822 
[B.N.F.C. 
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, io 
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 1 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. 
