Related Geological Conditions 29 



borne in mind that freshwater must once have been more 

 abundant proportionately than now. To what degree this 

 held true, however, is as yet undetermined. 



Ill Primitive freshwater and marine areas contrasted. 



But equally in geological, paleontological and biological 

 writings of the past and present century, the preponderat- 

 ing extent of the ocean; the highly dynamic action of it 

 in effecting crustal changes; the supposition that in it all life 

 originated, and from it all freshwater and land animals 

 emerged; also that the present ocean beds are fairly con- 

 tinuous with those of palaeozoic times; have been so in- 

 sisted on and elaborated, that the possibility of a different 

 interpretation has seemed superfluous. But reared and 

 educated as the writer was amid Carboniferous and Old 

 Red formations, the extensive deposits of these in which no 

 traces of marine life occurred, but in which abundant and 

 continuous beds of evident freshwater origin were followed 

 often through hundreds of feet in thickness, caused him 

 to query the correctness of the current interpretations. 



These impressions however of more than forty years 

 ago had been somewhat anticipated, and were succeeded 

 by like queries of other investigators. Thus, in the careful 

 and elaborate monograph by Rupert Jones on the Esther- 

 ieae {12) constant emphasis is laid on the freshwater 

 habitats of all existing species, and apparently also of all 

 species described from Old Red rocks upward. But the 

 usual presence and admixture with these of abundant fish, 

 eurypterid, and plant remains, some of which, and par- 

 ticularly the fishes, had been directly or tacitly claimed as 

 marine, constantly inclined him to hesitate in his final de- 

 cisions. And a like attitude was assumed by him in a more 

 recent article. 



A. Geikie, with wide experience as a field geologist as 

 well as a writer, in viewing the fish remains and associated 

 organisms of Old Red age, fully accepted a lacustrine habi- 

 tat for these, and so he designated their Scottish areas 

 of occurrence as Lake Orcadie, Lake Caledonia etc. 

 {7; 1008). 



