322 [B.N.F.O. 



place of origin. Unknown erratics were from time to time for- 

 warded to Dublin to Mr. A. M'Henry, M.R.I.A., of the Geo- 

 logical Survey of Ireland, whose unrivalled acquaintance with 

 Irish rocks was always generously placed at our service ; to 

 Professor Grenville A. J. Cole, M.R.I.A., F.G.S. (to whose 

 warm sympathy and kindly help our geological section owes 

 so much), to Professor W. W. Watts, F.R.S., and others, whose 

 special knowledge made them able to identify the rarer erratics, 

 and I gladly acknowledge the great assistance thus kindly given. 

 Immense aid was also obtained from the fine Bibliography of 

 Irish Glacial Geology 3 expressly compiled for this purpose by 

 Mr. R. Lloyd Praeger, B.E., M.R.I.A. 



We have more than a hundred different erratics in our 

 Club collection; n of these are unquestionably Scotch, 10 

 others may be of Scotch or Northern Irish origin, the remaining 

 86 being Irish. An erratic of Ballachulish slate is our most 

 northerly specimen, others from the Clyde Area, Cantyre, and 

 fragments of fossiliferous Silurian rocks from Girvan carry us 

 southward to Ailsa Craig, whose unique riebeckite rock is so 

 widely distributed in our boulder clays. Passing to Ireland, 

 we find fragments from the primary rocks of North Antrim, 

 Derry, and Tyrone, others from Cultra, Castle Espie, the Coasts- 

 of Down, and from, Armagh, joining the icy procession until we 

 reach in the pretty pink eurite found near Annalong our most 

 southerly parent rock. 



A remarkable change has come over geological thought 

 with regard to the glacial period in the dozen years that have 

 elapsed since our section commenced its work ; gradually the 

 controversy as to the origin of our drifts has died away, as the 

 conception of a vast ice sheet from, various confluent sources 

 moving over our islands, grinding solid rocks, picking up and 

 transporting fragments of every material met in its progress, 

 transforming the surface of the country by erosion and deposi- 

 tion, became widely accepted. The issues to be studied were 



3. A Bibliography of Irish Glacial and Post-glacial Geology. By R- 

 Lloyd Praeger, B.E., B.N.F.C. Proc. 1895-6. 



