Sorry about the mention of the Cliffs.

My friend from Donegal says that Eskydun is likely to be a townland by the River Eske or by the very scenic Lough Eske ,six miles from Donegal Town . Lough Eske is at the foot of the Blue Stack Mountains and feeds the Eske river.He says he'll ask around next time he's in Donegal Town if you don't hear before then.