64 W. Swanston — Clays overlying Basalt, Lough Neagh. 



stones and pebbles ; so compact is it, that it is with difficulty tbe 

 larger stones can be removed, but when taken out they almost all 

 exhibit the well-known form of glacial pebbles, and very many of 

 them retain quite distinctly the characteristic scratching and polishing 

 due to ice action. The miscellaneous character of the stones and 

 pebbles is also worthy of note. The following were noticed, 

 beginning with the most numerous and proceeding in the order of 

 their relative abundance : — Basalt (local), chalk and flint (Antrim), 

 sandstone and clay nodules (New Eed Marls?), quartz, mica-schist, 

 granite (red), etc. There is also a great abundance of lignite, in 

 pieces from several inches in length to mere particles, scattered 

 irregularly through the bed, and I was fortunate enough to find a 

 piece of grey siliceous sandstone containing plant-remains, principally 

 dicotyledonous leaves resembling those of the beech and willow, and 

 closely agreeing in character with the siliceous nodules which occur 

 in the plastic clay of Lough Neagh. 



The only conclusion that can be drawn from the foregoing is, — 

 that the beds in question containing Mytilus edulis and Foraminifera 

 are of marine, or, at least, of brackish-water origin. The common 

 mussel is at present found living from high- water to a few fathoms 

 in depth, and it is also found in tidal rivers, but never entirely out of 

 reach of the sea. Judging from the appearance of the fossils in the 

 clays, I am of the opinion that the animals lived and died where we 

 now find their remains ; or that they have, at least, suffered very 

 little disturbance. In many of them the valves are united and the 

 epidermis still preserved. Foraminifera are essentially marine 

 organisms ; a few only are known to inhabit brackish water. The 

 species detected in the clays in question indicate a depth of at least 

 a few fathoms, and may be found in almost every haul of the dredge 

 on suitable ground around our coasi, at moderate depths. 



The fact that the fossiliferous deposit reposes upon true Boulder- 

 clay containing well-marked glacial pebbles, at once proves that it is 

 not of Pliocene age, but either a Glacial or a Post-Glacial deposit. The 

 settling of this question would require further investigation than has 

 yet been given to the subject. The error into which Mr. Hardman 

 seems to have fallen, was, in hastily concluding that the Crumlin 

 River beds were identical with the beds of white clay, lignite, etc., 

 which occur along the southern shores of Longh Neagh, whereas 

 the latter beds do not seem to extend to within half a mile of the spot 

 where the fossils occur, nor do they in any way resemble them in 

 lithological character. 



What then is the age of the Lough Neagh clays and their associated 

 lignites, which are estimated as covering an area of 180 square 

 miles and to be in some places probably 500 feet thick ? 



Granted that they may repose upon the basalts — they may be of 

 any age between that to which the lower sheets of the Miocene beds 

 of the neighbourhood belong, and the clays of the Glacial epoch with 

 which the upper beds are undoubtedly associated. In all probability 

 they span the entire period, and are in part contemporaneous with 

 the lacustrine iron-ores, beauxite, and lithomarge of the Antrim 



