
Black Mixen
Summit Height: 650.1m (converted to OSGM15)
Summit Grid Reference: SO 19650 64399
Bwlch Height: 604.5m (converted to OSGM15)
Bwlch Grid Reference: SO 18812 65024
Drop: 45.7m
Dominance: 7.02%
Great Rhos
Summit Height: 659.9m (converted to OSGM15)
Summit Grid Reference: SO 18213 63896
Bwlch Height: 281.3m (converted to OSGM15, from previous
Trimble GeoXH 6000 survey)
Bwlch Grid Reference: SO 17776 71803 (from previous Trimble GeoXH
6000 survey)
Drop: 378.6m
Dominance: 57.38%
For details on the bwlch survey of Great Rhos
For an in-depth examination of the bylchau of Pegwn Mawr and Great Rhos
For details on the Bache Hill summit survey and its conclusions
For further details please consult the Trimble Survey Spreadsheet
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