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III. 



ON THE WASTE OF THE COAST OF IRELAND AS A FACTOR 

 IN IRISH HISTORY. By J. P. O'REILLY, C.E. 



[Eead December 9, 1901.] 



Having proposed to myself the examination of certain points relative 

 to the forms and structure of some of the ancient monuments of 

 Ireland, I was led on to the study of the past and present physical 

 geography of the country, as heing intimately connected with its 

 history, and, therefore, with that of the peoples to whom certain of 

 these monuments have been attributed. Modern historians show their 

 strong appreciation of this connexion, by the care they take to illustrate 

 by maps and drawings the localities or places wherein or whereat have 

 taken place the events which they treat of, as also in pointing out the 

 changes which have occurred in the localities since the period con- 

 sidered by them in their narration. That this is no easy task has 

 been shown by Sir Charles Lyell in his " Principles of Geology," 

 vol. i., p. 252, where he says : — 



"To those whose attention has never been called to the former 

 changes in the Earth's surface which geology reveals to us the position 

 of land and sea appear fixed and stable. It might not seem to have 

 undergone any material alteration since the earliest times of History ; 

 but when we inquire into the subject more closely we become convinced 

 that there is annually some small variation in the geography of the 

 globe. In every century the land is in some places raised and in 

 others depressed in level, and so likewise is the bed of the sea. By 

 these and other ceaseless changes the configuration of the Earth's siu-- 

 face has been remodelled, again and again, since it was the habita- 

 tion of organic beings ; and the bed of the ocean has been lifted up to 

 the height of some of the loftiest mountains ; the result is in general 

 view insignificant, if we consider how slightly the highest mountain 

 chains cause oui globe to differ from a perfect sphere. Chimborazo, 

 though it rises to more that 21,000 feet above the sea, would be 

 represented on a globe of about 6 feet diameter, by a grain of sand 

 somewhat less than iVth of an inch in diameter." 



R.I.A. PROC, VOL. XXIV., SEC. B.] -ST 



