208 Scientific Proceedings, Boyal Dublin Society. 



There are, indeed, in the neighbourhood- of different groups of 

 hills two distinct varieties of boulder-clay, viz. till below, and 

 moraine drift above ; but although in general there is a line of 

 boundary between, yet they are rarely separated by aqueous de- 

 posits ; while if they are so, the latter usually consist of from a few 

 inches to a few feet in thickness of fine sand or finely laminated 

 clay {book clay) ; and in such places there is nearly always a " lin- 

 ing " or rude stratification in the overlying moraine drift, as if it 

 had been finally arranged in water — or as if it had slipped down 

 from a higher level in the state of mud, or of mud and ice -slush 

 mixed together. In many places the latter is suggested, as on the 

 low, flattish ground this lining may be very conspicuous ; while as 

 we ascend to the higher sloping ground all traces of this stratifica- 

 cation gradually disappear.^ In no place, however, have I seen 

 regular continuous sands and gravels between these upper and 

 lower glacial drifts ; although in places, more especially along 

 some of the sea cliffs, there are miles of sections exposed. 



The section which appears to be most relied on as a proof of 

 the existence of these "middle gravels" in Ireland is that at the 

 Kilkenny marble quarry. Here, however, the upper member is 

 not a true glacial drift, but a very typical estuarine accumulation — 

 one common in the deep-seated Irish river-valleys, having in it 

 many striated fragments, but all more or less water- worn, while it 

 is similar to drift now accumulating in different long, narrow 

 estuaries. In some of these recent estuarine accumulations I have 

 found over 60 per cent, of these striated fragments. 



In various places along the coast from Killiney to Bray, both in 

 the railway cuttings and the clifi sections, it is quite evident that 

 the gravels, brick-clays, &c., were deposited at the base of a boul- 

 der-clay cliff, which at times slipped down and covered them, 

 thereby causing glacialoid drift to dovetail and merge into 

 gravels, sands, and clays. 



More or less similar phenomena can be seen in the coast cliffs 

 of Wicklow, Wexford, Waterford, Louth, Down, Antrim, &c., 

 and inland in numerous places. Inland, especially in the Co. 

 Tyrone, the gravel is often found surrounding glacial drift-hills, 



^ As has been pointed out elsewhere, on the N. W., or Carlow, slopes of Mount 

 Leinster, there is a lined glacialoid moraine drift that now extends out on to a recent 

 peat bog ("Geology of Ireland," p. 236). 



