Possible Historic Underwater Wall

DarkDusk

Hi,
A few years ago, I discovered an underwater wall while fishing on Lough Corrib. I didn't take much notice of it but now I'm thinking that could it have been built by humans 1,000's of years ago when the the water levels were much lower. It goes down about 20-30 feet into the water starting from an island (I'm not giving any exact info yet;)) but it does not start near the surface, rather down deeper in the water. It's about 2 feet wide and continues a a good bit until it cannot be seen any more as it goes deeper and the water darkens. Does anyone know what this could be? Or is it historic at all? (It looks a bit like loads of sandbags in a straight line but what purpose would they be?) When the weather clears up I'm going to return to the spot to investigate further and try to get some pics of it. I'm also thinking about getting in contact with divers to check it out. I haven't given you much info to go on but what do you think? What are the possibilities of this being built by Stone Age settlers?

Regards,
James.

Riamfada

What part of Mayo are you in. Are you near the Ceide system?

slowburner

You say it starts from an island.
The island could be a crannóg and the wall could be a causeway.
How big is the island and how far off the mainland?
If it is a fair bit off the mainland, then it is unlikely to be a crannóg - these were usually linked to the mainland.


From distant memory, I think there are quite a few of these subsurface walls off islands on the Corrib.
I always thought that they were relatively recent structures to enable boats to land safely either for angling or agriculture.

Water levels were considerably higher, even as recently as 150 years ago.
This link should put you near Oughterard where you can compare historical maps.
http://maps.osi.ie/publicviewer/#V1,515659,745594,4,3

Wibbs

I used to fish the Corrib a good bit back in the day. One year in the mid 90's IIRC there was a drought and the levels dropped a lot. In the ordinarily shallow areas now exposed were quite a few structures like you described. Most looked like field boundaries. They were common in some areas and completely absent in others. I suspect the lake boundaries have varied quite a bit over the centuries as lakes will, I've seen shoreline changes in only a couple of years. They're quite dynamic features. One good high water year and a bank can be forever breached making a new shoreline flooding these fields and their walls.

boneless

Check out info on fish traps. I think I have read about ones like you describe being found in Strangford. They were medieval.

slowburner

boneless wrote: »

Check out info on fish traps. I think I have read about ones like you describe being found in Strangford. They were medieval.

The fish traps of Strangford lough used the currents of the tide, as indeed did fish traps in the estuary of the river Fergus in Clare. see here
I'm not so sure that the same fishing techniques could apply in a freshwater lough.
Lakes certainly have currents, and they can sometimes be surprisingly forceful, but the problem for fish trapping would be that these freshwater currents are completely unpredictable, both in terms of magnitude and direction.