Friday, 8 July 2011

Art and Natural Selection on Brokeback Mountain



The Moelwyns, those haughty summits that tower above as you drive along from Porthmadog towards Blaenau Ffestiniog, have never really fired my imagination. Of course, they are magnificent and fascinating, with their abandoned quarries and mines, their complex geology, their forests and those two wonderful summits. From which the views are first class. I've roamed and investigated, and freely concede that I want to go back for more.
But the hills that really intrigue me are slightly more to the East. Standing like bulwarks above Llan Ffestiniog, Manod Mawr and his little brother Manod Bach are like old friends. They are in the corner of my vision whenever I venture out of the house, and preside over many of our mining adventures. I even felt slightly disloyal the other day when we climbed up over Cwmorthin to see the Manods looming like two enormous whales; it felt like I was sneaking up, catching them in an unguarded moment.
The Manods and Y Garnedd seen from the South Shoulder of Moelwyn Bach

They are even older than me. There's been a bit of a shake-up in Geological circles over the last ten years, but it is generally agreed that the Manods are the result of a very large Volcanic event over 500 million years ago. They're more complex than that, but you have to draw a line somewhere. Ironically, the name Manod means “snowdrift” in Welsh...

Manod Mawr is a long mountain when seen from the side, not the domed beauty that he appears from the south. There's been quarrying and mining since the early C19th and the latest work has ripped the back completely off, exposing the dark adits of the Graig Ddu, Bwlch Slaters and Manod North Pole workings. It's not really apparent from the normal viewpoint, but when you stand on the lip of the abyss, you realise just how deep the excavation has been.


Slate, of course, has always been the name of the game here. Mud, in another life... squashed, covered by volcanic ash, then by magma outflows, altering the rocks and changing the chemical compositions with heat and pressure. Then upheaval, cracking, more volcanic activity. More ash, more push, more pressure. Then a mile thick topping of ice.
Interesting times. The result is a complicated picture. The original mudstones are overlaid by microgranites, porphyritic and rhyolitic rocks, pockets of special minerals like lead, copper and so on. A fabulous mix. If you have been lucky enough to be allowed into the pit at Manod, some idea of the titanic activity can be seen from the exposed rock, like lumps of different chunks of plasticene folded together.

A huge boulder of volcanic bombs and ash, in a quartz matrix. The Ash, or Tuff, has weathered more than the quartz. Carreg-y-Fran in the background.
 Charles Darwin visited Manod Mawr on August 16th, 1831. According to his notes, he had a look around Carreg-y-Fran quarry. (He's probably referring to Frydd, the southernmost working of the Blaen-y-Cwm sett, which would be working around then.) He then tootled over to Manod and was impressed with the geology.

Manod ("Cwt-y-Bugail") quarry from Foel Gron. Sarn Helen runs in the middle foreground.
 Most people know about the Manod's more recent claim to fame, when the chambers of the mine were used to store Britain's art treasures during the second world war. I've read that the crown jewels were also stored there, but can't verify the truth of that. I know the road up Cwm Teigl to the Manod very well indeed; I wouldn't like to bring a modern truck up there, let alone a 1940 non-synchro mesh Thorneycroft laden with Van Dykes and Rembrandts.

It's a nice thought, though. Next time I'm at the Tate I'll look at that Van Dyck of King Charles on horseback and imagine the driver letting his tyres down to get under the Great Western Railway bridge at the bottom of Cwm Teigl, so that the painting can be safely deposited deep under the Manod in some dark slate chamber. Not the effect Van Dyck was looking for, but it makes the painting seem even finer for me.

The old powder hut from Manod North Pole Quarry.

4 comments:

geotopoi said...

Anther interesting report, Iain. The inclusion of a human figure really gives a sense of scale to the excavations.

Iain Robinson said...

Thanks, Graham. That was an amazing day at Manod quarry. I was stood near to Petra, thinking about having a peek down one of the exposed adits (something we'd been strictly forbidden) when I heard a low groan from the rock above the roof....exit stage left!

Marina Osmjana said...

Hello Ian!

I am really interested in going there soon. Wondering whether it is possible to go to the actual quarry bottom and whether I need to get any permission?
Thanks

Iain Robinson said...

Thanks for dropping by, Marina. When we went to the quarry it was under the ownership of Welsh Slate...it is now owned by the same company that runs Penrhyn and Pen-yr-Orsedd quarriess...I don't know how receptive they would be but you could always ask. It has recently increased production and is pretty busy.
You can always approach from the Manod side and look over to the quarry from the ridge there...it's quite a climb, but worth it.

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