838 presidext's address. 



permanent as regards position through long geological ages; we 

 now rejil}' W pointing to deep sea sediments of nearly all 

 geological periods, which have been uplifted from the ocean- 

 abysses to form portions of our continents; and as the result of 

 studv of the distribution of fossil organisms we can point almost 

 as confidently to the sites of old continents now sunk down into 

 the ocean depths. It seems clear that our knowledge of the 

 causes of earth movements is still in its infancy and that we 

 must be content to await awhile until we have further informa- 

 tion at our disposal." 



Captain Hutton says : — -" We know as a matter of fact that 

 continental areas are liable to subsidence, and that oceanic areas 

 are lialjle to elevation ; and we cannot as yet place a limit on 

 the possible amount of continental depression or of oceanic 

 elevation."* Further on (p. 411) he says :— 



" We certainly do find a large number of geological periods 

 represented in Europe, Asia, America, Australia, and New 

 Zealand, but in all cases there are also long periods unrepi*e- 

 sented, especially in the Palteozoic era, when there are many 

 physical breaks in continuity, accompanied by an almost complete 

 change in animal life, and Sir A. Ramsay says that these breaks 

 may each indicate a period of time as great as the vast accumula- 

 tions of the whole Silurian series. The question is, What was 

 the condition of these areas during the unrepresented periods T 

 Certainly they might have been land, but also they might, in 

 some cases at least, have been deep ocean." 



Rigidity of the Earth. 



As the facts of the deformation of the earth's surface as well as 

 that of alterations of climate depend largely upon the flexibility 

 of the crust, it will be interesting to consider shortly the con- 

 clusions that have been arrived at as to the rigidity of the earth. 



* "Has the Deep Ocean ever been Land?" New Zealand Journal of 

 Science, Vol. i. p. 410. 



