HILL: GEOLOGY OF JAMAICA. 



60 



Origin of White Limestones. 



Ill the foregoing processes we have not considered the possibility of 

 the chemical inorganic agencies. Walther has advocated that ammonium 

 carbonate derived from decaying animals may precipitate calcium carbon- 

 ate from sea water, but this is not the opinion of modern chemists. 

 Reinhard Braun^ summarizes the various processes producing oceanic 

 lime, and says that most, if not all, massive limestones and chalks are 

 of organic origin. 



The Oceanic Series. 



The upland white limestones or Oceanic Series, as we shall call the 

 Tertiary formations under discussion to distinguish them from the later 

 deposits of the Coastal Series, consist of white limestones of varying 

 texture and hardness, and probably aggregate 2,000 feet in thickness. 

 These present a perplexing series of surface and interstitial changes 

 under tlie influences of solution and oxidation, as explained iu their 

 detailed descriptions, which render their study a difficult task. They 

 consist of deeper water organic deposits and are free from coral reef 

 rock, littoral shell agglomerates (such as coquina, cantera, and caleche), 

 beach wash, seolian debris or other clastic formations which characterize 



1 Chemisclie Mineralogie, Leipsic, 1896, pp. 37G-379. 



