Sunday, 21 November 2010

Foel Gron and The Migneint


Y Gamallt and the Migneint, from Y Garnedd, above Foel Gron Quarry.
No, not a Welsh rock band, but a slate quarry... and a vast tract of boggy wilderness. The Migneint stretches for miles between Blaenau Ffestiniog and Bala and is a beautiful, precious, delicately balanced upland ecosystem. Recently, local government have decided that they should be seen to be doing something about it, and have produced lots of pink coloured maps and statements of intent. Good for them. As far as I know, the area is not under threat from anything... the doziest developers wouldn’t build “executive villas” on the Migneint even if anyone round here, apart from the second-homers, had any money. The houses would sink into the bog overnight. However there is now a carbon capture survey going on to assess levels of greenhouse gases emitted from the mire. Well, it will keep some folk in jobs, which has to be good.
Dyke swarms on the Migneint...looking towards Croes y ddwy afon quarry from Foel Gron.
I have to be honest, we didn’t actually set out to visit Foel Gron. It wasn’t first choice. Some people had posted photos up on the Geographia site and to be frank, it looked uninteresting; something to see when we’d exhausted everything else...i.e. never. So we set out for the lovely Llyn Morwynion and the delights of Drum quarry after parking in the layby near Llyn Dubach. It wasn’t long before we realised that the public footpath had been planned by folk who had webbed feet, or habitually wore waders. Attempts had been made to provide stability of the path by chucking old railway sleepers on the bog, but the outcome was like one of those Japanese TV shows where contestants have to surmount all sorts of muddy obstacles and hurt themselves while everyone laughs. We turned back.

At this point I noticed a road going up out of the bog half a mile away. The road to Foel Gron quarry. I said nothing, hoping that Petra would see it too. She had suffered a catastrophic full boot and sock soaking in the mud, so I wasn’t sure what her thoughts would be. I needn’t have worried, as, true to form, she announced her intent to blag Foel Gron and to hell with wet boots. What could I say?

The mystery structure
It was nice to be on a firm trackway, built on slate waste, as we took to the road. A notice warned of the danger posed by hidden shafts and mines, so that was a good sign. I have to say here that, while this kind of warning warms the cockles of my heart, our spidey senses are permanently alert for danger when in explore mode. The ever present threat of dying a horrible death in old mining locations shouldn’t be taken lightly, no matter how experienced an explorer one might be.

Then again, I was once run down by a bus in Manchester, not my favourite memory, and a month later an IRA bomb went off as I walked, sorry, hobbled down the very same street. All a matter of perspective and a helping of diligence, not that either would have helped me or those much less fortunate that day.

Back to the trackway. Our first encounter was a mysterious structure a little like a wheel pit, but without any evidence of water having been supplied to it. My best guess is a magazine, perhaps, or some sort of saw pit...but why not site this at the reduction area of the quarry instead of here? Anybody any ideas? We stumbled about, debating various theories for a while, then headed up the road along the side of Carreg Foel Gron. We were climbing up the side of a large dolerite dyke, one of many that poke beguilingly out of the morass hereabouts. The road turned to the right and we were faced with the first glimpse of the quarry, which looked interesting. There was some old machinery rusting away on the flat area in front of the twll; this had featured on Geograph, so wasn’t a surprise. What did intrigue me was the sheer amount of rock removed from the hill behind the slate quarry, and how the overburden looked so complicated geologically. Fascinating.

Looks like something from a Wild West ghost town
We tootled around taking photographs of the rusty old conveyor machine, trying to do something interesting with it, when I spotted a drainage adit. It was fenced off and very wet...nobody told me this was a mine! Interest levels raised immediately, we set off for the twll. This was a delightful scene, with two inaccesible holes appearing high up on the quarry face, obviously daylight holes for chambers. We skirted the barbed wire fence and it’s frequent notices, warning of falling and death. For some reason, after a while, the fence lost interest and stopped four feet away from the quarry face. Alert for hidden shafts and falling rocks, as the notices had helpfully suggested, we proceeded in to the twll.


Petra is standing beside the filled in lower adit below the first daylight chamber
It was quite magical. An almost level bed of slate had been quarried down to the country rock, where it had become friable and rustic. The useful vein had then been chased down an anticline, rather like it’s counterpart in Blaenau, at which point the miners had been called in. I knew from the excellent HendreCoed mining history web site that quarrying for slate had started here in 1874 and had only ended in 1938. The only strange thing was that there was very little slate waste. Allowing for the popular formula that there are ten tons of slate waste for every ton of finished slate, just where was it? Perhaps a great deal had been reduced to aggregate by the machine near the adit...this had been installed when the quarry had briefly been opened again for roadstone in 1991. As we approached the quarry face, a partially filled-in adit could be seen, flooded, with rails just visible under the blue coloured water. The rock here certainly didn’t look encouraging. Rhyolite and partially metamorphosed mudstones were everywhere, but unlike in our normal haunts above Blaenau Ffestiniog, there was no granite.



We made our way carefully to the next, lower twll, where an adit and a chamber beckoned. Here the rock was more convincing, with very long shot-blast lines on the working face testifying to some determined extraction. The low adit was similarly impassable here, but the chamber was reasonably easy to scramble into. The rock was dusty and sharp and great slabs of it were everywhere...this must have been a partially metamorphosed stage in the mud beds before the conditions for slate were perfect. The afternoon sun streamed into the chamber, which was a large one, although well filled with waste rock. Further in and several adits could be seen, all with deep, clear, bluish water and one with the remains of a winch sheave and track visible. In the centre of the large chamber was a submerged wagon, looking strangely two-dimensional in the water. A smaller chamber opened from this large one and there seemed to be an opening which led further, but we didn’t have sufficient lumens or rope with us to safely make sure of it. There was also a small, lower chamber which must have been connected. This was accessible by a little scramble down and was a lovely place with the light coming in from the partially blocked opening outside. The water sparkled blue, there were the remains of a winch and a rusted block hung from the ceiling. Perfect!


After a slightly uneasy scramble out of the chamber, trying not to disturb anything or leave any sign of our passage, we decided to inspect the quarry above the twll. Several fairly modern looking roadways headed up to four or five levels on the hillside. On the first level the rock became really fascinating. Various layers of strata testified to the enormous pressures that this area must have been under when it was an ocean. Dolerite and Rhyolite lay above large blocks of cream coloured rock, gradually transforming towards a wavy, thin vein of slate. Veins of other intrusive minerals appeared here and there. I wouldn’t have liked to have been around in Ordovician times when all this was going on. There were evenly graded piles of rock, tipped somewhat later by machinery, probably back in the nineties. These were most interesting, showing calchopyrites, iron staining and a wild mixture of rock types, even some wonderful chunks of mudstone with what looked like oolites embedded. Bits of zinc blende and quartz were dotted about as if a bumper box of rock samples had been accidentally spilt. The whole thing left me certain that a little knowledge about geology gained on a Glasgow Uni evening course twenty years ago is nowhere near enough.

Suffice to say that an exploration of the further levels left us more confused than ever about just what was extracted from these slopes, but it was a hugely enjoyable and interesting mooch. Although...I was aware at all times that below us the hillside was probably hollow and in places only a few feet of rock stood between us and the chamber below...

Looking down on the twll and Carreg Foel Gron from one of the quarry levels
We rounded the trip off with a stump up to the summit of Y Garnedd, the hill from which the quarry is carved. A wonderful, sun caressed view greeted us...the Moelwyns, looking as beguiling as ever in a fetching, diaphanous off-the shoulder number and my own beloved Blaenau Badlands, with distant Cwt-y-Bugail peeking cheekily from behind the Rhiwbach tramway. Mighty Manod Mawr presided over all, making little of the ravages from the quarry eating away at it’s middle, while away to the north east, the Gamallt stretched blackly under some cloud, refusing as yet to reveal the secrets of it’s two copper mines. I began to feel a huge wave of ...well.. love for this beautiful area. I know it’s not cool to exhibit symptoms like that about a landscape but there it is. Petra felt the same, although she has lived here most of her life. So ended an excellent explore and one that we might easily not have seen if it weren’t for that pesky Migneint bog.

The slopes of Manod Mawr with Manod Quarry (or as Welsh Slate erroniously call it, Cwt-y-Bugail) from Y Garnedd

1 comment:

geotopoi said...

"to hell with wet boots" - that's the spirit!

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