In October 2014 we confirmed shoreline features from a submerged and long established
shoreline at a depth of 15ft below current levels. Core samples from mid lake near Collinamuck  earlier this year revealed a drying event at 18ft below current levels.

This has massive implications for our knowledge  of the history of Lough Corrib, and implies that at some time in the not so distant past some possibly cataclysmic local event occurred that changed the landscape fundamentally.

Using a 15ft contour as a shoreline I  have produced  a chart of the old lake.
To avoid confusion I'll call it by the original name of Lough Orbsen, although it is highly likely that the shoreline predates the old name considerably.

There is a 3d image of the Long Shallow here

Videos of the Long Shallow limestone pavement with shoreline structures.

http://youtu.be/Etd5NyQ-wFw

http://youtu.be/LITGhxBPQx0

Video of the Adams Rock limestone pavement in what is now the Lower Corrib - watch for the line of rocks a short way in, they are 10ft underwater and look as though somebody placed them there in a neat straight line. Not an impossibility if the South lake was simply a river at the time.

http://youtu.be/u1IlChjqe94