The Glaciation of North-Eastern Ireland

The region to be described covers the counties of Antrim and Down, with parts of Armagh, Londonderry, Tyrone, Monaghan, and Louth, in all about 3200 square miles, and is included in sheets 6, 7, 8, 12, 13, 14, 18, 19, 20, 21, 26, 27, 28, 29, 34, 35, 36, 37, 47, 48, 49, 59, 60, 61, 70, and 71, of the maps of the Ordnance Survey of Ireland on the scale of 1 inch to the mile. The area is also covered by Bartholomew's ' ‘Quarter-inch to the mile map of Ireland’, Sheet 2, which contains most of the place-names used in this paper. References to the previous papers on the subject are collected in a (‘ Bibliography of Irish Glacial & Post-Glacial Geology ’ by R. LI. Praeger, Proc. Belfast Nat. Field-Club, App. (1896), and in a Summary of Recent Glacial Investigations by the B.N.F.C., ibid. App. vii (1905–1906). The area is naturally divided into four geographical units—the basaltic plateau of County Antrim, the Trias-filled valley of Belfast, the undulating Palaeozoic area of Down and Monaghan, and the igneous areas of the Mourne Mountains, Slieve Croob, and Carlingford. The great plateau of County Antrim is formed of Tertiary basalts lying unconformably upon various older rocks, including Dalradian schists, Carboniferous,Triassic, Liassic, and Cretaceous rocks. The present surface of the basalt country forms a trough with its axis running north and south. The central valley is occupied by Lough Neagh, the waters of which stand at 52 feet above, and the