938 T. W. VAUGHAN CHEMICAL DEPOSITS OV THE SEA 



Conditions are most favorable for the precipitation of calcium car- 

 bonate and for the accumulation of the precipitated material, which at 

 first is in a very finely divided state, where the temperature of the sea is 

 high and where there are relatively shallow bodies of water that are pro- 

 tected from heavy seas and strong currents. On actual coral reefs there 

 seems to be no chemically precipitated calcium carbonate, and there is but 

 little of it along the cliannels tlirough lagoons. The amount of material 

 of such an origin in specific localities is graded in accordance with the 

 character and strength of winds and local currents.^^ 



Organic Deposits 



In the investigation of organic deposits, after the mechanical analysis 

 lias been made, the separates are studied to determine the proportion of 

 each of the ingredients, composing each separate. In order to facilitate 

 tbe recognition of the ingredients, a reference collection of coccolitho- 

 phoridse, diatoms, calcareous algae, radiolaria, foraminifera, madrepo- 

 rarian and alcyonarian corals, echinoids, bryozoa, mollusks, Crustacea, 

 bones, etcetera, is necessary. The skeletons of the larger organisms are 

 prepared for study as thin sections and mounted crushed fragments. The 

 tables of the analyses of the skeletons of marine invertebrates and of cal- 

 careous algjp, recently prepared l)y F. W. Clarke and W. C. Wheeler, make 

 possible estimating the proportion of the chemical constituents contrib- 

 uted by each group of organisms that takes part in the formation of the 

 deposit. The following are estimates by Dr. M. I. Goldman of the aver- 

 ages for the composition of the marine invertebrates and calcareous alga} 

 at Murray Island, Australia, using the Clarke and Wheeler tables as the 

 basis of his estimates. Two tables of analyses, one of calcareous algae and 

 one of foraminifera, are here presented. It seems probable that Doctor 

 Goldman's estimate of the MgCOg content of the Corallinaceoe is a little 

 too high. 



11 This subject is discussed in considerable detail in the larger paper referred to in the 

 footnote on page 933. 



