96 JR. A. Daly — Limeless Ocean of P re-Cambrian Time. 



So far as known to the writer, this hypothesis as a whole 

 has not been stated in geological or biological literature. 

 Macallum has suggested that calcium salts were but sparingly 

 present in the " earlier Archaean seas, 1 " and notes the possibil- 

 ity that pre-Cambrian organisms could therefore not have 

 acquired the " lime habit " ; but he gives no explanation of the 

 supposed small content of lime in the sea-water.* Such explana- 

 tion is the kernel of the hypothesis. The present paper is in- 

 tended to be a statement of the chemical grounds on which may 

 be based a reasonable belief in a nearly limeless sea during most 

 of Eozoic time.f Incidentally, there is offered a suggestion 

 as to the origin of dolomite and of magnesian sediments so 

 abundantly represented in pre-Cambrian formations. The 

 origin of certain iron ores, cherts, jaspers and certain emana- 

 tions of petroleum and natural gas will also be briefly con- 

 sidered. 



The writer's sincere thanks are due to Mr. R. A. A. John- 

 ston of the Canadian Geological Survey for much help in dis- 

 cussing the basal chemical reactions. 



Precipitation of Lime Salts Through the Decomposition of 

 Dead Organisms. 



It follows from the main biological postulates of the hypoth- 

 esis that, in the earliest sea, the higher animal types, includ- 

 ing the active hunters and scavengers, were not yet evolved. 

 An important corollary is that the carcasses of countless ani- 

 mals living at the surface would, after death, fall to the sea- 

 floor, there accumulate and decompose. The rate of decay is 

 in some direct proportion to the temperature. It is in the 

 highest degree probable that the pre-Cambrian polar waters 

 were much warmer than the polar waters are now. Since the 

 bottom temperatures of the whole ocean-basin are influenced 

 by polar temperatures, it is fair to conclude that the bottom 

 temperatures of the pre-Cambrian sea were relatively high. 

 Animal carcasses fallen to the sea-floor would therefore not be 

 in cold storage but would undergo putrefaction. Murray 

 holds that putrefaction takes place even at the present low 

 temperatures of the sea-bottom.;}; 



During putrefaction ammonium carbonate is given off in 

 large volumes. This powerful alkali has the property of 

 rapidly converting the chloride and sulphate of calcium into 



* Transactions, Canadian Institute, toI. vii, 1903, p. 536. 



f Throughout this paper the term "Eozoic" will be used to designate the 

 entire pre-Paleozoic ason of life-history on the earth. Still earlier time will 

 be referred to as belonging to the " Azoic " aeon. 



^Report on the Deep Sea Deposits, Challenger Expedition, 1891, p. 256. 



