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 A PLEA FOR IRISH GLACIOI/DGY. 



BY MISS S. M. THOMPSON. 



Are we to have another Great lee Age ? If so, when ? Or 

 are we to consider that some unexplained and catastrophic 

 reason caused the glaciation whose traces are to be found al- 

 most everywhere over the surface of our continent ? These 

 questions are agitating the minds of geologists at present, and 

 the diversity of answers given may be assumed to indicate the 

 insufficiency of the evidence as yet accumulated to settle the 

 points in question. Perhaps rarely have so many different 

 opinions been held simultaneously by men well qualified to 

 pronounce judgment upon any special subject, as upon the 

 date, conditions, causes, and possible recurrence of an Ice Age ; 

 and the recent suggestion, that its date was not as remote as 

 supposed, has added zest to investigations into ice-action and 

 its traces. Some, who had carefully studied the subject in 

 former years, may wish to verify their previous conclusions, 

 and retain or modify them according to the results obtained ; 

 whilst others may be tempted by the interest of a subject so 

 fully illustrated in every journey they take, in every new spot 

 visited (at least in Ireland), to enrol themselves in the army 

 of patient accurate observers, whose systematic work is needed 

 to accumulate the mass of evidence required before any final 

 and satisfactory theory can be formulated by the master-minds 

 of our day. 



Just a hundred years have elapsed since the strife between 

 the Plutonists and Neptunists was raging in Edinburgh, whilst 

 William Smith was patiently and laboriously accumulating 

 the observations upon which stratigraphical geology was 

 founded. Nearly half a century was to pass before the chilly 

 suggestion of a glacial period came to clear up many vexed 

 questions, and explain many strange deposits ; and within the 

 last few years astronomers and physicists have claimed per- 

 mission to theorize upon the subject ; and Dr. James Croll has 

 given to the world the wonderful conception of regularly 

 recurring glacial periods 1 , depending upon the relative positions 

 of our sun and earth. Who can tell what additions to our 

 knowledge the next few years may bring, under the stimulat- 



1 J. Croll— " Climate and Time, ill their Geological Relations;" 

 London, 1875. 



