ON THE MOVEMENTS OF THE EARTH'S CRUST. 



By a. Blytt.* 



Translated by W. S. Dallas, F. L. S. 



This memoir is an attempt to furtber develop and establish ideas 

 which I i>ut forward five years ago. It contains an attempt to establish 

 a chronology in geology. It sets forth what tbe English call "a work- 

 ing hypothesis," withont claiming to be anything else. It was the dis- 

 tril)ution of plants which iirst introduced the author to this great ques- 

 tion ; but the problem of a chronology in geology can not be solved 

 without the cooperation, it may perhaps be said, of all naturalists. It 

 certainly can not finally be solved by any one man. In putting forth 

 my hypothesis I must in the first place beg for indulgence for the many 

 faults and imperfections with wiiich such an attempt must be affected, 

 and express a hope that in any case the hypothesis may be found worthy 

 of being further tested. 



Having endeavored in several memoirs on the distribution of plants, 

 on peat-mosses, shorelines, terraces, and morainic ridges, to show that 

 climates undergo periodical changes, I published in the Transactions 

 of the Society of Sciences for 1883 [No. 9) a memoir on alternation of 

 strata and its possible significance for the chronology of geolog^^ and 

 the theory of the modification of species. The essential contents of this 

 paper, as regards the present question of geological chronology, were 

 as follows: 



Alternations of strata, under which term is understood an alternation 

 of geological formations of different constitution, can be produced by 

 local conditions of rapidly passing change, without the action of general 

 and i)ersistent causes. But there are also causes of the latter kind 

 which effect an alternation of the strata. Two such periodically acting 

 causes are traceable in the geological series of deposits — a shorter. 



* "On the probable cause of the Displacement of Shore-lines,— an attempt at a 

 Geological Chronology." Read at the General Meetings of the Society of Science of 

 Cliristiania, December 9, 1887, and Jnne 1, 1888. Translated from the Niif Mcujazin 

 for Naturv'uhnHkahcrne, 1889; Bd. xxxi., pp, 240-297. (From the London, Edinburgh, 

 and Dublin, rhUosophieal Magazine, May and June, 1889, vol. xxvii, pp. 405-429, 

 and 487-519. ) 



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