Post date: Jun 25, 2009 4:00:57 PM

Myself, Emma and random assortment of climbers - 20th June 2009

We made a really surprising discovery out on Owey Island in Donegal at the weekend. We definitely seemed to be the first folk to properly explore a huge granite cave at least 300 metres long (Emma says 100 metres max - only a tape measure will confirm ;)) and possibly up to 40-odd metres high in places. Somewhat reminiscent of the first lake in Pollnagollum of the Boats only 4 times longer and almost as high in pink granite - and an absolutely baltic long swim! The walls were coated in some lovely mud formations but most interesting of all at the end of the cave the tunnel narrowed down and there were some amazing surreal-looking orange and black gour pools the like of which I've never seen before.

The passage did seem to continue beyond this but we didn't cross the formations as this would have been impossible without trashing them. Potentially more interesting was what looked like orange fungal or bacterial growths that were floating in the water at the far end of the cave. A bit like small orange cauliflowers. I have absolutely no idea what this stuff was but it looked like organic matter of some sort and it was at least 300 metres away form the entrance? Perhaps I'm just getting over excited about nothing important but I was wondering if anyone knows of a good academic contact who might be interested in taking a sample of this stuff?

***I have two amateur theories on the cave. Either it is a weak clay or mud band through the granite that has been eroded from the land over the centuries or more likely it was once a massive sea cave that has had a huge collapse cutting it off from the sea at the entrance possibly after the last ice age? I'm no expert but suffice to say it was unique and incredibly impressive and even had a one-metre-long mud stalactite and some excellent mud formations on the floor.

The local boat man suggested there are at least 3 other large caves on the island and I believe Owey is Irish for cave? We were thinking about heading back for a couple of days over the 12th so do let me know if anyone is up for a return trip to check out the other caves, take some photos and survey this beast properly.

Unfortunately I have no photos as we were swimming and left the camera in the tent.

Jock

*** Both these theories have now been debunked by Les:

There are a number of caves in the SW of England that are in granite. These and 'tors' (granite hills) are formed by the way that particular rock weathers. Granite doesn't have any clay in it but it does have veins and fractures from the cooling process of the molten rock. These are typically curved.

and John Kelly:

The actual geology is probably a body of talc or other weak material incorporated in the granite which has been easily eroded from within the granite to form the cave. Another possibility is a quartz/sulphide mineral vein which has oxidised and been eroded)

John was also able to dig out an old 19th century geological map that references the cave as Pollacore - but I'm still convinced we were the first to swim all the way to the funky gour pools.