Elusive crannógs

slowburner

Here is an image taken from the wonderful OSI mapviewer. It is from the 2005 orthophotography and shows Lough Sallagh which straddles the Leitrim/Longford county border.







It seems to me that there are at least five crannógs around the lake.
But if we toggle the view to either of the historical maps, there is no sign of the crannógs. It is curious that they were not even marked as islands by the surveyors.

Cailleachdubh

The archaeology forum's a bit of a slowburner these days... Fair play to you for keeping the campfires burning! This place would fall apart without you!

ps Yes that is curious about the islands. Are they on the RMP do you know? What edition OS map is that?

slowburner

I could only find one record for a crannóg in Lough Sallagh ( LE036-038 ).
I wonder if the big circular island is modern.

The second image is from the 6" historical b/w OSI map (1842ish).

mocmo

Interesting, on the historic 25" the area of the big island is shown as boggy (?) so it can't be that modern but it is huge and very regular....whatever that might mean, if anything.

The others look very like crannógs all right, I wonder if their 'appearance' is due to altered water levels. Tons of crannógs around those parts in fairness.

slowburner

That's a great point about changed water levels.
I think you are dead right.
If you look at the northern end of the lake, the inflow was a significantly bigger bay i.e more water in it. There are other pointers to falling levels if you compare the two images.
So maybe they were simply not known about at the time of the 6" or 25".

Presumably, turf harvesting has had a significant impact on water levels through drainage and its impact on topography.
Presumably the Shannon catchment arterial drainage plan of the 1940's and 50's was a significant contributor too.

Riamfada

Im out that way fairly often. Ill try and get a photo of the island and post back to see how low it lies.