56 The Irish Naturalist. April, 



Previous to this special Drift survey many observers 

 had been at work in the Dubhn area, and a number of 

 localities had already been noted for their arctic shells and 

 northern erratics. During the earlier decades of last century 

 Weaver, Scouler, Kelly and Oldham had worked at some 

 of the Drift deposits in the district and usually supported 

 the theory of a marine origin of both boulder-clay and 

 sands and gravels. In the sixties and seventies that great 

 leader in Irish glacial geology, the Rev. Maxwell Close, had 

 investigated the deposits at Caldbeck Castle and Bally- 

 edmonduff, and from these deposits had obtained many 

 species of mollusca and Crustacea, i 



In the years 1894-95 Prof. Sollas and R. LI. Praeger had 

 investigated the Kill-of-the-C^range and Killiney Bay 

 deposits, and many new records were obtained. Fifty-seven 

 species of mollusca were discovered ; and the presence of 

 fossils from the Lias of Ulster or Scotland, as erratics, was 

 noted. In addition to the new field records, a change of 

 opinion regarding the origin of the deposits was fore- 

 shadowed." 



The southerly- occurrence in the Drift of the Ailsa Craig 

 riebeckite had also already been observed by Prof. Cole 

 and Prof. Seymour. During the Drift survey many deposits 

 with shells and erratics were discovered, and from one of 

 these at Larch Hill, on the northern slopes of Tibradden, 

 at 650 feet above sea-level, thirty-five species of mollusca 

 were obtained.'^ 



Since the survey of the Dublin district was concluded 

 many further records have been made, two of which may be 

 noticed. In a boulder-clay near the upper edge of the 



1 Rev. Maxwell Close, " The Elevated Shell-bearing (travels near 

 Dublin," Joiirn. Roy. Geol. Soc, Ireland, vol. xiv., pp. 36-40 (1H73-77). 



" W. J. Sollas and R. LI. Praeger, " Notes on (ilacial Deposits in 

 Ireland," Irish Naturalist, vol. in., pp. 161-66, pp. 194-98 (1894), vol. iv., 

 pp. 3-^1-3^9 (1895)- 



'J. de W. Hinch, " A Contribution to the Glacial Geology of County 

 Dublin," Irish Naturalist, vol. xi., pp. 229-36 (1902). 



