508 



SCIENCE 



[N. S. Vol. XLI. No. 1057 



tion is probably the transformation of calcium 

 carbonate by the combined action of ammonia, 

 produced by bacteria either by the denitrifieation 

 of nitrates or by the fermentation of protein, to- 

 gether with carbon dioxide, produced either by the 

 respiration of large organisms or the fermentation 

 of carbohydrates by bacteria. Both ordinary crys- 

 tals of calcium carbonate and oolites may be pro- 

 duced by the growth of mixed cultures of bac- 

 teria, either in salt or fresh water. The zonal 

 structure of the oolites of bacterial origin and of 

 those found in nature in oolitic deposits appears 

 to be exactly the same; undoubtedly this shows the 

 similarity of the processes of their origin. 

 Coral Seefs and Seef Corals of the Southeastern 



United States, Their Geologic Sistory and Their 



Significance: Thomas Wayland Vaughan. 



After briefly alluding to some of the more re- 

 cent publications on coral reefs, the author stated 

 what in his opinion were the necessary lines of 

 investigation in order to understand the ecologic 

 factors influencing coral reef development, the con- 

 structional role of corals and other agents, and the 

 series of geologic events which preceded any par- 

 ticular coral reef development. The geologic his- 

 tory of the extensive coral reefs of the southeast- 

 ern United States and nearby West Indian islands, 

 which have been the subject of investigation for a 

 number of years, was outlined and the bearing they 

 have on the theory of coral reef formation was 

 indicated. 



The author stated his conclusions regarding the 

 Florida coral reefs as follows: (1) Corals have 

 played a subordinate part, usually a negligible part, 

 in the building of the Floridian plateau; (2) every 

 conspicuous development of coral reefs or reef 

 corals took place during subsidence; (3) in every 

 instance the coral reefs or reef corals have de- 

 veloped on platform basements which owe their 

 origin to geologic agencies other than those de- 

 pendent on the presence of corals. 



The older Tertiary reefs and reef corals of St. 

 Bartholomew, Antigua and Anguilla all grew on 

 subsiding basements. The relatively small propor- 

 tion of the contribution by corals to calcareous 

 sediments in Florida, the Bahamas and the West 

 Indies was shown. 



It was shown that the Floridian plateau was sim- 

 ilar in configuration to the Mosquito Bank off 

 Nicaragua, to Campeche Bank ofE Yucatan and to 

 Georges Bank off Massachusetts; the east side of 

 the Floridian plateau is similar to the continental 

 shelf off Cape Hatteras. The platform which sup- 

 ports the reef along the east coast of Florida ex- 



tends beyond the reef limits northward of Fowey 

 Rock. The reef platform of the Great Barrier Eeef 

 of Australia is similar to the continental shelf of 

 eastern North and Central America, and it con- 

 tinues south of the reef limits. Rosalind Bank, 

 Caribbean Sea, was compared with Rangiroa, 

 Paumotus, which is similar in essential features. 

 The complex history of the coral reef foundations 

 in Florida, Antigua, St. Martin, Anguilla and 

 Bermuda was described, and it was stated that 

 the formation of the platforms could not be re- 

 ferred solely to Pleistocene time. 



Attention was directed to the facts that around 

 the Island of Saba, in which volcanic activity has 

 so recently ceased that the crater is still preserved, 

 there was scarcely any platform at all; that in the 

 case of the young but slightly older volcanic island 

 of St. Kitts, the platform was narrow, while the 

 geologically much older islands standing above 

 the Antigua-Barbuda bank, the St. Martin 

 plateau, and the Virgin Bank, rise above platforms 

 which are miles across and have an area many times 

 greater than that of the present land surfaces. 

 Width of platform is therefore indicative not of 

 the amount of submergence, but of the stages at- 

 tained by planation processes. 



The conclusions were summarized as follows : 



1. Critical investigations of corals as construc- 

 tional geologic agents are bringing constantly in- 

 creasing proof that they are not so important as 

 was long believed, and that many of the phenom- 

 ena formerly attributed to them must be accounted 

 for by other agencies. Here it should be empha- 

 sized that the ecology of probably no other group 

 of marine organisms is known nearly so thoroughly 

 as that of corals. 



2. All known modern off-shore reefs which have 

 been investigated grow on platforms which have 

 been submerged in recent geologic time. 



3. No evidence has as yet been presented to show 

 that any barrier reef began to form as a fringing 

 reef on a sloping shore and was converted into a 

 barrier by subsidence; but it is clear that many, 

 if not all barrier reefs stand on marginal plat- 

 forms which already existed previous to recent sub- 

 mergence and the formation of the modern reefs. 



4. Study of the geologic history of coral reef 

 platforms has established that there were platforms 

 in early Tertiary time on the site of many of the 

 present-day platforms, and evidence has not as yet 

 been adduced to prove long-continued, uninter- 

 rupted subsidence in any coral reef area. There 

 have been many oscillations of sea level and re- 

 cent submergence is probably complicated in many 



