I9I4. 
Reviews. 
REVIEWS. 
CLARE ISLAND GEOLOGY. 
The Geology of Clare Island, Co. Mayo. By G. A. J. Cole, F.G.S. ; J. R. 
K'lLROE, A.R.C.Sc.l.; T. Hallissy, B.A., and E. A. Newell Arber, 
M.A. {Memoirs of the Geological Survey of Ireland). Pp. iv. + 54 
Map, 5 plates, and 4 text figures. Dublin : H. M. Stationery Office, 
1914. Price, 2S. 6d. 
In 1908 the committee in charge of the Natural History Survey of Clare 
Island decided to ask the assistance of the Geological Survey of Ireland 
in working out the Glacial and Post-glacial history of the island. This the 
Survey willingly consented to do, and the present memoir which deals 
with the solid geology (a revision of the older survey of 1875-76) as well as 
with the glacial geology of Clare Island, is an account of the results 
achieved. Regarding the revision of the solid geology — which was dealt 
with by Mr. J. R. Kilroe — considerable advances in our knowledge have 
to be noted. The rocks of the island consist wholly of sandstones, con- 
glomerates, shales and slates of Palaeozoic age, and it had been hoped 
that sufficient fossil evidence might be obtained to justify their correlation 
with the better known rocks of the mainland. The results as regards the 
older rocks were most disappointing, for although prolonged searches 
were made in what looked like suitable localities — as at Knocknaveen 
and Ballytoohy More — no fossils were obtained, and the decision to regard 
the four lower series as ranging from the Ordovician to the Old Red Sand - 
stone was come to on general and lithological grounds. From the Cap- 
nagower series Dr. Arber obtained sufficient, if scanty, evidence that these 
rocks might be classed with the Lower Carboniferous. Professor Cole 
contributes a series of lengthy notes on the mineralogy and petrology of 
the two main zones of movement and intrusion on the island, and in 
dealing with the zone of crushed rocks in Kill and Strake inclines to the 
view that these rocks — mica -schists, epidiorites, and serpentines — are 
metamorphics of the Dalradian series which have been brought to the 
surface by faulting, rather than altered portions of the local rocks involved 
in the fault movements. 
The Glacial and Post-glacial history of Clare Island being of the greatest 
importance in any discussion on the origin of the plants and animals which 
might be found there, special attention was directed to the subject by 
Mv. T. Hallissy, and as the result of his work on the island and the 
adjoining mainland we are now in possession of an extremely full account 
of what has occurred during recent geological times in this district. The 
glacial history of the island may be briefly stated. In immediately pre- 
Glacial times the island stood in practically the same relation to the main- 
land as at the present day, though the dividing channel may have been 
deeper. In glacial times the island was twice invaded by ice -sheets from 
the cast, the first invasion being the ice of the Central Irish Glacier, which 
laid down the very solid limestone Boulder-clay and produced the grooving 
