656 THE JOURNAL OF GEOLOGY. 



They also conclude that practically all the carbon of marine 

 organisms must ultimately be resolved into carbonic acid, the 

 quantity of that acid produced in this way must be enormous, 

 and cannot but exert a great solvent action not only on the dead 

 calcareous structure, but also on the minerals in the muds on the 

 floor of the ocean. 1 Of the effect of this destructive action, they 

 say : " In all cases, however, calcareous structures of all kinds 

 are slowly removed from the bottom of the ocean on the death 

 of the organisms, unless rapidly covered up by the accumulating 

 deposits, and in this way protected to a certain extent from the 

 solvent action of the sea-water. It is evident from the Challen- 

 ger investigations that whole classes of animals with hard calcar- 

 eous shells and skeletons, remains of which one might suppose 

 would be preserved in modern deposits, are not there repre- 

 sented ; although they are now living in immense numbers in the 

 surface waters or on the deposits at the bottom in some regions, 

 yet all traces of them have been removed by solution. A similar 

 removal of calcareous organic structures has undoubtedly taken 

 place in the marine formations of past geologic ages. 2 



From the preceding statements it is evident that initially the 

 greater part of the carbonate of lime is taken from the sea water 

 by organic agency, but in the working over of this material in 

 the chemical laboratory at the bottom of the sea a considerable 

 portion is taken up by the sea water as amorphous carbonate of 

 lime and thrown out in the crystalline form to form the matrix 

 of the undissolved shells, etc. 3 



Mr. Bailey Willis has recently studied the question of the 

 deposition of carbonate of lime, and states that " chemists 

 describe two conditions under which bicarbonate of lime may be 

 decomposed into neutral carbonate and carbonic acid : 1st, by 

 diminution of the tension of the carbonic acid in the atmosphere ; 

 2nd, by agitation of the solution." 

 1 Loc. cit, p. 255. 



2 Loc. cit., p. 277. In this connection I wish to ask the student to read Messrs. 

 Murray and Irvine's remarks on pp. 97-99, Proc. Roy. Soc, Edinburgh, Vol. 17, 1890. 



3Proc. Roy. Soc, Edinburgh, Vol. 17, 1890, pp. 94-95. 



