In the Report of the British Association for 1874 will be found the abstract of a paper on the Age and Mode of Formation of Lough Neagh, with a description of the Pliocene clays which form an ancient and extensive delta at its southern extremity. At the time I penned the paper in question, although I was perfectly satisfied from cumulative circumstantial evidence that the clays were of much more recent date than the Miocene Basalt which surrounds the lake on three sides, I had no actual proof to bring forward—the junction of the basalt and the clay beds being nowhere visible, so far as I had had an opportunity of examining the district, this comprising all the shores of the Lough, with the exception of a small corner near Crumlin; and it was therefore necessary to state, even at the risk of tediousness, the reasons why the clays must be considered to be the uppermost, and to be of Pliocene age.